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Sample records for cucurbit downy mildew

  1. Using next-generation sequencing to develop molecular diagnostics for Pseudoperonospora cubensis, the cucurbit downy mildew pathogen

    Science.gov (United States)

    Advances in Next Generation Sequencing (NGS) allow for rapid development of genomics resources needed to generate molecular diagnostics assays for infectious agents. NGS approaches are particularly helpful for organisms that cannot be cultured, such as the downy mildew pathogens, a group of biotrop...

  2. The Novel Oomycide Oxathiapiprolin Inhibits All Stages in the Asexual Life Cycle of Pseudoperonospora cubensis - Causal Agent of Cucurbit Downy Mildew.

    Directory of Open Access Journals (Sweden)

    Yigal Cohen

    Full Text Available Oxathiapiprolin is a new oomycide (piperidinyl thiazole isoxazoline class discovered by DuPont which controls diseases caused by oomycete plant pathogens. It binds in the oxysterol-binding protein domain of Oomycetes. Growth chambers studies with detached leaves and potted plants showed remarkable activity of oxathiapiprolin against Pseudoperonospora cubensis in cucurbits. The compound affected all stages in the asexual life cycle of the pathogen. It inhibited zoospore release, cystospore germination, lesion formation, lesion expansion, sporangiophore development and sporangial production. When applied to the foliage as a preventive spray no lesions developed due to inhibition of zoospore release and cystospore germination, and when applied curatively, at one or two days after inoculation, small restricted lesions developed but no sporulation occurred. When applied later to mature lesions, sporulation was strongly inhibited. Oxathiapiprolin suppressed sporulation of P. cubensis in naturally-infected leaves. It exhibited trans-laminar activity, translocated acropetaly from older to younger leaves, and moved from the root system to the foliage. Seed coating was highly effective in protecting the developed cucumber plants against downy mildew. UV microscopy observations made with cucumber leaves infected with P. cubensis revealed that inhibition of mycelium growth and sporulation induced by oxathiapiprolin was associated with callose encasement of the haustoria.

  3. Epidemiology and population biology of pseudoperonospora cubensis: a model system for management of downy mildews

    Science.gov (United States)

    The resurgence of cucurbit downy mildew has dramatically influenced production of cucurbits and disease management systems at multiple scales. Long-distance dispersal is a fundamental aspect of epidemic development that influences the timing and extent of disease outbreaks. Dispersal potential of th...

  4. Epidemiology and population biology of Pseudoperonospora cubensis: a model system for management of downy mildews.

    Science.gov (United States)

    Ojiambo, Peter S; Gent, David H; Quesada-Ocampo, Lina M; Hausbeck, Mary K; Holmes, Gerald J

    2015-01-01

    The resurgence of cucurbit downy mildew has dramatically influenced production of cucurbits and disease management systems at multiple scales. Long-distance dispersal is a fundamental aspect of epidemic development that influences the timing and extent of outbreaks of cucurbit downy mildew. The dispersal potential of Pseudoperonospora cubensis appears to be limited primarily by sporangia production in source fields and availability of susceptible hosts and less by sporangia survival during transport. Uncertainty remains regarding the role of locally produced inoculum in disease outbreaks, but evidence suggests multiple sources of primary inoculum could be important. Understanding pathogen diversity and population differentiation is a critical aspect of disease management and an active research area. Underpinning advances in our understanding of pathogen biology and disease management has been the research capacity and coordination of stakeholders, scientists, and extension personnel. Concepts and approaches developed in this pathosystem can guide future efforts when responding to incursions of new or reemerging downy mildew pathogens.

  5. Genetics of resistance against lettuce downy mildew

    Science.gov (United States)

    Lettuce (Lactuca sativa) is one of the most valuable vegetable crops in the U.S. Downy mildew (DM), caused by Bremia lactucae, is the most important foliar disease of lettuce worldwide, which decreases the quality of the marketable portion of the crop. The use of resistant varieties carrying dominan...

  6. Forecasting and management of hop downy mildew

    Science.gov (United States)

    Downy mildew of hop, caused by Pseudoperonospora humuli, is managed in the Pacific Northwestern U.S. by regular application of fungicides. A degree-day model that forecasts the first emergence of shoots systemically infection with P. humuli (termed basal spikes) and a risk index for secondary sprea...

  7. Epidemiology of Basil Downy Mildew.

    Science.gov (United States)

    Cohen, Yigal; Ben Naim, Yariv; Falach, Lidan; Rubin, Avia E

    2017-06-09

    Basil downy mildew (BDM) caused by the oomycete Peronospora belbahrii is a destructive disease of sweet basil (Ocimum basilicum) worldwide. It originated in Uganda in the 1930s and recently spread to Europe, the Middle East, Americas, and the Far East. Seed transmission may be responsible for its quick global spread. The pathogen attacks leaf blades, producing chlorotic lesions with ample dark asexual spores on the lower leaf surface. Oospores may form in the mesophyll of infected leaves. The asexual spores germinate on a wet leaf surface within 2 h and penetrate into the epidermis within 4 h. Spore germination and infection occur at a wide range of temperatures from 5 to 28.5°C. Infection intensity depends on the length of dew period, leaf temperature, and inoculum dose. The duration of latent period (from infection to sporulation) extends from 5 to 10 days, depending on temperature and light regime. The shortest is 5 days at 25°C under continuous light. Sporulation requires high humidity but not free leaf wetness. Sporulation occurs at 10 to 26°C. At the optimum temperature of 18°C, the process of sporulation requires 7.5 h at relative humidity ≥ 85%, with 3 h for sporophores emergence from stomata and 4.5 h for spore formation. Sporophores can emerge under light or darkness, but spore formation occurs in the dark only. Limited data are available on spore dispersal. Spores dispersed from sporulating plants contaminate healthy plants within 2 h of exposure. Settled spores may survive on leaf surface of healthy plants for prolonged periods, depending on temperature. Seed transmission of the disease occurs in Europe, but not in Israel or the United States. P. belbahrii in Israel also attacks species belonging to Rosemarinus, Nepeta, Agastache, Micromeria, and Salvia but not Plectranthus (coleus). A Peronospora species that infects coleus does not infect sweet basil. Control of BDM includes chemical, physical, and genetic means. The fungicide mefenoxam was

  8. Epidemiology and control of spinach downy mildew in coastal California

    Science.gov (United States)

    The most serious threat to global fresh market spinach production is spinach downy mildew, caused by the obligate biotrophic pathogen, Peronospora effusa. Downy mildew causes yellow chlorotic lesions on spinach leaf tissue, often accompanied by abundant sporulation on the undersides of leaves. Very ...

  9. Analysis of microsatellites from the transcriptome of downy mildew pathogens and their application for characterization of Pseudoperonospora populations

    Directory of Open Access Journals (Sweden)

    Emma C. Wallace

    2017-05-01

    Full Text Available Downy mildew pathogens affect several economically important crops worldwide but, due to their obligate nature, few genetic resources are available for genomic and population analyses. Draft genomes for emergent downy mildew pathogens such as the oomycete Pseudoperonospora cubensis, causal agent of cucurbit downy mildew, have been published and can be used to perform comparative genomic analysis and develop tools such as microsatellites to characterize pathogen population structure. We used bioinformatics to identify 2,738 microsatellites in the P. cubensis predicted transcriptome and evaluate them for transferability to the hop downy mildew pathogen, Pseudoperonospora humuli, since no draft genome is available for this species. We also compared the microsatellite repertoire of P. cubensis to that of the model organism Hyaloperonospora arabidopsidis, which causes downy mildew in Arabidopsis. Although trends in frequency of motif-type were similar, the percentage of SSRs identified from P. cubensis transcripts differed significantly from H. arabidopsidis. The majority of a subset of microsatellites selected for laboratory validation (92% produced a product in P. cubensis isolates, and 83 microsatellites demonstrated transferability to P. humuli. Eleven microsatellites were found to be polymorphic and consistently amplified in P. cubensis isolates. Analysis of Pseudoperonospora isolates from diverse hosts and locations revealed higher diversity in P. cubensis compared to P. humuli isolates. These microsatellites will be useful in efforts to better understand relationships within Pseudoperonospora species and P. cubensis on a population level.

  10. Comparison of three fungicide spray advisories for lettuce downy mildew

    NARCIS (Netherlands)

    Wu, B.M.; Subbarao, K.V.; Bruggen, van A.H.C.; Koike, S.T.

    2001-01-01

    Lettuce growers in coastal California have relied mainly on protective fungicide sprays to control downy mildew. Thus, timing of sprays before infection is critical for optimal results. A leaf-wetness-driven, infection-based advisory system, previously developed, did not always perform satisfactoril

  11. New Sources of Resistance to Cucurbit Powdery Mildew in Melon

    Science.gov (United States)

    Many physiological races of the cucurbit powdery mildew pathogen (CPM) Podosphaera xanthii (Castagne) Braun & Shishkoff have been reported on melon (Cucumis melo L.). Melon accession PI 313970 is the only reported source of host plant resistance to race S, which first appeared in Imperial Valley, CA...

  12. rDNA-ITS sequence analysis of pathogens of cucumber downy mildew and cucumber powdery mildew

    Institute of Scientific and Technical Information of China (English)

    Na WANG; Yajun MA; Cuiyun YANG; Guanghui DAI; Zhezhi WANG

    2008-01-01

    To determine the pathogens of cucumber downy mildew and cucumber powdery mildew by molecular marker,we amplified and sequenced the rDNA-ITS region of the pathogens of cucumber downy mildew and cucumber powdery mildew collected from the Shanghai region.The intra-/interspecific sequence difference was analyzed by rDNA-ITS sequence.The results show that the length of rDNA-ITS1 and rDNA-ITS2 of cucumber downy mildew's pathogen was 141 bp and 406 bp,respectively,with GC contents of 41.13% in ITS1 and 46.8% (Minhang and Jinshan District,sml and sm2) or 46.55% (Pudong District,sm3) in ITS2.The rDNA-ITS sequence was intraspecific conservation.The interspecific difference was related with their kin relationship.The pathogen of cucumber downy mildew was identified as Pseudoperonospora cubensis by molecular marker.The length of rDNA-ITS1 and rDNA-ITS2 of cucumber powdery mildew's pathogen was 136 bp and 89 bp,respectively,with GC contents being 59.56% and 66.29%,and rDNA-ITS sequence being highly conservative in this study that was the same as Sphaerotheca cucurbitae.But the sequence difference between the strains in the Shanghai region in this study with S.fuliginea was 4.5%,which was identified by morphology.It is suggested that the pathogen of cucumber powdery mildew should be further clarified and determined.

  13. Genome analyses of the sunflower pathogen Plasmopara halstedii provide insights into effector evolution in downy mildews and Phytophthora

    NARCIS (Netherlands)

    Sharma, Rahul; Xia, Xiaojuan; Cano, Liliana M; Evangelisti, Edouard; Kemen, Eric; Judelson, Howard; Oome, Stan; Sambles, Christine; van den Hoogen, D Johan; Kitner, Miloslav; Klein, Joël; Meijer, Harold J G; Spring, Otmar; Win, Joe; Zipper, Reinhard; Bode, Helge B; Govers, Francine; Kamoun, Sophien; Schornack, Sebastian; Studholme, David J; Van den Ackerveken, Guido; Thines, Marco

    2015-01-01

    BACKGROUND: Downy mildews are the most speciose group of oomycetes and affect crops of great economic importance. So far, there is only a single deeply-sequenced downy mildew genome available, from Hyaloperonospora arabidopsidis. Further genomic resources for downy mildews are required to study thei

  14. Mutants of downy mildew resistance in Lactuca sativa (lettuce).

    Science.gov (United States)

    Okubara, P A; Anderson, P A; Ochoa, O E; Michelmore, R W

    1994-07-01

    As part of our investigation of disease resistance in lettuce, we generated mutants that have lost resistance to Bremia lactucae, the casual fungus of downy mildew. Using a rapid and reliable screen, we identified 16 distinct mutants of Latuca sativa that have lost activity of one of four different downy mildew resistance genes (Dm). In all mutants, only a single Dm specificity was affected. Genetic analysis indicated that the lesions segregated as single, recessive mutations at the Dm loci. Dm3 was inactivated in nine of the mutants. One of five Dm 1 mutants was selected from a population of untreated seeds and therefore carried a spontaneous mutation. All other Dm1, Dm3, Dm5/8 and Dm7 mutants were derived from gamma- or fast neutron-irradiated seed. In two separate Dm 1 mutants and in each of the eight Dm3 mutants analyzed, at least one closely linked molecular marker was absent. Also, high molecular weight genomic DNA fragments that hybridized to a tightly linked molecular marker in wild type were either missing entirely or were truncated in two of the Dm3 mutants, providing additional evidence that deletions had occurred in these mutants. Absence of mutations at loci epistatic to the Dm genes suggested that such loci were either members of multigene families, were critical for plant survival, or encoded components of duplicated pathways for resistance; alternatively, the genes determining downy mildew resistance might be limited to the Dm loci.

  15. Resistance Against Basil Downy Mildew in Ocimum Species.

    Science.gov (United States)

    Ben-Naim, Yariv; Falach, Lidan; Cohen, Yigal

    2015-06-01

    Downy mildew, caused by the oomycete Peronospora belbahrii, is a devastating disease of sweet basil. In this study, 113 accessions of Ocimum species (83 Plant Introduction entries and 30 commercial entries) were tested for resistance against downy mildew at the seedling stage in growth chambers, and during three seasons, in the field. Most entries belonging to O. basilicum were highly susceptible whereas most entries belonging to O. americanum, O. kilimanadascharicum, O. gratissimum, O. campechianum, or O. tenuiflorum were highly resistant at both the seedling stage and the field. Twenty-seven highly resistant individual plants were each crossed with the susceptible sweet basil 'Peri', and the F1 progeny plants were examined for disease resistance. The F1 plants of two crosses were highly resistant, F1 plants of 24 crosses were moderately resistant, and F1 plants of one cross were susceptible, suggesting full, partial, or no dominance of the resistance gene(s), respectively. These data confirm the feasibility of producing downy mildew-resistant cultivars of sweet basil by crossing with wild Ocimum species.

  16. Effects of stacked quantitative resistances to downy mildew in lettuce do not simply add up

    NARCIS (Netherlands)

    Boer, den E.; Pelgrom, K.T.B.; Zhang, N.; Visser, R.G.F.; Niks, R.E.; Jeuken, M.J.W.

    2014-01-01

    Key message In a stacking study of eight resistance QTLs in lettuce against downy mildew, only three out of ten double combinations showed an increased resistance effect under field conditions. Abstract Complete race nonspecific resistance to lettuce downy mildew, as observed for the nonhost wild le

  17. Simple Sequence Repeat Markers Useful for Sorghum Downy Mildew (Peronosclerospora sorghi) and Related Species

    Science.gov (United States)

    A recent outbreak of sorghum downy mildew, in Texas, has led to the discovery of both metalaxyl resistance and a new pathotype in the causal organism, Peronosclerospora sorghi. These observations and the difficulty in resolving among phylogenetically related downy mildew pathogens dramatically poin...

  18. Nocturnal Fanning Suppresses Downy Mildew Epidemics in Sweet Basil.

    Science.gov (United States)

    Cohen, Yigal; Ben-Naim, Yariv

    2016-01-01

    Downy mildew is currently the most serious disease of sweet basil around the world. The oomycete causal agent Peronospora belbahrii requires ≥ 4h free leaf moisture for infection and ≥7.5h of water-saturated atmosphere (relative humidity RH≥95%) at night for sporulation. We show here that continued nocturnal fanning (wind speed of 0.4-1.5 m/s) from 8pm to 8am dramatically suppressed downy mildew development. In three experiments conducted during 2015, percent infected leaves in regular (non-fanned) net-houses reached a mean of 89.9, 94.3 and 96.0% compared to1.2, 1.7 and 0.5% in adjacent fanned net-houses, respectively. Nocturnal fanning reduced the number of hours per night with RH≥95% thus shortened the dew periods below the threshold required for infection or sporulation. In experiments A, B and C, the number of nights with ≥4h of RH≥95% was 28, 10 and 17 in the non-fanned net-houses compared to 5, 0 and 5 in the fanned net-houses, respectively. In the third experiment leaf wetness sensors were installed. Dew formation was strongly suppressed in the fanned net-house as compared to the non-fanned net-house. Healthy potted plants became infected and sporulated a week later if placed one night in the non-fanned house whereas healthy plants placed during that night in the fanned house remained healthy. Infected potted basil plants sporulated heavily after one night of incubation in the non-fanned house whereas almost no sporulation occurred in similar plants incubated that night in the fanned house. The data suggest that nocturnal fanning is highly effective in suppressing downy mildew epidemics in sweet basil. Fanning prevented the within-canopy RH from reaching saturation, reduced dew deposition on the leaves, and hence prevented both infection and sporulation of P. belbahrii.

  19. Host‐induced gene silencing inhibits the biotrophic pathogen causing downy mildew of lettuce

    National Research Council Canada - National Science Library

    Govindarajulu, Manjula; Epstein, Lynn; Wroblewski, Tadeusz; Michelmore, Richard W

    2015-01-01

    .... As a proof‐of‐concept, we generated stable transgenic lettuce plants expressing si RNA s targeting potentially vital genes of Bremia lactucae , a biotrophic oomycete that causes downy mildew, the most important...

  20. Sequencing of the Litchi Downy Blight Pathogen Reveals It Is a Phytophthora Species With Downy Mildew-Like Characteristics.

    Science.gov (United States)

    Ye, Wenwu; Wang, Yang; Shen, Danyu; Li, Delong; Pu, Tianhuizi; Jiang, Zide; Zhang, Zhengguang; Zheng, Xiaobo; Tyler, Brett M; Wang, Yuanchao

    2016-07-01

    On the basis of its downy mildew-like morphology, the litchi downy blight pathogen was previously named Peronophythora litchii. Recently, however, it was proposed to transfer this pathogen to Phytophthora clade 4. To better characterize this unusual oomycete species and important fruit pathogen, we obtained the genome sequence of Phytophthora litchii and compared it to those from other oomycete species. P. litchii has a small genome with tightly spaced genes. On the basis of a multilocus phylogenetic analysis, the placement of P. litchii in the genus Phytophthora is strongly supported. Effector proteins predicted included 245 RxLR, 30 necrosis-and-ethylene-inducing protein-like, and 14 crinkler proteins. The typical motifs, phylogenies, and activities of these effectors were typical for a Phytophthora species. However, like the genome features of the analyzed downy mildews, P. litchii exhibited a streamlined genome with a relatively small number of genes in both core and species-specific protein families. The low GC content and slight codon preferences of P. litchii sequences were similar to those of the analyzed downy mildews and a subset of Phytophthora species. Taken together, these observations suggest that P. litchii is a Phytophthora pathogen that is in the process of acquiring downy mildew-like genomic and morphological features. Thus P. litchii may provide a novel model for investigating morphological development and genomic adaptation in oomycete pathogens.

  1. THE USE OF ENDOPHYTIC FUNGI AS BIOPESTICIDE AGAINST DOWNY MILDEW PERONOSCLEROSPORA SPP. ON MAIZE

    OpenAIRE

    AMIN, NUR; La Daha; Nasruddin, Andi; Junaed, M; Iqbal, Andi

    2013-01-01

    Downy mildew is a major disease of maize caused by the fungus Peronosclerospora spp., widely distributed in all corn production centers in Indonesia. The disease can cause considerable losses; even total losses have been reported occurring on susceptible varieties. The purpose of the research was to determine the effectiveness of some isolates of endophytic fungi for the control of downy mildew on maize. The study consisted of four isolate treatments: Aspergillus spp., Trichoderma spp, Beauv...

  2. Identification of QTLs conferring resistance to downy mildew in legacy cultivars of lettuce

    Science.gov (United States)

    Many cultivars of lettuce (Lactuca sativa L.), the most popular leafy vegetable, are susceptible to downy mildew disease caused by Bremia lactucae. Cultivars Iceberg and Grand Rapids that were released in 18th and 19th century, respectively, have high levels of quantitative resistance to downy milde...

  3. Inheritance of downy mildew (Plasmopara viticola) and anthracnose (Sphaceloma ampelinum) resistance in grapevines.

    Science.gov (United States)

    Poolsawat, O; Mahanil, S; Laosuwan, P; Wongkaew, S; Tharapreuksapong, A; Reisch, B I; Tantasawat, P A

    2013-12-13

    Downy mildew (Plasmopara viticola) and anthracnose (Sphaceloma ampelinum) are two of the major diseases of most grapevine (Vitis vinifera L.) cultivars grown in Thailand. Therefore, breeding grapevines for improved downy mildew and anthracnose resistance is crucial. Factorial crosses were made between three downy mildew and/or anthracnose resistant lines ('NY88.0517.01', 'NY65.0550.04', and 'NY65.0551.05'; male parents) and two or three susceptible cultivars of V. vinifera ('Black Queen', 'Carolina Black Rose', and/or 'Italia'; female parents). F1 hybrid seedlings were evaluated for downy mildew and anthracnose resistance using a detached/excised leaf assay. For both diseases, the general combining ability (GCA) variance among male parents was significant, while the variance of GCA among females and the specific combining ability (SCA) variance were not significant, indicating the prevalence of additive over non-additive gene actions. The estimated narrow sense heritabilities of downy mildew and anthracnose resistance were 55.6 and 79.2%, respectively, suggesting that downy mildew/anthracnose resistance gene(s) were highly heritable. The 'Carolina Black Rose x NY65.0550.04' cross combination is recommended for future use.

  4. Nocturnal Fanning Suppresses Downy Mildew Epidemics in Sweet Basil.

    Directory of Open Access Journals (Sweden)

    Yigal Cohen

    Full Text Available Downy mildew is currently the most serious disease of sweet basil around the world. The oomycete causal agent Peronospora belbahrii requires ≥ 4h free leaf moisture for infection and ≥7.5h of water-saturated atmosphere (relative humidity RH≥95% at night for sporulation. We show here that continued nocturnal fanning (wind speed of 0.4-1.5 m/s from 8pm to 8am dramatically suppressed downy mildew development. In three experiments conducted during 2015, percent infected leaves in regular (non-fanned net-houses reached a mean of 89.9, 94.3 and 96.0% compared to1.2, 1.7 and 0.5% in adjacent fanned net-houses, respectively. Nocturnal fanning reduced the number of hours per night with RH≥95% thus shortened the dew periods below the threshold required for infection or sporulation. In experiments A, B and C, the number of nights with ≥4h of RH≥95% was 28, 10 and 17 in the non-fanned net-houses compared to 5, 0 and 5 in the fanned net-houses, respectively. In the third experiment leaf wetness sensors were installed. Dew formation was strongly suppressed in the fanned net-house as compared to the non-fanned net-house. Healthy potted plants became infected and sporulated a week later if placed one night in the non-fanned house whereas healthy plants placed during that night in the fanned house remained healthy. Infected potted basil plants sporulated heavily after one night of incubation in the non-fanned house whereas almost no sporulation occurred in similar plants incubated that night in the fanned house. The data suggest that nocturnal fanning is highly effective in suppressing downy mildew epidemics in sweet basil. Fanning prevented the within-canopy RH from reaching saturation, reduced dew deposition on the leaves, and hence prevented both infection and sporulation of P. belbahrii.

  5. Cucurbit powdery mildews: Methodology for objective determination and denomination of races

    Science.gov (United States)

    Cucurbit powdery mildew (CPM), a disease on field and greenhouse cucurbit crops worldwide, is caused most frequently by two obligate erysiphaceous ectoparasites (Golovinomyces orontii s.l., Podosphaera xanthii) that are highly variable in their pathogenicity and virulence. Various, independent syste...

  6. Genetic investigation of the nonhost resistance of wild lettuce, Lactuca saligna, to lettuce downy mildew, Bremia lactucae

    NARCIS (Netherlands)

    Boer, den E.

    2014-01-01

    Abstract Downy mildew (Bremia lactucae) in lettuce (Lactuca sativa) is a devastating foliar disease causing high losses in lettuce cultivation. The wild lettuce and nonhost species, Lactuca saligna, is absolute resistant to downy mildew and cross-fertile with L. sativa, albeit with

  7. Real-time PCR and spore trap-based detection of the downy mildew pathogen, Peronospora effusa

    Science.gov (United States)

    Peronospora effusa is an obligate pathogen and the causal agent of downy mildew on spinach. The pathogen can be dispersed by splashing rain and wind, and may overwinter as oospores. Outbreaks of downy mildew on spinach are common in the cool climate of central coastal California, including the Sal...

  8. Genetic characterization of quantitative resistance to Bremia lactucae, the causal organism of lettuce downy mildew

    Science.gov (United States)

    Lettuce (Lactuca sativa) is one of the most valuable vegetable crops in the United States. Downy mildew (DM), caused by Bremia lactucae, is the most important foliar disease of lettuce worldwide, which decreases the quality of the marketable portion of the crop. The use of resistant varieties carryi...

  9. Genetic dissection of nonhost resistance of wild lettuce, Lactuca saligna, to downy mildew

    NARCIS (Netherlands)

    Zhang, N.

    2008-01-01

    Lettuce downy mildew is the most destructive disease in lettuce (Lactuca spp.) cultivation and is caused by Bremia lactucae. The successful cross between its host L. sativa and the nonhost, L. saligna, and offers a rare chance to study the genetics of the nonhost resistance. From a set of 29 Backcro

  10. Genetic dissection of Lactuca saligna nonhost resistance to downy mildew at various lettuce developmental stages

    NARCIS (Netherlands)

    Zhang, N.; Lindhout, P.; Niks, R.E.; Jeuken, M.J.W.

    2009-01-01

    This study used the pathosystem of lettuce (Lactuca spp.) and downy mildew (Bremia lactucae) as a model to investigate the inheritance of nonhost resistance, and focused on the contribution of quantitative trait loci (QTLs) to nonhost resistance at various developmental stages in the lettuce life cy

  11. Effector identification in the lettuce downy mildew Bremia lactucae by massively parallel transcriptome sequencing

    NARCIS (Netherlands)

    Stassen, J.H.; Seidl, M.F.; Vergeer, P.W.; Nijman, I.J.; Snel, B.; Cuppen, E.; van den Ackerveken, G.

    2012-01-01

    Lettuce downy mildew (Bremia lactucae) is a rapidly adapting oomycete pathogen affecting commercial lettuce cultivation. Oomycetes are known to use a diverse arsenal of secreted proteins (effectors) to manipulate their hosts. Two classes of effector are known to be translocated by the host: the

  12. Downy mildew on coleus (Plectranthus scutellarioides) caused by Peronospora belbahrii sensu lato in Tennessee

    Science.gov (United States)

    Coleus (Plectranthus scutellarioides [syn. = Solenostemon scutellarioides]) is a popular ornamental plant in the mint family (Lamiaceae), prized for its colorful and showy foliage. In August 2015, disease symptoms typical of downy mildew were observed at two sites in Nashville, Tennessee: (i) at the...

  13. Effector identification in the lettuce downy mildew Bremia lactucae by massively parallel transcriptome sequencing

    NARCIS (Netherlands)

    Stassen, J.H.; Seidl, M.F.; Vergeer, P.W.; Nijman, I.J.; Snel, B.; Cuppen, E.; van den Ackerveken, G.

    2012-01-01

    Lettuce downy mildew (Bremia lactucae) is a rapidly adapting oomycete pathogen affecting commercial lettuce cultivation. Oomycetes are known to use a diverse arsenal of secreted proteins (effectors) to manipulate their hosts. Two classes of effector are known to be translocated by the host: the RXLR

  14. Identification of breeding signatures in grapevine hybrids, donors of resistances against downy and powdery mildew

    NARCIS (Netherlands)

    Vezzulli, S.; Peressotti, E.; Banchi, E.; Dolzani, C.; Micheli, S.; Stefanini, M.; Salamini, F.; Velasco, R.; Riaz, S.; Walker, M.A.; Reisch, B.I.; De Weg, Van W.E.; Bink, M.C.

    2015-01-01

    Grapevine (Vitis vinifera L.) is one of the most valuable crops in the world, but has been often plagued by encountering new parasites that still represent a major constraint, such as downy (DM) and powdery (PM) mildew. Nowadays, growers are still obliged to recur to a massive use of pesticides t

  15. Identification of breeding signatures in grapevine hybrids, donors of resistances against downy and powdery mildew

    NARCIS (Netherlands)

    Vezzulli, S.; Peressotti, E.; Banchi, E.; Dolzani, C.; Micheli, S.; Stefanini, M.; Salamini, F.; Velasco, R.; Riaz, S.; Walker, M.A.; Reisch, B.I.; De Weg, Van W.E.; Bink, M.C.

    2015-01-01

    Grapevine (Vitis vinifera L.) is one of the most valuable crops in the world, but has been often plagued by encountering new parasites that still represent a major constraint, such as downy (DM) and powdery (PM) mildew. Nowadays, growers are still obliged to recur to a massive use of pesticides

  16. Assessing the vulnerability of sorghum converted lines to anthracnose and downy mildew infection

    Science.gov (United States)

    A total of 59 converted sorghum lines and six checks were evaluated for resistance to two foliar fungal diseases, anthracnose and downy mildew (SDM) in 2008 and 2009 growing seasons at the Texas A&M AgriLife Research Farm, College Station, Texas. In 2008, 23 lines exhibited resistance (35%), 29 sus...

  17. Association of RGA-SSCP markers with resistance to downy mildew and anthracnose in grapevines.

    Science.gov (United States)

    Tantasawat, P A; Poolsawat, O; Prajongjai, T; Chaowiset, W; Tharapreuksapong, A

    2012-07-02

    Downy mildew (Plasmopara viticola) and anthracnose (Sphaceloma ampelinum) are two major diseases that severely affect most grapevine (Vitis vinifera) cultivars grown commercially in Thailand. Progress of conventional breeding programs of grapevine for improved resistance to these diseases can be speeded up by selection of molecular markers associated with resistance traits. We evaluated the association between 13 resistance gene analog (RGA)-single-strand conformation polymorphism (SSCP) markers with resistance to downy mildew and anthracnose in 71 segregating progenies of seven cross combinations between susceptible cultivars and resistant lines. F(1) hybrids from each cross were assessed for resistance to downy mildew and anthracnose (isolates Nk4-1 and Rc2-1) under laboratory conditions. Association of resistance traits with RGA-SSCP markers was evaluated using simple linear regression analysis. Three RGA-SSCP markers were found to be significantly correlated with anthracnose resistance, whereas significant correlation with downy mildew resistance was observed for only one RGA-SSCP marker. These results demonstrate the usefulness of RGA-SSCP markers. Four candidate markers with significant associations to resistance to these two major diseases of grapevine were identified. However, these putative associations between markers and resistance need to be verified with larger segregating populations before they can be used for marker-assisted selection.

  18. Correlations between the contents of phytic acid and inorganic phosphorous and downy mildew resistance of corn inbred lines

    OpenAIRE

    Pantipa Na Chiangmai*; Phrutiya Nilprapruck; Warapon Bunkoed; Phakatip Yodmingkhwan; Chokechai Aekatasanawan; Mana Kanjanamaneesathian

    2015-01-01

    Seeds of corn inbred lines collected at the National Corn and Sorghum Research Center (NCSRC), Kasetsart University, were analyzed to determine the contents of phytic acid (PA) and inorganic phosphorous (InP). These 28 and 29 inbred lines were cultivated at the NCSRC (in the 2008 late rainy season and 2009 early rainy season) to evaluate their resistance to corn downy mildew caused by Peronosclerospora sorghi. Results showed that the values of the PA, InP contents and downy mildew...

  19. Effects of Heat Shock on Photosynthetic Properties, Antioxidant Enzyme Activity, and Downy Mildew of Cucumber (Cucumis sativus L.).

    Science.gov (United States)

    Ding, Xiaotao; Jiang, Yuping; Hao, Ting; Jin, Haijun; Zhang, Hongmei; He, Lizhong; Zhou, Qiang; Huang, Danfeng; Hui, Dafeng; Yu, Jizhu

    2016-01-01

    Heat shock is considered an abiotic stress for plant growth, but the effects of heat shock on physiological responses of cucumber plant leaves with and without downy mildew disease are still not clear. In this study, cucumber seedlings were exposed to heat shock in greenhouses, and the responses of photosynthetic properties, carbohydrate metabolism, antioxidant enzyme activity, osmolytes, and disease severity index of leaves with or without the downy mildew disease were measured. Results showed that heat shock significantly decreased the net photosynthetic rate, actual photochemical efficiency, photochemical quenching coefficient, and starch content. Heat shock caused an increase in the stomatal conductance, transpiration rate, antioxidant enzyme activities, total soluble sugar content, sucrose content, soluble protein content and proline content for both healthy leaves and downy mildew infected leaves. These results demonstrate that heat shock activated the transpiration pathway to protect the photosystem from damage due to excess energy in cucumber leaves. Potential resistance mechanisms of plants exposed to heat stress may involve higher osmotic regulation capacity related to an increase of total accumulations of soluble sugar, proline and soluble protein, as well as higher antioxidant enzymes activity in stressed leaves. Heat shock reduced downy mildew disease severity index by more than 50%, and clearly alleviated downy mildew development in the greenhouses. These findings indicate that cucumber may have a complex physiological change to resist short-term heat shock, and suppress the development of the downy mildew disease.

  20. Effects of Heat Shock on Photosynthetic Properties, Antioxidant Enzyme Activity, and Downy Mildew of Cucumber (Cucumis sativus L..

    Directory of Open Access Journals (Sweden)

    Xiaotao Ding

    Full Text Available Heat shock is considered an abiotic stress for plant growth, but the effects of heat shock on physiological responses of cucumber plant leaves with and without downy mildew disease are still not clear. In this study, cucumber seedlings were exposed to heat shock in greenhouses, and the responses of photosynthetic properties, carbohydrate metabolism, antioxidant enzyme activity, osmolytes, and disease severity index of leaves with or without the downy mildew disease were measured. Results showed that heat shock significantly decreased the net photosynthetic rate, actual photochemical efficiency, photochemical quenching coefficient, and starch content. Heat shock caused an increase in the stomatal conductance, transpiration rate, antioxidant enzyme activities, total soluble sugar content, sucrose content, soluble protein content and proline content for both healthy leaves and downy mildew infected leaves. These results demonstrate that heat shock activated the transpiration pathway to protect the photosystem from damage due to excess energy in cucumber leaves. Potential resistance mechanisms of plants exposed to heat stress may involve higher osmotic regulation capacity related to an increase of total accumulations of soluble sugar, proline and soluble protein, as well as higher antioxidant enzymes activity in stressed leaves. Heat shock reduced downy mildew disease severity index by more than 50%, and clearly alleviated downy mildew development in the greenhouses. These findings indicate that cucumber may have a complex physiological change to resist short-term heat shock, and suppress the development of the downy mildew disease.

  1. Isolation and evaluation of proteolytic actinomycete isolates as novel inducers of pearl millet downy mildew disease protection

    Science.gov (United States)

    Jogaiah, Sudisha; Kurjogi, Mahantesh; Govind, Sharathchandra Ramasandra; Huntrike, Shekar Shetty; Basappa, Vedamurthy Ankala; Tran, Lam-Son Phan

    2016-01-01

    Native endophytic actinomycetes isolated from pearl millet roots were examined for their efficacy to protect pearl millet against downy mildew. Nineteen of 39 isolates were found to be proteolytic, of which 7 strains could directly suppress the sporangium formation of Sclerospora graminicola, the pearl millet downy mildew pathogen. Thus, mycelial suspensions containing either spores or cell-free extract of these 7 isolates were used for seed-coating and -soaking treatments to test for their induction of downy mildew resistance. Results indicated that seed-coating overall provided better protection to downy mildew than seed-soaking. In both treatments, the tested isolates demonstrated differential abilities in downy mildew disease protection, with Streptomyces griseus SJ_UOM-07-09 and Streptosporangium roseum SJ_UOM-18-09 showing the highest protection rates. Additionally, the levels of disease protection conferred by the actinomycetes were just slightly lower than that of the systemic fungicide Apron, suggesting their effectiveness. Further studies revealed that the more rapid root colonization by SJ_UOM-18-09 resulted in faster and higher induced resistance in comparison with SJ_UOM-07-09 under greenhouse conditions, indicating that SJ_UOM-18-09 was superior than SJ_UOM-07-09 in inducing resistance. Results from this study provide comprehensive information on biocontrol functions of SJ_UOM- 18-09 with great potential to control downy mildew disease in pearl millet. PMID:27499196

  2. Evidence for cucurbit powdery mildew pathogen races based on watermelon differentials

    Science.gov (United States)

    Powdery mildew (PM) caused by Podosphaera xanthii occurs in open fields and greenhouses and can severely limit cucurbit production. Presently seven races of P. xanthii have been identified using melon (Cucumis melo) differentials. Physiological races of this pathogen have not been classified for ot...

  3. Cucurbit powdery mildew of melon incited by Podosphaera xanthii: global and western U.S. perspectives

    Science.gov (United States)

    Cucurbit powdery mildew (CPM) is a major problem of melon (Cucumis melo L.) production worldwide, that is mostly caused by two fungi: Podosphaera xanthii and Golovinomyces cichoracearum (DC) V.P. Heluta (formerly Erysiphe cichoracearum). The two species may co-infect in some areas of northern Europe...

  4. Powdery mildew resistant cucurbit rootstocks confer tolerance to grafted susceptible watermelon scions

    Science.gov (United States)

    Cucurbit powdery mildew (PM) caused by Podosphaera xanthii can impact seedling growth and cause serious losses in greenhouse and open fields. We have developed watermelon and bottle gourd germplasm lines with high levels of resistance to PM. A PM susceptible watermelon cultivar Mickey Lee (ML) was g...

  5. Tolerance to Cucurbit Powdery Mildew in USDA Bottle Gourd (Lagenaria siceraria) Plant Introductions (PI)

    Science.gov (United States)

    Powdery mildew (Podosphaera xanthii) can cause severe damage to cucurbit crops grown in open fields and greenhouses. Bottle gourd plants (Lagenaria siceraria) are being used throughout the world as rootstocks for grafting watermelon. In recent years, there has been a growing interest in the USA in...

  6. Rapid Staining Method to Detect and Identify Downy Mildew (Peronospora belbahrii in Basil

    Directory of Open Access Journals (Sweden)

    Adolfina R. Koroch

    2013-07-01

    Full Text Available Premise of the study: Demand for fresh-market sweet basil continues to increase, but in 2009 a new pathogen emerged, threatening commercial field/greenhouse production and leading to high crop losses. This study describes a simple and effective staining method for rapid microscopic detection of basil downy mildew (Peronospora belbahrii from leaves of basil (Ocimum basilicum. Methods and Results: Fresh leaf sections infected with P. belbahrii were placed on a microscope slide, cleared with Visikol™, and stained with iodine solution followed by one drop of 70% sulfuric acid. Cell walls of the pathogen were stained with a distinct coloration, providing a high-contrast image between the pathogen and plant. Conclusions: This new staining method can be used successfully to identify downy mildew in basil, which then can significantly reduce its spread if identified early, coupled with mitigation strategies. This technique can facilitate the control of the disease, without expensive and specialized equipment.

  7. Genetic dissection of nonhost resistance of wild lettuce, Lactuca saligna, to downy mildew

    OpenAIRE

    Zhang, N.

    2008-01-01

    Lettuce downy mildew is the most destructive disease in lettuce (Lactuca spp.) cultivation and is caused by Bremia lactucae. The successful cross between its host L. sativa and the nonhost, L. saligna, and offers a rare chance to study the genetics of the nonhost resistance. From a set of 29 Backcross Inbred Lines (BILs) representing in total 96% of the L. saligna genome, 15 introgressions were identified to contribute to this resistance at one to four tested lettuce developmental stages and ...

  8. Daytime Solar Heating Controls Downy Mildew Peronospora belbahrii in Sweet Basil.

    Directory of Open Access Journals (Sweden)

    Yigal Cohen

    Full Text Available The biotrophic oomycete Peronospora belbahrii causes a devastating downy mildew disease in sweet basil. Due to the lack of resistant cultivars current control measures rely heavily on fungicides. However, resistance to fungicides and strict regulation on their deployment greatly restrict their use. Here we report on a 'green' method to control this disease. Growth chamber studies showed that P. belbahrii could hardly withstand exposure to high temperatures; exposure of spores, infected leaves, or infected plants to 35-45 °C for 6-9 hours suppressed its survival. Therefore, daytime solar heating was employed in the field to control the downy mildew disease it causes in basil. Covering growth houses of sweet basil already infected with downy mildew with transparent infra-red-impermeable, transparent polyethylene sheets raised the daily maximal temperature during sunny hours by 11-22 °C reaching 40-58 °C (greenhouse effect. Such coverage, applied for a few hours during 1-3 consecutive days, had a detrimental effect on the survival of P. belbahrii: killing the pathogen and/or suppressing disease progress while enhancing growth of the host basil plants.

  9. Spatial analysis of lettuce downy mildew using geostatistics and geographic information systems.

    Science.gov (United States)

    Wu, B M; van Bruggen, A H; Subbarao, K V; Pennings, G G

    2001-02-01

    ABSTRACT The epidemiology of lettuce downy mildew has been investigated extensively in coastal California. However, the spatial patterns of the disease and the distance that Bremia lactucae spores can be transported have not been determined. During 1995 to 1998, we conducted several field- and valley-scale surveys to determine spatial patterns of this disease in the Salinas valley. Geostatistical analyses of the survey data at both scales showed that the influence range of downy mildew incidence at one location on incidence at other locations was between 80 and 3,000 m. A linear relationship was detected between semivariance and lag distance at the field scale, although no single statistical model could fit the semi-variograms at the valley scale. Spatial interpolation by the inverse distance weighting method with a power of 2 resulted in plausible estimates of incidence throughout the valley. Cluster analysis in geographic information systems on the interpolated disease incidence from different dates demonstrated that the Salinas valley could be divided into two areas, north and south of Salinas City, with high and low disease pressure, respectively. Seasonal and spatial trends along the valley suggested that the distinction between the downy mildew conducive and nonconducive areas might be determined by environmental factors.

  10. Daytime Solar Heating Controls Downy Mildew Peronospora belbahrii in Sweet Basil.

    Science.gov (United States)

    Cohen, Yigal; Rubin, Avia E

    2015-01-01

    The biotrophic oomycete Peronospora belbahrii causes a devastating downy mildew disease in sweet basil. Due to the lack of resistant cultivars current control measures rely heavily on fungicides. However, resistance to fungicides and strict regulation on their deployment greatly restrict their use. Here we report on a 'green' method to control this disease. Growth chamber studies showed that P. belbahrii could hardly withstand exposure to high temperatures; exposure of spores, infected leaves, or infected plants to 35-45 °C for 6-9 hours suppressed its survival. Therefore, daytime solar heating was employed in the field to control the downy mildew disease it causes in basil. Covering growth houses of sweet basil already infected with downy mildew with transparent infra-red-impermeable, transparent polyethylene sheets raised the daily maximal temperature during sunny hours by 11-22 °C reaching 40-58 °C (greenhouse effect). Such coverage, applied for a few hours during 1-3 consecutive days, had a detrimental effect on the survival of P. belbahrii: killing the pathogen and/or suppressing disease progress while enhancing growth of the host basil plants.

  11. Effect of climate change on infection of grapevine by downy and powdery mildew under controlled environment.

    Science.gov (United States)

    Pugliese, M; Gullino, M L; Garibaldi, A

    2011-01-01

    Plant responses to elevated CO2 and temperature have been much studied in recent years, but effects of climate change on pathological responses are largerly unknown. The pathosystems grapevine (Vitis vinifera) - downy mildew (Plasmopara viticola) and powdery mildew (Erysiphe necatrix) were chosen as models to assess the potential impact of increased CO2 and temperature on disease incidence and severity under controlled environment. Grapevine potted plants were grown in phytotrons under 4 different simulated climatic conditions: (1) standard temperature (ranging from 18 degrees to 22 degrees C) and standard CO2 concentration (450 ppm); (2) standard temperature and elevated CO2 concentration (800 ppm); (3) elevated temperature (ranging from 22 degrees to 26 degrees C, 4 degrees C higher than standard) and standard CO2 concentration; (4) elevated temperature and CO2 concentration. Each plant was inoculated with a spore suspension containing 5x10(5) cfu/ml. Disease index and physiological parameters (chlorophyll content, fluorescence, assimilation rate) were assessed. Results showed an increase of the chlorophyll content with higher temperatures and CO2 concentration, to which consequently corresponded an higher fluorescence index. Disease incidence of downy mildew increased when both CO2 and temperatures were higher, while an increase in CO2 did not influenced powdery mildew incidence, probably due to the increased photosynthetic activity of plants under such conditions. Considering that the rising concentrations of CO2 and other greenhouse gases will lead to an increase in global temperature and longer seasons, we can assume that this will allow more time for pathogens evolution and could increase pathogen survival, indirectly affecting downy and powdery mildews of grapevine.

  12. Initiative for international cooperation of researchers and breeders related to determination and denomination of cucurbit powdery mildew races

    Science.gov (United States)

    Cucurbit powdery mildew (CPM) is caused most frequently by two obligate erysiphaceous ectoparasites, Golovinomyces orontii s.l. and Podosphaera xanthii, that are highly variable in virulence. Various independent systems of CPM race determination and denomination cause a chaotic situation in cucurbit...

  13. Potential Sources of Resistance to Cucurbit Powdery Mildew in US Plant Introductions (PI) of Lagenaria Siceraria (bottle gourd)

    Science.gov (United States)

    Powdery mildew (Podosphaera xanthii) can cause severe damage to cucurbit crops grown in open fields and greenhouses. In recent years, there has been a growing interest in the USA in grafting watermelon plants onto various cucurbit rootstocks. Bottle gourd plants (Lagenaria siceraria) are being use...

  14. Specific In Planta Recognition of Two GKLR Proteins of the Downy Mildew Bremia lactucae Revealed in a Large Effector Screen in Lettuce

    NARCIS (Netherlands)

    Stassen, J.H.M.; Boer, den E.; Vergeer, P.W.J.; Andel, A.; Ellendorff, U.; Pelgrom, K.T.B.; Pel, M.; Schut, J.; Zonneveld, O.; Jeuken, M.J.W.; Ackerveken, van den G.

    2013-01-01

    Breeding lettuce (Lactuca sativa) for resistance to the downy mildew pathogen Bremia lactucae is mainly achieved by introgression of dominant downy mildew resistance (Dm) genes. New Bremia races quickly render Dm genes ineffective, possibly by mutation of recognized host-translocated effectors or by

  15. Genetics and mapping of a novel downy mildew resistance gene, Pl18, introgressed from wild Helianthus argophyllus into cultivated sunflower (Helianthus annuus L.)

    Science.gov (United States)

    Sunflower downy mildew is considered to be the most destructive foliar disease that has spread to every major sunflower-growing country of the world, except Australia. A new dominant downy mildew resistance gene (Pl18) transferred from wild Helianthus argophyllus (PI 494573) into cultivated sunflowe...

  16. Correlations between the contents of phytic acid and inorganic phosphorous and downy mildew resistance of corn inbred lines

    Directory of Open Access Journals (Sweden)

    Pantipa Na Chiangmai

    2015-10-01

    Full Text Available Seeds of corn inbred lines collected at the National Corn and Sorghum Research Center (NCSRC, Kasetsart University, were analyzed to determine the contents of phytic acid (PA and inorganic phosphorous (InP. These 28 and 29 inbred lines were cultivated at the NCSRC (in the 2008 late rainy season and 2009 early rainy season to evaluate their resistance to corn downy mildew caused by Peronosclerospora sorghi. Results showed that the values of the PA, InP contents and downy mildew infection were statistically different among these inbred lines in both seasons. However, there were no correlations between the contents of either PA or InP and downy mildew infection.

  17. Macro- and microscopic leaf characteristics of six grapevine genotypes (Vitis spp.) with different susceptibilities to grapevine downy mildew

    OpenAIRE

    Boso Alonso, Susana; Alonso-Villaverde Iglesias, Virginia; Santiago Blanco, José Luis; Gago Montaña, Pilar; Dürrenberger, M.; Düggelin, M.; Kassemeyer, H. H.; Martínez Rodríguez, María del Carmen

    2010-01-01

    This work reports the leaf morphology of six grapevine genotypes, five belonging to Vitis vinifera and one to Vitis riparia. Earlier studies on these genotypes showed different levels of susceptibility to grapevine downy mildew (Plasmopara viticola). The aim of this work was to detect differences between the leaf morphology of these cultivars at the macro- and microscopic levels, and to characterize morphological traits which could be associated with susceptibility and resistance to downy ...

  18. Simple sequence repeat markers useful for sorghum downy mildew (Peronosclerospora sorghi and related species

    Directory of Open Access Journals (Sweden)

    Odvody Gary N

    2008-11-01

    Full Text Available Abstract Background A recent outbreak of sorghum downy mildew in Texas has led to the discovery of both metalaxyl resistance and a new pathotype in the causal organism, Peronosclerospora sorghi. These observations and the difficulty in resolving among phylogenetically related downy mildew pathogens dramatically point out the need for simply scored markers in order to differentiate among isolates and species, and to study the population structure within these obligate oomycetes. Here we present the initial results from the use of a biotin capture method to discover, clone and develop PCR primers that permit the use of simple sequence repeats (microsatellites to detect differences at the DNA level. Results Among the 55 primers pairs designed from clones from pathotype 3 of P. sorghi, 36 flanked microsatellite loci containing simple repeats, including 28 (55% with dinucleotide repeats and 6 (11% with trinucleotide repeats. A total of 22 microsatellites with CA/AC or GT/TG repeats were the most abundant (40% and GA/AG or CT/TC types contribute 15% in our collection. When used to amplify DNA from 19 isolates from P. sorghi, as well as from 5 related species that cause downy mildew on other hosts, the number of different bands detected for each SSR primer pair using a LI-COR- DNA Analyzer ranged from two to eight. Successful cross-amplification for 12 primer pairs studied in detail using DNA from downy mildews that attack maize (P. maydis & P. philippinensis, sugar cane (P. sacchari, pearl millet (Sclerospora graminicola and rose (Peronospora sparsa indicate that the flanking regions are conserved in all these species. A total of 15 SSR amplicons unique to P. philippinensis (one of the potential threats to US maize production were detected, and these have potential for development of diagnostic tests. A total of 260 alleles were obtained using 54 microsatellites primer combinations, with an average of 4.8 polymorphic markers per SSR across 34

  19. Resistance to downy mildew in lettuce ‘La Brillante’ is conferred by dm50 gene and multiple QTL

    Science.gov (United States)

    Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar La Brillante has a high level of field resistance to the disease in California. Testing of a mapping popu...

  20. Elicitation of resistance and associated defense responses in Trichoderma hamatum induced protection against pearl millet downy mildew pathogen

    Science.gov (United States)

    Siddaiah, Chandra Nayaka; Satyanarayana, Niranjan Raj; Mudili, Venkataramana; Kumar Gupta, Vijai; Gurunathan, Selvakumar; Rangappa, Shobith; Huntrike, Shekar Shetty; Srivastava, Rakesh Kumar

    2017-01-01

    Endophytic Trichoderma hamatum UoM 13 isolated from pearl millet roots was evaluated for its efficiency to suppress downy mildew disease. Under laboratory conditions, T. hamatum seed treatment significantly enhanced pearl millet seed germination and seedling vigor. T. hamatum seed treatment resulted in systemic and durable immunity against pearl millet downy mildew disease under greenhouse and field conditions. T. hamatum treated seedlings responded to downy mildew infection with high lignification and callose deposition. Analysis of defense enzymes showed that T. hamatum treatment significantly enhanced the activities of glucanase, peroxidase, phenylalanine ammonia-lyase, and polyphenol oxidase in comparison to untreated control. RT-PCR analysis revealed differentially expressed transcripts of the defense enzymes and PR-proteins in treated, untreated, and checks, wherein PR-1, PR-5, and cell wall defense HRGPs were significantly over expressed in treated seedlings as against their lower expression in controls. T. hamatum treatment significantly stimulated endogenous salicylic acid (SA) levels and significantly upregulated important SA biosynthesis gene isochorismate synthase. The results indicated that T. hamatum UoM13 treatment induces resistance corresponding to significant over expression of endogenous SA, important defense enzymes, PR-proteins, and HRGPs, suggesting that SA biosynthetic pathway is involved in pearl millet for mounting systemic immunity against downy mildew pathogen. PMID:28322224

  1. Pl17 is a novel gene independent of known downy mildew resistance genes in the cultivated sunflower (Helianthus annuus L.)

    Science.gov (United States)

    Downy mildew (DM), caused by Plasmopara halstedii (Farl.) Berl. et de Toni, is one of the serious sunflower diseases in the world due to its high virulence and the variability of the pathogen. DM resistance in the USDA inbred line, HA 458, has been shown to be effective against all virulent races of...

  2. Extracts of Inula viscosa Control Downy Mildew of Grapes Caused by Plasmopara viticola.

    Science.gov (United States)

    Cohen, Yigal; Wang, Wenqiao; Ben-Daniel, Bat-Hen; Ben-Daniel, Yigal

    2006-04-01

    ABSTRACT The oily paste extracts of Inula viscosa leaves made with organic solvents were effective in controlling downy mildew caused by Plasmopara viticola in detached leaf tissues of grapes in growth chambers. Thin-layer chromatography of such extracts revealed the presence of 11 Rf regions of which four contained highly effective compounds against the disease. Two major inhibitory compounds, each comprising 10.6% of the total paste weight, were identified as tomentosin and costic acid. An emulsified concentrate formulation of the oily paste extracts provided excellent activity against the disease in the field. The effective dose (concentration) required for 90% control of the disease in treated shoots in the field was below 0.125% (paste in water). No seasonal fluctuations were observed in the control efficacy of six extracts made from I. viscosa leaves harvested during the period of May to July. In whole vines, treated and artificially inoculated, the paste concentration required for 90% control of the disease ranged between 0.30 to 0.37%, whereas in naturally infected vines it was 0.58%. It appears that I. viscosa is a valuable source for fungicidal preparations against downy mildew of grapes. This is the first report on the control of a disease with I. viscosa extracts under field conditions.

  3. Identification of QTLs conferring resistance to downy mildew in legacy cultivars of lettuce.

    Science.gov (United States)

    Simko, Ivan; Atallah, Amy J; Ochoa, Oswaldo E; Antonise, Rudie; Galeano, Carlos H; Truco, Maria Jose; Michelmore, Richard W

    2013-10-07

    Many cultivars of lettuce (Lactuca sativa L.), the most popular leafy vegetable, are susceptible to downy mildew disease caused by Bremia lactucae. Cultivars Iceberg and Grand Rapids that were released in the 18th and 19th centuries, respectively, have high levels of quantitative resistance to downy mildew. We developed a population of recombinant inbred lines (RILs) originating from a cross between these two legacy cultivars, constructed a linkage map, and identified two QTLs for resistance on linkage groups 2 (qDM2.1) and 5 (qDM5.1) that determined resistance under field conditions in California and the Netherlands. The same QTLs determined delayed sporulation at the seedling stage in laboratory experiments. Alleles conferring elevated resistance at both QTLs originate from cultivar Iceberg. An additional QTL on linkage group 9 (qDM9.1) was detected through simultaneous analysis of all experiments with mixed-model approach. Alleles for elevated resistance at this locus originate from cultivar Grand Rapids.

  4. Cloning and Expression Analysis of Downy Mildew Resistance-Related cDNA Sequences in Melon

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    Melon downy mildew caused by Pseudoperonospora cubensis leads to significant losses in melon yields worldwide.Reverse-transcription Polymerase Chain Reaction (RT-PCR) was performed using cDNAs as templates from melonHuangdanzi induced with fungus Pseudoperonospora cubensis, and degenerate primers designed based on the conserved amino acid sequences of known plant disease-resistance genes. A polymorphic cDNA fragment which we named mp-19was cloned and sequenced. The Open Reading Frame (ORF) of this product comprised of 510 base pairs which encodes DNA or RNA-binding protein with 170 amino acids. The putative amino acid sequence of mp-19 appeared highly homologous with those of NBS-type resistant-genes isolated from other plants. Southern blot indicated that the melon genome contained more than 3 copies of mp-19. The obvious expression differences detected by semi-quantitative RTPCR could be observed between resistant-line Huangdanzi and susceptible-line Jiashi after Pseudoperonospora cubensis infection, which implied that mp-19 gene may be related to the resistance of downy mildew in melon.

  5. GENETIC DIVERSITY OF S3 MAIZE GENOTYPES RESISTANT TO DOWNY MILDEW BASED ON SSR MARKERS

    Directory of Open Access Journals (Sweden)

    Amran Muis

    2016-02-01

    Full Text Available The compulsory requirement for releasing new high yielding maize varieties is resistance to downy mildew. The study aimed to determine the level of homozygosity, genetic diversity, and  genetic distance of 30 S3 genotypes of maize. Number of primers to be used were 30 polymorphic SSR loci which are distributed over the entire maize genomes. The S3 genotypes used were resistant to downy mildew with homozygosity level of >80%, genetic distance between the test and tester strains >0.7, and anthesis silking interval (ASI between inbred lines and tester lines was maximum 3 days. The results showed that 30 SSR primers used were spread evenly across the maize genomes which were manifested in the representation of SSR loci on each chromosome of a total of 10 chromosomes. The levels of polymorphism ranged from 0.13 to 0.78, an average of 0.51, and the number of alleles ranged from 2 to 8 alleles per SSR locus, an average of 4 alleles per SSR locus. The size of nucleotides in each locus also varied from 70 to 553 bp. Cophenetic correlation value (r at 0.67 indicated that the Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA was less reliable for differentiating genotypes in five groups. Of the total of 30 genotypes analyzed, 17 genotypes had homozygosity level of >80% so it can be included in the hybrid assembly program.

  6. Morphological and molecular characterization of the causal agent of downy mildew on Quinoa (Chenopodium quinoa).

    Science.gov (United States)

    Choi, Young-Joon; Danielsen, Solveig; Lübeck, Mette; Hong, Seung-Beom; Delhey, Rolf; Shin, Hyeon-Dong

    2010-05-01

    Downy mildew is an economically important and widespread disease in quinoa (Chenopodium quinoa) growing areas. Although in many studies Peronospora farinosa is most commonly regarded as the causal agent of the disease, identification and classification of the pathogen remain still uncertain due to its taxonomic confusion. Thirty-six Peronospora isolates from quinoa with different geographic origins including Argentina, Bolivia, Denmark, Ecuador, and Peru were morphologically and molecularly compared with Peronospora species from other Chenopodium species. The morphology of three herbarium specimens was similar to that of P. variabilis, which originated from C. album, characterized by flexuous to curved ultimate branchlets and pedicellated conidia. Phylogenetic analysis based on ITS rDNA sequences also placed the quinoa pathogen within the same clade as P. variabilis. Within the ITS rDNA sequences of the quinoa pathogens, two base substitutions were found, which separated the majority of the Danish isolates from isolates from South America, but no sequence difference was found among the isolates from different cultivars of quinoa. The present results indicate that the pathogen responsible for the quinoa downy mildew is identical to Peronospora variabilis and that it should not be lumped with P. farinosa as claimed previously by most studies.

  7. Transcriptome and Small RNAome Dynamics during a Resistant and Susceptible Interaction between Cucumber and Downy Mildew

    Directory of Open Access Journals (Sweden)

    Alyssa Burkhardt

    2016-03-01

    Full Text Available Cucumber ( L. downy mildew, caused by the obligate oomycete pathogen (Berk. and Curt. Rostov., is the primary factor limiting cucumber production. Although sources of resistance have been identified, such as plant introduction line PI 197088, the genes and processes involved in mediating resistance are still unknown. In the current study, we conducted a comprehensive transcriptome and small RNAome analysis of a resistant (PI 197088 and susceptible (‘Vlaspik’ cucumber during a time course of infection using Illumina sequencing. We identified significantly differentially expressed (DE genes within and between resistant and susceptible cucumber leaves over a time course of infection. Weighted gene correlation network analyses (WGCNA created coexpression modules containing genes with unique expression patterns between Vlaspik and PI 197088. Recurring data trends indicated that resistance to cucumber downy mildew is associated with earlier response to the pathogen, hormone signaling, and regulation of nutrient supply. Candidate resistance genes were identified from multiple transcriptome analyses and literature support. Additionally, parallel sequencing of small RNAs (sRNAs from cucumber and during the infection time course was used to identify and quantify novel and existing microRNA (miRNA in both species. Predicted miRNA targets of cucumber transcripts suggest a complex interconnectedness of gene expression regulation in this plant–pathogen system. This work bioinformatically uncovered gene expression patterns involved in the mediation of or response to resistance. Herein, we provide the foundation for future work to validate candidate resistance genes and miRNA-based regulation proposed in this study.

  8. Downy mildew resistance induced by Trichoderma harzianum T39 in susceptible grapevines partially mimics transcriptional changes of resistant genotypes

    Directory of Open Access Journals (Sweden)

    Perazzolli Michele

    2012-11-01

    Full Text Available Abstract Background Downy mildew, caused by Plasmopara viticola, is one of the most severe diseases of grapevine and is commonly controlled by fungicide treatments. The beneficial microorganism Trichoderma harzianum T39 (T39 can induce resistance to downy mildew, although the molecular events associated with this process have not yet been elucidated in grapevine. A next generation RNA sequencing (RNA-Seq approach was used to study global transcriptional changes associated with resistance induced by T39 in Vitis vinifera Pinot Noir leaves. The long-term aim was to develop strategies to optimize the use of this agent for downy mildew control. Results More than 14.8 million paired-end reads were obtained for each biological replicate of T39-treated and control leaf samples collected before and 24 h after P. viticola inoculation. RNA-Seq analysis resulted in the identification of 7,024 differentially expressed genes, highlighting the complex transcriptional reprogramming of grapevine leaves during resistance induction and in response to pathogen inoculation. Our data show that T39 has a dual effect: it directly modulates genes related to the microbial recognition machinery, and it enhances the expression of defence-related processes after pathogen inoculation. Whereas several genes were commonly affected by P. viticola in control and T39-treated plants, opposing modulation of genes related to responses to stress and protein metabolism was found. T39-induced resistance partially inhibited some disease-related processes and specifically activated defence responses after P. viticola inoculation, causing a significant reduction of downy mildew symptoms. Conclusions The global transcriptional analysis revealed that defence processes known to be implicated in the reaction of resistant genotypes to downy mildew were partially activated by T39-induced resistance in susceptible grapevines. Genes identified in this work are an important source of markers

  9. Breakdown of resistance to grapevine downy mildew upon limited deployment of a resistant variety

    Directory of Open Access Journals (Sweden)

    Bellin Diana

    2010-07-01

    Full Text Available Abstract Background Natural disease resistance is a cost-effective and environmentally friendly way of controlling plant disease. Breeding programmes need to make sure that the resistance deployed is effective and durable. Grapevine downy mildew, caused by the Oomycete Plasmopara viticola, affects viticulture and it is controlled with pesticides. Downy mildew resistant grapevine varieties are a promising strategy to control the disease, but their use is currently restricted to very limited acreages. The arising of resistance-breaking isolates under such restricted deployment of resistant varieties would provide valuable information to design breeding strategies for the deployment of resistance genes over large acreages whilst reducing the risks of the resistance being defeated. The observation of heavy downy mildew symptoms on a plant of the resistant variety Bianca, whose resistance is conferred by a major gene, provided us with a putative example of emergence of a resistance-breaking isolate in the interaction between grapevine and P. viticola. Results In this paper we describe the emergence of a P. viticola isolate (isolate SL that specifically overcomes Rpv3, the major resistance gene carried by Bianca at chromosome 18. We show that isolate SL has the same behaviour as two P. viticola isolates avirulent on Bianca (isolates SC and SU when inoculated on susceptible plants or on resistant plants carrying resistances derived from other sources, suggesting there is no fitness cost associated to the virulence. Molecular analysis shows that all three isolates are genetically closely related. Conclusions Our results are the first description of a resistance-breaking isolate in the grapevine/P. viticola interaction, and show that, despite the reduced genetic variability of P. viticola in Europe compared to its basin of origin and the restricted use of natural resistance in European viticulture, resistance-breaking isolates overcoming monogenic

  10. Use of suppression subtractive hybridization to identify downy mildew genes expressed during infection of Arabidopsis thaliana.

    Science.gov (United States)

    Bittner-Eddy, Peter D; Allen, Rebecca L; Rehmany, Anne P; Birch, Paul; Beynon, Jim L

    2003-11-01

    SUMMARY Peronospora parasitica is an obligate biotrophic oomycete that causes downy mildew in Arabidopsis thaliana and Brassica species. Our goal is to identify P. parasitica (At) genes that are involved in pathogenicity. We used suppression subtractive hybridization (SSH) to generate cDNA libraries enriched for in planta-expressed parasite genes and up-regulated host genes. A total of 1345 clones were sequenced representing cDNA fragments from 25 putative P. parasitica (At) genes (Ppat 1-25) and 618 Arabidopsis genes. Analyses of expression patterns showed that 15 Ppats were expressed only in planta. Eleven Ppats encoded peptides with homology (BlastP values planta-expressed genes from P. parasitica (At) that complements other gene discovery approaches such as EST sequencing.

  11. Genetic dissection of sex determinism, inflorescence morphology and downy mildew resistance in grapevine.

    Science.gov (United States)

    Marguerit, Elisa; Boury, Christophe; Manicki, Aurélie; Donnart, Martine; Butterlin, Gisèle; Némorin, Alice; Wiedemann-Merdinoglu, Sabine; Merdinoglu, Didier; Ollat, Nathalie; Decroocq, Stéphane

    2009-05-01

    A genetic linkage map of grapevine was constructed using a pseudo-testcross strategy based upon 138 individuals derived from a cross of Vitis vinifera Cabernet Sauvignon x Vitis riparia Gloire de Montpellier. A total of 212 DNA markers including 199 single sequence repeats (SSRs), 11 single strand conformation polymorphisms (SSCPs) and two morphological markers were mapped onto 19 linkage groups (LG) which covered 1,249 cM with an average of 6.7 cM between markers. The position of SSR loci in the maps presented here is consistent with the genome sequence. Quantitative traits loci (QTLs) for several traits of inflorescence and flower morphology, and downy mildew resistance were investigated. Two novel QTLs for downy mildew resistance were mapped on linkage groups 9 and 12, they explain 26.0-34.4 and 28.9-31.5% of total variance, respectively. QTLs for inflorescence morphology with a large effect (14-70% of total variance explained) were detected close to the Sex locus on LG 2. The gene of the enzyme 1-aminocyclopropane-1-carboxylic acid synthase, involved in melon male organ development and located in the confidence interval of all QTLs detected on the LG 2, could be considered as a putative candidate gene for the control of sexual traits in grapevine. Co-localisations were found between four QTLs, detected on linkage groups 1, 14, 17 and 18, and the position of the floral organ development genes GIBBERELLIN INSENSITIVE1, FRUITFULL, LEAFY and AGAMOUS. Our results demonstrate that the sex determinism locus also determines both flower and inflorescence morphological traits.

  12. Polygalacturonase-inhibitor proteins in pearl millet: possible involvement in resistance against downy mildew

    Institute of Scientific and Technical Information of China (English)

    S. Ashok Prabhu; K. Ramachandra Kini; S. Niranjan Raj; Bruno M. Moerschbacher; H. S. Shetty

    2012-01-01

    Polygalacturonase-inhibitor protein (PGIP) is a defense protein found in plant cell walls.It prevents the degradation of pectin by modulating the endo-polygalacturonase activity.The present study has used heterologous antibean PGIP probes to investigate the role of PGIP in pearl millet [Pennisetum glaucum (L) R.Br.] resistance against downy mildew caused by oomycete pathogen Sclerospora graminicola (Sacc.) Schroet.Northern blot analysis using bean pgip2 DNA fragment as probe showed an early and marked induction of transcripts (~1.2 kb) upon pathogen-inoculation in pearl millet cultivar resistant to downy mildew,with the maximum level observed at 24 and 48 h post-inoculation (h.p.i.).Western blot analysis of pearl millet total cell wall proteins using antibodies against bean PGIP showed the presence of a major band of ~43 kDa,and several minor ones.The protein accumulation was higher in resistant seedlings than in susceptible seedlings with a differential expression observed only in the case of incompatible interaction.lmmunocytochemical localization in epidermal peelings of coleoptiles and tissue-printing showed a similar trend in the PGIP accumulation.PGIP was found to localize in the epidermal as well as in the vascular regions of tissues.Higher accumulation was observed in the stomatal guard cells of resistant cultivar inoculated with the pathogen.PGIP activity of pearl millet total protein extracts when assayed against Aspergillus niger PG displayed differential PG inhibitory activities between the resistant and suceptible cultivars with resistant sample showing the highest inhibition of 16%,post-pathogen treatment.Thus,PGIP appeared to be an important player in pearl millet-S,graminicola interaction leading to host resistance.

  13. Biocontrol agent Bacillus amyloliquefaciens LJ02 induces systemic resistance against cucurbits powdery mildew.

    Science.gov (United States)

    Li, Yunlong; Gu, Yilin; Li, Juan; Xu, Mingzhu; Wei, Qing; Wang, Yuanhong

    2015-01-01

    Powdery mildew is a fungal disease found in a wide range of plants and can significantly reduce crop yields. Bacterial strain LJ02 is a biocontrol agent (BCA) isolated from a greenhouse in Tianjin, China. In combination of morphological, physiological, biochemical and phylogenetic analyses, strain LJ02 was classified as a new member of Bacillus amyloliquefaciens. Greenhouse trials showed that LJ02 fermentation broth (LJ02FB) can effectively diminish the occurrence of cucurbits powdery mildew. When treated with LJ02FB, cucumber seedlings produced significantly elevated production of superoxide dismutase, peroxidase, polyphenol oxidase and phenylalanine ammonia lyase as compared to that of the control. We further confirmed that the production of free salicylic acid (SA) and expression of one pathogenesis-related (PR) gene PR-1 in cucumber leaves were markedly elevated after treating with LJ02FB, suggesting that SA-mediated defense response was stimulated. Moreover, LJ02FB-treated cucumber leaves could secrete resistance-related substances into rhizosphere that inhibit the germination of fungi spores and the growth of pathogens. Finally, we separated bacterium and its fermented substances to test their respective effects and found that both components have SA-inducing activity and bacterium plays major roles. Altogether, we identified a BCA against powdery mildew and its mode of action by inducing systemic resistance such as SA signaling pathway.

  14. Transformation of the cucurbit powdery mildew pathogen Podosphaera xanthii by Agrobacterium tumefaciens.

    Science.gov (United States)

    Martínez-Cruz, Jesús; Romero, Diego; de Vicente, Antonio; Pérez-García, Alejandro

    2017-03-01

    The obligate biotrophic fungal pathogen Podosphaera xanthii is the main causal agent of powdery mildew in cucurbit crops all over the world. A major limitation of molecular studies of powdery mildew fungi (Erysiphales) is their genetic intractability. In this work, we describe a robust method based on the promiscuous transformation ability of Agrobacterium tumefaciens for reliable transformation of P. xanthii. The A. tumefaciens-mediated transformation (ATMT) system yielded transformants of P. xanthii with diverse transferred DNA (T-DNA) constructs. Analysis of the resultant transformants showed the random integration of T-DNA into the P. xanthii genome. The integrations were maintained in successive generations in the presence of selection pressure. Transformation was found to be transient, because in the absence of selection agent, the introduced genetic markers were lost due to excision of T-DNA from the genome. The ATMT system represents a potent tool for genetic manipulation of P. xanthii and will likely be useful for studying other biotrophic fungi. We hope that this method will contribute to the development of detailed molecular studies of the intimate interaction established between powdery mildew fungi and their host plants.

  15. Nitric oxide donor seed priming enhances defense responses and induces resistance against pearl millet downy mildew disease

    DEFF Research Database (Denmark)

    Manjunatha, G.; Raj, S. Niranjan; Shetty, Nandini Prasad

    2008-01-01

    , a structural analog of NO donor lacking NO moiety failed to protect the pearl millet plants from downy mildew indicating a role for NO in induced host resistance. Spatio-temporal studies corroborated that the protection offered by NO donor treatment was systemic in nature and a minimum of 3-day time gap...... experiments with NO donors showed no adverse effect either on the host or pathogen. Aqueous SNP seed treatment with or without polyethylene glycol (PEG) priming was the most effective in inducing the host resistance against downy mildew both under greenhouse and field conditions. Potassium Ferrocyanide...... between the inducer treatment and subsequent pathogen inoculation was necessary for maximum resistance development. Disease protection ability of NO donors was also validated as durable in nature. Conversely, prior-treatment with NO scavenger 2-4-carboxyphenyl-4,4,5,5 tetrazoline-1-oxyl-3-oxide potassium...

  16. Impact of major gene resistance management for sunflower on fitness of Plasmopara halstedii (downy mildew populations

    Directory of Open Access Journals (Sweden)

    Tourvieille de Labrouhe Denis

    2010-01-01

    Full Text Available Changes in virulence of Plasmopara halstedii populations under different major gene (Pl management strategies were studied over 5 years continuous cropping of one sunflower hybrid under netting cages. Strategies were monoculture of forms of the hybrid with 1 gene or with combinations of 2 genes, alternation of different genes, and mixtures of several different forms of the hybrid. Monoculture with single resistance genes led to loss of efficient resistance after 3 years, with high levels of disease and increased variability of the pathogen, whatever the Pl gene used. Combinations of genes, alternation and mixtures gave longer term control of downy mildew. In particular, combinations of resistance genes coming from both female and male parents of the hybrid (such that even impurities had a resistance gene gave the best control and least variation in pathogen virulence. Results are discussed with the object of durable control of downy mildew by all methods available.

  17. High dilutions of Sulphur and relationship with the onion thrips, downy mildew incidence and yield of onion in organic system

    Directory of Open Access Journals (Sweden)

    Paulo Antonio de Souza Gonçalves

    2015-12-01

    Full Text Available The objective of this research was to evaluate high dilutions of Sulphur on the incidence of onion thrips, downy mildew, chlorophyll content and yield of onion under organic production system. The study was carried out at Ituporanga Experiment Station of Epagri, Santa Catarina State, Brazil, from August to December of 2011, 2012 and 2013. Treatments were foliar sprays of 0.5% Sulphur at high dilutions 6, 12 and 30 CH (CH, hahnemannian centesimal scale and untreated plot as control check. The experimental design was a randomized block design with four replications. The incidence and damage of onion thrips, reduction of the severity of downy mildew, chlorophyll index, total and commercial yield, bulb weight, postharvest conservation were not influenced by the treatments.

  18. Development and dissection of diagnostic SNP markers for the downy mildew resistance genes PlArg and Pl8 and maker-assisted gene pyramiding in sunflower (Helianthus annuus L.)

    Science.gov (United States)

    Downy mildew, which is caused by fungus Plasmopara halstedii (Farl.) Berlese & de Toni, is one of the most important diseases that affect sunflower production globally. Two downy mildew resistance genes, PlArg and Pl8, were discovered in the late 1980s. Over two decades, PlArg is still effective aga...

  19. Research Progress of Induced Resistance to Cucumber Downy Mildew%黄瓜霜霉病诱导抗性的研究进展

    Institute of Scientific and Technical Information of China (English)

    侯丽琴; 李长松; 徐作珽; 李林; 齐军山; 张博; 杨革

    2012-01-01

    Cucumber downy mildew is a worldwide disease, and also an destructive disease in protected cucumber production. The disease spreads fast and has a great threat to cucumber production. In this paper, the research progress of inducer types to cucumber downy mildew, induced mechanism and relevant genes on downy mildew resistance were reviewed and summarized, and then the developing trend was prospected.%黄瓜霜霉病是一种世界性病害,也是保护地黄瓜生产上的一种毁灭性病害.本文概述了黄瓜霜霉病诱抗剂种类、诱抗机制、抗霜霉病相关基因等方面的研究进展,并对未来发展趋势提出了展望.

  20. Decay of genes encoding the oomycete flagellar proteome in the downy mildew Hyaloperonospora arabidopsidis.

    Directory of Open Access Journals (Sweden)

    Howard S Judelson

    Full Text Available Zoospores are central to the life cycles of most of the eukaryotic microbes known as oomycetes, but some genera have lost the ability to form these flagellated cells. In the plant pathogen Phytophthora infestans, genes encoding 257 proteins associated with flagella were identified by comparative genomics. These included the main structural components of the axoneme and basal body, proteins involved in intraflagellar transport, regulatory proteins, enzymes for maintaining ATP levels, and others. Transcripts for over three-quarters of the genes were up-regulated during sporulation, and persisted to varying degrees in the pre-zoospore stage (sporangia and motile zoospores. Nearly all of these genes had orthologs in other eukaryotes that form flagella or cilia, but not species that lack the organelle. Orthologs of 211 of the genes were also absent from a sister taxon to P. infestans that lost the ability to form flagella, the downy mildew Hyaloperonospora arabidopsidis. Many of the genes retained in H. arabidopsidis were also present in other non-flagellates, suggesting that they play roles both in flagella and other cellular processes. Remnants of the missing genes were often detected in the H. arabidopsidis genome. Degradation of the genes was associated with local compaction of the chromosome and a heightened propensity towards genome rearrangements, as such regions were less likely to share synteny with P. infestans.

  1. Effector identification in the lettuce downy mildew Bremia lactucae by massively parallel transcriptome sequencing.

    Science.gov (United States)

    Stassen, Joost H M; Seidl, Michael F; Vergeer, Pim W J; Nijman, Isaäc J; Snel, Berend; Cuppen, Edwin; Van den Ackerveken, Guido

    2012-09-01

    Lettuce downy mildew (Bremia lactucae) is a rapidly adapting oomycete pathogen affecting commercial lettuce cultivation. Oomycetes are known to use a diverse arsenal of secreted proteins (effectors) to manipulate their hosts. Two classes of effector are known to be translocated by the host: the RXLRs and Crinklers. To gain insight into the repertoire of effectors used by B. lactucae to manipulate its host, we performed massively parallel sequencing of cDNA derived from B. lactucae spores and infected lettuce (Lactuca sativa) seedlings. From over 2.3 million 454 GS FLX reads, 59 618 contigs were assembled representing both plant and pathogen transcripts. Of these, 19 663 contigs were determined to be of B. lactucae origin as they matched pathogen genome sequences (SOLiD) that were obtained from >270 million reads of spore-derived genomic DNA. After correction of cDNA sequencing errors with SOLiD data, translation into protein models and filtering, 16 372 protein models remained, 1023 of which were predicted to be secreted. This secretome included elicitins, necrosis and ethylene-inducing peptide 1-like proteins, glucanase inhibitors and lectins, and was enriched in cysteine-rich proteins. Candidate host-translocated effectors included 78 protein models with RXLR effector features. In addition, we found indications for an unknown number of Crinkler-like sequences. Similarity clustering of secreted proteins revealed additional effector candidates. We provide a first look at the transcriptome of B. lactucae and its encoded effector arsenal.

  2. Response of sorghum accessions from Chad and Uganda to natural infection by the downy mildew pathogen, Peronosclerospora sorghi in Mexico and the USA

    Science.gov (United States)

    In this study, 78 accessions from Chad, West Africa and 20 photoperiod insensitive accessions from Uganda, East Africa were evaluated for downy mildew resistance in Ocotlan, Mexico in 2004 and 2005. Ninety-four of these accessions were also evaluated at two locations in Wharton County, Texas, USA, ...

  3. Lactuca saligna, a non-host for lettuce downy mildew (Bremia lactucae), harbors a new race-specific Dm gene and three QTL's for resistance

    NARCIS (Netherlands)

    Jeuken, M.J.W.; Lindhout, P.

    2002-01-01

    Lactuca sativa (lettuce) is susceptible to Bremia lactucae (downy mildew). In cultivated and wild Lactuca species, Dm genes have been identified that confer race-specific resistance. However, these genes were soon rendered ineffective by adaptation of the pathogen. Lactuca saligna (wild lettuce) is

  4. Screening exotic sorghum germplasm, hybrids and elite lines for resistance to a new virulent pathotype (P6) of Peronsclerospora sorghi causing downy mildew

    Science.gov (United States)

    A recent outbreak of sorghum downy mildew (SDM) in Texas has led to the discovery of both metalaxyl fungicide resistance and a new pathotype, P6, in the causal organism Peronsclerospora sorghi. New and alternate sources of the host plant resistance are needed for successful management of SDM. To i...

  5. Genetic signature of a range expansion and leap-frog event after the recent invasion of Europe by the grapevine downy mildew pathogen Plasmopara viticola

    NARCIS (Netherlands)

    Fontaine, Michael C.; Austerlitz, Frederic; Giraud, Tatiana; Labbe, Frederic; Papura, Daciana; Richard-Cervera, Sylvie; Delmotte, Francois

    2013-01-01

    Biologic invasions can have important ecological, economic and social consequences, particularly when they involve the introduction and spread of plant invasive pathogens, as they can threaten natural ecosystems and jeopardize the production of human food. Examples include the grapevine downy mildew

  6. Growth and Decline and Control Countermeasures of Grape Downy Mildew%葡萄霜霉病田间消长规律及防治对策

    Institute of Scientific and Technical Information of China (English)

    马俊义; 范咏梅; 姜新丽; 刘新智; 周泽容; 韩先旭

    2011-01-01

    [目的]调查研究葡萄霜霉病的田间流行动态,以期提出合理的用药时间和药剂种类.[方法]采用5点法对新疆北部昌吉市葡萄霜霉病的田间消长规律进行调查,采用叶盘法测定不同药剂对葡萄藉霉病菌的敏感性;采用生测法筛选葡萄霜霉病田间药剂.[结果]6-7月降雨量和降雨次数是导致北疆葡萄霜霉病流行的主要因子之一.霜疫必克、杜邦易保对葡萄霜霉病菌表现出较强的毒力,对葡萄霜霉病菌比较敏感,属一个敏感水平,杀毒矾次之,而甲霜灵对葡萄霜霉菌表现出极不敏感.通过两年对10种药剂的田间药效试验表明:在葡萄霜霉病发病期喷施安克、霜疫必克、杀毒矾,隔7d喷一次,连续喷2次,相对防效达61.59%-71.70%,比其它药剂防效明显.[结论]新疆昌吉葡萄霜霉病的发生危害程度与降雨日持续时间和雨量大小呈一定的相关性.安克、霜疫必克、杀毒矾三种杀菌剂具有良好控制病害蔓延效果,且属低毒农药,对葡萄安全,对环境污染小,值得推广应用.%[ Objective]ln this paper, Crape downy mildew epidemic dynamics were investigated in Xinjiang in order to provide reasonable treatment time and type of chemicals against the disease. [Method ] By 5 - point method, epidemic dynamic of grape downy mildew was investigated in Changji city in northem Xinjiang; using the leaf disc method , it was determined for the aensitivity of different fungicides to the pathogen of grape downy mildew; the fungicides which were sensitive to grape downy mildew were screened by bioassay. [ Result]ln June and July, the amount of precipitation is one major factor which led to the popular of grape downy mildew in northem Xinjiang. The fungicides (SYBK and DuPont) showed strong virulence to grape downy mildew pathogen , more sensitive to downy mildew of grape than other fungicides, such as Oxadixyl+ Mancozeb, and metalaxyl on grape downy mildew pathogen were very

  7. Occurrence and control of Wheat Downy Mildew%小麦霜霉病的发生与防治

    Institute of Scientific and Technical Information of China (English)

    秦玉芬

    2013-01-01

    小麦霜霉病是一种以土壤传染为主的真菌病害,主要在苗期阶段侵染.在防治上我们通过采取以轮作、选种抗病品种、加强肥水管理和药剂拌种等综合防治措施,使其得到了有效控制.%The wheat downy mildew is a kind of fungi diseases which are mainly infected by soil and the wheat ismainly contaminated during seeding stage.In prevention,we mainly take comprehensive preventive health measures such as rotation,choosing disease-resistant seed,the enhancement the management of fertilizer and water,medicament mixed with seed etc to extend effective control.

  8. Toward the Identification of Two Glycoproteins Involved in the Stomatal Deregulation of Downy Mildew-Infected Grapevine Leaves.

    Science.gov (United States)

    Guillier, Christelle; Gamm, Magdalena; Lucchi, Géraldine; Truntzer, Caroline; Pecqueur, Delphine; Ducoroy, Patrick; Adrian, Marielle; Héloir, Marie-Claire

    2015-11-01

    Stomata remain abnormally opened and unresponsive to abscisic acid in grapevine leaves infected by downy mildew. This deregulation occurs from 3 days postinoculation and increases concomitantly with leaf colonization by the pathogen. Using epidermal peels, we demonstrated that the active compound involved in this deregulation is located in the apoplast. Biochemical assays showed that the active compound present in the apoplastic fluids isolated from Plasmopara viticola-infected grapevine leaves (IAF) is a CysCys bridge-independent, thermostable and glycosylated protein. Fractionation guided assays based on chromatography coupled to stomatal response and proteomic analysis allowed the identification of both plant and pathogen proteins in the active fraction obtained from IAF. Further in silico analysis and discriminant filtrations based on the comparison between predictions and experimental indications lead to the identification of two Vitis vinifera proteins as candidates for the observed stomatal deregulation.

  9. Resistance to Downy Mildew in Lettuce 'La Brillante' is Conferred by Dm50 Gene and Multiple QTL.

    Science.gov (United States)

    Simko, Ivan; Ochoa, Oswaldo E; Pel, Mathieu A; Tsuchida, Cayla; Font I Forcada, Carolina; Hayes, Ryan J; Truco, Maria-Jose; Antonise, Rudie; Galeano, Carlos H; Michelmore, Richard W

    2015-09-01

    Many cultivars of lettuce (Lactuca sativa L.) are susceptible to downy mildew, a nearly globally ubiquitous disease caused by Bremia lactucae. We previously determined that Batavia type cultivar 'La Brillante' has a high level of field resistance to the disease in California. Testing of a mapping population developed from a cross between 'Salinas 88' and La Brillante in multiple field and laboratory experiments revealed that at least five loci conferred resistance in La Brillante. The presence of a new dominant resistance gene (designated Dm50) that confers complete resistance to specific isolates was detected in laboratory tests of seedlings inoculated with multiple diverse isolates. Dm50 is located in the major resistance cluster on linkage group 2 that contains at least eight major, dominant Dm genes conferring resistance to downy mildew. However, this Dm gene is ineffective against the isolates of B. lactucae prevalent in the field in California and the Netherlands. A quantitative trait locus (QTL) located at the Dm50 chromosomal region (qDM2.2) was detected, though, when the amount of disease was evaluated a month before plants reached harvest maturity. Four additional QTL for resistance to B. lactucae were identified on linkage groups 4 (qDM4.1 and qDM4.2), 7 (qDM7.1), and 9 (qDM9.2). The largest effect was associated with qDM7.1 (up to 32.9% of the total phenotypic variance) that determined resistance in multiple field experiments. Markers identified in the present study will facilitate introduction of these resistance loci into commercial cultivars of lettuce.

  10. [An early warning method of cucumber downy mildew in solar greenhouse based on canopy temperature and humidity modeling].

    Science.gov (United States)

    Wang, Hui; Li, Mei-lan; Xu, Jian-ping; Chen, Mei-xiang; Li, Wen-yong; Li, Ming

    2015-10-01

    The greenhouse environmental parameters can be used to establish greenhouse nirco-climate model, which can combine with disease model for early warning, with aim of ecological controlling diseases to reduce pesticide usage, and protecting greenhouse ecological environment to ensure the agricultural product quality safety. Greenhouse canopy leaf temperature and air relative humidity, models were established using energy balance and moisture balance principle inside the greenhouse. The leaf temperature model considered radiation heat transfer between the greenhouse crops, wall, soil and cover, plus the heat exchange caused by indoor net radiation and crop transpiration. Furthermore, the water dynamic balance in the greenhouse including leaf transpiration, soil evaporation, cover and leaf water vapor condensation, was considered to develop a relative humidity model. The primary infection and latent period warning models for cucumber downy mildew (Pseudoperonospora cubensis) were validated using the results of the leaf temperature and relative humidity model, and then the estimated disease occurrence date of cucumber downy mildew was compared with actual disease occurrence date of field observation. Finally, the results were verified by the measured temperature and humidity data of September and October, 2014. The results showed that the root mean square deviations (RMSDs) of the measured and estimated leaf temperature were 0.016 and 0.024 °C, and the RMSDs of the measured and estimated air relative humidity were 0.15% and 0.13%, respectively. Combining the result of estimated temperature and humidity models, a cucumber disease early warning system was established to forecast the date of disease occurrence, which met with the real date. Thus, this work could provide the micro-environment data for the early warning system of cucumber diseases in solar greenhouses.

  11. Historical introgression of the downy mildew resistance gene Rpv12 from the Asian species Vitis amurensis into grapevine varieties.

    Directory of Open Access Journals (Sweden)

    Silvia Venuti

    Full Text Available The Amur grape (Vitis amurensis Rupr. thrives naturally in cool climates of Northeast Asia. Resistance against the introduced pathogen Plasmopara viticola is common among wild ecotypes that were propagated from Manchuria into Chinese vineyards or collected by Soviet botanists in Siberia, and used for the introgression of resistance into wine grapes (Vitis vinifera L.. A QTL analysis revealed a dominant gene Rpv12 that explained 79% of the phenotypic variance for downy mildew resistance and was inherited independently of other resistance genes. A Mendelian component of resistance-a hypersensitive response in leaves challenged with P. viticola-was mapped in an interval of 0.2 cM containing an array of coiled-coil NB-LRR genes on chromosome 14. We sequenced 10-kb genic regions in the Rpv12(+ haplotype and identified polymorphisms in 12 varieties of V. vinifera using next-generation sequencing. The combination of two SNPs in single-copy genes flanking the NB-LRR cluster distinguished the resistant haplotype from all others found in 200 accessions of V. vinifera, V. amurensis, and V. amurensis x V. vinifera crosses. The Rpv12(+ haplotype is shared by 15 varieties, the most ancestral of which are the century-old 'Zarja severa' and 'Michurinets'. Before this knowledge, the chromosome segment around Rpv12(+ became introgressed, shortened, and pyramided with another downy mildew resistance gene from North American grapevines (Rpv3 only by phenotypic selection. Rpv12(+ has an additive effect with Rpv3(+ to protect vines against natural infections, and confers foliar resistance to strains that are virulent on Rpv3(+ plants.

  12. QTL identification in an interspecific grapevine cross segregating for resistance to Powdery Mildew, Downy Mildew, Black Rot, and Phylloxera

    Science.gov (United States)

    Grapevine is a highly heterozygous plant with a complex genetic background. Here, we report the use of an F1 family (N = 125) from a cross of MN1264 × MN1246 made in 2010. The cross contains at least six Vitis species in its ancestry and segregates for resistance to powdery mildew (Erysiphe necator)...

  13. Molecular detection of Peronospora variabilis in quinoa seed and phylogeny of the quinoa downy mildew pathogen in South America and the United States.

    Science.gov (United States)

    Testen, Anna L; del Mar Jiménez-Gasco, María; Ochoa, José B; Backman, Paul A

    2014-04-01

    Quinoa (Chenopodium quinoa) is an important export of the Andean region, and its key disease is quinoa downy mildew, caused by Peronospora variabilis. P. variabilis oospores can be seedborne and rapid methods to detect seedborne P. variabilis have not been developed. In this research, a polymerase chain reaction (PCR)-based detection method was developed to detect seedborne P. variabilis and a sequencing-based method was used to validate the PCR-based method. P. variabilis was detected in 31 of 33 quinoa seed lots using the PCR-based method and in 32 of 33 quinoa seed lots using the sequencing-based method. Thirty-one of the quinoa seed lots tested in this study were sold for human consumption, with seed originating from six different countries. Internal transcribed spacer (ITS) and cytochrome c oxidase subunit 2 (COX2) phylogenies were examined to determine whether geographical differences occurred in P. variabilis populations originating from Ecuador, Bolivia, and the United States. No geographical differences were observed in the ITS-derived phylogeny but the COX2 phylogeny indicated that geographical differences existed between U.S. and South American samples. Both ITS and COX2 phylogenies supported the existence of a Peronospora sp., distinct from P. variabilis, that causes systemic-like downy mildew symptoms on quinoa in Ecuador. The results of these studies allow for a better understanding of P. variabilis populations in South America and identified a new causal agent for quinoa downy mildew. The PCR-based seed detection method allows for the development of P. variabilis-free quinoa seed, which may prove important for management of quinoa downy mildew.

  14. Identification and characterization of potential NBS-encoding resistance genes and induction kinetics of a putative candidate gene associated with downy mildew resistance in Cucumis

    Directory of Open Access Journals (Sweden)

    Wan Hongjian

    2010-08-01

    Full Text Available Abstract Background Due to the variation and mutation of the races of Pseudoperonospora cubensis, downy mildew has in recent years become the most devastating leaf disease of cucumber worldwide. Novel resistance to downy mildew has been identified in the wild Cucumis species, C. hystrix Chakr. After the successful hybridization between C. hystrix and cultivated cucumber (C. sativus L., an introgression line (IL5211S was identified as highly resistant to downy mildew. Nucleotide-binding site and leucine-rich repeat (NBS-LRR genes are the largest class of disease resistance genes cloned from plant with highly conserved domains, which can be used to facilitate the isolation of candidate genes associated with downy mildew resistance in IL5211S. Results Degenerate primers that were designed based on the conserved motifs in the NBS domain of resistance (R proteins were used to isolate NBS-type sequences from IL5211S. A total of 28 sequences were identified and named as cucumber (C. sativus = CS resistance gene analogs as CSRGAs. Polygenetic analyses separated these sequences into four different classes. Quantitative real-time polymerase chain reaction (qRT-PCR analysis showed that these CSRGAs expressed at different levels in leaves, roots, and stems. In addition, introgression from C. hystrix induced expression of the partial CSRGAs in cultivated cucumber, especially CSRGA23, increased four-fold when compared to the backcross parent CC3. Furthermore, the expression of CSRGA23 under P. cubensis infection and abiotic stresses was also analyzed at different time points. Results showed that the P. cubensis treatment and four tested abiotic stimuli, MeJA, SA, ABA, and H2O2, triggered a significant induction of CSRGA23 within 72 h of inoculation. The results indicate that CSRGA23 may play a critical role in protecting cucumber against P. cubensis through a signaling the pathway triggered by these molecules. Conclusions Four classes of NBS-type RGAs were

  15. Differential recognition of highly divergent downy mildew avirulence gene alleles by RPP1 resistance genes from two Arabidopsis lines.

    Science.gov (United States)

    Rehmany, Anne P; Gordon, Anna; Rose, Laura E; Allen, Rebecca L; Armstrong, Miles R; Whisson, Stephen C; Kamoun, Sophien; Tyler, Brett M; Birch, Paul R J; Beynon, Jim L

    2005-06-01

    The perception of downy mildew avirulence (Arabidopsis thaliana Recognized [ATR]) gene products by matching Arabidopsis thaliana resistance (Recognition of Peronospora parasitica [RPP]) gene products triggers localized cell death (a hypersensitive response) in the host plant, and this inhibits pathogen development. The oomycete pathogen, therefore, is under selection pressure to alter the form of these gene products to prevent detection. That the pathogen maintains these genes indicates that they play a positive role in pathogen survival. Despite significant progress in cloning plant RPP genes and characterizing essential plant components of resistance signaling pathways, little progress has been made in identifying the oomycete molecules that trigger them. Concluding a map-based cloning effort, we have identified an avirulence gene, ATR1NdWsB, that is detected by RPP1 from the Arabidopsis accession Niederzenz in the cytoplasm of host plant cells. We report the cloning of six highly divergent alleles of ATR1NdWsB from eight downy mildew isolates and demonstrate that the ATR1NdWsB alleles are differentially recognized by RPP1 genes from two Arabidopsis accessions (Niederzenz and Wassilewskija). RPP1-Nd recognizes a single allele of ATR1NdWsB; RPP1-WsB also detects this allele plus three additional alleles with divergent sequences. The Emco5 isolate expresses an allele of ATR1NdWsB that is recognized by RPP1-WsB, but the isolate evades detection in planta. Although the Cala2 isolate is recognized by RPP1-WsA, the ATR1NdWsB allele from Cala2 is not, demonstrating that RPP1-WsA detects a novel ATR gene product. Cloning of ATR1NdWsB has highlighted the presence of a highly conserved novel amino acid motif in avirulence proteins from three different oomycetes. The presence of the motif in additional secreted proteins from plant pathogenic oomycetes and its similarity to a host-targeting signal from malaria parasites suggest a conserved role in pathogenicity.

  16. Identification of downy mildew resistance gene candidates by positional cloning in maize (Zea mays subsp. mays; Poaceae)1

    Science.gov (United States)

    Kim, Jae Yoon; Moon, Jun-Cheol; Kim, Hyo Chul; Shin, Seungho; Song, Kitae; Kim, Kyung-Hee; Lee, Byung-Moo

    2017-01-01

    Premise of the study: Positional cloning in combination with phenotyping is a general approach to identify disease-resistance gene candidates in plants; however, it requires several time-consuming steps including population or fine mapping. Therefore, in the present study, we suggest a new combined strategy to improve the identification of disease-resistance gene candidates. Methods and Results: Downy mildew (DM)–resistant maize was selected from five cultivars using a spreader row technique. Positional cloning and bioinformatics tools were used to identify the DM-resistance quantitative trait locus marker (bnlg1702) and 47 protein-coding gene annotations. Eventually, five DM-resistance gene candidates, including bZIP34, Bak1, and Ppr, were identified by quantitative reverse-transcription PCR (RT-PCR) without fine mapping of the bnlg1702 locus. Conclusions: The combined protocol with the spreader row technique, quantitative trait locus positional cloning, and quantitative RT-PCR was effective for identifying DM-resistance candidate genes. This cloning approach may be applied to other whole-genome-sequenced crops or resistance to other diseases. PMID:28224059

  17. Antisporulant Activity of Watery Extracts of Plants against Sclerospora graminicola Causing Downy Mildew Disease of Pearl Millet

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    S. A. Deepak

    2007-01-01

    Full Text Available Watery extracts of forty plant species commonly growing in across India have been screened for antisporulant activity against Sclerospora graminicola (Sacc. Schroet., the causative agent of pearl millet downy mildew. The collection represented 38 genera of 30 families. The extracts of thirteen species did not show any effect, whereas the activity of extracts of Allium sativum, Clematis gouriana, Evolvulus alsinoides, Mimusops elengi, Parthenium hysterophorus, Piper nigrum and Tagetes erecta were commensurable to that of marketed botanical fungicides and Mikal 70 wp. The crude extracts of 12 species (Agave americana, Aloe vera, Artemisia parviflora, Citrus limon, Citrus sinensis, Eucalyptus globosus, Euphorbia hirta, Leucas aspera, Murraya koenigi, Ocimum sanctum, Santalum album and Zingiber offinale completely inhibited the zoosprorangium formation while in the case of remaining 8 plants the crude extracts reduced only partially the sporulation. The antisporulant activity of commercialised Azadirachta preparation (Nutri-Neem was more pronounced than that of Reynutria based one (Milsana and Sabadilla (veratrin, however, these botanical preparations held off synthetic fungicides and the most active watery extracts.

  18. Lactuca saligna, a non-host for lettuce downy mildew ( Bremia lactucae), harbors a new race-specific Dm gene and three QTLs for resistance.

    Science.gov (United States)

    Jeuken, M.; Lindhout, P.

    2002-08-01

    Lactuca sativa (lettuce) is susceptible to Bremia lactucae (downy mildew). In cultivated and wild Lactuca species, Dm genes have been identified that confer race-specific resistance. However, these genes were soon rendered ineffective by adaptation of the pathogen. Lactuca saligna (wild lettuce) is resistant to all downy mildew races and can be considered as a non-host. Therefore, L. saligna might be an alternative source for a more-durable resistance to downy mildew in lettuce. In order to analyze this resistance, we have developed an F(2) population based on a resistant L. saligna x susceptible L. sativa cross. This F(2) population was fingerprinted with AFLP markers and tested for resistance to two Bremia races NL14 and NL16. The F(2) population showed a wide and continuous range of resistance levels from completely resistant to completely susceptible. By comparison of disease tests, we observed a quantitative resistance against both Bremia races as well as a race-specific resistance to Bremia race NL16 and not to NL14. QTL mapping revealed a qualitative gene ( R39) involved in the race-specific resistance and three QTLs ( RBQ1, RBQ2 and RBQ3) involved in the quantitative resistance. The qualitative gene R39 is a dominant gene that gives nearly complete resistance to race NL16 in L. saligna CGN 5271 and therefore it showed features similar to Dm genes. The three QTLs explained 51% of the quantitative resistance against NL14, which indicated that probably only the major QTLs have been detected in this F(2) population. The perspectives for breeding for durable resistance are discussed.

  19. Molecular cloning of a coiled-coil-nucleotide-binding-site-leucine-rich repeat gene from pearl millet and its expression pattern in response to the downy mildew pathogen.

    Science.gov (United States)

    Veena, Mariswamy; Melvin, Prasad; Prabhu, Sreedhara Ashok; Shailasree, Sekhar; Shetty, Hunthrike Shekar; Kini, Kukkundoor Ramachandra

    2016-03-01

    Downy mildew caused by Sclerospora graminicola is a devastating disease of pearl millet. Based on candidate gene approach, a set of 22 resistance gene analogues were identified. The clone RGPM 301 (AY117410) containing a partial sequence shared 83% similarity to rice R-proteins. A full-length R-gene RGA RGPM 301 of 3552 bp with 2979 bp open reading frame encoding 992 amino acids was isolated by the degenerate primers and rapid amplification of cDNA ends polymerase chain reaction (RACE-PCR) approach. It had a molecular mass of 113.96 kDa and isoelectric point (pI) of 8.71. The sequence alignment and phylogenetic analysis grouped it to a non-TIR NBS LRR group. The quantitative real-time PCR (qRT-PCR) analysis revealed higher accumulation of the transcripts following inoculation with S. graminicola in the resistant cultivar (IP18296) compared to susceptible cultivar (7042S). Further, significant induction in the transcript levels were observed when treated with abiotic elicitor β-aminobutyric acid (BABA) and biotic elicitor Pseudomonas fluorescens. Exogenous application of phytohormones jasmonic acid or salicylic acid also up-regulated the expression levels of RGA RGPM 301. The treatment of cultivar IP18296 with mitogen-activated protein kinase (MPK) inhibitors (PD98059 and U0126) suppressed the levels of RGA RGPM 301. A 3.5 kb RGA RGPM 301 which is a non-TIR NBS-LRR protein was isolated from pearl millet and its up-regulation during downy mildew interaction was demonstrated by qRT-PCR. These studies indicate a role for this RGA in pearl millet downy mildew interaction.

  20. Identification and introgression of QTLs implicated in resistance to sorghum downy mildew (Peronosclerospora sorghi (Weston and Uppal) C. G. Shaw) in maize through marker-assisted selection

    Indian Academy of Sciences (India)

    H. C. Lohithaswa; K. Jyothi; K. R. Sunil Kumar; Puttaramanaik; Shailaja Hittalmani

    2015-12-01

    Sorghum downy mildew caused by Peronosclerospora sorghi is a major disease of maize and resistance is under the control of polygenes which necessitated identification of quantitative-trait loci (QTLs) for initiating marker-assisted introgression of resistant QTLs in elite susceptible inbred lines. In the present study, QTLs for sorghum downy mildew (SDM) resistance in maize were identified based on cosegregation with linked simple sequence repeats in 185 F2 progeny from a cross between susceptible (CM500-19) and resistant (MAI105) parents. F3 families were screened in the National Sorghum Downy Mildew Screening Nursery during 2010 and 2011. High heritability was observed for the disease reaction. The final map generated using 87 SSR markers had 10 linkage groups, spanning a length of 1210.3 cM. Although, we used only 87 SSR markers for mapping, the per cent of genome within 20 cM to the nearest marker was 88.5. Three putative QTLs for SDM resistance were located on chromosomes 3 (bin 3.01), 6 (bin 6.01) and 2 (bin 2.02) using composite interval mapping. The locus on chromosome 3 had a major effect and explained up to 12.6% of the phenotypic variation. The other two QTLs on chromosomes 6 and 2 had minor effects with phenotypic variation of 7.1 and 2%. The three QTLs appeared to have additive effects on resistance. The QTLs on chromosomes 3 and 6 were successfully used in the marker-assisted selection programme for introgression of resistance to SDM in eight susceptible maize lines.

  1. Exogenous Trehalose Treatment Enhances the Activities of Defense-Related Enzymes and Triggers Resistance against Downy Mildew Disease of Pearl Millet

    Science.gov (United States)

    Govind, Sharathchandra R.; Jogaiah, Sudisha; Abdelrahman, Mostafa; Shetty, Hunthrike S.; Tran, Lam-Son P.

    2016-01-01

    In recent years, diverse physiological functions of various sugars are the subject of investigations. Their roles in signal transduction in plant responses to adverse biotic and abiotic stress conditions have become apparent, and growing scientific evidence has indicated that disaccharides like sucrose and trehalose mediate plant defense responses in similar way as those induced by elicitors against the pathogens. Trehalose is a well-known metabolic osmoregulator, stress-protectant and non-reducing disaccharide existing in a variety of organisms, including fungi, bacteria, and plants. Commercially procured trehalose was applied to seeds of susceptible pearl millet (Pennisetum glaucum) cultivar “HB3,” and tested for its ability to reduce downy mildew disease incidence by induction of resistance. Seed treatment with trehalose at 200 mM for 9 h recorded 70.25% downy mildew disease protection, followed by those with 100 and 50 mM trehalose which offered 64.35 and 52.55% defense, respectively, under greenhouse conditions. Furthermore, under field conditions treatment with 200 mM trehalose for 9 h recorded 67.25% downy mildew disease protection, and reduced the disease severity to 32.75% when compared with untreated control which displayed 90% of disease severity. Trehalose did not affect either sporangial formation or zoospore release from sporangia, indicating that the reduction in disease incidence was not due to direct inhibition but rather through induction of resistance responses in the host. Additionally, trehalose was shown to enhance the levels of polyphenol oxidase, phenylalanine ammonia lyase, and peroxidase, which are known as markers of both biotic and abiotic stress responses. Our study shows that osmoregulators like trehalose could be used to protect plants against pathogen attacks by seed treatment, thus offering dual benefits of biotic and abiotic stress tolerance. PMID:27895647

  2. Analyzing Lettuce Downy Mildew with Fourier Transform Infrared Spectroscopy%莴苣霜霉病的傅里叶变换红外光谱分析

    Institute of Scientific and Technical Information of China (English)

    杨春艳; 刘飞; 梁云峰; 吉恒

    2014-01-01

    Fourier transform infrared spectroscopy (FTIR) was used to obtain the spectra of leaf, edible stem, taproot and fibrous roots of normal and downy mildew lettuce plants at the adult stage. The results showed that for normal and downy mildew lettuce plants, the main components of leaves and edible stem were protein, carbohydrates and lipids. For fibrous roots, the main components were cellulose and lignin. For taproots of normal plants,the main components were cellulose, lignin and lipids, but cellulose, lignin and protein were the main components of downy mildew plants. Relative to normal plants,the structure of carbohydrates and protein in leaves was changed. The relative content of lipids and carbohydrates increased. Protein and lipids in edible stems was decreased while carbohydrates was increased. Cellulose and lignin in taproot and fibrous roots were decreased. The ratio of the relative content of lignin to that of cellulose in mildew plants was higher than that in normal plants. It is indicated that FTIR could be used to study effects of the downy mildew on different parts of the lettuce, providing spectroscopy information for studying lettuce downy mildew.%利用傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FTIR)技术测定了成株期莴苣(Lactuca sativa L.var.angustana Irish)正常植株和霜霉病植株的叶片、食用茎、主根和须根4个部位的红外光谱。结果表明,两种植株叶片和食用茎中的主要成分均为蛋白质、多糖和脂类物质,须根中的主要物质成分为纤维素和木质素,正常植株主根中的主要成分是纤维素、木质素和脂类物质,霜霉病主根中的主要成分是纤维素、木质素和蛋白质;与正常植株相比,霜霉病植株叶片中蛋白质和多糖的组成或结构发生了变化,且脂类和多糖类物质相对含量有所增加,食用茎中蛋白质和脂类物质的相对含量均低于正常植株,而多糖类物质相对

  3. A transgenic mutant of Lactuca sativa (lettuce) with a T-DNA tightly linked to loss of downy mildew resistance.

    Science.gov (United States)

    Okubara, P A; Arroyo-Garcia, R; Shen, K A; Mazier, M; Meyers, B C; Ochoa, O E; Kim, S; Yang, C H; Michelmore, R W

    1997-11-01

    One hundred and ninety-two independent primary transformants of lettuce cv. Diana were obtained by co-cultivation with Agrobacterium tumefaciens carrying constructs containing maize Ac transposase and Ds. R2 families were screened for mutations at four genes (Dm) for resistance to downy mildew. One family, designated dm3t524, had lost resistance to an isolate of Bremia lactucae expressing the avirulence gene Avr3. Loss of resistance segregated as a single recessive allele of Dm3. The mutation was not due to a large deletion as all molecular markers flanking Dm3 were present. Loss of Dm3 activity co-segregated with a T-DNA from which Ds had excised. Genomic DNA flanking the right border of this T-DNA was isolated by inverse polymerase chain reaction. This genomic sequence was present in four to five copies in wild-type cv. Diana. One copy was missing in all eight deletion mutants of Dm3 and altered in dm3t524, indicating tight physical linkage to Dm3. Three open reading frames (ORFs) occurred in a 6.6-kb region flanking the insertion site; however, expression of these ORFs was not detected. No similarities were detected between these ORFs and resistance genes cloned from other species. Transgenic complementation with 11-to 27-kb genomic fragments of Diana spanning the insertion site failed to restore Dm3 function to two ethyl methanesulfonate (EMS)-induced mutants of Dm3 or to cv. Cobham Green, which naturally lacks Dm3 activity. Therefore, either the T-DNA inserted extremely close to, but not within, Dm3 and the mutation may have been caused by secondary movement of Ds, or Dm3 activity is encoded by a gene extending beyond the fragments used for complementation.

  4. Preliminary Trial of 11 New Hybrid Maize Genotype to The Resistance on Java Downy Mildew (Peronosclerospora maydis

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    Budi Setyawan

    2016-04-01

    Full Text Available Maize or corn (Zea mays L. belongs to the family of grasses (Poaceae.  Maize is grown globally and one of the most important cereal crop in the world.  In many countries, corn is the main agricultural crop, and are used as food, feed and industrial raw materials. Together with rice and wheat, corn included in the cereals that provide about 65% carbohydrates and 50% protein that humans need. For this purpose, many developing countries, especially in Asia and Africa are in a strong effort to increase their corn yields through the use of better seeds.  Although in Indonesia, corn is the second important food crop after rice, however, with the rapid growth of the livestock industry, corn is a major component (60% in feed ingredient.  It is estimated that more than 55% of the corn used for feed in Indonesia.  Java Downy Mildew (Peronosclerospora maydis is the main disease that is concerned by maize corn growers. This disease often resulting in substantial losses for farmers, even reach 100% in susceptible genotypes.  Therefore trial on 11 new prospective hybrids was conducted with the expectation that they can be classified in the criteria “less resistant or higher” according to the criteria of modified Reid (2005.  Of the 11 new hybrids, 3 new hybrids (27.3% classified in the criteria “very resistant”, 4 new hybrids (36.4% classified in the criteria “resistant”, 2 new hybrid (18.2% classified in the criteria “less resistant”, and 2 other new hybrids (18.2% classified in the criteria “less susceptible”.

  5. Over-expression of VvWRKY1 in grapevines induces expression of jasmonic acid pathway-related genes and confers higher tolerance to the downy mildew.

    Directory of Open Access Journals (Sweden)

    Chloé Marchive

    Full Text Available Most WRKY transcription factors activate expression of defence genes in a salicylic acid- and/or jasmonic acid-dependent signalling pathway. We previously identified a WRKY gene, VvWRKY1, which is able to enhance tolerance to fungal pathogens when it is overexpressed in tobacco. The present work analyzes the effects of VvWRKY1 overexpression in grapevine. Microarray analysis showed that genes encoding defence-related proteins were up-regulated in the leaves of transgenic 35S::VvWRKY1 grapevines. Quantitative RT-PCR analysis confirmed that three genes putatively involved in jasmonic acid signalling pathway were overexpressed in the transgenic grapes. The ability of VvWRKY1 to trans-activate the promoters of these genes was demonstrated by transient expression in grape protoplasts. The resistance to the causal agent of downy mildew, Plasmopara viticola, was enhanced in the transgenic plants. These results show that VvWRKY1 can increase resistance of grapevine against the downy mildew through transcriptional reprogramming leading to activation of the jasmonic acid signalling pathway.

  6. Specific in planta recognition of two GKLR proteins of the downy mildew Bremia lactucae revealed in a large effector screen in lettuce.

    Science.gov (United States)

    Stassen, Joost H M; den Boer, Erik; Vergeer, Pim W J; Andel, Annemiek; Ellendorff, Ursula; Pelgrom, Koen; Pel, Mathieu; Schut, Johan; Zonneveld, Olaf; Jeuken, Marieke J W; Van den Ackerveken, Guido

    2013-11-01

    Breeding lettuce (Lactuca sativa) for resistance to the downy mildew pathogen Bremia lactucae is mainly achieved by introgression of dominant downy mildew resistance (Dm) genes. New Bremia races quickly render Dm genes ineffective, possibly by mutation of recognized host-translocated effectors or by suppression of effector-triggered immunity. We have previously identified 34 potential RXLR(-like) effector proteins of B. lactucae that were here tested for specific recognition within a collection of 129 B. lactucae-resistant Lactuca lines. Two effectors triggered a hypersensitive response: BLG01 in 52 lines, predominantly L. saligna, and BLG03 in two L. sativa lines containing Dm2 resistance. The N-terminal sequences of BLG01 and BLG03, containing the signal peptide and GKLR variant of the RXLR translocation motif, are not required for in planta recognition but function in effector delivery. The locus responsible for BLG01 recognition maps to the bottom of lettuce chromosome 9, whereas recognition of BLG03 maps in the RGC2 cluster on chromosome 2. Lactuca lines that recognize the BLG effectors are not resistant to Bremia isolate Bl:24 that expresses both BLG genes, suggesting that Bl:24 can suppress the triggered immune responses. In contrast, lettuce segregants displaying Dm2-mediated resistance to Bremia isolate Bl:5 are responsive to BLG03, suggesting that BLG03 is a candidate Avr2 protein.

  7. Detection of Verticillium wilt of olive trees and downy mildew of opium poppy using hyperspectral and thermal UAV imagery

    Science.gov (United States)

    Calderón Madrid, Rocío; Navas Cortés, Juan Antonio; Montes Borrego, Miguel; Landa del Castillo, Blanca Beatriz; Lucena León, Carlos; Jesús Zarco Tejada, Pablo

    2014-05-01

    The present study explored the use of high-resolution thermal, multispectral and hyperspectral imagery as indicators of the infections caused by Verticillium wilt (VW) in olive trees and downy mildew (DM) in opium poppy fields. VW, caused by the soil-borne fungus Verticillium dahliae, and DM, caused by the biotrophic obligate oomycete Peronospora arborescens, are the most economically limiting diseases of olive trees and opium poppy, respectively, worldwide. V. dahliae infects the plant by the roots and colonizes its vascular system, blocking water flow and eventually inducing water stress. P. arborescens colonizes the mesophyll, appearing the first symptoms as small chlorotic leaf lesions, which can evolve to curled and thickened tissues and systemic infections that become deformed and necrotic as the disease develops. The work conducted to detect VW and DM infection consisted on the acquisition of time series of airborne thermal, multispectral and hyperspectral imagery using 2-m and 5-m wingspan electric Unmanned Aerial Vehicles (UAVs) in spring and summer of three consecutive years (2009 to 2011) for VW detection and on three dates in spring of 2009 for DM detection. Two 7-ha commercial olive orchards naturally infected with V. dahliae and two opium poppy field plots artificially infected by P. arborescens were flown. Concurrently to the airborne campaigns, olive orchards and opium poppy fields were assessed "in situ" to assess actual VW severity and DM incidence. Furthermore, field measurements were conducted at leaf and crown level. The field results related to VW detection showed a significant increase in crown temperature (Tc) minus air temperature (Ta) and a decrease in leaf stomatal conductance (G) as VW severity increased. This reduction in G was associated with a significant increase in the Photochemical Reflectance Index (PRI570) and a decrease in chlorophyll fluorescence. DM asymptomatic leaves showed significantly higher NDVI and lower green/red index

  8. Incidence of downy mildew Plasmopara viticola (Berk. et Curtis ex. de Bary Berl. et de Toni in Terceira island, Azores

    Directory of Open Access Journals (Sweden)

    Matej Zorman

    2008-12-01

    Full Text Available Downy mildew is one of the most economically important disease affecting vine production in Terceira island, Azores. By its incidence, frequency and quantity of pathogens, supported with favourable temperate humid climate conditions, this disease is difficult to control in terms of sustainable integrated plant protection policy. The objectives of INTERFRUTA project were to determine the incidence of the disease, to better understand it and to adopt an adequate forecasting model with necessary adjustments to predict the disease appearance and its in-time integrated plant protection control measures. Plasmopara viticola was directly observed in two weeks time periods on seven representative vineyards at different altitudes. Three of the monitored plots were established during study inside one plantation. Incidence was registered as result of visual symptoms in percentage, where 10% of plants in each vineyard were observed. Seasonal evolution of the disease was studied in one of the wine producing area.O Míldio é uma das doenças que mais afecta a vinha, na ilha Terceira, Açores. É uma doença fúngica de difícil controlo, pela sua incidência e frequência de aparecimento. Os objectivos do projecto INTERFRUTA II foram determinar a incidência desta doença para melhorar o conhecimento sobre esta e adoptar e validar um modelo matemático adequado à previsão do aparecimento da doença de modo a permitir a aplicação de medidas de protecção integrada. A evolução do míldio foi acompanhada em sete parcelas de vinha, da área vitivinícola dos Biscoitos, através da observação visual de folhas. Numa das parcelas, três dos talhões não foram tratados para servirem de controlo. Em cada parcela foram observadas 10% das plantas, tendo sido registada a percentagem de plantas com sintomas visuais da presença de míldio.

  9. Proteome of Plasmopara viticola-infected Vitis vinifera provides insights into grapevine Rpv1/Rpv3 pyramided resistance to downy mildew.

    Science.gov (United States)

    Nascimento-Gavioli, Maria Carolina Andrade; Agapito-Tenfen, Sarah Zanon; Nodari, Rubens Onofre; Welter, Leocir José; Sanchez Mora, Fernando David; Saifert, Luciano; da Silva, Aparecido Lima; Guerra, Miguel Pedro

    2017-01-16

    Grapevine is one of the major fruit crops worldwide and requires phytochemical use due to susceptibility to numerous pests, including downy mildew. The pyramiding of previous identified QTL resistance regions allows selection of genotypes with combined resistance loci in order to build up sustainable resistance. This study investigates resistance response of pyramided plants containing Rpv1 and Rpv3 loci to Plasmopara viticola infection process. Phenotypic characterization showed complete resistance and lack of necrotic hypersensitive response spots. Principal Component Analysis revealed infected 96hpi (hours post-inoculation) samples with the most distant proteomes of the entire dataset, followed by the proteome of infected 48hpi samples. Quantitative and qualitative protein differences observed using 2-DE gels coupled to nanoHPLC-ESI-MS/MS analysis showed a lack of transient breakdown in defense responses (biphasic modulation) accompanying the onset of disease. Forty-one proteins were identified, which were mainly included into functional categories of redox and energy metabolism. l-ascorbate degradation pathway was the major altered pathway and suggests up-regulation of anti-oxidant metabolism in response to apoplastic oxidative burst after infection. Overall, these data provide new insights into molecular basis of this incompatible interaction and suggests several targets that could potentially be exploited to develop new protection strategies against this pathogen. This study provide new insights into the molecular basis of incompatible interaction between Plasmopara viticola and pyramided Rpv1/Rpv3 grapevine and suggests several targets that could potentially be exploited to develop new protection strategies against this pathogen. This is the first proteomic characterization of resistant grapevine available in the literature and it presents contrasting proteomic profiles of that of susceptible plants. The resistance against downy mildew in grapevine has been

  10. Study on Fungicide Screening for Un -pollutive Control of Grape Downy Mildew and Its Control Techniques%葡萄霜霉病无公害防治药剂筛选及控害技术研究

    Institute of Scientific and Technical Information of China (English)

    周步海; 李红阳; 陈志谊; 周加春; 杨华; 张俊喜

    2011-01-01

    The control effects of 6 commonly - used effective fungicide varieties (Dimethomorph, Azoxystrobin and so on) against grape downy mildew in the field were tested. The results indicated that Dimethomorph, Azoxystrobin and Propineb had better prevention and control effects on the occurrence of grape downy mildew. The other 3 kinds of fungicides could be used as the alternative fungicides in order to delay the resistance of its pathogen to the fungicides. Simultaneously, according to the occurrence characteristics of grape downy mildew, the integrated prevention and control techniques of this disease were put forward.%选取烯酰吗啉、阿米西达等6种对葡萄霜霉病有效的常用杀菌剂品种进行田间试验,结果表明:阿米西达、丙森锌2种药剂对预防和控制霜霉病的发生有较好的效果,可推荐使用;另外4种药剂可在控害过程中作为轮换药剂,与其他农药搭配使用,以延缓病原菌抗药性的产生.同时针对病害发生特点对其综合防控技术进行了研究集成.

  11. The antagonistic strain Bacillus subtilis UMAF6639 also confers protection to melon plants against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses.

    Science.gov (United States)

    García-Gutiérrez, Laura; Zeriouh, Houda; Romero, Diego; Cubero, Jaime; de Vicente, Antonio; Pérez-García, Alejandro

    2013-05-01

    Biological control of plant diseases has gained acceptance in recent years. Bacillus subtilis UMAF6639 is an antagonistic strain specifically selected for the efficient control of the cucurbit powdery mildew fungus Podosphaera fusca, which is a major threat to cucurbits worldwide. The antagonistic activity relies on the production of the antifungal compounds iturin and fengycin. In a previous study, we found that UMAF6639 was able to induce systemic resistance (ISR) in melon and provide additional protection against powdery mildew. In the present work, we further investigated in detail this second mechanism of biocontrol by UMAF6639. First, we examined the signalling pathways elicited by UMAF6639 in melon plants, as well as the defence mechanisms activated in response to P. fusca. Second, we analysed the role of the lipopeptides produced by UMAF6639 as potential determinants for ISR activation. Our results demonstrated that UMAF6639 confers protection against cucurbit powdery mildew by activation of jasmonate- and salicylic acid-dependent defence responses, which include the production of reactive oxygen species and cell wall reinforcement. We also showed that surfactin lipopeptide is a major determinant for stimulation of the immune response. These results reinforce the biotechnological potential of UMAF6639 as a biological control agent.

  12. Disentangling Peronospora on Papaver: phylogenetics, taxonomy, nomenclature and host range of downy mildew of opium poppy (Papaver somniferum and related species.

    Directory of Open Access Journals (Sweden)

    Hermann Voglmayr

    Full Text Available Based on sequence data from ITS rDNA, cox1 and cox2, six Peronospora species are recognised as phylogenetically distinct on various Papaver species. The host ranges of the four already described species P. arborescens, P. argemones, P. cristata and P. meconopsidis are clarified. Based on sequence data and morphology, two new species, P. apula and P. somniferi, are described from Papaver apulum and P. somniferum, respectively. The second Peronospora species parasitizing Papaver somniferum, that was only recently recorded as Peronospora cristata from Tasmania, is shown to represent a distinct taxon, P. meconopsidis, originally described from Meconopsis cambrica. It is shown that P. meconopsidis on Papaver somniferum is also present and widespread in Europe and Asia, but has been overlooked due to confusion with P. somniferi and due to less prominent, localized disease symptoms. Oospores are reported for the first time for P. meconopsidis from Asian collections on Papaver somniferum. Morphological descriptions, illustrations and a key are provided for all described Peronospora species on Papaver. cox1 and cox2 sequence data are confirmed as equally good barcoding loci for reliable Peronospora species identification, whereas ITS rDNA does sometimes not resolve species boundaries. Molecular phylogenetic data reveal high host specificity of Peronospora on Papaver, which has the important phytopathological implication that wild Papaver spp. cannot play any role as primary inoculum source for downy mildew epidemics in cultivated opium poppy crops.

  13. [Chromosomal structure of the hybrids between Allium cepa L. and Allium fistulosum L. with relative resistance to downy mildew based on in situ hybridization].

    Science.gov (United States)

    Budylin, M V; Kan, L Iu; Romanov, V S; Khrustaleva, L I

    2014-04-01

    Genomic in situ hybridization (GISH) was used for a chromosomal composition study of the later generations of interspecific hybrids between A. cepa L. and A. fistulosum L., which are relatively resistant to downy mildew (peronosporosis). GISH revealed that F2 hybrids, which did not produce seeds, were triploids (2n = 3x = 24) with 24 chromosomes and possessed in their compliments 16 chromosomes of A. fistulosum L. and eight chromosomes of A. cepa L. or eight chromosomes of A. fistulosum L. and 16 chromosomes of A. cepa L. The advanced F5 hybrid, which produced few seeds, was amphidiploid with 32 chromosomes. BC1F5 hybrid was triploid with eight chromosomes of A. fistulosum L. and 16 chromosomes of A. cepa L., which did not produce seeds. BC2 (BC1F5) plant was amphidiploid that possessed 4 recombinant chromosomes and produced few seeds. GISH results point to 2n-gametes formation in macro- and microsporogenesis of the hybrids. The mechanism of 2n-gametes formation and the possibility of apomixes events in the backcrossing progeny are discussed.

  14. The Control Effect Comparison of Six Kinds of Fungicides on the Downy Mildew of Tangshan Autumn Cucumber%6种药剂对唐山秋瓜霜霉病的防治效果比较

    Institute of Scientific and Technical Information of China (English)

    吴志会; 韩晓清; 张尚卿; 彭学文

    2014-01-01

    为确定防治唐山秋瓜霜霉病的最佳药剂,以清水作对照,对6种供试药剂进行了防治效果比较试验。结果表明:6种药剂均对唐山秋瓜生长安全,且均对唐山秋瓜霜霉病具有一定的防治效果,其中,阿米西达(120 g/hm2)对唐山秋瓜霜霉病的防治效果始终在90%以上,防效最好,且药效持续时间最长;72%克露WP (540 g/hm2)和大生M-4580%WP (900 g/hm2)防效次之,对霜霉病的防治效果始终维持在80%以上。建议在生产上各供试药剂轮换交替使用,以延缓唐山秋瓜霜霉病抗药性的产生。%Taking clean water as the contrast, the control effects of six kinds of fungicides was tested to determine the best medicament to control downy mildew of Tangshan autumn cucumber.The results showed that six kinds of tested fungicides were safety to the growth of Tangshan autumn cucumber , and they all had a certain control effect on the Tangshan autumn cucumber downy mildew.Azoxystrobin (120 g/hm2) had the best control effect on the Tangshan autumn cucumber downy mildew , its control effect always above 90%, followed by 64% mancozeb 8%cymoxanil WP ( 540 g/hm2 ) and 80% mancozeb WP ( 900 g/hm2 ) , their control effect were always above 80%.It was suggested that all of the tested fungicides should be used altermately to delay the drug resistance of Tangshan autumn cucumber downy mildew in production.

  15. General and species-specific transcriptional responses to downy mildew infection in a susceptible (Vitis vinifera and a resistant (V. riparia grapevine species

    Directory of Open Access Journals (Sweden)

    Lovato Arianna

    2010-02-01

    Full Text Available Abstract Background Downy mildew is a destructive grapevine disease caused by Plasmopara viticola (Berk. and Curt. Berl. and de Toni, which can only be controlled by intensive fungicide treatments. Natural sources of resistance from wild grapevine (Vitis species are used in conventional breeding approaches, but the signals and effectors involved in resistance in this important crop species are not well understood. Results Early transcriptional changes associated with P. viticola infection in susceptible V. vinifera and resistant V. riparia plants were analyzed using the Combimatrix microarray platform. Transcript levels were measured 12 and 24 h post-inoculation, reflecting the time points immediately preceding the onset of resistance in V. riparia, as determined by microscopic analysis. Our data indicate that resistance in V. riparia is induced after infection, and is not based on differences in basal gene expression between the two species. The strong and rapid transcriptional reprogramming involves the induction of pathogenesis-related proteins and enzymes required for the synthesis of phenylpropanoid-derived compounds, many of which are also induced, albeit to a lesser extent, in V. vinifera. More interestingly, resistance in V. riparia also involves the specific modulation of numerous transcripts encoding components of signal transduction cascades, hypersensitive reaction markers and genes involved in jasmonate biosynthesis. The limited transcriptional modulation in V. vinifera represents a weak attempted defense response rather than the activation of compatibility-specific pathways. Conclusions Several candidate resistance genes were identified that could be exploited in future biotechnological approaches to increase disease resistance in susceptible grapevine species. Measurements of jasmonic acid and methyl jasmonate in infected leaves suggest that this hormone may also be involved in V. riparia resistance to P. viticola.

  16. General and species-specific transcriptional responses to downy mildew infection in a susceptible (Vitis vinifera) and a resistant (V. riparia) grapevine species

    Science.gov (United States)

    2010-01-01

    Background Downy mildew is a destructive grapevine disease caused by Plasmopara viticola (Berk. and Curt.) Berl. and de Toni, which can only be controlled by intensive fungicide treatments. Natural sources of resistance from wild grapevine (Vitis) species are used in conventional breeding approaches, but the signals and effectors involved in resistance in this important crop species are not well understood. Results Early transcriptional changes associated with P. viticola infection in susceptible V. vinifera and resistant V. riparia plants were analyzed using the Combimatrix microarray platform. Transcript levels were measured 12 and 24 h post-inoculation, reflecting the time points immediately preceding the onset of resistance in V. riparia, as determined by microscopic analysis. Our data indicate that resistance in V. riparia is induced after infection, and is not based on differences in basal gene expression between the two species. The strong and rapid transcriptional reprogramming involves the induction of pathogenesis-related proteins and enzymes required for the synthesis of phenylpropanoid-derived compounds, many of which are also induced, albeit to a lesser extent, in V. vinifera. More interestingly, resistance in V. riparia also involves the specific modulation of numerous transcripts encoding components of signal transduction cascades, hypersensitive reaction markers and genes involved in jasmonate biosynthesis. The limited transcriptional modulation in V. vinifera represents a weak attempted defense response rather than the activation of compatibility-specific pathways. Conclusions Several candidate resistance genes were identified that could be exploited in future biotechnological approaches to increase disease resistance in susceptible grapevine species. Measurements of jasmonic acid and methyl jasmonate in infected leaves suggest that this hormone may also be involved in V. riparia resistance to P. viticola. PMID:20167053

  17. Identification of Molecular Genetic Markers Tightly Linked to Downy Mildew Resistant Genes in Grape%与葡萄抗霜霉病基因紧密连锁的 分子遗传标记

    Institute of Scientific and Technical Information of China (English)

    罗素兰; 贺普超; 周鹏; 郑学勤

    2001-01-01

    Bulk segregant analysis (BSA), randomly amplified polymorphic DNA(RAPD) and sequence characterized amplified region (SCAR) methods were used to tag the downy mildew-resistant genes of grape with molecular markers. Parents and their 60 individuals of an F1 progeny resulting from a cross 88-110 between 83-4-96 (Vitis quinquangularis, downy mildew-resistant) and Muscat Rose (V. vinifera, downy mildew-susceptible), three F2 progenies resulting from three crosses of self-cross and inter-cross of 88-110 F1 seedlings, as well as another interspecific F1 hybrids of 88-84 cross [Xun-3 (V. quinquangularis, downy mildew-resistant)×Ugni Blanc (V. vinifera, downy mildew-susceptible)] and the wild grapes native to China were used for the study. Among 280 Operon primers, 160 gave distinct band patterns. One RAPD marker OPO06-1500 was tightly linked to a major gene resistant to Plasmopara viticola (RPv-1). Based on Mapmaker software analysis, the map distance between RPv-1 and OPO06-1500 was 1.7cM. Marker OPO06-1500 was cloned and sequenced. According to the sequence, two specific primers were designed to amplify all plant materials. RAPD marker was converted into SCAR marker (SCO06-1500). One distinct single band only in resistant plants was amplified, whose size was the same as that of the RAPD marker. The SCAR marker’s popularity was confirmed, and it could be used for the identification of hybrid resistant to P. viticola and will be potentially useful in the development of new resistant grape cultivars.%以种间杂交组合88-110[83-4-96(毛葡萄,抗霜霉病)×粉红玫瑰(欧洲葡萄,感霜霉病)]的F1代(60个单株)及其自交或互交所得的3个F2代为试材,应用BSA、RAPD和SCAR方法研究了葡萄抗霜霉病基因的分子标记。共筛选了280个Operon引物,其中160个引物扩增出了清晰的DNA条带,发现了RAPD标记OPO06-1500与葡萄抗霜霉病主效基因(RPv-1)紧密连锁,经Mapmarker软件连锁分析,OPO06

  18. Development and dissection of diagnostic SNP markers for the downy mildew resistance genes Pl Arg and Pl 8 and maker-assisted gene pyramiding in sunflower (Helianthus annuus L.).

    Science.gov (United States)

    Qi, L L; Talukder, Z I; Hulke, B S; Foley, M E

    2017-02-03

    Diagnostic DNA markers are an invaluable resource in breeding programs for successful introgression and pyramiding of disease resistance genes. Resistance to downy mildew (DM) disease in sunflower is mediated by Pl genes which are known to be effective against the causal fungus, Plasmopara halstedii. Two DM resistance genes, Pl Arg and Pl 8 , are highly effective against P. halstedii races in the USA, and have been previously mapped to the sunflower linkage groups (LGs) 1 and 13, respectively, using simple sequence repeat (SSR) markers. In this study, we developed high-density single nucleotide polymorphism (SNP) maps encompassing the Pl arg and Pl 8 genes and identified diagnostic SNP markers closely linked to these genes. The specificity of the diagnostic markers was validated in a highly diverse panel of 548 sunflower lines. Dissection of a large marker cluster co-segregated with Pl Arg revealed that the closest SNP markers NSA_007595 and NSA_001835 delimited Pl Arg to an interval of 2.83 Mb on the LG1 physical map. The SNP markers SFW01497 and SFW06597 delimited Pl 8 to an interval of 2.85 Mb on the LG13 physical map. We also developed sunflower lines with homozygous, three gene pyramids carrying Pl Arg , Pl 8 , and the sunflower rust resistance gene R 12 using the linked SNP markers from a segregating F2 population of RHA 340 (carrying Pl 8 )/RHA 464 (carrying Pl Arg and R 12 ). The high-throughput diagnostic SNP markers developed in this study will facilitate marker-assisted selection breeding, and the pyramided sunflower lines will provide durable resistance to downy mildew and rust diseases.

  19. Efeito de indutores no controle de míldio em Vitis labrusca Effect of elicitors in the control of downy mildew in Vitis labrusca

    Directory of Open Access Journals (Sweden)

    Regina Ceres Torres da Rosa

    2007-03-01

    to resource with the fungicide use aiming at its control. Aiming at to substitute the agrotóxico use it was evaluated in the cities of Are Vicente Férrer - PE (area 1, Natuba - PB (area 2 and Macaparana - PE (area 3 the effect of the induction of resistance promoted for DL- beta - aminobutyric acid (BABA, Agro-Mos (AM + Crop-set (Cs, Codavit (Cd and Ecolife (Ec was evaluated on grape variety 'Isabel'. Results have showed that AM + Cs was superior to the others treatments in reducing disease severity. In relation to efficiency control the AM + Cs treatment reduced disease severity in 37,46%, 35,97% and 18, 57% in the area 1, 2 and 3, respectively. The disease severity in the areas 1, 2, and 3, fitted the Y= e-3,36 . e-0,019t- (R= 0,66**, Y= 1/1 + 14,63 .e-0,037t (R= 0,84** and Y= e-4,13 . e- -0,034t (R= 0,62**, respectively. The severity of downy mildew in function of the time in the area 1, fit the gompertz model, except in the BABA treatment that was described by the equation logstic. In the area 2, a predominant model did not fit data from all treatments. The monomolecular model was described more frequently than others, in the treatments of area 3.

  20. Reaction of melon genotypes to the gummy stem blight and the downy mildew Reação de genótipos de melão ao crestamento gomoso e ao míldio

    Directory of Open Access Journals (Sweden)

    Gil R dos Santos

    2009-06-01

    Full Text Available The gummy stem blight (Didymella bryoniae and the downy mildew (Pseudoperonospora cubensis are two foremost melon (Cucumis melo diseases, considering their effects on yield and fruit quality. Despite the importance of such diseases, relatively few studies have been done so far on the identification of resistance sources to D. bryoniae and P. cubensis in Brazil. This work aimed at evaluating the resistance of commercial melon genotypes to the gummy stem blight and the downy mildew. Firstly, the most aggressive and representative D. bryoniae isolate was selected. Subsequently, the resistance of 86 melon genotypes to stem infection was studied upon greenhouse conditions by inoculating with the previously selected isolate. Afterwards, the resistance to mildew and leaf infection by D. bryoniae of 28 melon genotypes was evaluated in the field, under natural infection. In the greenhouse, all 86 melon genotypes were infected and showed stem infection symptoms caused by D. bryoniae four days after inoculation. Nevertheless, a significant variation on the resistance levels of the melon genotypes was found. Under field conditions and natural inoculation, genotypes Taslaki and Sary Juliabi were the most susceptible to leaf infection by D. bryoniae, significantly differing from the other genotypes. The lowest levels of susceptibility were identified in genotypes Perlita Busle S1, Valenciano Elíptico, Glaver, MR1, and 2526. All genotypes were susceptible to the downy mildew, albeit differing in susceptibility levels.O crestamento gomoso do caule (Didymella bryoniae e o míldio (Pseudoperonospora cubensis estão entre as principais doenças do meloeiro (Cucumis melo ocasionando redução da produtividade e da qualidade dos frutos. Apesar da importância dessas doenças, são poucos os trabalhos envolvendo a identificação de fontes de resistência a D. bryoniae e a P. cubensis no Brasil. O objetivo deste trabalho foi avaliar a resistência de gen

  1. Using SSH Technology to Identify Relevant Genes Resistant to Cucumber Downy Mildew%利用SSH技术鉴定黄瓜抗霜霉病相关基因

    Institute of Scientific and Technical Information of China (English)

    刘大军; 秦智伟; 周秀艳; 辛明; 武涛

    2014-01-01

    Adopting SSH technology,this paper studied on the difference expressive genes of downy mildew resistant cucumber inbred line ‘M801-3-1’ before and after the infection of downy mildew.Disease-resistant cucumber material vaccinated downy mildew and unvaccinated cDNA library was constructed using SSH technology.Forty-eight positive clones were obtained by reverse Northern blot hybridization detection, and 14 UniESTs were obtained including 8 singletons and 6 contigs via molecular biology software.The SSH-EST genes function analysis indicated that oxidative stress resistance and chloroplast reconstruction and protection mechanisms had very important role on disease resistance.At the same time,the paper put forward that Clpb,HSP70,HSP22 and peptidyl-prolyl cis-trans isomerase might be involved in the R gene-mediated defense reaction,and smHSP might be the ‘defending target’ of R protein,responsible for monitoring intracellular exception.This study has provided a key evidence for revealing the relations between active oxygen mechanism and R gene mediate protection mechanism.%采用SSH技术对黄瓜抗霜霉病自交系M801-3-1侵染霜霉病菌前后的差异表达基因进行了研究。利用 SSH 技术构建抗病黄瓜材料接种霜霉病菌和未接种差异表达的差减cDNA文库。经反向Northern blot杂交检测,共得到48个阳性克隆。利用分子生物学软件对测序后的序列进行质量检测和聚类、拼接,共得到14个UniESTs,其中包括8个singletons和6个contigs。通过SSH-EST代表基因功能的分析,说明抗氧化胁迫能力和叶绿体的重建和保护机制对抗病品种抗病有重要作用。同时,提出SSH-EST代表的clpb、HSP70、HSP22和肽脯氨酰顺反异构酶还可能参与了R基因介导的防御反应,smHSP有可能就是R蛋白的“保卫靶”,负责监测细胞内的异常,这一发现为揭示活性氧机制和R基因介导的防卫机制之间的关系提供了关键证据。

  2. Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action.

    Science.gov (United States)

    Gafni, Aviva; Calderon, Claudia E; Harris, Raviv; Buxdorf, Kobi; Dafa-Berger, Avis; Zeilinger-Reichert, Einat; Levy, Maggie

    2015-01-01

    Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis as mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew.

  3. Biological control of the cucurbit powdery mildew pathogen Podosphaera xanthii by means of the epiphytic fungus Pseudozyma aphidis and parasitism as a mode of action

    Directory of Open Access Journals (Sweden)

    Aviva eGafni

    2015-03-01

    Full Text Available Epiphytic yeasts, which colonize plant surfaces, may possess activity that can be harnessed to help plants defend themselves against various pathogens. Due to their unique characteristics, epiphytic yeasts belonging to the genus Pseudozyma hold great potential for use as biocontrol agents. We identified a unique, biologically active isolate of the epiphytic yeast Pseudozyma aphidis that is capable of inhibiting Botrytis cinerea via a dual mode of action, namely induced resistance and antibiosis. Here, we show that strain L12 of P. aphidis can reduce the severity of powdery mildew caused by Podosphaera xanthii on cucumber plants with an efficacy of 75%. Confocal and scanning electron microscopy analyses demonstrated P. aphidis proliferation on infected tissue and its production of long hyphae that parasitize the powdery mildew hyphae and spores as an ectoparasite. We also show that crude extract of P. aphidis metabolites can inhibit P. xanthii spore germination in planta. Our results suggest that in addition to its antibiosis mode of action, P. aphidis may also act as an ectoparasite on P. xanthii. These results indicate that P. aphidis strain L12 has the potential to control powdery mildew.

  4. 基于半监督模糊聚类的黄瓜霜霉病受害程度识别研究%Research on Disease Level of Cucumber Downy Mildew Based on Partial Fuzzy C-means Algorithm

    Institute of Scientific and Technical Information of China (English)

    施伟民; 杨昔阳; 李志伟

    2012-01-01

    通过定义一种新的半监督模糊聚类算法,提高聚类算法的运行效率和可解释性,结合Fisher线性判别分析,对黄瓜霜霉病的受害程度进行识别研究.针对7个关于叶片色调信息的统计特征,利用判别分析提取出2个主分量.结合一部分叶片的类别属性,对所有叶片的这2个主分量,进行半监督聚类分析.结果表明,对于类别属性已知的叶片,聚类结果与已知类别的一致率达100%,而对于类别未知的数据,一致率也达到95%以上.%A novel fuzzy C-means algorithm is proposed to improve the intelligibility and computing efficiency of semi-supervised cluster algorithm. Based on Fisher linear discriminant and the proposed algorithm, the disease level of cucumber leaves infected by cucumber downy mildew are studied. 7 hue statistics of cucumber leaves are measured,and 2 feature parameters are founded based on linear discriminant analysis. The result of the partial Fuzzy Gmeuns alyorithm shows that the correct recognition rata is 100% on sample data,and above 95% on test data.

  5. 萝卜霜霉病、黑斑病、白斑病、白锈病、炭疽病和黑根病的识别与防治技术%ldentification and Control Method of Radish Downy Mildew, Melasma, Leuko-derma, White Rust, An-thracnose and Black Root

    Institute of Scientific and Technical Information of China (English)

    金苹

    2012-01-01

    This paper introduced the damage characteristics and occurrence regularity of radish downy mildew, melasma, leukoderma, white rust, an-thracnose and black root. Then it pro-posed the corresponding control methods from two aspects including agricultural control and chemical control.%介绍了萝卜霜霉病、黑斑病、白斑病、白锈病、炭疽病及黑根病的危害症状、发病特点,指出各种病害的识别特点,并从农业措施、化学防治等方面提出了相应的防治方法。

  6. Influência das condições climáticas sobre a eficácia de fungicidas empregados para o controle do míldio em Vitis vinifera Effect of environmental conditions on efficacy of fungicides to downy mildew control in Vitis vinifera

    Directory of Open Access Journals (Sweden)

    Ana Beatriz Costa Czermainski

    2004-02-01

    Full Text Available Um dos fatores a serem manejados para a máxima produtividade de um vinhedo é o míldio, doença causada por Plasmopara viticola, que afeta regiões produtoras de uva do mundo inteiro. No Brasil, são necessárias diversas aplicações de fungicida para seu controle. Diferentes princípios ativos são encontrados no mercado. Com base em resultados de ensaios de fungicidas para controle do míldio em Vitis vinifera conduzidos em 1995 e 1996, foi analisada a influência dos fatores climáticos temperatura do ar, precipitação e umidade relativa do ar sobre a eficácia dos produtos disponíveis. Os experimentos foram instalados na Embrapa Uva e Vinho, sobre a cv. Tannat, conduzida no sistema espaldeira. A análise dos fatores ambientais apontou períodos de infecções primárias e secundárias. A maior ocorrência de chuvas e alta umidade relativa do ar foram determinantes da maior severidade do míldio no ano de 1996. A análise da incidência e do índice de intensidade de doença em folhas e em cachos, indicou maior eficácia dos fungicidas cymoxanil + mancozeb, metalaxil + mancozeb e dithianona, nos dois anos. Os princípios ativos cúpricos - oxicloreto de cobre, isolado ou combinado com mancozeb, e sulfato de cobre - não foram eficazes para controlar o míldio nos cachos sob condições climáticas favoráveis à doença.One of the factors to be managed for maximum vineyard productivity is the downy mildew, disease caused by Plasmopara viticola that affects grape production in many parts of the world. In Brazil, several fungicide applications for its control are necessary. Different active ingredients are available on the market. The influence of climatic factors (air temperature, rainfall and relative humidity on fungicide efficacy in Vitis vinifera was analyzed using results of fungicide trials for downy mildew control as a base. The experiments were carried out at Embrapa Uva e Vinho with the cv. Tannat conducted on vertical trellis

  7. Aplicação foliar de tratamentos para o controle do míldio e da podridão-de-escamas de bulbos de cebola Foliar spray of treatments in the control of downy mildew and bulb rot in onion

    Directory of Open Access Journals (Sweden)

    João Américo Wordell Filho

    2007-12-01

    Full Text Available Em experimento de campo, avaliou-se o efeito da aplicação foliar de tratamentos para o controle do míldio (Peronospora destructor e da podridão de bulbos (Burkholderia cepacia de cebola: testemunha, clorotalonil/metalaxyl + clorotalonil, fosfito de potássio, fertilizante foliar (03-00-16, N-P-K, calda bordalesa, calda bordalesa/fosfito de potássio, acibenzolar-S-methyl, pulverizados semanalmente; extrato de alga (Ulva fasciata e ulvana, aplicados a cada 7, 14 e 21 dias. Somente a pulverização semanal com fungicidas sintéticos ou com o fertilizante (03-00-16; 400 mL de p.c./100 L foi capaz de reduzir significativamente a severidade do míldio, em 60 ou 23%, respectivamente, em relação à testemunha não pulverizada, sem aumentar o rendimento de bulbos. O tratamento com fertilizantes ricos em potássio resultou em maior incidência da podridão de bulbos armazenados por cinco meses. O conteúdo de açúcares solúveis e incidência da podridão de bulbos de cebola foram correlacionados significativamente (-0,629, p A field experiment was carried out to evaluate the effect of foliar sprays with the following treatments on the downy mildew (Peronospora destructor and bulb rot (Burkholderia cepacia in onions: non-treated control, fungicide chlorotalonil/metalaxyl + chlorotalonil, potassium phosphite, foliar fertilizer (03-00-16, N-P-K, bordeaux mixture, bordeaux mixture/potassium phosphite, acibenzolar-S-methyl weekly applied; extract of alga Ulva fasciata and ulvan sprayed every 7, 14 and 21 days. Only the weekly spraying of fungicides and fertilizer (03-00-16, 400 mL/100 L significantly reduced the mildew severity by 60 and 23%, respectively, but did not increase the bulb yield. The foliar application of potassium rich fertilizers resulted in a higher incidence of rotten bulbs after 5 months in storage. Soluble sugar content and rot incidence of onion bulbs were significantly correlated (-0,629, p < 0,05.

  8. 壳聚糖与水杨酸复配对小白菜霜霉病与盐胁迫复合逆境的诱抗作用%Role of chitosan and salicylic acid application in induction of Brassica chinensis resistance to dual stress of downy mildew and salt stress

    Institute of Scientific and Technical Information of China (English)

    徐芬芬; 李坚; 罗晓燕

    2011-01-01

    为探明壳聚糖(CTS)和水杨酸(SA)复配处理对小白菜(Brassica chinensis L.)复合逆境的诱抗作用和效果,采用根际施用结合叶面喷洒的方法,研究了CTS与SA复配对小白菜盐和霜霉病胁迫复合逆境的诱抗作用.结果表明:SA、CTS单一与复配施用均能显著降低复合逆境下小白菜的盐害指数和病情指数,提高复合逆境下小白菜的株高、展开叶数、最大叶片面积和单株干质量等形态指标,促进小白菜在复合逆境下的正常生长,降低小白菜叶片的丙二醛(MDA)含量,增强过氧化物酶(POD)、多酚氧化酶(PPO)等保护酶的活性.在复合逆境下,SA、CTS复配施用对小白菜的诱导抗病和抗盐效果显著,盐害指数和病情指数均低于SA、CTS单一处理,且抗病和抗盐的共效系数均分别为-14.76和1.72,均表现为相加作用.%The role of chitosan (CTS) and salicylic acid (SA) compound application in induction of pakchoi (Bras-sica chinensis L. ) resistance to dual stress of downy mildew and salt stress was studied by the method of rhizosphere application with foliar spray. The results showed that both separate and joint application of SA and CTS significantly reduced salt injury index and disease index of pakchoi under the dual stress, increased the plant height, the number of expanding leaves, maximum leaf area, plant dry weight and other morphological indicators, and promoted the normal growth of pakchoi under dual stress, reduced malondialdehyde (MDA) content of leaves, and enhanced peroxidase (POD) and polyphenol oxidase (PPO) activities. The effects of CTS and SA joint application on the induction of resistance against downy mildew or salt stress in pakchoi were significant under the dual stress, with the salt injury index and disease index lower than those of single CTS or SA application. In the treatment of CTS and SA joint application, the coefficients of disease resistance and salt tolerance were -14.76 and 1

  9. Novas raças de Bremia lactucae, agente causador do míldio da alface, identificadas no estado de São Paulo New races of Bremia lactucae, causal agent of lettuce downy mildew, identified in São Paulo state, Brazil

    Directory of Open Access Journals (Sweden)

    Jean de O Souza

    2011-09-01

    Full Text Available O objetivo deste trabalho foi relatar o surgimento de raças de Bremia lactucae, agente causal do míldio nas principais regiões produtoras de alface do estado de São Paulo. O estudo foi realizado no Laboratório de Melhoramento Genético de Hortaliças do Departamento de Produção Vegetal da UNESP, Campus de Jaboticabal. No período de 2006 e 2007, foram coletados 36 isolados de B. lactucae de diferentes regiões produtoras de alface no estado. Para identificação das raças foram utilizadas as cultivares diferenciadoras conforme o código "Sextet". Foram identificadas três novas raças, SPBl:02, SPBl:03 e SPBl:04 com os referidos comportamentos do fungo: (63/31/19/00, (63/63/19/00 e (63/63/03/00. Os genes Dm-14, Dm-17, Dm-18, Dm-37 e Dm-38 conferem resistência a essas novas raças identificadas.The objective of this paper was to report new races of lettuce downy mildew causal agent Bremia lactucae in São Paulo State. The study was carried out in the laboratory of Crop Genetics in the Department of Crop Science at the college of Agricultural and Veterinary Sciences, Jaboticabal campus. A total of 36 isolates of B. lactucae was collected in different regions. The identification of races was based on compatibility reaction on the differential cultivars of the "Sextet". Three new races of B. lactucae, SPBl:02 (63/31/19/00, SPBl:03 (63/63/19/00 and SPBl:04 (63/63/03/00 were identified according to "Sextet" code. Genes Dm-14, Dm-17, Dm-18, Dm-37 and Dm-38 confer resistance to these new races identified.

  10. Podosphaera xanthii but not Golovinomyces cichoracearum infects Cucurbits in a Greenhouse at Salinas, California

    Science.gov (United States)

    Two fungal species are the primary causes of cucurbit powdery mildew (CPM): Podosphaera xanthii and Golovinomyces cichoracearum. CPM on melon (Cucumis melo L.), cucumber (C. sativus L.) and summer squash (Cucurbita pepo L.) in a greenhouse at Salinas, California in winter 2011 was confirmed to be in...

  11. Tolerance to powdery mildew conferred in susceptible watermelon scion by grafting on resistant rootstocks

    Science.gov (United States)

    Cucurbit powdery mildew (PM) caused by Podosphaera xanthii, can impact seedling growth and cause serious losses in greenhouse and open field production. We have developed several watermelon and bottle gourd germplasm lines with high levels of resistance to PM. A PM susceptible cultivar Mickey Lee ...

  12. Confirming resistance in bottle gourd germplasm by quantifying powdery mildew conidia using a cellometer

    Science.gov (United States)

    Powdery mildew (PM) caused by Podosphaera xanthii, an important foliar disease affecting cucurbit crops grown in the United States, commonly occurs on foliage, petioles, and stems. We have developed two highly resistant bottle gourd (Lagenaria siceraria) germplasm (USVL351 and USVL482) for use in o...

  13. Application and validation of a warning system for grapevine downy mildew controlusing fungicides Aplicação e validação de um sistema de aviso para o controle do míldio da videira, com fungicidas

    Directory of Open Access Journals (Sweden)

    Erlei Melo Reis

    2013-03-01

    Full Text Available Most warning systems for plant disease control are based on Vinho, in Bento Gonçalves - RS, during the growing seasons 2000/ weather models dependent on the relationships between leaf wetness 01, 2002/03 and 2003/2004, using the grape cultivar Isabel. The duration and mean air temperature in this period considering the conventional system used by local growers was compared with the target disease intensity. For the development of a warning system to new warning system by using different cumulative daily disease severity control grapevine downy mildew, the equation generated by Lalancette values (CDDSV as the criterion to schedule fungicide application and et al. (7 was used. This equation was employed to elaborate a critical reapplication. In experiments conducted in 2003/04, CDDSV of 12 - period table and program a computerized device, which records, though 14 showed promising to schedule the first spraying and the interval electronic sensors, leaf wetness duration, mean temperature in this between fungicide applications, reducing by 37.5% the number of period and automatically calculates the daily value of probability of applications and maintaining the same control efficiency in leaves infection occurrence. The system was validated at Embrapa Uva e and bunches, similarly to the conventional system.A maioria dos sistemas de aviso para o controle de doenças de O sistema foi validado na Embrapa Uva e Vinho, em Bento Gonçalves plantas utilizam como fundamento o modelo climático baseado - RS, conduzido nas safras agrícolas de 2000/01, 2002/03 e 2003/ nas interações entre a duração do molhamento foliar e a 2004 utilizando-se o cultivar Isabel. O sistema convencional utilizado temperatura média nesse período sobre a intensidade da doença pelos produtores foi comparado com o modelo de aviso utilizando alvo. No desenvolvimento de um modelo de aviso para o controle como critério indicador do momento para a aplicação e reaplicação do m

  14. The effects of biological control of Bacillus subtilis strains on downy mildew and anthracnose diseases of harvested litchi fruits%枯草芽胞杆菌对离体荔枝果实霜疫霉病、炭疽病的防治效果

    Institute of Scientific and Technical Information of China (English)

    黄庶识; 黄曦; 张荣灿; 许兰兰; 雷富; 黄荣韶

    2011-01-01

    Four antagonistic bacteria strains, OR-1, OR-2, OR-3 and ON-6, which were isolated and screened from soil under litchi trees and identified as Bacillus subtilis morphologically and molecularly, were used to evaluate the control effect on downy mildew and anthracnose diseases of harvested litchi fruits. The results showed that all 4 strains had obvious inhibiting action on mycelial growth of Peronophy-thora litchii and Colletrichum gloeosporiodes, among them, ON-6 strain had the highest inhibitory rate to mycelial growth of two litchi pathogenic fungi, the ratio were 92.34% and 70. 36% respectively; the next best was ON-1, its ratio were 82. 93% and 54. 61% severally. The browning index of the four strains treatment groups was lower than that of the control group and fungicide groups significantly ( P <0.05 ) , in which OR-1 strain had the best impact. Metabolites of four B. subtilis strains had a better effect in pre-venting P. litchii and C. gloeosporiodes on the surface of fresh fruits than those of CK group and fungicide groups at room temperature for 3 -4 d or at 4 X. for 40 d significantly (P < 0. 05 ) , which ON-6 strain showed best at room temperature, likewise, ON-6 and ON-3 strains showed best at 4 °C , indicated that the four B. subtilis strains could inhibit litchi pathogenic fungi on the surface of fruits determinately, and extend the period of storage and delay the fresh fruits to brown stain at room temperature or at 4 t.%为了进一步明确从土壤中筛选得到的拮抗细菌OR-1、OR-2、OR-3、ON-6的分类地位和生防效果,采用形态学观察、理化特性结合分子生物学方法,鉴定这4株细菌皆为枯草芽胞杆菌Bacillussubitilis.拮抗菌对荔枝霜疫霉菌、炭疽菌菌丝生长均具有明显抑制作用,ON-6菌株的发酵液对菌丝生长的抑制率最高,分别为92.34%和70.36%,其次是OR-1菌株.拮抗菌处理组褐变指数均小于对照组以及杀菌剂处理组,且差异达显著水平(P<0.05),OR

  15. Detecção e variabilidade de Plasmopara halstedii no Brasil e avaliação da resistência de genótipos de girassol ao míldio Detection and variability of Plasmopara halstedii in Brazil and resistance of sunflower genotypes to downy mildew

    Directory of Open Access Journals (Sweden)

    Regina Maria Villas Bôas de Campos Leite

    2007-12-01

    Full Text Available Este trabalho foi conduzido com o objetivo de identificar a raça fisiológica de Plasmopara halstedii que ocorreu em plantas de girassol coletadas no campo experimental da Embrapa Soja, Londrina, PR, em 1998, 2001 e 2002 e avaliar a reação de genótipos de girassol ao míldio. Plântulas de girassol das diferenciadoras de raças e das cultivares foram inoculadas com suspensão de zoosporângios do patógeno e foram plantadas em caixas contendo areia autoclavada. As plântulas foram mantidas em câmara climatizada, com temperatura controlada em 21ºC, por 11 dias. Em seguida, as plantas foram aspergidas intensamente com água destilada, cobertas com saco plástico e mantidas no escuro, a 18ºC. No dia seguinte, foi observada a presença de esporulação nos cotilédones. As plantas que apresentaram esporulação foram consideradas suscetíveis e as sem esporulação foram resistentes. O resultado indicou tratar-se da raça 330 (antiga raça 7 americana, nas três ocasiões. Os genótipos de girassol Embrapa 122, BRS 191 e as cultivares de girassol ornamental BRS Capri M, BRS Encanto M, BRS Oásis, BRS Paixão M, BRS Pesqueiro M, BRS Refúgio M, BRS Saudade M e BRS Saudade U e seus respectivos parentais foram suscetíveis a P. halstedii raça 330. Os genótipos AGROBEL 910, AGROBEL 920, AGROBEL 960, AGROBEL 965, C11, EXP38, M734, M742 e RUMBOSOL 91 foram resistentes à raça 330 do patógeno e podem ser indicados aos agricultores para uso em regiões de risco de ocorrência da doença.This research was carried out for identifying the physiological race of Plasmopara halstedii occurring in sunflower at the experimental field of Embrapa Soybean, Londrina, PR, Brazil, in 1998, 2001 and 2002 by evaluating the reaction of sunflower genotypes inoculated with downy mildew pathogen. Sunflower seedlings of the differentials set to identify races and of the cultivars were inoculated by immersion in zoosporangia suspension and were grown in autoclaved

  16. Susceptibility level of cucumber downy mildew (Pseudoperonospora cubensis to metalaxyl

    Directory of Open Access Journals (Sweden)

    Bagi Ferenc F.

    2009-01-01

    Full Text Available Level of susceptibility of Pseudoperonospora cubensis isolate from Ratkovo to metalaxyl in concentrations 50, 100, 200, 400 and 800 μg/ml was investigated. The trials were conducted on cotyledon and fully developed young leaves using cucumber cultivar Haroš. Reduced level of susceptibility was detected in metalaxyl concentrations of 50, 100 and 200 μg/ml because the intensity of sporulation in these treatments was on the same level as in control. Sporulation was also observed on developed leaves treated with metalaxyl in concentrations of 400 and 800 μg/ml.

  17. Atahualpa’s Revenge: The Spread of Quinoa Downy Mildew

    OpenAIRE

    Testen, Anna L.; Backman, Paul A.

    2011-01-01

    Metadata only record The Andean crop quinoa, Chenopodium quinoa, has gained popularity in recent years due to its nutritious seed and desirable agricultural traits, such as its tolerance to drought and high saline soils. Prized by the Inca, quinoa is now highly desirable to health conscious consumers in North America and Europe. Quinoa also has interesting applications to plant pathology, including being a “universal” virus host as well as its production of antimicrobial compounds. Quinoa ...

  18. Resistance to Powdery Mildews

    DEFF Research Database (Denmark)

    Siwoszek, Agnieszka Izabela

    how the basic resistance components contribute to resistance against powdery mildews. Furthermore, I propose an alternative strategy of achieving resistance to barley powdery mildew by application of peptide aptamers. Peptide aptamers are small proteins selected to specifically target conserved Yx......C motif of barley powdery mildew effectors. I present a proof-of-concept study in Arabidopsis, where overexpression of peptide aptamers significantly reduced the susceptibility to barley powdery mildew. Moreover, I set the discovery in a bigger context by summarizing genetic engineering technologies...

  19. Importance of prumycin produced by Bacillus amyloliquefaciens SD-32 in biocontrol against cucumber powdery mildew disease.

    Science.gov (United States)

    Tanaka, Keijitsu; Fukuda, Mutsumi; Amaki, Yusuke; Sakaguchi, Takatoshi; Inai, Koji; Ishihara, Atsushi; Nakajima, Hiromitsu

    2017-05-30

    Powdery mildew disease of cucurbits is caused mainly by Podosphaera fusca, which is one of the most important limiting factors in cucurbit production worldwide. Previously we reported that Bacillus amyloliquefaciens biocontrol strain SD-32 produces C17 bacillomycin D and [Ile]surfactin, and that these metabolites play important roles in SD-32's biocontrol over cucumber gray mold disease. Our further investigation demonstrated that the culture broth and its supernatant suppressed cucumber powdery mildew disease in greenhouse experiments. However, the active principle(s) remained unknown. The active compound was isolated from the culture supernatant after anti-powdery mildew disease activity-guided purification and identified as prumycin. Prumycin significantly suppressed the disease, whereas bacillomycin D and [Ile]surfactin did not. Prumycin did not induce the expression of plant defense genes (PR1a and VSP1), suggesting that it does not act via plant defense response. Light microscopic observations of prumycin-treated cucumber cotyledon suggested that prumycin inhibits the conidial germination of P. fusca. This study demonstrates that prumycin is a major factor in SD-32's suppression of cucumber powdery mildew disease. Our findings shed light for the first time on prumycin's role in biocontrol by Bacillus against this disease. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  20. Cultivation and uses of cucurbits

    Science.gov (United States)

    Cultivated cucurbits have spread through trade and exploration from their respective Old and New World centers of origin to the six arable continents and are important in local, regional and world trade. Cucumber (Cucumis sativus L.), melon (Cucumis melo L.), pumpkin, squash and gourd (Cucurbita spp...

  1. Resistance to Powdery Mildews

    DEFF Research Database (Denmark)

    Siwoszek, Agnieszka Izabela

    in majority of them. Resistance to barley powdery mildew in the field is controlled by use of resistant varieties in a combination with fungicides. Early disease management is crucial for effective control. Yet, the pathogen commonly develops fungicide resistance due to simple point mutations. Several studies...... investigated reduced fitness of plants as a cost of resistance to pathogens. In case of barley powdery mildew, most common resistance (mlo) is linked to a higher susceptibility to other pathogens and spontaneous necrosis that leads to yield reduction. Thus, there is a clear need for alternative methods of crop...... protection. In the present study, I provide an overview of the current knowledge about plant pathogens and plant disease resistance. I use Arabidopsis as a model to investigate the mechanism of non-host resistance, presumed to be the most durable and broad-spectrum form of resistance. I attempt to determine...

  2. Management of Powdery Mildew in Squash by Plant and Alga Extract Biopesticides.

    Science.gov (United States)

    Zhang, Shouan; Mersha, Zelalem; Vallad, Gary E; Huang, Cheng-Hua

    2016-12-01

    Although many fungicides are registered for use to control powdery mildew on cucurbits, management of resistance to fungicides in pathogen populations still remains a major challenge. Two biopesticides Regalia SC and HMO 736 were evaluated in the greenhouse and field for their efficacy against powdery mildew in squash. In greenhouses, Regalia SC alone significantly (P powdery mildew compared to the nontreated control, and was as effective as the chemical standard Procure 480SC (triflumizole). In alternation with Procure 480SC, Regalia SC demonstrated greater or equivalent effects on reducing the disease. HMO 736 alone showed varying levels of disease control, but alternating with Procure 480SC significantly improved control efficacy. In addition, application of Regalia SC or HMO 736 each in alternation with Procure 480SC significantly increased the chlorophyll content in leaves and the total fresh weight of squash plants, when compared with the water control, Regalia SC and HMO 736 alone. In field trials, application of Regalia SC and HMO 736 each alone significantly reduced disease severity in one of two field trials during the early stage of disease development, but not during later stages when disease pressure became high. Both Regalia SC and HMO 736 each applied in alternation with Procure 480SC significantly improved the control efficacy compared to Procure 480SC alone. Results from this study demonstrated that an integrated management program can be developed for powdery mildew in squash by integrating the biopesticides Regalia SC, HMO 736 with the chemical fungicide Procure 480SC.

  3. Powdery Mildew Control and Yield Response of Inodorus Melon

    Directory of Open Access Journals (Sweden)

    Ippolito Camele

    Full Text Available The research was carried out on melon (Cucumis melo L. var. inodorus Naud. in 2006 and 2007 at “Pantanello” Experimental Farm (40° 24’N; 16° 48’E; 10 m a.s.l.; Metaponto, southern Italy to evaluate the efficacy of a low environmental impact control strategy against powdery mildew of cucurbits. Winter melon was treated with a new anti-oidium formulation, called Stifénia, obtained from fenugreek seeds and stimulating the plant self-defence. The adopted experimental design included two control strategies (1. biological, using Stifénia and 2. conventional, using penconazole, myclobutanil and sulphur and an untreated control (treated with water alone applied to two cultivars of inodorus melon (cv ‘Amarillo’ and HF1 ‘Cocorito’, the latter a genotype resistant to powdery mildew. Stifénia applications were not effective against the disease; in fact, there were no differences in percentage of attacked plant surface between treated plots and untreated ones. The melon marketable yield was significantly higher with the conventional strategy respect to Stifénia and control. Repeated applications of Stifénia resulted in a significant decrease of marketable yield even in comparison with the untreated control. The cultivars significantly affected powdery mildew development, since the resistant one (‘Cocorito’ was attacked later and damaged always lower than the non-resistant genotype (‘Amarillo’. Laboratory analyses carried out on infected leaves always confirmed that Golovinomyces cichoracearum D.C. was responsible of the disease.

  4. Cucurbits [Cucumber, melon, pumpkin and squash

    Science.gov (United States)

    The focus of this chapter is on the edible members of the Cucurbitaceae family. The three important food-grade cucurbit genera Citrullus, Cucumis, and Cucurbita include the species Citrullus lanatus watermelons), Cucumis melo (cantaloupes and other sweet melons), Cucumis sativa (cucumbers and pick...

  5. The Podosphaera fusca TUB2 gene, a molecular "Swiss Army knife" with multiple applications in powdery mildew research.

    Science.gov (United States)

    Vela-Corcía, David; Bellón-Gómez, Davinia; López-Ruiz, Francisco; Torés, Juan Antonio; Pérez-García, Alejandro

    2014-02-01

    The powdery mildew fungus Podosphaera fusca (synonym Podosphaera xanthii) is the main causal agent of cucurbit powdery mildew and one of the most important limiting factors for cucurbit production worldwide. Despite the fungus' economic importance, very little is known about the physiological and molecular processes involved in P. fusca biology and pathogenesis. In this study, we isolated and characterised the β-tubulin-encoding gene of P. fusca (PfTUB2) to develop molecular tools with different applications in powdery mildew research. PfTUB2 is predicted to encode a protein of 447 amino acid residues. The coding region is interrupted by six introns that occur at approximately the same positions as the introns present in other fungal TUB2-like genes. Once cloned, the PfTUB2 sequence information was used in different applications. Our results showed that the TUB2 gene is a good marker for molecular phylogenetics in powdery mildew fungi but it is unsuitable for the analysis of intraspecific diversity in P. fusca. The expression of PfTUB2 was proven to be stable in different temperature conditions, supporting its use as a reference gene in quantitative gene expression studies. Furthermore, an allele-specific PCR assay for the detection of resistance to methyl-2-benzimidazole carbamate (MBC) fungicides in P. fusca was developed based on the correlation between the single amino acid change E198A in β-tubulin and the MBC resistance phenotype. Lastly, PfTUB2 was used as a target gene in the development of a high-throughput method to quantify fungal growth in plant tissues.

  6. OUTBREAK OF MAIZE DOWNY MILDEW (Sclerophthora macrospora IN SLOVENIA IN 1999

    Directory of Open Access Journals (Sweden)

    Stanislav Trdan

    2000-12-01

    Full Text Available In 1999 a pronounced infection of maize with fungus Sclerophthora macrospora occurred in Slovenia, especially in its north-eastern and eastern regions. Symptoms, typical for infection with this fungus, were found on app. 1800 ha, which means on about 2.5 % of the acreage on which maize is grown. The infected plants were found only on those fields, or parts of those fields, which were flooded for some time soon after sowing or emergence of the crop. The percentage of the plants infected by the fungus was between 5 and 90 %, depending on the type of soil. This article presents different disease causing fungi, their taxonomy, and deals in detail with the species Sclerophthora macrospora, the only disease causing organism under our growing conditions. The article deals with hosts of the fungus, typical symptoms of the disease on maize (“crazy top”, pathogen biology, the mode of infection, its survival under unfavorable conditions, and possible protection against the infection. The article also describes the actual situation in Slovenia, and adds a comment on possible regular occurrences of this disease in future.

  7. Photosynthetic responses of lettuce to downy mildew infection and cytokinin treatment.

    Science.gov (United States)

    Prokopová, Jitka; Spundová, Martina; Sedlárová, Michaela; Husicková, Alexandra; Novotný, Radko; Dolezal, Karel; Naus, Jan; Lebeda, Ales

    2010-08-01

    Changes in primary metabolism of lettuce, Lactuca sativa L. (cv. Cobham Green), induced by compatible interaction with the biotrophic oomycete pathogen Bremia lactucae Regel (race BL 16), under two intensities of illumination in the presence and absence of exogenous cytokinins were studied by chlorophyll fluorescence imaging. Thirteen days post-inoculation leaf discs infected by B. lactucae exhibited impairments of photosynthesis associated with biotrophic infections, including: reductions in photosynthetic pigment contents and the maximum quantum yield of photosystem II photochemistry (F(V)/F(M)), inhibition of electron transport (Phi(PSII)) and increased non-photochemical chlorophyll fluorescence quenching (NPQ). Detected changes in photosynthetic parameters correlated with the leaf area colonized by the pathogen's intercellular hyphae. Applications of two cytokinins, benzylaminopurine and meta-topolin, previously shown to suppress B. lactucae sporulation if applied 24 h prior to inoculation at a concentration of 200 microM, retarded the pathogen's asexual reproduction with no apparent negative effects on the host's photosynthetic apparatus. However, long-lasting treatment of healthy tissues with this high concentration of exogenous cytokinin led to effects parallel to pathogenesis: reductions in photosynthetic pigment contents accompanied by inhibition of photosystem II photochemistry and electron transport. These effects of both prolonged exposure to cytokinins and the pathogenesis were weaker in discs exposed to the lower photosynthetic photon flux density. The role of cytokinins in plant-biotrophic pathogen interactions and their potential as disease control agents are discussed.

  8. Linkage analysis of genes for resistance to downy mildew (Bremia lactucae) in lettuce (Lactuca sativa).

    Science.gov (United States)

    Hulbert, S H; Michelmore, R W

    1985-08-01

    The genetics of specific resistance was studied in F2 populations which segregated for either one or two resistance genes. The resistance factors 1, 11 and 14 which had not previously been characterized genetically segregated as single dominant genes (Dm). Resistance was determined by three linkage groups; R 1/14, 2, 3, and 6 in the first, R 5/8, and 10 in the second and R 4, 7 and 11 in the third. Cultivars of lettuce commonly used in the differential series to detect virulence to R3 and R10, were demonstrated to carry two tightly linked resistance genes. Implications of this linkage arrangement to the manipulation and characterization of these resistance genes are discussed.

  9. Plasmopara halstedii virus causes hypovirulence in Plasmopara halstedii, the downy mildew pathogen of the sunflower.

    Science.gov (United States)

    Grasse, Wolfgang; Zipper, Reinhard; Totska, Maria; Spring, Otmar

    2013-08-01

    Plasmopara halstedii virus (PhV) is an isometric virus recently found in the oomycete Plasmopara halstedii. The fully sequenced virus genome consists of two ss(+)RNA strands encoding for the virus polymerase and the coat protein, respectively. Most of previously screened field isolates of P. halstedii were found to harbor PhV, but effects of PhV on the pathogenicity and aggressiveness of the oomycete have not been investigated yet. To assess the influence of PhV on the infectivity of P. halstedii, virus-free isolates of the oomycete were searched for, cultivated on sunflower and used for single zoospore infection. Four genetically homogenous strains belonging to three different pathotypes (710, 730, 750) were established. Subcultures of each strain were successfully infected with PhV. This afforded pairs of isogenic strains with and without virus and allowed assessment of the pathogenicity (susceptibility to specific sunflower genotypes) and aggressiveness (intensity of infection, time scale and density of sporulation) in cultivation of sunflower. While no significant difference was found in the pathogenicity of P. halstedii strains with and without virus towards sunflower seedlings of different resistance (pathotype differentials), the aggressiveness of the oomycete was diminished by PhV. Compared to the virus-free strains, the time required for the first sporulation (latent period) increased by about 1 day post inoculation. Progression of the pathogen from the hypocotyl into the epicotyl of sunflower (systemic infection) was reduced by about one third in the presence of virus. In the virus containing strains, the average density of sporangia produced per cm² cotyledon reached only 75% of the virus-free controls. In summary, the presence of PhV leads to hypovirulence effects by weakening the aggressiveness of P. halstedii.

  10. Identification and functional analysis of downy mildew effectors in lettuce and Arabidopsis

    NARCIS (Netherlands)

    Stassen, J.H.M.|info:eu-repo/dai/nl/314004416

    2012-01-01

    Oomycete pathogens cause large losses in many crop plants. Chemical control measures are undesirable and are becoming less effective. Resistance breeding has traditionally made use of dominant resistance genes to which oomycete pathogens have often been quick to adapt. Novel approaches towards

  11. Susceptibility of Arabidopsis to the downy mildew pathogen Hyaloperonospora parasitica : A reverse genetics approach

    NARCIS (Netherlands)

    de Jong, H.M.

    2008-01-01

    The research described in this thesis was performed to gain insight into disease susceptibility in the model system Arabidopsis thaliana – Hyaloperonospora parasitica. The aim was to identify host genes that support the infection process. For this, global expression profiling using DNA microarrays w

  12. First report of downy mildew caused by Peronospora sp. on Agastache in the United States

    Science.gov (United States)

    Hyssops (Agastache spp. and cultivars) are fragrant perennial plants in the mint family (Lamiaceae), primarily native to North America. Hybrid Agastache are bred as ornamental plants, valued for their showy flowers and aromatic scents that attract pollinators to the landscape. In May 2015, a commerc...

  13. Registration of an oilseed sunflower germplasm HA-DM1 resistant to sunflower downy mildew

    Science.gov (United States)

    HA-DM1 (Reg. No.xxx, PI 674793) sunflower (Helianthus annuus L.) germplasm was developed and released cooperatively by the USDA-ARS, Sunflower and Plant Biology Research Unit and the North Dakota Agricultural Experiment Station in 2015. HA-DM1 is a BC2F4 derived oilseed maintainer line from the cros...

  14. Management of Powdery Mildew in Squash by Plant and Alga Extract Biopesticides

    Directory of Open Access Journals (Sweden)

    Shouan Zhang

    2016-12-01

    Full Text Available Although many fungicides are registered for use to control powdery mildew on cucurbits, management of resistance to fungicides in pathogen populations still remains a major challenge. Two biopesticides Regalia SC and HMO 736 were evaluated in the greenhouse and field for their efficacy against powdery mildew in squash. In greenhouses, Regalia SC alone significantly (P < 0.05 reduced powdery mildew compared to the nontreated control, and was as effective as the chemical standard Procure 480SC (triflumizole. In alternation with Procure 480SC, Regalia SC demonstrated greater or equivalent effects on reducing the disease. HMO 736 alone showed varying levels of disease control, but alternating with Procure 480SC significantly improved control efficacy. In addition, application of Regalia SC or HMO 736 each in alternation with Procure 480SC significantly increased the chlorophyll content in leaves and the total fresh weight of squash plants, when compared with the water control, Regalia SC and HMO 736 alone. In field trials, application of Regalia SC and HMO 736 each alone significantly reduced disease severity in one of two field trials during the early stage of disease development, but not during later stages when disease pressure became high. Both Regalia SC and HMO 736 each applied in alternation with Procure 480SC significantly improved the control efficacy compared to Procure 480SC alone. Results from this study demonstrated that an integrated management program can be developed for powdery mildew in squash by integrating the biopesticides Regalia SC, HMO 736 with the chemical fungicide Procure 480SC.

  15. Powdery Mildew Disease Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Somerville, Shauna C.

    2010-08-31

    The overall goal of this project was to characterize the PMR5 protein, a member of the DUF231/TBR family, and to determine its role in plant cell wall biogenesis. Since the pmr5 mutants are also resistant to the fungal powdery mildew pathogen, we wished to determine what specific cell wall changes are associated with disease resistance and why. The graduate student working on this project made mutations in the putative active site of PMR5, assuming it is a member of the SGNH/GDSL esterase superfamily (Anantharaman and Aravind, 2010, Biology Direct 5, 1). These mutants were inactive in planta suggesting that PMR5 is a functional enzyme and not a binding protein or chaperone. In addition, she determined that cell wall preparations from the pmr5 mutant exhibited a modest reduction (13%) in total acetyl groups. To pursue characterization further, the graduate student expressed the PMR5 protein in a heterologous E. coli system. She could purify PMR5 using a two step protocol based on tags added to the N and C terminus of the protein. She was able to show the PMR5 protein bound to pectins, including homogalacturonan, but not to other cell wall components (e.g., xyloglucans, arabinans). Based on these observations, a postdoctoral fellow is currently developing an enzyme assay for PMR5 based on the idea that it may be acetylating the homogalacturonic acid pectin fraction. Our initial experiments to localize PMR5 subcellularly suggested that it occurred in the endoplasmic reticulum. However, since the various pectins are believed to be synthesized in the Golgi apparatus, we felt it necessary to repeat our results using a native promoter expression system. Within the past year, we have demonstrated conclusively that PMR5 is localized to the endoplasmic reticulum, a location that sets it apart from most cell wall biogenesis and modification enzymes. The graduate student contributed to the characterization of two suppressor mutants, which were selected as restoring powdery

  16. Fungicidal preparations from Inula viscose

    OpenAIRE

    2002-01-01

    Inula viscosa is a perennial plant native to the Mediterranean Basin. Extracts made from the shoots of this plant exhibited a strong fungicidal activity in vitro and in vivo. TLC analyses revealed at least 7 fungicidal compounds. Most are lipophilic. When such extracts were sprayed on the leaf surface of crop plants they effectively controlled downy mildew in grape, cucumber and tabacco; late blight in potato and tomato; gray mold in cucumber and tomato; and, powdery mildew in cucurbits and c...

  17. Interaction between powdery mildew and barley with ¤mlo5¤ mildew resistance

    DEFF Research Database (Denmark)

    Lyngkjær, M.F.; Østergård, Hanne

    1998-01-01

    Powdery mildew infection of barley with the mlo5 barley powdery mildew resistance gene was examined, using near-isogenic barley lines, with and without mlo5 resistance, and two near-isogenic powdery mildew isolates, HL3/5 and GE3 with high (virulent) or low (avirulent) penetration efficiency...

  18. NMR study on self-assembled cage complex of hexamethylenetetramine and cucurbit[n]urils

    Institute of Scientific and Technical Information of China (English)

    SHEN Yongqiang; XUE Saifeng; ZHAO Yunjie; ZHU Qianjiang; TAO Zhu

    2003-01-01

    Self-assembled complexes between cage compounds cucurbit[n = 5-8]urils and hexamethylenetetramine were studied by using NMR techniques. Experimental results reveal that hexamethylenetetramine can lid cucurbit[5]uril to forming self-assembled capsules in which nothing is encapsulated yet; the cavity of the cucurbit[7]uril can accommodate a hexamethylenetetramine molecule to form a self- assembled host-guest inclusion. Moreover, both the cavity interaction of the cucurbit[7]uril with hexamethylenetetramine·HCl and the portal interaction of the dipole carbonyl of the cucurbit[7]uril with hexamethylenetetramine·HCl lead to form self-assembled capsules in which the hexamethylenetetramine·HCl are encapsulated in the hexamethylenetetramine·HCl "lidded" cucurbit[7]uril. Although the structures of the portal and cavity to cucurbit[5]uril are similar, there is no obvious interaction between decamethylcucurbit[5]uril and hexamethylenetetramine, and also between cucurbit [6]uril or cucurbit[8]uril and hexamethylenetetramine.

  19. Complexation behavior of cucurbit[6]uril with short polypeptides

    Energy Technology Data Exchange (ETDEWEB)

    Buschmann, Hans-Juergen [Deutsches Textilforschungszentrum Nord-West e.V., Adlerstrasse 1, D-47798 Krefeld (Germany)]. E-mail: buschmann@dtnw.de; Mutihac, Lucia [University of Bucharest, Department of Analytical Chemistry, 4-12 Blvd. Regina Elisabeta, 703461 Bucharest (Romania); Mutihac, Radu-Cristian [Deutsches Textilforschungszentrum Nord-West e.V., Adlerstrasse 1, D-47798 Krefeld (Germany); Schollmeyer, Eckhard [Deutsches Textilforschungszentrum Nord-West e.V., Adlerstrasse 1, D-47798 Krefeld (Germany)

    2005-06-15

    The binding properties of cucurbit[6]uril towards various peptides have been investigated in acidic aqueous solution. Stability constants and thermodynamic values of the complex formation between following peptides: glycyl-L-alanine, L-leucyl-L-valine, glycyl-L-asparagine, L-leucyl-L-phenylalanine, L-leucyl-L-tryptophan, glycyl-L-histidine, L-glutathione reduced ({gamma}-L-glutamyl-L-cysteinyl-glycine, GSH), and DL-leucyl-glycyl-DL-phenylalanine) with cucurbit[6]uril in aqueous formic acid (50%, v/v) have been calculated from calorimetric titrations. From these results it can be seen that the peptides form exclusion complexes with cucurbit[6]uril. Due to the polar peptide bond they are not included within the hydrophobic cavity of cucurbit[6]uril. The complex formation is favoured by entropic contributions. The release of water molecules from the polar amino groups of the peptides and the carbonyl groups of cucurbituril are responsible.

  20. Confirmation of bean leaf beetle, Cerotoma trifurcata, feeding on cucurbits

    Directory of Open Access Journals (Sweden)

    R.L. Koch

    2004-02-01

    Full Text Available The objective of these studies was to assess the degree to which bean leaf beetle, Cerotoma trifurcata (Forster, will feed on cucurbits. In 2003, we documented an infestation of C. trifurcata in a commercial pumpkin field near Rosemount, MN, USA. To evaluate C. trifurcata feeding on cucurbits, we conducted laboratory no-choice and choice test feeding studies. In the laboratory, C. trifurcata fed most heavily on cotyledon-stage cucumber plants, followed by pumpkin and squash. With soybean plants present, C. trifurcata still fed on cucumber plants. However, C. trifurcata appeared to prefer soybeans until the quality of the soybean plants was diminished through feeding damage. This is the first known report of C. trifurcata feeding on cucurbits. The pest potential of C. trifurcata in cucurbit cropping systems should be further evaluated.

  1. Anticancer and anti-inflammatory activities of some dietary cucurbits.

    Science.gov (United States)

    Sharma, Dhara; Rawat, Indu; Goel, H C

    2015-04-01

    In this study, we investigated few dietary cucurbits for anticancer activity by monitoring cytotoxic (MTT and LDH assays), apoptotic (caspase-3 and annexin-V assays), and also their anti-inflammatory effects by IL-8 cytokine assay. Aqua-alcoholic (50:50) whole extracts of cucurbits [Lagenaria siceraria (Ls), Luffa cylindrica (Lc) and Cucurbita pepo (Cp)] were evaluated in colon cancer cells (HT-29 and HCT-15) and were compared with isolated biomolecule, cucurbitacin-B (Cbit-B). MTT and LDH assays revealed that the cucurbit extracts and Cbit-B, in a concentration dependent manner, decreased the viability of HT-29 and HCT-15 cells substantially. The viability of lymphocytes was, however, only marginally decreased, yielding a potential advantage over the tumor cells. Caspase-3 assay revealed maximum apoptosis with Ls while annexin V assay demonstrated maximum efficacy of Lc in this context. These cucurbits have also shown decreased secretion of IL-8, thereby revealing their anti-inflammatory capability. The results have demonstrated the therapeutic potential of dietary cucurbits in inhibiting cancer and inflammatory cytokine.

  2. Quantitative Morphological and Biochemical Studies on Human Downy Hairs using 3-D Quantitative Phase Imaging

    CERN Document Server

    Lee, SangYun; Lee, Yuhyun; Park, Sungjin; Shin, Heejae; Yang, Jongwon; Ko, Kwanhong; Park, HyunJoo; Park, YongKeun

    2015-01-01

    This study presents the morphological and biochemical findings on human downy arm hairs using 3-D quantitative phase imaging techniques. 3-D refractive index tomograms and high-resolution 2-D synthetic aperture images of individual downy arm hairs were measured using a Mach-Zehnder laser interferometric microscopy equipped with a two-axis galvanometer mirror. From the measured quantitative images, the biochemical and morphological parameters of downy hairs were non-invasively quantified including the mean refractive index, volume, cylinder, and effective radius of individual hairs. In addition, the effects of hydrogen peroxide on individual downy hairs were investigated.

  3. Using a limited mapping strategy to identify major QTLs for resistance to grapevine powdery mildew (Erysiphe necator) and their use in marker-assisted breeding.

    Science.gov (United States)

    Riaz, S; Tenscher, A C; Ramming, D W; Walker, M A

    2011-04-01

    A limited genetic mapping strategy based on simple sequence repeat (SSR) marker data was used with five grape populations segregating for powdery mildew (Erysiphe necator) resistance in an effort to develop genetic markers from multiple sources and enable the pyramiding of resistance loci. Three populations derived their resistance from Muscadinia rotundifolia 'Magnolia'. The first population (06708) had 97 progeny and was screened with 137 SSR markers from seven chromosomes (4, 7, 9, 12, 13, 15, and 18) that have been reported to be associated with powdery or downy mildew resistance. A genetic map was constructed using the pseudo-testcross strategy and QTL analysis was carried out. Only markers from chromosome 13 and 18 were mapped in the second (04327) and third (06712) populations, which had 47 and 80 progeny, respectively. Significant QTLs for powdery mildew resistance with overlapping genomic regions were identified for different tissue types (leaf, stem, rachis, and berry) on chromosome 18, which distinguishes the resistance in 'Magnolia' from that present in other accessions of M. rotundifolia and controlled by the Run1 gene on chromosome 12. The 'Magnolia' resistance locus was termed as Run2.1. Powdery mildew resistance was also mapped in a fourth population (08391), which had 255 progeny and resistance from M. rotundifolia 'Trayshed'. A locus accounting for 50% of the phenotypic variation mapped to chromosome 18 and was named Run2.2. This locus overlapped the region found in the 'Magnolia'-based populations, but the allele sizes of the flanking markers were different. 'Trayshed' and 'Magnolia' shared at least one allele for 68% of the tested markers, but alleles of the other 32% of the markers were not shared indicating that the two M. rotundifolia selections were very different. The last population, 08306 with 42 progeny, derived its resistance from a selection Vitis romanetii C166-043. Genetic mapping discovered a major powdery mildew resistance locus

  4. Recessive resistance to Cucurbit yellow stunting disorder virus in melon

    Science.gov (United States)

    Cucurbit yellow stunting disorder virus (CYSDV) reduces melon (Cucumis melo L.) fruit quality and yield in many parts of the world. CYSDV and its vector, sweetpotato whitefly (MEAM1 cryptic species of Bemisia tabaci; SPWF) are a devastating combination in the Sonoran Desert areas of California and A...

  5. Distribution of downy mildew (Bremia Lactucae Regel) resistances in a genebank collection of lettuce and its wild relatives

    NARCIS (Netherlands)

    Treuren, van R.; Arend, van der A.J.M.; Schut, J.W.

    2013-01-01

    Genebanks serve as a rich source of diversity that can be exploited for crop improvement. However, large numbers of accessions usually have to be evaluated to find material with the characters of interest, and therefore, enhanced trait information can facilitate the more efficient selection of acces

  6. Computing Integrated Ratings from Heterogeneous Phenotypic Assessments: A Case Study of Lettuce Postharvest Quality and Downy Mildew Resistance

    Science.gov (United States)

    Comparing performance of a large number of accessions simultaneously is not always possible. Typically, only subsets of all accessions are tested in separate trials with only some (or none) of the accessions overlapping between subsets. Using standard statistical approaches to combine data from such...

  7. Preliminary Trial of 11 New Hybrid Maize Genotype to The Resistance on Java Downy Mildew (Peronosclerospora maydis)

    OpenAIRE

    Budi Setyawan; Irfan Suliansyah; Aswaldi Anwar; Etti Swasti

    2016-01-01

    Maize or corn (Zea mays L.) belongs to the family of grasses (Poaceae).  Maize is grown globally and one of the most important cereal crop in the world.  In many countries, corn is the main agricultural crop, and are used as food, feed and industrial raw materials. Together with rice and wheat, corn included in the cereals that provide about 65% carbohydrates and 50% protein that humans need. For this purpose, many developing countries, especially in Asia and Africa are in a strong effort to ...

  8. Characterization of Cucumber Mosaic Virus Originating from Cucurbits in Serbia

    Directory of Open Access Journals (Sweden)

    Ana Vučurović

    2011-01-01

    Full Text Available Cucumber mosaic virus (CMV is considered one of the most economically importantplant viruses and has a worldwide distribution and a very wide host range including plantsfrom family Cucurbitaceae. In Serbia, on cucurbits CMV was detected in single and mixedinfections with Zucchini yellow mosaic virus (ZYMV and Watermelon mosaic virus (WMV. Viruses,including CMV, are constantly present in cucurbit crops, but their frequency changesby year and locality. Surveys and sample collections were conducted in cucurbit crops inthe period from 2008 to 2009 at 15 localities in Vojvodina province, and sample testing wascarried out using the DAS-ELISA method and commercially available antisera for six economicallymost important cucurbit viruses. In 2008, a total of 51 samples were collected from13 cucurbit crops of oilseed pumpkin Olinka variety, squash, and bottle gourd and CMV wasdetected in a total of 55% of tested samples with symptoms of viral infection. The most commoninfectious type was mixed infection with ZYMV and WMV (35.3%, and then mixedinfection with ZYMV (17.7% and WMV (2%. A total of 599 symptomatic samples of oilseedpumpkin Olinka variety, zucchini squash varieties Beogradska and Tosca, squash, and wintersquash were collected in 15 cucurbits crops in 2009. CMV was present in 4.4% of totalcollected samples, in single infections in 1.3%, and in mixed with WMV or ZYMV in 1.3%, and1.8%. Five CMV isolates were obtained by mechanical inoculations of N. glutinosa and oneof them was selected for further biological characterization. Test plants which were describedto be hosts of CMV expressed symptoms characteristic for those caused by CMV afterinoculations by isolate 115-08. CMV specific primers Au1u/Au2d were used to amplify an850 bp fragment using RT-PCR method. Amplified fragment encodes the entire viral coatprotein (CP gene and partial 5’ and 3’ UTRs of two selected CMV isolates. Amplified fragmentswere sequenced and deposited in the NCBI, where

  9. Triticale powdery mildew: population characterization and wheat gene efficiency.

    Science.gov (United States)

    Bouguennec, Annaig; Trottet, Maxime; du Cheyron, Philippe; Lonnet, Philippe

    2014-01-01

    Powdery mildew has emerged on triticale in the early 2000s in many locations, probably due to a host range expansion of the wheat formae speciales, Blumeria graminis f.sp. tritici. Many triticale cultivars are highly susceptible to powdery mildew, mainly in seedling stage, revealing a probably narrow genetic basis for powdery mildew resistance genes (Pm). Moreover, as Blumeria graminis is an obligate biotrophic fungus, it is very time consuming and difficult to maintain powdery mildew isolates for a non-specialized laboratory and populations can evolve. In order to identify wheat Pm genes efficient against natural populations of powdery mildew, wheat differential hosts and triticale seedlings were inoculated below susceptible triticale crop naturally contaminated by mildew, in several locations and several years. Symptoms on seedlings were measured after approximately two weeks of incubation in favorable fungus growth conditions. According to these data, we classified the Pm genes presents in our wheat differential hosts set in 3 classes: Pm already overcame by triticale powdery mildew, Pm having variable effects and Pm still efficient against triticale mildew. Data on triticale seedlings allowed us to identify some few triticale cultivars resistant to Blumeria graminis in seedling stage. We will try to identify Pm genes present in those cultivars next year by testing them with the characterized isolates of powdery mildew from Gent University. Nevertheless, interspecific crossing of wheat, resistant to powdery mildew in seedling stage, and rye have been initiated to introduce potentially interesting genes for resistance in triticale.

  10. Origin and evolution of cultivated cucurbits Origem e evolução de cucurbitáceas cultivadas

    Directory of Open Access Journals (Sweden)

    Dilson Antônio Bisognin

    2002-08-01

    Full Text Available Cucurbits (Cucurbitaceae are among the most important plant families supplying humans with edible products and useful fibers. Plants of this family are very similar in above ground development, but they have high genetic diversity for fruit shape and other fruit characteristics, resulting in a variety of uses. The objective of this review was to discuss the origin and evolution of the most important cultivated cucurbits. Understanding the evolutionary history and domestication process increase the possibility for better exploiting the genetic diversity for cultivar development. The domestication selection in cucurbits was for shape, less bitter flesh, larger and fewer seeds, and larger fruit size, resulting in high genetic diversity within and among cultivated species. This variation can be associated with the wide range of uses that require different shape, size and a constant ratio between fruit length and fruit diameter. The discussion of the breeding history indicates how artificial selection could speed up changes in fruit characteristics to attend specific uses and increase adaptation to a variety of environmental conditions in which cucurbits are growing worldwide. Although interspecific hybridization has been employed in cucurbit breeding more than in any other family, there is still a high potential for increasing its application for germplasm and cultivar development.As cucurbitáceas (Cucurbitaceae são uma das mais importantes famílias de plantas utilizadas para produção de alimentos e fibras. Apesar de a parte aérea das plantas desta família ser muito similar em seu desenvolvimento, grande variabilidade genética tem sido mantida para formato e outras características de fruto, o que aumenta o seu potencial de uso. O objetivo desta revisão foi discutir a origem e a evolução das cucurbitáceas cultivadas. A história da evolução e o conhecimento das alterações ocorridas durante este processo podem facilitar a utiliza

  11. The Hibernation of the oak Mildew

    NARCIS (Netherlands)

    Kerling, L.C.P.

    1966-01-01

    The oak mildew invaded Western Europa in the years 1908 and 1909. Since then this parasite, Microsphaera alphitoides Griff. & Maubl. (syn. M. quercina (Schw.) Burr.) has occurred regularly in the Netherlands on oak seedlings and oak coppice, mainly Quercus pedunculata Ehr. (syn. Q. robur L. ). After

  12. The origin and composition of cucurbit "phloem" exudate.

    Science.gov (United States)

    Zhang, Cankui; Yu, Xiyan; Ayre, Brian G; Turgeon, Robert

    2012-04-01

    Cucurbits exude profusely when stems or petioles are cut. We conducted studies on pumpkin (Cucurbita maxima) and cucumber (Cucumis sativus) to determine the origin and composition of the exudate. Morphometric analysis indicated that the exudate is too voluminous to derive exclusively from the phloem. Cold, which inhibits phloem transport, did not interfere with exudation. However, ice water applied to the roots, which reduces root pressure, rapidly diminished exudation rate. Sap was seen by microscopic examination to flow primarily from the fascicular phloem in cucumber, and several other cucurbit species, but primarily from the extrafascicular phloem in pumpkin. Following exposure of leaves to 14CO2, radiolabeled stachyose and other sugars were detected in the exudate in proportions expected of authentic phloem sap. Most of this radiolabel was released during the first 20 s. Sugars in exudate were dilute. The sugar composition of exudate from extrafascicular phloem near the edge of the stem differed from that of other sources in that it was high in hexose and low in stachyose. We conclude that sap is released from cucurbit phloem upon wounding but contributes negligibly to total exudate volume. The sap is diluted by water from cut cells, the apoplast, and the xylem. Small amounts of dilute, mobile sap from sieve elements can be obtained, although there is evidence that it is contaminated by the contents of other cell types. The function of P-proteins may be to prevent water loss from the xylem as well as nutrient loss from the phloem.

  13. Differential Colonization Dynamics of Cucurbit Hosts by Erwinia tracheiphila.

    Science.gov (United States)

    Vrisman, Cláudio M; Deblais, Loïc; Rajashekara, Gireesh; Miller, Sally A

    2016-07-01

    Bacterial wilt is one of the most destructive diseases of cucurbits in the Midwestern and Northeastern United States. Although the disease has been studied since 1900, host colonization dynamics remain unclear. Cucumis- and Cucurbita-derived strains exhibit host preference for the cucurbit genus from which they were isolated. We constructed a bioluminescent strain of Erwinia tracheiphila (TedCu10-BL#9) and colonization of different cucurbit hosts was monitored. At the second-true-leaf stage, Cucumis melo plants were inoculated with TedCu10-BL#9 via wounded leaves, stems, and roots. Daily monitoring of colonization showed bioluminescent bacteria in the inoculated leaf and petiole beginning 1 day postinoculation (DPI). The bacteria spread to roots via the stem by 2 DPI, reached the plant extremities 4 DPI, and the plant wilted 6 DPI. However, Cucurbita plants inoculated with TedCu10-BL#9 did not wilt, even at 35 DPI. Bioluminescent bacteria were detected 6 DPI in the main stem of squash and pumpkin plants, which harbored approximately 10(4) and 10(1) CFU/g, respectively, of TedCu10-BL#9 without symptoms. Although significantly less systemic plant colonization was observed in nonpreferred host Cucurbita plants compared with preferred hosts, the mechanism of tolerance of Cucurbita plants to E. tracheiphila strains from Cucumis remains unknown.

  14. Two species of Gelechioidea (Lepidoptera) from Southeast Asia associated with downy rose myrtle, Rhodomyrtus tomentosa (Myrtaceae)

    Science.gov (United States)

    Two species of Gelechioidea (Lepidoptera), Metharmostis multilineata Adamski, n. sp. (Cosmopterigidae), and Idiophantis soreuta Meyrick, 1906 (Gelechiidae), were collected in southeastern Asia for evaluation as potential biocontrol agents against downy rose myrtle, Rhodomyrtus tomentosa (Aiton) Hass...

  15. Phylogenetic Relationships Among Cucurbit Species Used as Rootstocks for Grafting Watermelon

    Science.gov (United States)

    There is an increased interest in the United States in grafting watermelon on cucurbit rootstocks to control soilborne diseases. Several cucurbit species including Lagenaria siceraria, Cucurbita spp. and Benincasa hispida (wax gourds) have been used in Asia as rootstocks for watermelon. In our pre...

  16. EDR2 negatively regulates salicylic acid-based defenses and cell death during powdery mildew infections of Arabidopsis thaliana

    Directory of Open Access Journals (Sweden)

    Nishimura Marc

    2007-07-01

    Full Text Available Abstract Background The hypersensitive necrosis response (HR of resistant plants to avirulent pathogens is a form of programmed cell death in which the plant sacrifices a few cells under attack, restricting pathogen growth into adjacent healthy tissues. In spite of the importance of this defense response, relatively little is known about the plant components that execute the cell death program or about its regulation in response to pathogen attack. Results We isolated the edr2-6 mutant, an allele of the previously described edr2 mutants. We found that edr2-6 exhibited an exaggerated chlorosis and necrosis response to attack by three pathogens, two powdery mildew and one downy mildew species, but not in response to abiotic stresses or attack by the bacterial leaf speck pathogen. The chlorosis and necrosis did not spread beyond inoculated sites suggesting that EDR2 limits the initiation of cell death rather than its spread. The pathogen-induced chlorosis and necrosis of edr2-6 was correlated with a stimulation of the salicylic acid defense pathway and was suppressed in mutants deficient in salicylic acid signaling. EDR2 encodes a novel protein with a pleckstrin homology and a StAR transfer (START domain as well as a plant-specific domain of unknown function, DUF1336. The pleckstrin homology domain binds to phosphatidylinositol-4-phosphate in vitro and an EDR2:HA:GFP protein localizes to endoplasmic reticulum, plasma membrane and endosomes. Conclusion EDR2 acts as a negative regulator of cell death, specifically the cell death elicited by pathogen attack and mediated by the salicylic acid defense pathway. Phosphatidylinositol-4-phosphate may have a role in limiting cell death via its effect on EDR2. This role in cell death may be indirect, by helping to target EDR2 to the appropriate membrane, or it may play a more direct role.

  17. Cucurbit[8]uril/cucurbit[7]uril controlled off/on fluorescence of the acridizinium and 9-aminoacridizinium cations in aqueous solution.

    Science.gov (United States)

    Wang, Ruibing; Yuan, Lina; Ihmels, Heiko; Macartney, Donal H

    2007-01-01

    The blue fluorescence of acridizinium bromide (ADZ+) and the green fluorescence of 9-aminoacridizinium bromide (AADZ+) in aqueous solutions can be almost entirely switched off upon the double inclusion of these guests in the cavity of cucurbit[8]uril (CB[8]) owing to the formation of a nonfluorescent, noncovalent dimer complex, and then fluorescence can be effectively restored by adding cucurbit[7]uril (CB[7]) to the complex because it competitively extracts the fluorophores out of the CB[8] cavity.

  18. Mildew-omics: How global analyses aid the understanding of life and evolution of powdery mildews

    Directory of Open Access Journals (Sweden)

    Laurence Veronique Bindschedler

    2016-02-01

    Full Text Available The common powdery mildew plant diseases are caused by ascomycete fungi of the order Erysiphales. Their characteristic life style as obligate biotrophs renders functional analyses in these species challenging, mainly because of experimental constraints to genetic manipulation. Global large-scale (-omics approaches are thus particularly valuable and insightful for the characterisation of the life and evolution of powdery mildews. Here we review the knowledge obtained so far from genomic, transcriptomic and proteomic studies in these fungi. We consider current limitations and challenges regarding these surveys and provide an outlook on desired future investigations on the basis of the various –omics technologies.

  19. Spatial aggregation of pathotypes of barley powdery mildew

    DEFF Research Database (Denmark)

    O'Hara, R.B.; Brown, J.K.M.

    1997-01-01

    Aggregation in the distribution of pathotypes of Erysiphe graminis f.sp. hordei, the barley powdery mildew pathogen, was investigated in field plots of 'Golden Promise', 'Proctor' and 'Tyra'. 'Golden Promise' and 'Proctor' have no effective mildew resistance alleles, whereas 'Tyra' has Mla1, which...

  20. Distributional changes and range predictions of downy brome (Bromus tectorum) in Rocky Mountain National Park

    Science.gov (United States)

    Bromberg, J.E.; Kumar, S.; Brown, C.S.; Stohlgren, T.J.

    2011-01-01

    Downy brome (Bromus tectorum L.), an invasive winter annual grass, may be increasing in extent and abundance at high elevations in the western United States. This would pose a great threat to high-elevation plant communities and resources. However, data to track this species in high-elevation environments are limited. To address changes in the distribution and abundance of downy brome and the factors most associated with its occurrence, we used field sampling and statistical methods, and niche modeling. In 2007, we resampled plots from two vegetation surveys in Rocky Mountain National Park for presence and cover of downy brome. One survey was established in 1993 and had been resampled in 1999. The other survey was established in 1996 and had not been resampled until our study. Although not all comparisons between years demonstrated significant changes in downy brome abundance, its mean cover increased nearly fivefold from 1993 (0.7%) to 2007 (3.6%) in one of the two vegetation surveys (P = 0.06). Although the average cover of downy brome within the second survey appeared to be increasing from 1996 to 2007, this slight change from 0.5% to 1.2% was not statistically significant (P = 0.24). Downy brome was present in 50% more plots in 1999 than in 1993 (P = 0.02) in the first survey. In the second survey, downy brome was present in 30% more plots in 2007 than in 1996 (P = 0.08). Maxent, a species-environmental matching model, was generally able to predict occurrences of downy brome, as new locations were in the ranges predicted by earlier generated models. The model found that distance to roads, elevation, and vegetation community influenced the predictions most. The strong response of downy brome to interannual environmental variability makes detecting change challenging, especially with small sample sizes. However, our results suggest that the area in which downy brome occurs is likely increasing in Rocky Mountain National Park through increased frequency and cover

  1. The effectivity of Tilletiopsis albescens in biocontrol of powdery mildew

    DEFF Research Database (Denmark)

    Knudsen, I.M.B.; Skou, J.P.

    1993-01-01

    Tilletiopsis albescens grows well on powdery mildew fungi inoculated on barley or cucumber leaves and causes collapse of the colonies. Application of ballistospores or cut mycelium was equally effective for biocontrol, and the effectiveness tended to increase exponentially with the concentration...... of germinating units (conidia and cut mycelium) applied. Seventy percent relative humidity or more is required for effective biocontrol. Two applications of T. albescens in the period from 3 days before to 3 days after inoculation with powdery mildew were more effective than one. Applications before inoculation...... or 7 days after inoculation with powdery mildew had little effect. T. albescens followed the powdery mildew as it was disseminated to uninoculated leaves, but this did not result in an effective biocontrol. The potential for using T. albescens for biocontrol of powdery mildews is discussed....

  2. A novel fluorometric determination of melamine using cucurbit[7]uril

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yunyou, E-mail: zy161299@mail.ahnu.edu.c [Anhui Key Laboratory of Functional Molecular Solids and Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China); Yang Juan; Liu Min; Wang Sufan; Lu Qin [Anhui Key Laboratory of Functional Molecular Solids and Anhui Key Laboratory of Chemo-Biosensing, College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241000 (China)

    2010-05-15

    Melamine is a toxic compound to both animals and human beings, and is connected to various diseases, such as kidney stones and bladder cancer. For the efficient detection of melamine, we have developed a novel sensitive cucurbit[7]uril (CB7) sensor with a detection limit at 0.20 mug mL{sup -1}, and applied it to detect melamine in tainted milk. Fluorescence studies indicate that CB7 forms complex with melamine in a 1:1 mole ratio. The binding constant at various temperatures has been calculated and the interaction mechanism has been discussed based on molecular modeling result.

  3. Biology of Anastrepha grandis (Diptera: Tephritidae) in Different Cucurbits.

    Science.gov (United States)

    Bolzan, Anderson; Nava, Dori E; Garcia, Flávio R M; Valgas, Ricardo A; Smaniotto, Giovani

    2015-06-01

    Anastrepha grandis (Macquart) (Diptera: Tephritidae) is one of the main pests of cucurbits in Brazil. Losses occur due to the damage caused to the fruits and the embargo on exports, as A. grandis is considered a quarantine pest in countries that import Brazilian cucurbits. This study aimed to evaluate the development of A. grandis in hosts of the Cucurbitaceae family. The hosts used were stem squash (Cucurbita pepo L.), squash (Cucurbita moschata Duchesne), chayote [Sechium edule (Jacq.) Swartz], mini watermelon [Citrullus lanatus (Thunb.) Matsum & Nakai], Spanish melon (Cucumis melo L.), hybrid squash "Tetsukabuto" (C. moschata×Cucurbita maxima Duchesne), and salad cucumber (Cucumis sativus L.). We evaluated the viability and duration of egg-to-pupa period, pupal weight, sex ratio, and average number of pupae per fruit under controlled conditions of temperature, relative humidity, and photophase. The preoviposition and oviposition periods, fecundity, fertility, and longevity of females were determined for adults. Hosts of the genus Cucurbita provided a better development of A. grandis in comparison with other hosts, and presented a greater number of insects on fruit as well as higher infestation rate. Fecundity and longevity were also higher for females that developed in hosts of the genus Cucurbita, although values of these biological parameters varied between stem squash, squash, hybrid squash "Tetsukabuto."

  4. Simultaneous multiplex PCR detection of seven cucurbit-infecting viruses.

    Science.gov (United States)

    Kwon, Ji Yeon; Hong, Jin Sung; Kim, Min Jea; Choi, Sun Hee; Min, Byeong Eun; Song, Eun Gyeong; Kim, Hyun Hee; Ryu, Ki Hyun

    2014-09-01

    Two multiplex polymerase chain reaction (PCR) systems using dual priming oligonucleotide (DPO) primers were developed for the simultaneous detection of seven cucurbit-infecting viruses. One system allows for the detection of papaya ringspot virus, watermelon mosaic virus, and zucchini yellow mosaic virus, whereas the other permits the detection of cucumber green mottle mosaic virus, cucumber fruit mottle mosaic virus, kyuri green mottle mosaic virus, and zucchini green mottle mosaic virus. Viral species-specific DPO primers developed in this study detected as little as 10 fg/μl of viral RNA under monoplex conditions and 10 pg/μl of viral RNA under multiplex conditions. Multiplex PCR using the DPO primer sets was capable of amplifying viral genes at annealing temperatures ranging from 53 °C to 63 °C. Whereas the use of conventional primers gave rise to non-specific bands, the DPO primers detected target viral genes in the absence of non-specific amplification. When these DPO multiplex primer sets were applied to virus-infected cucurbit samples obtained in the field, multiple infection as well as single infection was accurately identified. This novel approach could also detect multiple viruses in infected seeds. The reliability of multiplex PCR systems using DPO primers for plant virus detection is discussed.

  5. Effects of soil amendments on germination and emergence of downy brome (Bromus tectorum) and Hilaria jamesii

    Science.gov (United States)

    Belnap, J.; Sherrod, S.K.; Miller, M.E.

    2003-01-01

    Downy brome is an introduced Mediterranean annual grass that now dominates millions of hectares of western U.S. rangelands. The presence of this grass has eliminated many native species and accelerated wildfire cycles. The objective of this study was to identify soil additives that allowed germination but inhibited emergence of downy brome, while not affecting germination or emergence of the native perennial grass Hilaria jamesii. On the basis of data from previous studies, we focused on additives that altered the availability of soil nitrogen (N), phosphorus (P), and potassium (K). Most water-soluble treatments inhibited downy brome germination and emergence. We attribute the inhibitory effects of these treatments to excessive salinity and ion-specific effects of the additives themselves. An exception to this was oxalic acid, which showed no effect. Most water-insoluble treatments had no effect in soils with high P but did have an effect in soils with low P. Zeolite was effective regardless of P level, probably due to the high amounts of Na+ it added to the soil solution. Most treatments at higher concentrations resulted in lower downy brome emergence rates in soils currently dominated by downy brome than in uninvaded (but theoretically invadable) Hilaria soils. This difference is possibly attributable to inherent differences in labile soil P. In Stifa soils, where Stipa spp. grow, but which are generally considered to be uninvadable by downy brome, additions of high amounts of N resulted in lower emergence. This may have been an effect of NH4+ interference with uptake of K or other cations or toxicity of high N. We also saw a positive relationship between downy brome emergence and pH in Stipa soils. Hilaria development parameters were not as susceptible to the treatments, regardless of concentration, as downy brome. Our results suggest that there are additions that may be effective management tools for inhibiting downy brome in calcareous soils, including (1

  6. Elemental micro-PIXE mapping of hypersensitive lesions in Lagenaria sphaerica (Cucurbitaceae) resistant to Sphaerotheca fuliginea (powdery mildew)

    Science.gov (United States)

    Weiersbye-Witkowski, I. M.; Przybylowicz, W. J.; Straker, C. J.; Mesjasz-Przybylowicz, J.

    1997-07-01

    Genotypes of the Southern African cucurbit, Lagenaria sphaerica, that are resistant to powdery-mildew ( Sphaerotheca fuliginea) exhibit foliar hypersensitive (HS) lesions on inoculation with this fungal pathogen. Elemental distributions across radially symmetrical HS lesions, surrounding unlesioned leaf tissue and uninoculated leaf tissue, were obtained using the true elemental imaging system (Dynamic Analysis) of the NAC Van de Graaff nuclear microprobe. Raster scans of 3 MeV protons were complemented by simultaneous PIXE and BS point analyses. The composition of cellulose (C 6H 10O 5) was used as constant matrix composition for scans, and the sample thickness was found from BS spectra. Si and elements heavier than Ca contributed to matrix composition within HS lesions and the locally elevated Ca raised the limits of detection for some trace metals of interest. In comparison to uninoculated tissue, inoculated tissue was characterised by higher overall concentrations of all measured elements except Cu. Fully developed, 6 day-old HS lesions and the surrounding tissue could be divided into five zones, centred on the fungal infection site. Each zone was characterized by distinct local elemental distributions (either depletion, or accumulation to potentially phytotoxic levels).

  7. A study of the Fenton-mediated oxidation of methylene blue-cucurbit[n]uril complexes.

    Science.gov (United States)

    Fuenzalida, Tomás; Fuentealba, Denis

    2015-04-01

    Cucurbit[n]urils efficiently decreased the Fenton-mediated oxidation of encapsulated dyes, providing a mechanism for some control and selectivity over the degradation. The encapsulation of methylene blue into cucurbit[7]uril made it highly refractory against Fenton oxidation in the dark or under UVA light irradiation. However, the oxidation of the encapsulated dye was significantly enhanced under visible light irradiation. This behavior was selective for the cucurbit[7]uril complex and not for the cucurbit[8]uril complex, which achieved the same degree of protection irrespective of the irradiation conditions. This different reactivity of the complexes was further discussed in terms of their excited state properties. The main mechanism for protection was the seclusion of the dye into cucurbit[n]urils as shown by the fact that the non-encapsulated dye safranin was protected much less than methylene blue. Additionally, cucurbit[n]urils efficiently trapped hydroxyl radicals, which contributed significantly to the protection of the dyes from Fenton-mediated oxidation.

  8. Process-based management approaches for salt desert shrublands dominated by downy brome

    Science.gov (United States)

    Downy brome grass (Bromus tectorum L.) invasion has severely altered key ecological processes such as disturbance regimes, soil nutrient cycling, community assembly, and successional pathways in semi-arid Great Basin salt desert shrublands. Restoring the structure and function of these severly alte...

  9. Epidemiology of Cucurbit yellow stunting disorder virus in the US Southwest and development of virus resistant melon

    Science.gov (United States)

    Cucurbit yellow stunting disorder virus (CYSDV), emerged in the Southwest USA in 2006, where it is transmitted by the MEAM1 cryptic species of Bemisia tabaci. The virus results in late-season infection of spring melon crops with limited economic impact; however, all summer and fall cucurbits become ...

  10. Thiol accumulation and cysteine desulfhydrase activity in H2S-fumigated leaves and leaf homogenates of cucurbit plants

    NARCIS (Netherlands)

    Schütz, Bärbel; De Kok, Luit J.; Rennenberg, Heinz

    1991-01-01

    Fumigation of both, cucurbit plants and cucurbit leaf homogenates with hydrogen sulfide (H2S) resulted in an increase in soluble thiol, mainly glutathione and cysteine. In leaf homogenates this increase was counteracted or prevented by the addition at 1 mM of inhibitors of pyridoxalphosphate depende

  11. Taxonomic revision and phylogenetic analyses of rubber powdery mildew fungi.

    Science.gov (United States)

    Liyanage, K K; Khan, Sehroon; Brooks, Siraprapa; Mortimer, Peter E; Karunarathna, Samantha C; Xu, Jianchu; Hyde, Kevin D

    2017-02-09

    Powdery mildew is a fungal disease that infects a wide range of plants, including rubber trees, which results in a reduction of latex yields of up to 45%. The causal agent of powdery mildew of rubber was first described as Oidium heveae, but later morpho-molecular research suggested that in the past, O. heveae has been confused with Erysiphe quercicola. However, it is still under debate whether the causal agent should be classified as a species of the genus Erysiphe emend. or Golovinomyces and Podosphaera, respectively. Therefore, the aim of this study was to undertake the morpho-molecular characterization of powdery mildew species associated with rubber trees, thus resolving these taxonomic issues. Morphological observation under light and scanning electron microscopes (SEM) clearly identified two morphotypes of the rubber powdery mildew. With the support of morphological and phylogenetic data, one of the two morphotypes was identified as the asexual morph of E. quercicola, while the second morphotype is still insufficiently known and according to the morphological results obtained we assume that it might belong to the genus Golovinomyces. More collections and additional molecular data are required for final conclusions regarding the exact taxonomic position of the second morphotype of rubber powdery mildew and its relation to the name O. heveae. The haplotype analysis identified eight haplotype groups of E. quercicola indicating the high genetic diversity of the species.

  12. Cucurbit[6]uril-Promoted Click Chemistry for Protein Modification.

    Science.gov (United States)

    Finbloom, Joel A; Han, Kenneth; Slack, Clancy C; Furst, Ariel L; Francis, Matthew B

    2017-07-19

    Azide-alkyne cycloaddition is a powerful reaction for the formation of bioconjugates. When catalyzed by Cu(I) or strain promotion, this cycloaddition is considered to be a "click" reaction with many applications in chemical biology and materials science. We report a new type of azide-alkyne click chemistry for the synthesis of protein conjugates using cucurbit[6]uril (CB6) supramolecular chemistry. CB6-promoted azide-alkyne cycloaddition has been previously used for the synthesis of rotaxanes but has not been applied to the development of complex bioconjugates. By developing new substrates for CB6 click that do not contain any cross-reactive functional groups and by optimizing reaction conditions, we converted CB6 click chemistry from a rotaxane synthesis tool into a useful bioconjugation technique. Using these new parameters, we synthesized a series of protein conjugates including protein-peptide, protein-DNA, protein-polymer, and protein-drug conjugates. We further demonstrated that CB6 click can be used in conjunction with strain-promoted azide-alkyne cycloaddition to generate distinct bioconjugates in protein mixtures. CB6 click is a promising new reaction for the development of protein conjugates and can be applied toward the synthesis of complex biomaterials for a wide range of applications.

  13. Synthesis and Crystal Structure of a Binuclear Gadolinium(Ⅲ) Complex Bridged by Cucurbit[6]uril

    Institute of Scientific and Technical Information of China (English)

    Gui Ling ZHANG; Zhi Yong WU; Yan Tuan LI; Da Qi WANG; Jian Min DOU

    2006-01-01

    A new cucurbit[6]uril bridged binuclear complex {[Gd(H2O)6]2[Q6(H2O)]}Cl6·4H2O,where Q6 represents cucurbit[6]uril, has been synthesized and characterized by X-ray diffraction.The crystal structure shows that the complex has an extended cucurbit[6]uril-bridged structure consisting of two gadolinium(Ⅲ) ions, in which each gadolinium(Ⅲ) ion is coordinated with two neighboring carbonylic oxygen atoms of Q6 and six oxygen atoms of water molecules that leans toward one side of the portal. One disordered guest water molecule resides in the Q6 molecule cavity and occupies two different positions. Hydrogen bonds assemble the complex to three-dimensional supramolecular structure.

  14. Powdery Mildew Resistance in 268 Entries of Hordeum vulgare

    DEFF Research Database (Denmark)

    Jiang, W.M.; Jørgensen, Jørgen Helms; Torp, J

    1984-01-01

    A collection of 24 'Spontaneum' barley [H. vulgare ssp. spontaneum] entries and one comprising 244 Ethiopian barleys [H. vulgare ssp. vulgare] were tested for resistance to 4 powdery mildew [used by Erysiphe graminis f. sp. hordei] cultures that carried genes for virulence corresponding to most...... of the known powdery mildew resistance genes. The infection types and spectra of resistance were compared to those of 31 test lines with 35 known resistance genes to find possible new resistance genes and to reveal known resistance genes. The collections may possess some new and some known resistance genes...

  15. The relationship between powdrey mildew (Sphaerotheca fuliginea) resistance and leaf chlorosis sensitivity in cucumber (Cucumis sativus) studied in single seed descent lines

    NARCIS (Netherlands)

    Zijlstra, S.; Jansen, R.C.; Groot, S.P.C.

    1995-01-01

    The genetic relation between powdery mildew resistance and sensitivity for leaf chlorosis of glasshouse cucumber was investigated. The powdery mildew resistant, leaf chlorosis sensitive hybrid variety 'Profito' was crossed with the powdery mildew susceptible, non chlorosis sensitive hybrid variety '

  16. The relationship between powdery mildew (Sphaerotheca fuliginea) resistance and leaf chlorosis sensitivity in cucumber (Cucumis sativus) studied in single seed descent lines

    NARCIS (Netherlands)

    Zijlstra, S.; Jansen, R.C.; Groot, S.P.C.

    1995-01-01

    The genetic relation between powdery mildew resistance and sensitivity for leaf chlorosis of glasshouse cucumber was investigated. The powdery mildew resistant, leaf chlorosis sensitive hybrid variety 'Profito' was crossed with the powdery mildew susceptible, non chlorosis sensitive hybrid variety '

  17. Recessive resistance to Cucurbit yellow stunting disorder virus in melon TGR 1551

    Science.gov (United States)

    Cucurbit yellow stunting disorder virus (CYSDV) reduces melon (Cucumis melo L.) fruit quality and yield in many parts of the world. Host plant resistance of melon to CYSDV is a high priority for sustainable melon production in affected production areas. High-level resistance to CYSDV exhibited by TG...

  18. First report of zucchini tigre mosaic virus infecting several cucurbit plants in China

    Science.gov (United States)

    Pumpkin (Cucurbita moschata Duch.), Cucumber (Cucumis sativus Linn.) and Zucchini (Cucurbita pepo Linn.) are important crops in tropical and subtropical regions in the world, and they are popular vegetable crops in China. There are currently 59 viruses known infecting cucurbit plants which including...

  19. Supramolecular Controlled Cargo Release via Near Infrared Tunable Cucurbit[7]uril-Gold Nanostars.

    Science.gov (United States)

    Han, Yanwei; Yang, Xiran; Liu, Yingzhu; Ai, Qiushuang; Liu, Simin; Sun, Chunyan; Liang, Feng

    2016-02-26

    The near infrared (NIR) absorption and average particle size of gold nanostars (GNSs) can be precisely controlled by varying the molar ratios of cucurbit[7]urils (CB[7]) and GNSs in aqueous solution. GNSs modified with CB[7] achieved high cargo loading with thermally activated release upon the NIR laser irradiation.

  20. Size-tunable supramolecular nanoparticles mediated by ternary cucurbit (8)uril host-guest interactions

    NARCIS (Netherlands)

    Stoffelen, C.; Huskens, Jurriaan

    2013-01-01

    The formation of size-tunable, supramolecular nanoparticles (SNPs), employing cucurbit[8]uril-assisted naphthol–viologen charge-transfer complexes, is strongly time and temperature dependent. Yet, the ternary complex formation is fast at all temperatures employed. This indicates that SNP formation

  1. The cucurbits of mediterranean antiquity: identification of taxa from ancient images and descriptions.

    Science.gov (United States)

    Janick, Jules; Paris, Harry S; Parrish, David C

    2007-12-01

    A critical analysis was made of cucurbit descriptions in Dioscorides' De Materia Medica, Columella's De Re Rustica and Pliny's Historia Naturalis, works on medicine, agriculture and natural science of the 1st century ce, as well as the Mishna and Tosefta, compilations of rabbinic law derived from the same time period together with cucurbit images dating from antiquity including paintings, mosaics and sculpture. The goal was to identify taxonomically the Mediterranean cucurbits at the time of the Roman Empire. By ancient times, long-fruited forms of Cucumis melo (melon) and Lagenaria siceraria (bottle gourd) were selected, cultivated and used as vegetables around the Mediterranean and, in addition, bottle-shaped fruits of L. siceraria were employed as vessels. Citrullus lanatus (watermelons) and round-fruited forms of Cucumis melo (melons) were also consumed, but less commonly. A number of cucurbit species, including Bryonia alba, B. dioica, Citrullus colocynthis and Ecballium elaterium, were employed for medicinal purposes. No unequivocal evidence was found to suggest the presence of Cucumis sativus (cucumber) in the Mediterranean area during this era. The cucumis of Columella and Pliny was not cucumber, as commonly translated, but Cucumis melo subsp. melo Flexuosus Group (snake melon or vegetable melon).

  2. Host Selection, Growth, and Survival of Melonworm (Lepidoptera: Crambidae) on Four Cucurbit Crops Under Laboratory Conditions

    Science.gov (United States)

    Panthi, B. R.; Seal, D. R.; Capinera, J. L.; Nuessly, G. S.; Martin, C. G.

    2016-01-01

    The melonworm, Diaphania hyalinata L. (Lepidoptera: Crambidae), is one of the most serious insect problems affecting cucurbit production. We evaluated the relative preference and suitability of yellow squash, zucchini, cucumber, and watermelon to melonworm by measuring its oviposition, larval feeding preference, survivorship, and developmental responses in the laboratory. Whole plants were used for oviposition study, whereas host leaf discs were used for all the other studies. Watermelon feeding resulted in the longest larval development period (14.3 d), greatest prepupal weights and survivals rates (92%; first instar to adult) among the four crops. However, for watermelon, adult oviposition preference (199.5 eggs/♀), egg survival (70%), and larval feeding (4.1% defoliation) were numerically or statistically lowest, and larval head capsule widths and whole-body lengths were smallest. When differences occurred among these variables, yellow squash, zucchini, and cucumber were each typically higher (or quicker to develop) than watermelon. So why do melonworm adults not prefer watermelon, or at least select it as frequently as squash and cucumber when ovipositing? The answer likely is that there might be some variation in the important chemical components among these cucurbits. We suggest that comparison of kairomones and allomones from watermelon and related cucurbits would be very useful for determining the combination resulting in the lowest risk of damage to the more susceptible cucurbits (assuming the levels can be modified without seriously affecting the crops). PMID:27400704

  3. Hop powdery mildew control through alteration of spring pruning practices

    Science.gov (United States)

    Since 1997, Podosphaera macularis, the causal agent of hop powdery mildew, has become a recurrent threat to hops in the Pacific Northwest because of the potential to reduce cone yield and quality. Disease management practices often involve preventative fungicide applications, but alternative approac...

  4. Structure and evolution of barley powdery mildew effector candidates

    DEFF Research Database (Denmark)

    Pedersen, Carsten; Themaat, Emiel Ver Loren van; McGuffin, Liam J.;

    2012-01-01

    Protein effectors of pathogenicity are instrumental in modulating host immunity and disease resistance. The powdery mildew pathogen of grasses Blumeria graminis causes one of the most important diseases of cereal crops. B. graminis is an obligate biotrophic pathogen and as such has an absolute...

  5. Identification of novel powdery mildew resistance sources in wheat

    Science.gov (United States)

    Powdery mildew is a globally dominating disease of wheat with a high occurrence frequency, and genetic resistance plays an important role in managing this devastating disease. The objectives of this study were to evaluate leaf rust resistance and the underlying genes of breeding lines in the USA, a...

  6. Response of yellow flowering magnolia varieties to powdery mildew, 2015

    Science.gov (United States)

    Yellow flowering varieties of Magnolia spp. hybrids were planted in April 2008 in a field plot with Waynesboro loam soil at the Otis L. Floyd Nursery Research Center in McMinnville, TN. Severity of powdery mildew was determined on 14 Jul, 21 Aug and 15 Oct using a scale of 0-100% foliage affected. ...

  7. Structure and evolution of barley powdery mildew effector candidates

    DEFF Research Database (Denmark)

    Pedersen, Carsten; Themaat, Emiel Ver Loren van; McGuffin, Liam J.;

    2012-01-01

    Protein effectors of pathogenicity are instrumental in modulating host immunity and disease resistance. The powdery mildew pathogen of grasses Blumeria graminis causes one of the most important diseases of cereal crops. B. graminis is an obligate biotrophic pathogen and as such has an absolute...... requirement to suppress or avoid host immunity if it is to survive and cause disease....

  8. Characterization of the small RNA component of leaves and fruits from four different cucurbit species

    Directory of Open Access Journals (Sweden)

    Jagadeeswaran Guru

    2012-07-01

    Full Text Available Abstract Background MicroRNAs (miRNAs are a class of non-coding small RNAs involved in post-transcriptional regulation of gene expression critical for plant growth and development, stress responses and other diverse biological processes in plants. The Cucurbitaceae or cucurbit family represents some of economically important species, particularly those with edible and medicinal fruits. Genomic tools for the molecular analysis of members of this family are just emerging. Partial draft genome sequence became available recently for cucumber and watermelon facilitating investigation of the small RNA component of the transcriptomes in cucurbits. Results We generated four small RNA libraries from bottle gourd (Lagenaria siceraria, Cucurbita moschata, Cucurbita pepo, and, watermelon (Citrullus lanatus var. lanatus in order to identify conserved and novel lineage specific miRNAs in these cucurbits. Deep sequencing of small RNA libraries from these species resulted in 1,597,263, 532,948, 601,388, and 493,384 unique sRNA reads from bottle gourd, moschata, pepo and watermelon, respectively. Sequence analysis of these four libraries resulted in identification of 21 miRNA families that are highly conserved and 8 miRNA families that are moderately conserved in diverse dicots. We also identified 4 putative novel miRNAs in these plant species. Furthermore, the tasiRNAs were identified and their biogenesis was determined in these cucurbits. Small RNA blot analysis or q-PCR analyses of leaf and fruit tissues of these cucurbits showed differential expression of several conserved miRNAs. Interestingly, the abundance of several miRNAs in leaves and fruits of closely related C. moschata and C. pepo was also distinctly different. Target genes for the most conserved miRNAs are also predicted. Conclusion High-throughput sequencing of small RNA libraries from four cucurbit species has provided a glimpse of small RNA component in their transcriptomes. The analysis also

  9. Identification, distribution and incidence of viruses in field-grown cucurbit crops of Iran

    Directory of Open Access Journals (Sweden)

    K. Bananej

    2009-01-01

    Full Text Available A survey of viruses in the major cucurbit-growing areas of 17 provinces in Iran was conducted in 2005 and 2006. A total of 1699 leaf samples were collected from melon, squash, cucumber and watermelon plants showing various virus-like symptoms. Screening for 11 cucurbit viruses by double-antibody sandwich ELISA (DAS-ELISA or RT-PCR, found that 71% of the samples were infected by at least one virus, of which Cucurbit aphid-borne yellows virus (CABYV was the most common overall, occurring in 49, 47, 40, and 33% of cucumber, squash, melon, and watermelon samples respectively. The second most common virus on melon and watermelon was Watermelon mosaic virus (WMV (incidence 30–33%; on cucumber, Cucumber mosaic virus (CMV(33%; and on squash, Zucchini yellow mosaic virus (ZYMV(38%. To our knowledge, this is the first report of Melon necrotic spot virus (MNSV and Zucchini yellow fl eck virus (ZYFV in Iran. Mixed infections occurred in 49% of symptomatic samples. Mixed infections were relatively frequent in squash (58% and melon (55%. The most frequent double infections were WMV+CABYV and ZYMV+CABYV in melon, squash and cucumber, followed by WMV+ZYMV. In watermelon, the most frequent double infection was WMV+ZYMV, followed by WMV+CABYV. The high frequency of CABYV, WMV and ZYMV in the samples assayed on all four cucurbit crops and in all areas surveyed, as well as the detection of Watermelon chlorotic stunt virus (WmCSV and Cucumber vein yellowing virus (CVYV in northern and southern Iran, suggest that these viruses represent a potential threat to cucurbit crops in Iran.

  10. Selection pressure exerted by host resistance genes shapes the population genetic structure of the lettuce downy mildew, Bremia lactucae, in France

    OpenAIRE

    Valade, Romain; Ducasse, Aurélie; Maisonneuve, Brigitte; Neema, Claire,

    2012-01-01

    Most pathogens are submitted to high selection pressure which can be induced by several variables (climatic, biotic, anthropogenicoe) according to their life traits. In the case of plant pathogens, host resistance may be considered as the main driving force of pathogen evolution, with pathogens evolving to overcome host resistance. In the interaction between Bremia lactucae and Lactuca sativa, several specific resistance genes are used to counter this pathogen in crops. In turn, pathogens sho...

  11. A comparison of Peronospora parasitica (Downy mildew) isolates from Arabidopsis thaliana and Brassica oleracea using amplified fragment length polymorphism and internal transcribed spacer 1 sequence analyses.

    Science.gov (United States)

    Rehmany, A P; Lynn, J R; Tör, M; Holub, E B; Beynon, J L

    2000-07-01

    Amplified fragment length polymorphism (AFLP) fingerprints and internal transcribed spacer 1 (ITS1) sequences from 27 Peronospora parasitica isolates (collected from Arabidopsis thaliana or Brassica oleracea), 5 Albugo candida isolates (from the same hosts and from Capsella bursa-pastoris), and 1 Bremia lactucae isolate (from Lactuca sativa) were compared. The AFLP analysis divided the isolates into five groups that correlated with taxonomic species and, in most cases, with host origin. The only exception was a group consisting of A. candida isolates from both B. oleracea and C. bursa-pastoris. ITS1 sequence analysis divided the isolates into the same five groups, demonstrated the divergence between P. parasitica isolates from A. thaliana and B. oleracea, and, using previously published ITS1 sequences, clearly showed the relationship between A. candida isolates from different hosts.

  12. Use of chitosan against downy mildew of rose%几丁聚糖控制月季霜霉病的研究

    Institute of Scientific and Technical Information of China (English)

    孙彤

    2002-01-01

    几丁聚糖是几丁质脱乙酰基后得到的一种氨基多糖.其产品0.5%OS-施特灵可控制月季霜霉病Peronospora sparsa,每隔10天以500倍液连续施药3次,控制效果达80%左右.

  13. Efeito de indutores no controle de míldio em Vitis labrusca Effect of elicitors in the control of downy mildew in Vitis labrusca

    OpenAIRE

    Regina Ceres Torres da Rosa; Rildo Sartori Barbosa Coelho; Selma Cavalcante Cruz de Holanda Tavares; Vanildo Alberto Leal Bezerra Cavalcanti

    2007-01-01

    A cultura da uva, Vitis labrusca, é de grande importância econômica para a região do vale do Siriji - PE. No entanto, nos últimos anos, o míldio da videira vem pondo em risco essa atividade, fazendo com que os produtores invistam bastante recurso com o uso de fungicida visando o seu controle. Visando substituir o uso de agrotóxico foi avaliado nos municípios de São Vicente Férrer - PE (área 1), Natuba - PB (área 2) e Macaparana - PE (área 3) o efeito da indução de resistência promovida por ác...

  14. Arbuscular mycorrhizal symbiosis stimulates key genes of the phenylpropanoid biosynthesis and stilbenoid production in grapevine leaves in response to downy mildew and grey mould infection.

    Science.gov (United States)

    Bruisson, Sébastien; Maillot, Pascale; Schellenbaum, Paul; Walter, Bernard; Gindro, Katia; Deglène-Benbrahim, Laurence

    2016-11-01

    Grapevine (Vitis spp) is susceptible to serious fungal diseases usually controlled by chemical treatments. Arbuscular mycorrhizal fungi (AMF) are obligate plant symbionts which can stimulate plant defences. We investigated the effect of mycorrhization on grapevine stilbenoid defences. Vitis vinifera cvs Chasselas, Pinot noir and the interspecific hybrid Divico, on the rootstock 41B, were mycorrhized with Rhizophagus irregularis before leaf infection by Plasmopara viticola or Botrytis cinerea. Gene expression analysis showed an up-regulation of PAL, STS, and ROMT, involved in the stilbenoid biosynthesis pathway, in plant leaves, 48 h after pathogen inoculation. This defense response could be potentiated under AMF colonization, with an intensity level depending on the gene, the plant cultivar and/or the pathogen. We also showed that higher amounts of active forms of stilbenoids (i.e trans-form of resveratrol, ε- and δ-viniferins and pterostilbene) were produced in mycorrhized plants of the three genotypes in comparison with non-mycorrhized ones, 10 days post-inoculation with either pathogen. These results support the hypothesis that AMF root colonization enhances defence reactions against a biotrophic and a necrotrophic pathogen, in the aerial parts of grapevine. Copyright © 2016 Elsevier Ltd. All rights reserved.

  15. Characterization of a hydroxyproline-rich glycoprotein in pearl millet and its differential expression in response to the downy mildew pathogen Sclerospora graminicola

    NARCIS (Netherlands)

    Sujeeth, Neerakkal; Kini, Ramachandra K.; Shailasree, Sekhar; Wallaart, Eelco; Shetty, Shekar H.; Hille, Jacques; Barna, B.

    2012-01-01

    A monoclonal antibody, JIM 20, derived against an extensin type of hydroxyproline-rich glycoprotein (HRGP) from pea, showed high affinity for HRGP in pearl millet [Pennisetum glaucum (L.) R. Br.]. Electrophoretic separation of Tris-SDS extracted proteins from suspension cells of pearl millet reveale

  16. Downy mildew (Peronospora parasitica) resistance genes in Arabidopsis vary in functional requirements for NDR1, EDS1, NPR1 and salicylic acid accumulation.

    Science.gov (United States)

    McDowell, J M; Cuzick, A; Can, C; Beynon, J; Dangl, J L; Holub, E B

    2000-06-01

    To better understand the genetic requirements for R gene-dependent defense activation in Arabidopsis, we tested the effect of several defense response mutants on resistance specified by eight RPP genes (for resistance to Peronospora parasitica) expressed in the Col-0 background. In most cases, resistance was not suppressed by a mutation in the SAR regulatory gene NPR1 or by expression of the NahG transgene. Thus, salicylic acid accumulation and NPR1 function are not necessary for resistance mediated by these RPP genes. In addition, resistance conferred by two of these genes, RPP7 and RPP8, was not significantly suppressed by mutations in either EDS1 or NDR1. RPP7 resistance was also not compromised by mutations in EIN2, JAR1 or COI1 which affect ethylene or jasmonic acid signaling. Double mutants were therefore tested. RPP7 and RPP8 were weakly suppressed in an eds1-2/ndr1-1 background, suggesting that these RPP genes operate additively through EDS1, NDR1 and as-yet-undefined signaling components. RPP7 was not compromised in coi1/npr1 or coi1/NahG backgrounds. These observations suggest that RPP7 initiates resistance through a novel signaling pathway that functions independently of salicylic acid accumulation or jasmonic acid response components.

  17. The Arabidopsis downy mildew resistance gene, RPP13-Nd, functions independently of NDR1 and EDS1 and does not require the accumulation of salicylic acid.

    Science.gov (United States)

    Bittner-Eddy, P D; Beynon, J L

    2001-03-01

    RPP13-Nd-mediated resistance prevents parasitism by five isolates of Peronospora parasitica (At) in a transgenic Arabidopsis. Columbia background. We tested the effect of a number of known disease resistance mutations on the RPP13-Nd function and found that resistance remained unaltered in plants carrying mutations in either EDS1 or NDR1 and in double ndr1-1/eds1-2 mutant lines. Furthermore, we found that pbs2, pad4-1, npr1-1, and rps5-1, which compromise resistance to a number of P. parasitica (At) isolates, had no affect on RPP13-Nd function. In addition, RPP13-Nd-mediated resistance remained unchanged in a background of salicylic acid depletion (nahG). We conclude that RPP13-Nd is the first Arabidopsis R gene product reported to act via a novel signaling pathway that is independent of salicylic acid-mediated responses and is completely independent of NDR1 and EDS1.

  18. Implications of Farmers' Propensity to Discontinue Adoption of Downy-Mildew Resistant Maize and Improved Cowpea Varieties for Extension Education in Southwestern Nigeria

    Science.gov (United States)

    Oladele, O. I.; Adekoya, A. E.

    2006-01-01

    This paper examines the implications of farmers' propensity to discontinue the adoption of agricultural technologies in southwestern Nigeria. This is predicated on the fact that extension education process should be proactive in addressing farmers in order to sustain the adoption process. Empirical studies looking at diffusion processes from an…

  19. Cucurbit[6]uril: A Possible Host for Noble Gas Atoms.

    Science.gov (United States)

    Pan, Sudip; Mandal, Subhajit; Chattaraj, Pratim K

    2015-08-27

    Density functional and ab initio molecular dynamics studies are carried out to investigate the stability of noble gas encapsulated cucurbit[6]uril (CB[6]) systems. Interaction energy, dissociation energy and dissociation enthalpy are calculated to understand the efficacy of CB[6] in encapsulating noble gas atoms. CB[6] could encapsulate up to three Ne atoms having dissociation energy (zero-point energy corrected) in the range of 3.4-4.1 kcal/mol, whereas due to larger size, only one Ar or Kr atom encapsulated analogues would be viable. The dissociation energy value for the second Ar atom is only 1.0 kcal/mol. On the other hand, the same for the second Kr is -0.5 kcal/mol, implying the instability of the system. The noble gas dissociation processes are endothermic in nature, which increases gradually along Ne to Kr. Kr encapsulated analogue is found to be viable at room temperature. However, low temperature is needed for Ne and Ar encapsulated analogues. The temperature-pressure phase diagram highlights the region in which association and dissociation processes of Kr@CB[6] would be favorable. At ambient temperature and pressure, CB[6] may be used as an effective noble gas carrier. Wiberg bond indices, noncovalent interaction indices, electron density, and energy decomposition analyses are used to explore the nature of interaction between noble gas atoms and CB[6]. Dispersion interaction is found to be the most important term in the attraction energy. Ne and Ar atoms in one Ng entrapped analogue are found to stay inside the cavity of CB[6] throughout the simulation at 298 K. However, during simulation Ng2 units in Ng2@CB[6] flip toward the open faces of CB[6]. After 1 ps, one Ne atom of Ne3@CB[6] almost reaches the open face keeping other two Ne atoms inside. At lower temperature (77 K), all the Ng atoms in Ngn@CB[6] remain well inside the cavity of CB[6] throughout the simulation time (1 ps).

  20. Detection of Papaya ringspot virus type W infecting the cucurbit weed Cucumis melo var. dudaim in Florida

    Science.gov (United States)

    This is the first report of Papaya ringspot virus type W infecting Cucumis melo var. dudaim, a cucurbit weed, in Florida. It provides an overview of this virus reservoir for growers, extension workers, crop consultants and research and regulatory scientists....

  1. Synthesis and Crystal Structure of Macrocyclic Cavitand Cucurbit[5]uril and Its Supramolecular Adduct with Cu(Ⅱ)

    Institute of Scientific and Technical Information of China (English)

    LIU,Si-Min(刘思敏); HUANG,Zi-Xiang(黄子祥); WU,Xiao-Jun(吴晓军); LIANG,Feng(梁峰); WU,Cheng-Tai(吴成泰)

    2004-01-01

    The first supramolecular adduct (H3O)2[Cu(H2O)4](SO4)2·2(C30H30N20O10)·24(H2O) based on cucurbit[5]uril was synthesized and characterized by single crystal X-ray diffraction analysis. In the adduct, copper ion is coordinated by four oxygen atoms from H2O. The latter links two cucurbit[5]uril molecules due to a complicated hydrogen bonding containing lattice water molecules.

  2. Inactivation of mildew in rough rice and wheat by gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wang Jun, E-mail: jwang@zju.edu.c [Department of Biosystems Engineering, Zhejiang University, 268 Kaixuan Road, Hangzhou 310029 (China); Yu Yong [Department of Biosystems Engineering, Zhejiang University, 268 Kaixuan Road, Hangzhou 310029 (China)

    2010-06-15

    Rough rice and wheat were irradiated by gamma ray ({sup 60}Co) with different doses and the mildew inactivation efficacy was investigated after 0, 6 and 12 month storage. Five genera of mildew in rough rice and wheat were detected, including Alternaria, Fusarium, Aspergillus, Penicillium and Rhizopus. For Aspergillus, four genera of mold were detected, including Aspergillus Kawachii, Aspergillus glaucus, Aspergillus niger, Aspergillus flavus. Detection rates of the five genera of mildew and four genera of Aspergillus were all reduced with increasing dose after 0, 6 and 12 months storage. The detection rates of the other four genera of mildew had no significant change during storage.

  3. Biological and Molecular Characterization of a Korean Isolate of Cucurbit aphid-borne yellows virus Infecting Cucumis Species in Korea.

    Science.gov (United States)

    Choi, Seung-Kook; Yoon, Ju-Yeon; Choi, Gug-Seoun

    2015-12-01

    Surveys of yellowing viruses in plastic tunnels and in open field crops of melon (Cucumis melo cultivar catalupo), oriental melon (C. melo cultivar oriental melon), and cucumber (C. sativus) were carried out in two melon-growing areas in 2014, Korea. Severe yellowing symptoms on older leaves of melon and chlorotic spots on younger leaves of melon were observed in the plastic tunnels. The symptoms were widespread and included initial chlorotic lesions followed by yellowing of whole leaves and thickening of older leaves. RT-PCR analysis using total RNA extracted from diseased leaves did not show any synthesized products for four cucurbit-infecting viruses; Beet pseudo-yellows virus, Cucumber mosaic virus, Cucurbit yellows stunting disorder virus, and Melon necrotic spot virus. Virus identification using RT-PCR showed Cucurbit aphid-borne yellows Virus (CABYV) was largely distributed in melon, oriental melon and cucumber. This result was verified by aphid (Aphis gossypii) transmission of CABYV. The complete coat protein (CP) gene amplified from melon was cloned and sequenced. The CP gene nucleotide and the deduced amino acid sequence comparisons as well as phylogenetic tree analysis of CABYV CPs showed that the CABYV isolates were undivided into subgroups. Although the low incidence of CABYV in infections to cucurbit crops in this survey, CABYV may become an important treat for cucurbit crops in many different regions in Korea, suggesting that CABYV should be taken into account in disease control of cucurbit crops in Korea.

  4. Biological and Molecular Characterization of a Korean Isolate of Cucurbit aphid-borne yellows virus Infecting Cucumis Species in Korea

    Directory of Open Access Journals (Sweden)

    Seung-Kook Choi

    2015-12-01

    Full Text Available Surveys of yellowing viruses in plastic tunnels and in open field crops of melon (Cucumis melo cultivar catalupo, oriental melon (C. melo cultivar oriental melon, and cucumber (C. sativus were carried out in two melon-growing areas in 2014, Korea. Severe yellowing symptoms on older leaves of melon and chlorotic spots on younger leaves of melon were observed in the plastic tunnels. The symptoms were widespread and included initial chlorotic lesions followed by yellowing of whole leaves and thickening of older leaves. RT-PCR analysis using total RNA extracted from diseased leaves did not show any synthesized products for four cucurbit-infecting viruses; Beet pseudo-yellows virus, Cucumber mosaic virus, Cucurbit yellows stunting disorder virus, and Melon necrotic spot virus. Virus identification using RT-PCR showed Cucurbit aphid-borne yellows Virus (CABYV was largely distributed in melon, oriental melon and cucumber. This result was verified by aphid (Aphis gossypii transmission of CABYV. The complete coat protein (CP gene amplified from melon was cloned and sequenced. The CP gene nucleotide and the deduced amino acid sequence comparisons as well as phylogenetic tree analysis of CABYV CPs showed that the CABYV isolates were undivided into subgroups. Although the low incidence of CABYV in infections to cucurbit crops in this survey, CABYV may become an important treat for cucurbit crops in many different regions in Korea, suggesting that CABYV should be taken into account in disease control of cucurbit crops in Korea.

  5. Cucurbit[7]uril disrupts aggregate formation between rhodamine B dyes covalently attached to glass substrates.

    Science.gov (United States)

    Halterman, Ronald L; Moore, Jason L; Yip, Wai Tak

    2011-07-01

    Dye aggregation is detrimental to the performance of high optical density dye-doped photonic materials. To overcome this challenge, the ability of cucurbit[7]uril (CB7) as a molecular host to disrupt aggregate formation on glass substrates was examined. Rhodamine B was covalently attached to glass slides by initially coating the surface with azidohexylsiloxane followed by copper-catalyzed "click" triazole formation with rhodamine B propargyl ester. The absorption and emission spectra of rhodamine B coated slides in water indicated diverse heterogeneous properties as surface dye density varied. Fluorescence quenching due to dye aggregation was evident at high surface dye density. Addition of aqueous cucurbit[7]uril (CB7) to the surface-tethered dyes perturbed the spectra to reveal a considerable reduction in heterogeneity, which suggested that the presence of a surface in close proximity does not significantly impair CB7's ability to complex with tethered rhodamine B.

  6. Triple emission from p-dimethylaminobenzonitrile-cucurbit[8]uril triggers the elusive excimer emission.

    Science.gov (United States)

    Sayed, Mhejabeen; Biedermann, Frank; Uzunova, Vanya D; Assaf, Khaleel I; Bhasikuttan, Achikanath C; Pal, Haridas; Nau, Werner M; Mohanty, Jyotirmayee

    2015-01-01

    The intriguing dual-emission behavior of p- dimethylaminobenzonitrile (DMABN) and the identity of the associated excited states is, arguably, the most extensively investigated and also controversially discussed molecule- specific phenomenon of modern photochemistry. We have now found a new, third fluorescence band when DMABN is encapsulated within the water-soluble molecular container cucurbit[8]uril (CB8). It is centered between the previously observed emissions and assigned to the elusive excimer emission from DMABN through 1:2 CB8:DMABN complex formation. Heating of the CB8⋅(DMABN)2 complex from 0 to 100 °C results in the dissociation of the ternary complex and restoration of the dual-emission properties of the monomer. Alternatively, monomer emission can be obtained by selecting cucurbit[7]uril (CB7), a host homologue that is too small to accommodate two DMABN molecules, or by introducing ethyl instead of methyl groups at the amino terminus of the aminobenzonitrile guest.

  7. Cucurbit[7]uril as a tool in the green synthesis of gold nanoparticles.

    Science.gov (United States)

    Premkumar, Thathan; Geckeler, Kurt E

    2010-12-03

    A simple, green, one-pot synthesis of gold nanoparticles was achieved through the reaction of an aqueous mixture of potassium tetrachloroaurate(III) and the macrocycle cucurbit[7]uril in the presence of sodium hydroxide at room temperature without introducing any kind of traditional reducing agents and/or external energy. The as-prepared gold nanoparticles showed catalytic activity for the reduction reaction of 4-nitrophenol in the presence of NaBH(4), which has been established by visual inspection and UV/Vis spectroscopy. This report is the first for the preparation of gold nanoparticles using cucurbit[7]uril in aqueous media through chemical reduction without employing conventional reducing agents and/or external energy.

  8. Rationalization of pesticide treatments against powdery mildew of grape.

    Science.gov (United States)

    Spera, G; La Torre, A; Gianferro, M; Bugliosi, R

    2007-01-01

    The powdery mildew represents one of the diseases which affect the grape, it is diffused in all agricultural regions with variable intensity and epidemic course in operation of many microclimatic factors. The powdery mildew of grape is caused from Uncinala necator (Schw.) Burr. (nowadays named Erysiphe necator Schwein.); it is controlled with systemic therapy and contact chemicaL products. In some vineyards located in Latium (central Italy), different field trials have been carried out purposely to rationalize the treatments against E. necator. We have studied the powdery mildew infections through monitoring a set of environmental parameters, the evaluation of cultivar sensibility, the agricultural production method and the area characteristics. We have analysed the following environmental parameters monitoring every 15 minutes: precipitation, soil temperature, solar radiation, wind direction, wind speed, atmospheric relative humidity, atmospheric temperature, leaf wetness, soil humidity to cm 20 and soil humidity to cm 40. Besides, we have used Artificial Intelligence analysis techniques to try to forecast U. necator infections. Guideline EPPO/OEPP PP 1/4 (4) has been used. The trials were conducted in conventional and organic farms. In 2 conventional farms and in organic farm we have considered 1 untreated control thesis, in order to follow the course of infection, 1 standard farm reference thesis (standard), where the treatments were carried out according to the usual farm procedures and 1 thesis where the treatments were carried out according to examining the environmental data. In another conventional vineyard, we have considered only 1 untreated control thesis and 1 standard farm reference thesis (standard) to study disease trend. The achieved results have underlined the possibility (through the knowledge of data pedoclimatic and cultural) to position the treatments against the powdery mildew so that to reduce their number. The lower number of treatments that

  9. LIFEGUARD proteins support plant colonization by biotrophic powdery mildew fungi.

    Science.gov (United States)

    Weis, Corina; Hückelhoven, Ralph; Eichmann, Ruth

    2013-09-01

    Pathogenic microbes manipulate eukaryotic cells during invasion and target plant proteins to achieve host susceptibility. BAX INHIBITOR-1 (BI-1) is an endoplasmic reticulum-resident cell death suppressor in plants and animals and is required for full susceptibility of barley to the barley powdery mildew fungus Blumeria graminis f.sp. hordei. LIFEGUARD (LFG) proteins resemble BI-1 proteins in terms of predicted membrane topology and cell-death-inhibiting function in metazoans, but display clear sequence-specific distinctions. This work shows that barley (Hordeum vulgare L.) and Arabidopsis thaliana genomes harbour five LFG genes, HvLFGa-HvLFGe and AtLFG1-AtLFG5, whose functions are largely uncharacterized. As observed for HvBI-1, single-cell overexpression of HvLFGa supports penetration success of B. graminis f.sp. hordei into barley epidermal cells, while transient-induced gene silencing restricts it. In penetrated barley epidermal cells, a green fluorescent protein-tagged HvLFGa protein accumulates at the site of fungal entry, around fungal haustoria and in endosomal or vacuolar membranes. The data further suggest a role of LFG proteins in plant-powdery mildew interactions in both monocot and dicot plants, because stable overexpression or knockdown of AtLFG1 or AtLFG2 also support or delay development of the powdery mildew fungus Erysiphe cruciferarum on the respective Arabidopsis mutants. Together, this work has identified new modulators of plant-powdery mildew interactions, and the data further support functional similarities between BI-1 and LFG proteins beyond cell death regulation.

  10. CHARACTERIZATION OF CUCURBIT PRODUCTION SYSTEMS AND DISEASE PREVALENCE IN MUNICIPALITIES IN PERNAMBUCO

    Directory of Open Access Journals (Sweden)

    GERFFESON THIAGO MOTA DE ALMEIDA SILVA

    2016-01-01

    Full Text Available Cucurbits have great economic, nutritional and social importance in the Brazilian semiarid region. In this region, many factors can result in reduced productivity of these crops, especially fungal and viral diseases. Therefore, knowledge of cucurbits is crucial for proper disease management. The objective of this work was to identify the major diseases of cucurbits grown in some municipalities in the Hinterland of the state of Pernambuco. Thus, plant samples were collected with symptoms in crops in the municipalities of Salgueiro, Serra Talhada, Floresta, Petrolândia, Ibimirim, Custódia and Inajá. A questionnaire was also applied to gather information about the production profile of producers. Seven fungal pathogens infecting cucurbits were identified: Pseudoperonospora cubensis, Colletotrichum sp., Podosphaera xanthii, Rhizoctonia solani, Didymella bryoniae, Fusarium sp. e Alternaria sp., and three viruses as well: Papaya ringspot virus - watermelon strain (PRSV-W, Watermelon mosaic virus (WMV, Zucchini yellow mosaic virus (ZYMV. It was found that in small crops, there is limited search for technical information om cropping, and these crops originate mostly from native seeds, in contrast to medium and large producers, who use improved cultivars. The melon and watermelon crops are the most commercially exploited, while pumpkins are used in subsistence agriculture. As for plant health problems, most respondents reported knowing the main diseases that occur in crops and perform disease control based on personal experience and / or through the help of the technical assistance provided by agricultural stores. In a few cases, in large farms, there was an agronomist to assist in this type of control.

  11. Binding Studies of Cucurbit[7]uril with Gold Nanoparticles Bearing Different Surface Functionalities‡

    OpenAIRE

    Tonga, Gulen Yesilbag; Mizuhara, Tsukasa; Saha, Krishnendu; Jiang, Ziwen; Hou, Singyuk; Das, Riddha; Rotello, Vincent M.

    2015-01-01

    Host-guest interactions between a synthetic receptor, cucurbit[7]uril (CB[7]), and gold nanoparticles (AuNPs) have been quantified using isothermal titration calorimetry. AuNPs were functionalized with ligands containing tertiary or quaternary benzylamine derivatives, with electron donating or withdrawing groups at the para position of the benzene ring. Analysis of binding interactions reveals that functional groups at the para position have no significant effect on binding constant. However,...

  12. Determination of nevirapine in the presence of cucurbit(7uril with a gold electrode

    Directory of Open Access Journals (Sweden)

    ELÍAS BLANCO

    2014-02-01

    Full Text Available The electrochemical oxidation of nevirapine, an anti-HIV drug, at a gold electrode was studied by voltammetric techniques. Nevirapine showed a signal that interfered with a working electrode wave. This interference was solved by the use of cucurbit(7uril allowing nevirapine to be determined in tablets (80.4 % recovery, presence of stavudine and lamivudine and urine (98.4 %.

  13. Cucurbits depicted in Byzantine mosaics from Israel, 350–600 ce

    Science.gov (United States)

    Avital, Anat; Paris, Harry S.

    2014-01-01

    Background and Aims Thousands of floor mosaics were produced in lands across the Roman and Byzantine empires. Some mosaics contain depictions of agricultural produce, potentially providing useful information concerning the contemporary presence and popularity of crop plants in a particular geographical region. Hundreds of floor mosaics produced in Israel during the Byzantine period have survived. The objective of the present work was to search these mosaics for Cucurbitaceae in order to obtain a more complete picture of cucurbit crop history in the eastern Mediterranean region. Results and Conclusions Twenty-three mosaics dating from 350–600 ce were found that had images positively identifiable as cucurbits. The morphological diversity of the cucurbit fruits in the mosaics of Israel is greater than that appearing in mosaics from any other Roman or Byzantine provincial area. The depicted fruits vary in shape from oblate to extremely long, and some are furrowed, others are striped and others lack definite markings. The cucurbit taxa depicted in the mosaics are Cucumis melo (melon), Citrullus lanatus (watermelon), Luffa aegyptiaca (sponge gourd) and Lagenaria siceraria (bottle gourd). Cucumis melo is the most frequently found taxon in the mosaics and is represented by round dessert melons and long snake melons. Fruits of at least two cultivars of snake melons and of watermelons are represented. To our knowledge, images of sponge gourds have not been found in Roman and Byzantine mosaics elsewhere. Indeed, the mosaics of Israel contain what are probably the oldest depictions of Luffa aegyptiaca in Mediterranean lands. Sponge gourds are depicted often, in 11 of the mosaics at eight localities, and the images include both mature fruits, which are useful for cleaning and washing, and immature fruits, which are edible. Only one mosaic has images positively identifiable as of bottle gourds, and these were round–pyriform and probably used as vessels. PMID:24948671

  14. Assessment of Field-Grown Cucurbit Crops and Weeds within Farms in South-West Nigeria for Viral Diseases

    Directory of Open Access Journals (Sweden)

    Emily Ibitaiyewa AYO-JOHN

    2014-09-01

    Full Text Available Cucurbits are economic crops in Nigeria which serve as additional nutritional supplements and also good sources of income for farmers. Viral diseases are a worldwide problem of cucurbits and a major limiting factor for cucurbit production. A survey of farmer’s fields where cucurbit crops were grown was carried out to assess the incidence and severity of virus symptoms and viruses associated with the crops and weeds in selected locations in Ogun and Osun, in southwest Nigeria, in June, 2012. In all, 38 leaf samples were collected in Ogun state and 52 in Osun state from cucurbit crops and weeds. Leaf samples were tested against  Cucumber mosaic virus (CMV, Melon necrotic spot virus (MNSV, Papaya ringspot virus (PRSV, Watermelon mosaic virus (WMV,Zucchini yellow mosaic virus (ZYMV and Cucumber green mottle mosaic virus (CGMMV using Double Antibody Sandwich (DAS enzyme-linked immunosorbent assay (ELISA. All the fields surveyed had virus symptom incidences of 100% except for melon fields in Osun state with incidences of between 10 and 30%. In Ogun state, the occurrence of CMV was 5/31 (16.1% while MNSV was detected in Lagenaria siceraria and T. occidentalis and it occurred in 6.5% of the leaf samples. In Osun state, CMV was detected in watermelon, melon and weeds found in all locations surveyed. The occurrence of CMV was 9/38 (23.7% in the cucurbit crops and in 78.6% (11/14 of the weeds. PRSV and WMV also occurred in mixed infection with CMV in 7.1% respectively. CMV was the most widespread and prevalent virus infecting cucurbit crops and weeds.Cucurbits are economic crops in Nigeria which serve as additional nutritional supplements and also good sources of income for farmers. Viral diseases are a worldwide problem of cucurbits and a major limiting factor for cucurbit production. A survey of farmer’s fields where cucurbit crops were grown was carried out to assess the incidence and severity of virus symptoms and viruses associated with the crops

  15. Population dynamics, distribution, and species diversity of fruit flies on cucurbits in Kashmir Valley, India.

    Science.gov (United States)

    Ganie, S A; Khan, Z H; Ahangar, R A; Bhat, H A; Hussain, Barkat

    2013-01-01

    Given the economic importance of cucurbits and the losses incurred by fruit fly infestation, the population dynamics of fruit flies in cucurbit crops and the influence of abiotic parameters, such as temperature, relative humidity, rainfall, and total sunshine hours per day on the fruit fly population were studied. The study was carried out at six locations; in district Srinagar the locations were Batmaloo, Shalimar, and Dal, while in district Budgam the locations were Chadoora, Narkara, and Bugam (Jammu and Kashmir, India). Various cucurbit crops, such as cucumber, bottle gourd, ridge gourd and bitter gourd, were selected for the study. With regard to locations, mean fruit fly population was highest (6.09, 4.55, 3.87, and 3.60 flies/trap/week) at Batamaloo and Chadoora (4.73, 3.93, 2.73, and 2.73 flies/trap/week) on cucumber, bottle gourd, ridge gourd, and bitter gourd, respectively. The population of fruit flies was significantly correlated with the minimum and maximum temperature. The maximum species diversity of fruit flies was 0.511, recorded in Chadoora. Bactrocera cucurbitae (Coquillett) (Diptera: Tephritidae) was the most predominant species in both Srinagar and Budgam, followed by B. dorsalis (Hendel) and B. tau (Walker), while B. scutellaris (Bezzi) was found only in Chadoora. Results of the present investigation may be utilized in developing a sustainable pest management strategy in the agroecological system.

  16. Application of Multiplex RT-PCR for Detection of Cucurbit-infecting Tobamovirus

    Directory of Open Access Journals (Sweden)

    Budi Setiadi Daryono

    2015-11-01

    Full Text Available Cucumber green mottle mosaic virus (CGMMV and Kyuri green mottle mosaic virus (KGMMV are seed borne viruses and they are also transmitted mechanically during agricultural practice and through water. Hence, these viruses have potential diseases widely distributed throughout the world. To detect different strains of CGMMV and KGMMV, several specific primers for each virus were designed for single and multiplex RT-PCR. The results of single and multiplex RT-PCR showed that CGMMV was detected in zucchini isolated in Bali-Indonesia, while KGMMV was detected both in zucchini isolated in Bali-Indonesia and Cucumis metuliferus isolated in Thailand. Furthermore, artificial co-infection of these two viruses was prepared and carried out using two different ways of viral RNAs extraction. Based on the results, it could be reported that viral RNAs for cDNA amplification by multiplex RT-PCR could be extracted from a mixture of infected leaves or separate extraction of each viruses infected leaves. In addition, results presented in this study demonstrated the application of multiplex RT-PCR to simultaneously detect CGMMV and KGMMV from cucurbit leaves using a mixture of four primers and its feasibility as a sensitive and rapid laboratory assay. Since, no multiplex RT-PCR technique has been described for the detection of CGMMV and KGMMV, this technique can be a good option for sensitive and reliable tool for detection of two major cucurbit infecting Tobamoviruses.Keywords : Cucurbit infecting Tobamovirus, multiplex RT-PCR, seed borne viruses

  17. Occurrence and distribution of ten viruses infecting cucurbit plants in Guilan province, Iran.

    Science.gov (United States)

    Gholamalizadeh, R; Vahdat, A; Keshavarz, T; Elahinia, A; Bananej, K

    2008-01-01

    During the 2006 and 2007 growing seasons, a systematic survey was conducted in open-field of melon (Cucumis melo L.), cucumber (C. sativus L.), squash (Cucurbita sp.), and watermelon (Citrulus lanatus L.) crops in 16 major cucurbit-growing areas of Guilan province in Iran. Symptomatic leaf samples were collected and screened by double-antibody sandwich ELISA (DAS-ELISA) or RT-PCR to detect Zucchini yellow mosaic virus (ZYMV), Watermelon mosaic virus (WMV), Cucurbit aphid-borne yellows virus (CABYV), Cucumber mosaic virus (CMV), Squash mosaic virus (SqMV), Papaya ringspot virus type W (PRSV-W), Watermelon chlorotic stunt virus (WmCSV), Melon necrotic spot virus (MNSV), Zucchini yellow fleck virus (ZYFV), and Ourmia melon virus (OuMV). The majority of tested samples (73.7%) were infected by at least one of the viruses considered. OuMV, ZYMV, WMV, and WmCSV were the most prevalent viruses and were detected in tested cucurbit plants. The incidence of multiple infections with 2 or more viruses was also relatively high, 63.3, 48.6, 42.7, and 26.7% of the infected samples of melon, cucumber, squash, and watermelon, respectively. The high incidence of OuMV and WmCSV suggested that these viruses might turn out to be an important threat for the melon and cucumber crops in the province.

  18. The Origin and Composition of Cucurbit “Phloem” Exudate1[OA

    Science.gov (United States)

    Zhang, Cankui; Yu, Xiyan; Ayre, Brian G.; Turgeon, Robert

    2012-01-01

    Cucurbits exude profusely when stems or petioles are cut. We conducted studies on pumpkin (Cucurbita maxima) and cucumber (Cucumis sativus) to determine the origin and composition of the exudate. Morphometric analysis indicated that the exudate is too voluminous to derive exclusively from the phloem. Cold, which inhibits phloem transport, did not interfere with exudation. However, ice water applied to the roots, which reduces root pressure, rapidly diminished exudation rate. Sap was seen by microscopic examination to flow primarily from the fascicular phloem in cucumber, and several other cucurbit species, but primarily from the extrafascicular phloem in pumpkin. Following exposure of leaves to 14CO2, radiolabeled stachyose and other sugars were detected in the exudate in proportions expected of authentic phloem sap. Most of this radiolabel was released during the first 20 s. Sugars in exudate were dilute. The sugar composition of exudate from extrafascicular phloem near the edge of the stem differed from that of other sources in that it was high in hexose and low in stachyose. We conclude that sap is released from cucurbit phloem upon wounding but contributes negligibly to total exudate volume. The sap is diluted by water from cut cells, the apoplast, and the xylem. Small amounts of dilute, mobile sap from sieve elements can be obtained, although there is evidence that it is contaminated by the contents of other cell types. The function of P-proteins may be to prevent water loss from the xylem as well as nutrient loss from the phloem. PMID:22331409

  19. Identification of mildew resistance in wild and cultivated Central Asian grape germplasm

    OpenAIRE

    Riaz, Summaira; Boursiquot, Jean-Michel; Dangl, Gerald; Lacombe, Thierry; Laucou, Valerie; Tenscher, Alan C; Walker, M. Andrew

    2013-01-01

    Abstract Background Cultivated grapevines, Vitis vinifera subsp. sativa, evolved from their wild relative, V. vinifera subsp. sylvestris. They were domesticated in Central Asia in the absence of the powdery mildew fungus, Erysiphe necator, which is thought to have originated in North America. However, powdery mildew resistance has previously been discovered in two Central Asian cultivars and in Chinese Vitis species. ...

  20. QTL mapping of powdery mildew resistance in WI 2757 cucumber (Cucumis sativus L)

    Science.gov (United States)

    Powdery mildew is a serious fungal disease of cucumber and other cucurbot crops in the US and many other parts of the world. Resistant cultivars have been deployed in production for a long time, but the genetic mechanisms of powdery mildew resistance in cucumber are not well understood. In a three-y...

  1. Evaluation and Quantitative trait loci mapping of resistance to powdery mildew in lettuce

    Science.gov (United States)

    Lettuce (Lactuca sativa L.) is the major leafy vegetable that is susceptible to powdery mildew disease under greenhouse and field conditions. We mapped quantitative trait loci (QTLs) for resistance to powdery mildew under greenhouse conditions in an interspecific population derived from a cross betw...

  2. Indirect effect of a transgenic wheat on aphids through enhanced powdery mildew resistance.

    Directory of Open Access Journals (Sweden)

    Simone von Burg

    Full Text Available In agricultural ecosystems, arthropod herbivores and fungal pathogens are likely to colonise the same plant and may therefore affect each other directly or indirectly. The fungus that causes powdery mildew (Blumeria graminis tritici and cereal aphids are important pests of wheat but interactions between them have seldom been investigated. We studied the effects of powdery mildew of wheat on two cereal aphid species, Metopolophium dirhodum and Rhopalosiphum padi. We hypothesized that aphid number and size will be smaller on powdery mildew-infected plants than on non-infected plants. In a first experiment we used six commercially available wheat varieties whereas in the second experiment we used a genetically modified (GM mildew-resistant wheat line and its non-transgenic sister line. Because the two lines differed only in the presence of the transgene and in powdery mildew resistance, experiment 2 avoided the confounding effect of variety. In both experiments, the number of M. dirhodum but not of R. padi was reduced by powdery mildew infection. Transgenic mildew-resistant lines therefore harboured bigger aphid populations than the non-transgenic lines. For both aphid species individual size was mostly influenced by aphid number. Our results indicate that plants that are protected from a particular pest (powdery mildew became more favourable for another pest (aphids.

  3. Indirect effect of a transgenic wheat on aphids through enhanced powdery mildew resistance.

    Science.gov (United States)

    von Burg, Simone; Álvarez-Alfageme, Fernando; Romeis, Jörg

    2012-01-01

    In agricultural ecosystems, arthropod herbivores and fungal pathogens are likely to colonise the same plant and may therefore affect each other directly or indirectly. The fungus that causes powdery mildew (Blumeria graminis tritici) and cereal aphids are important pests of wheat but interactions between them have seldom been investigated. We studied the effects of powdery mildew of wheat on two cereal aphid species, Metopolophium dirhodum and Rhopalosiphum padi. We hypothesized that aphid number and size will be smaller on powdery mildew-infected plants than on non-infected plants. In a first experiment we used six commercially available wheat varieties whereas in the second experiment we used a genetically modified (GM) mildew-resistant wheat line and its non-transgenic sister line. Because the two lines differed only in the presence of the transgene and in powdery mildew resistance, experiment 2 avoided the confounding effect of variety. In both experiments, the number of M. dirhodum but not of R. padi was reduced by powdery mildew infection. Transgenic mildew-resistant lines therefore harboured bigger aphid populations than the non-transgenic lines. For both aphid species individual size was mostly influenced by aphid number. Our results indicate that plants that are protected from a particular pest (powdery mildew) became more favourable for another pest (aphids).

  4. Powdery mildew caused by Podosphaera macularis on hop (Humulus lupulus) in North Carolina

    Science.gov (United States)

    In June 2015, a grower in western North Carolina detected powdery mildew in a small hop yard. Characteristic colonies of the pathogen where observed on cultivars Cashmere, Cascade, and Chinook. Leaves with powdery mildew were collected from cultivar Cashmere for confirmation of the pathogen identi...

  5. Characterization of resistance to powdery mildew in the Hop cultivars Newport and Comet

    Science.gov (United States)

    Hop powdery mildew, caused by Podosphaera macularis, is an important disease in the Northwestern U.S. Outbreaks of powdery mildew on cultivars previously resistant to the disease have been reported increasingly with the emergence of virulent pathogen strains capable of overcoming a commonly deployed...

  6. Role of MLO genes in susceptibility to powdery mildew in apple and grapevine

    NARCIS (Netherlands)

    Pessina, Stefano

    2016-01-01

    Powdery mildew (PM) is a major fungal disease that threatens thousands of plant species. PM is caused by Podosphaera leucotricha in apple and Erysiphe necator in grapevine. Powdery mildew is controlled by frequent applications of fungicides, having negative effects on the environment, and leading to

  7. Downy Brome (Bromus tectorum L. and Broadleaf Weed Control in Winter Wheat with Acetolactate Synthase-Inhibiting Herbicides

    Directory of Open Access Journals (Sweden)

    Patrick W. Geier

    2013-04-01

    Full Text Available A study was conducted for three seasons in northwest Kansas, USA to evaluate acetolactate synthase (ALS-inhibiting herbicides for downy brome (Bromus tectorum L. and winter annual broadleaf weed control in winter wheat. Herbicides included pyroxsulam at 18.4 g ai ha−1, propoxycarbazone-Na at 44 g ai ha−1, premixed propoxycarbazone-Na & mesosulfuron-methyl at 27 g ai ha−1, and sulfosulfuron at 35 g ai ha−1. The herbicides were applied postemergence in fall and spring seasons. Averaged over time of application, no herbicide controlled downy brome more than 78% in any year. When downy brome densities were high, control was less than 60%. Pyroxsulam controlled downy brome greater than or similar to other herbicides tested. Flixweed (Descurainia sophia L., blue mustard [Chorispora tenella (Pallas DC.], and henbit (Lamium amplexicaule L. control did not differ among herbicide treatments. All herbicides tested controlled flixweed and blue mustard at least 87% and 94%, respectively. However, none of the herbicides controlled henbit more than 73%. Fall herbicide applications improved weed control compared to early spring applications; improvement ranged from 3% to 31% depending on the weed species. Henbit control was greatly decreased by delaying herbicide applications until spring compared to fall applications (49% vs. 80% control. Herbicide injury was observed in only two instances. The injury was ≤13% with no difference between herbicides and the injury did not impact final plant height or grain yield.

  8. Inhibition of Blumeria graminis germination and germling development within colonies of oat mildew

    DEFF Research Database (Denmark)

    Carver, T.L.W.; Roberts, P.C.; Thomas, B.J.;

    2001-01-01

    established oat mildew colonies, most formed abnormal, hypha-like germ tubes. Since they did not form appressoria, and ere thus Unable to attempt penetration, it was impossible to determine whether oat mildew colonies induced accessibility of underlying oat epidermal cells. However, when superficial...... ff. spp. formed normal appressoria. This was also true When conidia germinated within established barley mildew colonies. Within barley mildew colonies, appressoria of f. sp. hordei penetrated epidermal cells formed haustoria more frequently than appressoria distant from colonies. Similarly, ff. spp...... structures of established colonies were removed, germlings of all ff. spp. formed appressoria freely,, on cells containing oat mildew colony haustoria. Furthermore, these cells showed high level induced accessibility not only to f. sp. avenae but also to the normally non-pathogenic ff, spp. This indicated...

  9. Assessing the movement of Cucurbit yellow stunting disorder virus in susceptible and tolerant cucumber germplasms using serological and nucleic acid based methods

    Science.gov (United States)

    Cucurbit yellow stunting disorder virus (CYSDV) is an emerging virus causing significant yield losses in cucurbits. Simple but reliable detection and quantification methods constitute an important support to disease management. In a susceptible germplasm CYSDV was detected 5 days post-inoculation (D...

  10. Detection and quantitation of two cucurbit criniviruses in mixed infection by real-time RT-PCR.

    Science.gov (United States)

    Abrahamian, Peter E; Seblani, Rewa; Sobh, Hana; Abou-Jawdah, Yusuf

    2013-11-01

    Cucurbit chlorotic yellows virus (CCYV) and Cucurbit yellow stunting disorder virus (CYSDV) are whitefly-transmitted criniviruses infecting cucurbit crops inducing similar symptoms. Single and multiplex RT-PCR protocols were developed and evaluated on cucurbit samples collected from commercial greenhouses. Primers and probes were designed from the highly conserved heat shock protein 70 homolog (Hsp70h) gene. Conventional RT-PCR and multiplex RT-PCR assays showed high specificity and suitability for routine screening. TaqMan-based quantitative real-time RT-PCR (RT-qPCR) protocols were also developed for the detection and quantitation of both viruses occurring in single or mixed infection. The assays proved to be highly specific with no cross amplification. RT-qPCR assays showed a 100-1000 times improved sensitivity over conventional RT-PCR. Virus titers in mixed infections were compared to singly infected plants by RT-qPCR. CYSDV and CCYV titers decreased in double infected plants. This paper reports highly specific conventional RT-PCR and quantitative real-time PCR assays for detection, quantitation and differentiation between two closely related cucurbit-infecting criniviruses.

  11. Switching of emission of a styryl dye in cucurbit[7]uril: A comprehensive experimental and theoretical study

    Science.gov (United States)

    Manna, Anamika; Chakravorti, Sankar

    2015-04-01

    Intriguing colour change and change in fluorescence band of 2-(4-(dimethylamino)styryl)-1-methylpyridinium iodide from nonpolar to polar protic solvent, and also from molecular container cucurbit[7]uril environment to polar protic solvent has been reported here. This interesting colour change of this dye with respect to the medium makes this dye useful as a sensor. Change in spectral characteristics of DASPMI along with change of colour from orange to yellow with increasing polarity of medium is interpreted as due to negative solvatochromatism. Complexations of probe-cucurbit[7]uril (1:1 and 2:1) cause structural change of the probe molecule due to hydrogen bond interaction of cationic part of the dye with Cdbnd O group of cucurbit[7]uril and the colour change of the solution ensued. On addition of sodium chloride to the inclusion complex the dye is released from cucurbit[7]uril interior with colour of the solution reverted back. Theoretical results show that one carbon atom in the styryl part containing the positive charge gets too close to a carbon atom of cucurbit[7]uril to cause a phenomenal increase of dipole moment by 10X.

  12. Multi-Dimensional Analysis of Large, Complex Slope Instability: Case study of Downie Slide, British Columbia, Canada. (Invited)

    Science.gov (United States)

    Kalenchuk, K. S.; Hutchinson, D.; Diederichs, M. S.

    2013-12-01

    Downie Slide, one of the world's largest landslides, is a massive, active, composite, extremely slow rockslide located on the west bank of the Revelstoke Reservoir in British Columbia. It is a 1.5 billion m3 rockslide measuring 2400 m along the river valley, 3300m from toe to headscarp and up to 245 m thick. Significant contributions to the field of landslide geomechanics have been made by analyses of spatially and temporally discriminated slope deformations, and how these are controlled by complex geological and geotechnical factors. Downie Slide research demonstrates the importance of delineating massive landslides into morphological regions in order to characterize global slope behaviour and identify localized events, which may or may not influence the overall slope deformation patterns. Massive slope instabilities do not behave as monolithic masses, rather, different landslide zones can display specific landslide processes occurring at variable rates of deformation. The global deformation of Downie Slide is extremely slow moving; however localized regions of the slope incur moderate to high rates of movement. Complex deformation processes and composite failure mechanism are contributed to by topography, non-uniform shear surfaces, heterogeneous rockmass and shear zone strength and stiffness characteristics. Further, from the analysis of temporal changes in landslide behaviour it has been clearly recognized that different regions of the slope respond differently to changing hydrogeological boundary conditions. State-of-the-art methodologies have been developed for numerical simulation of large landslides; these provide important tools for investigating dynamic landslide systems which account for complex three-dimensional geometries, heterogenous shear zone strength parameters, internal shear zones, the interaction of discrete landslide zones and piezometric fluctuations. Numerical models of Downie Slide have been calibrated to reproduce observed slope behaviour

  13. Field assessment of partial resistance to powdery mildew in spring barley

    DEFF Research Database (Denmark)

    Nørgaard Knudsen, J. Chr.; Dalsgaard, H. H.; Jørgensen, Jørgen Helms

    1986-01-01

    Partial resistance to powdery mildew in spring barley was evaluated in three plot types: large isolation plots, in 1.4 m2 plots in chessboard design with guard plots of spring wheat and in single rows. Percentage leaf area covered by powdery mildew was scored four to six times during the season....... The relationship between single scores of amount of powdery mildew on the upper four leaves and the area under the disease progress curve was high in all plot designs during the first two to three weeks after heading, allowing selection for the trait by one or two scorings. Differential ranking of varieties...

  14. Binding Studies of Cucurbit[7]uril with Gold Nanoparticles Bearing Different Surface Functionalities.

    Science.gov (United States)

    Tonga, Gulen Yesilbag; Mizuhara, Tsukasa; Saha, Krishnendu; Jiang, Ziwen; Hou, Singyuk; Das, Riddha; Rotello, Vincent M

    2015-06-03

    Host-guest interactions between a synthetic receptor, cucurbit[7]uril (CB[7]), and gold nanoparticles (AuNPs) have been quantified using isothermal titration calorimetry. AuNPs were functionalized with ligands containing tertiary or quaternary benzylamine derivatives, with electron donating or withdrawing groups at the para position of the benzene ring. Analysis of binding interactions reveals that functional groups at the para position have no significant effect on binding constant. However, headgroups bearing a permanent positive charge increased the binding of AuNPs to CB[7] ten-fold compared to monomethyl counterparts.

  15. Survey on The Occurrence of Viruses Infecting Cucurbits in Yogyakarta and Central Java

    Directory of Open Access Journals (Sweden)

    Budi Setiadi Daryono

    2009-12-01

    Full Text Available Cucurbits are grown throughout the Java Island as dry season crops. Plants having mosaic, mottling, chlorosis and leaf distortion symptoms were frequently found in most of the cucurbit fields during the survey which conducted in Central Java including Sleman, Kulon Progo, and Klaten during July–September 2000 and 2001. Using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA; Cucumber mosaic virus (CMV, Cucumber green mottle mosaic virus (CGMMV and Kyuri green mottle mosaic virus (KGMMV were found infecting cucurbits. CMV was widespread, infecting 48.9% of the samples tested followed by CGMMV (12.8% and KGMMV (6.4%, while others samples (31.9% were not tested, double infections were common with 8.5 % of the samples being infected with two viruses (CGMMV and KGMMV and 34% with three viruses (CMV, CGMMV, and KGMMV. Severe mosaic and mottle symptoms were associated most often with single infection of CGMMV and KGMMV respectively. In addition, these are the first detections of CGMMV and KGMMV infecting cucurbit plants in Indonesia. Tanaman labu-labuan umumnya tumbuh sepanjang musim kemarau diPulau Jawa. Tanaman labu-labuan dengan gejala mosaik, klorosis, mottling dan bentuk daun serta buah yang berubah banyak dijumpai selama survei yang dilakukan di Kulon Progo, Sleman dan Klaten pada bulan Juli sampai September tahun 2000 dan 2001. Deteksi menggunakan metode double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA telah berhasil mengetahui keberadaan dan infeksiCucumber mosaic virus(CMV,Cucumber green mottle mosaic virus (CGMMV dan Kyuri green mottle mosaic virus (KGMMV pada tanaman labu-labuan di tiga kabupaten tersebut. CMV menginfeksi tanaman labu-labuan tinggi yaitu 48,9% dari jumlah sampel tanaman yang dikoleksi, kemudian CGMMV (12,8% dan KGMMV(6,4%, sedangkan sebanyak 14 sampel tanaman (31,9%tidak dideteksi.Infeksi ganda banyak ditemukan dan 8,5 % sampel tanaman terinfeksi oleh dua jenis virus (CGMMV dan

  16. Taxonomic and functional diversity of cultured seed associated microbes of the cucurbit family.

    Science.gov (United States)

    Khalaf, Eman M; Raizada, Manish N

    2016-06-27

    Endophytes are microbes that colonize plant internal tissues without causing disease. In particular, seed-associated endophytes may be vectors for founder microbes that establish the plant microbiome, which may subsequently contribute beneficial functions to their host plants including nutrient acquisition and promotion of plant growth. The Cucurbitaceae family of gourds (e.g., cucumbers, melons, pumpkin, squash), including its fruits and seeds, is widely consumed by humans. However, there is limited data concerning the taxonomy and functions of seed-associated endophytes across the Cucurbitaceae family. Here, bacteria from surface-sterilized seeds of 21 curcurbit varieties belonging to seven economically important species were cultured, classified using 16S rRNA gene sequencing, and subjected to eight in vitro functional tests. In total, 169 unique seed-associated bacterial strains were cultured from selected cucurbit seeds. Interestingly, nearly all strains belonged to only two phyla (Firmicutes, Proteobacteria) and only one class within each phyla (Bacilli, γ-proteobacteria, respectively). Bacillus constituted 50 % of all strains and spanned all tested cucurbit species. Paenibacillus was the next most common genus, while strains of Enterobacteriaceae and lactic acid bacteria were also cultured. Phylogenetic trees showed limited taxonomic clustering of strains by host species. Surprisingly, 33 % of strains produced the plant hormone, indole-3-acetic acid (auxin), known to stimulate the growth of fruits/gourds and nutrient-acquiring roots. The next most common nutrient acquisition traits in vitro were (in rank order): nitrogen fixation/N-scavenging, phosphate solubilisation, siderophore secretion, and production of ACC deaminase. Secretion of extracellular enzymes required for nutrient acquisition, endophyte colonization and/or community establishment were observed. Bacillus strains had the potential to contribute all tested functional traits to their hosts

  17. Interaction of host-guest complexes of cucurbit[n]urils with double probe guests

    Institute of Scientific and Technical Information of China (English)

    MA; Peihua; DONG; Jun; XIANG; Shuangchun; XUE; Saifeng; ZH

    2004-01-01

    [1]Freeman, W. A., Mock, W. L., Shih, N. Y., Cucurbituril, J. Am.Chem. Soc., 1981, 103: 7367-7368.[2]Day, A. I., Arnold, A. P., Method for synthesis cucurbiturils, WO 0068232, 2000, 8.[3]Kim, J., Jung, I. S., Kim, S. Y. et al., New cucurbituril homologues: syntheses, isolation, characterization, and X-ray crystal structures of cucurbit[n]uril (n = 5, 7 and 8), J. Am. Chem. Soc.,2000, 122(3): 540-541.[4]Day, A. I., Blanck, R. J, Amold, A. P., A cucurbituril-based gyroscane: a new supramolecular form, Angew. Chem. Int. Ed., 2002,41(2): 275-277.[5]Blanck, R. J., Sleeman, A. J. White, T. J. et al., Cucurbit[7]uril and o-carborane self-assemble to form a molecular ball bearing,Nano. Lett., 2002, 2(2), 147-149.[6]Liu, J. X., Tao, Z., Xue, S. F. et al., Investigation of host-guest compounds of cucurbit[n = 5-8]uril with some piperazine derivatives, Chin. J. Inorg. Chem., 2004, 20(2): 139-147[7]Zhou, Y. L., Liu, Y., Inclusion complex of β-cyclodextrin and α-aminopyridine and its assembling behavior, Science in China,Ser. B, 2004, 34(1): 68-74.[8]Ong, W., Kaifer, A. E., Molecular encapsulation by cucurbit[7]uril of the apical 4,4'-bipyridinium residuein newkome-type dendrime,Angew. Chem. Inter. Ed., 2003, 42: 2164-2167.[9]Samsonenko, D. G., Gerasko, O. A., Mitkina, T. V. et al., Synthesis and crystal structure of supramolecular adducts of macrocyclic cavitand cucurbituril with chromium (Ⅲ) and nickel (Ⅱ) aqua complexes, Russian J. Coord. Chem. (Translation of Koordinatsionnaya Khimiya), 2003, 29(3): 166-174.[10]He, X. Y., Li, G., Chen, H. L., A new cucurbituril-based metallo-rotaxane, Inorg. Chem. Commun., 2002, (5): 633-641.[11]Fedin, V. P., Sokolov, M. N., Dybtsev, D. N. et al., Supramolecular assemblies of [Mo3Se4Clx(H2O)9-x](4-x)+ with cucurbituril;complementarity control through the variation of x, Inorg. Chim.Acta., 2002, 331(1): 31-38.[12]Lorenzo, S., Day, A., Craig, D. et al., The first endoannular metal halide

  18. Fungal species that cause powdery mildew in greenhouse-grown cucumber and melon in Paraná State, Brazil=Espécies de fungos que causam oídio em casas de vegetação cultivadas com pepino e melão no Estado do Paraná, Brasil

    Directory of Open Access Journals (Sweden)

    Dauri José Tessmann

    2012-07-01

    Full Text Available The powdery mildew caused by Oidium spp. is an important disease for several crops of the Cucurbitaceae family. Although the teleomorphs, Podosphaera xanthii and Golovinomyces cichoracearum, currently have already been described as the causal agents of powdery mildew in Brazil, only P. xanthii is considered the main causal agent of powdery mildew field epidemics. The objective of this work was to identify and determine the prevalence of the species causing powdery mildew in cucumber (Cucumis sativus and melon (Cucumis melo var. reticulatus grown in greenhouses in the State of Paraná in Brazil. The morphological traits of the conidial stages, such as the presence of fibrosin bodies and a germinative tube, were used to identify the species. Leaves exhibiting high severity of powdery mildew were collected from plants of 13 plastic greenhouses during different seasons in 2003/2004 and in different regions of Paraná State. In all environments, a significant prevalence of P. xanthii (80-100% was observed affecting parthenocarpic or ordinary cucumber and melon. Golovinomyces cichoracearum was observed in six greenhouses, with up to 20% of conidia of this species on the samples.O oidio, causado por Oidium sp. é uma importante doença para espécies de plantas cultivadas da família das cucurbitáceas. Apesar das espécies teleomórficas Podosphaera xanthii e Golovinomyces cichoracearum já terem sido citadas como causadoras de oídio no Brasil, geralmente em trabalhos publicados atualmente tem-se referenciado somente a P. xanthii como agente causal dessa doença em cucurbitáceas em cultivo convencional. Por isso, este trabalho teve como objetivo identificar e quantificar a freqüência de ocorrência dessas duas espécies causadoras de oídio nas culturas de pepino (Cucumis sativus e melão nobre (Cucumis melo var. reticulatus conduzidas em estufas plásticas no Estado do Paraná. Para a identificação de P. xanthii e G. cichoracearum utilizaram

  19. Effects of sunlight exposure on grapevine powdery mildew development.

    Science.gov (United States)

    Austin, Craig N; Wilcox, Wayne F

    2012-09-01

    Natural and artificially induced shade increased grapevine powdery mildew (Erysiphe necator) severity in the vineyard, with foliar disease severity 49 to 75% higher relative to leaves in full sun, depending on the level of natural shading experienced and the individual experiment. Cluster disease severities increased by 20 to 40% relative to those on check vines when ultraviolet (UV) radiation was filtered from sunlight reaching vines in artificial shading experiments. Surface temperatures of leaves in full sunlight averaged 5 to 8°C higher than those in natural shade, and in one experiment, filtering 80% of all wavelengths of solar radiation, including longer wavelengths responsible for heating irradiated tissues, increased disease more than filtering UV alone. In controlled environment experiments, UV-B radiation reduced germination of E. necator conidia and inhibited both colony establishment (hyphal formation and elongation) and maturity (latent period). Inhibitory effects of UV-B radiation were significantly greater at 30°C than at 20 or 25°C. Thus, sunlight appears to inhibit powdery mildew development through at least two mechanisms, i.e., (i) UV radiation's damaging effects on exposed conidia and thalli of the pathogen; and (ii) elevating temperatures of irradiated tissues to a level supraoptimal or inhibitory for pathogen development. Furthermore, these effects are synergistic at temperatures near the upper threshold for disease development.

  20. Phenotypic characterization of papaya genotypes to determine powdery mildew resistance

    Directory of Open Access Journals (Sweden)

    Marcelo Vivas

    2017-06-01

    Full Text Available In support of breeding of papaya (Carica papaya, the disease incidence and severity of powdery mildew (Ovulariopsis caricicola were evaluated in papaya genotypes. Two experiments in complete randomized blocks were carried out, one in the field and the other in a greenhouse. In field experiments, the lowest mean disease incidence was observed on the genotypes ‘Costa Rica’ and ‘Baixinho Super’, and the lowest mean disease severity on ‘Caliman M5’, ‘GTF’, ‘SH 11-08’, and ‘JS 11’. In the greenhouse experiment, the genotypes ‘Caliman M5’, ‘Golden’, ‘Kapoho Solo’, ‘Waimanalo’, ‘Mamão Bené’, ‘SH 12-07’, ‘JS 12’, and ‘GTF’ had the lowest mean incidence in at least one evaluation. On the other hand, for severity, the genotypes ‘Diva’, ‘Sunrise Solo 72/12’, ‘Kapoho Solo PA’, ‘Waimanalo’, ‘Maradol’, ‘Maradol GL’, ‘SH 15-04’, ‘FMV, ‘JS 12-4’, ‘SH 12-07’ and ‘Sekati FLM’ had the lowest means. These results indicate these genotypes for a possible use in breeding for reduction of powdery mildew intensity

  1. Transcriptome sequencing in a Tibetan barley landrace with high resistance to powdery mildew.

    Science.gov (United States)

    Zeng, Xing-Quan; Luo, Xiao-Mei; Wang, Yu-Lin; Xu, Qi-Jun; Bai, Li-Jun; Yuan, Hong-Jun; Tashi, Nyima

    2014-01-01

    Hulless barley is an important cereal crop worldwide, especially in Tibet of China. However, this crop is usually susceptible to powdery mildew caused by Blumeria graminis f. sp. hordei. In this study, we aimed to understand the functions and pathways of genes involved in the disease resistance by transcriptome sequencing of a Tibetan barley landrace with high resistance to powdery mildew. A total of 831 significant differentially expressed genes were found in the infected seedlings, covering 19 functions. Either "cell," "cell part," and "extracellular region" in the cellular component category or "binding" and "catalytic" in the category of molecular function as well as "metabolic process" and "cellular process" in the biological process category together demonstrated that these functions may be involved in the resistance to powdery mildew of the hulless barley. In addition, 330 KEGG pathways were found using BLASTx with an E-value cut-off of powdery mildew infection.

  2. Supramolecular interaction of methotrexate with cucurbit[7]uril and analytical application

    Science.gov (United States)

    Chang, Yin-Xia; Zhang, Xiang-Mei; Duan, Xue-Chao; Liu, Fan; Du, Li-Ming

    2017-08-01

    The supramolecular interaction between cucurbit[7]uril (CB[7]) as the host and the anti-cancer drug methotrexate (MTX) as the guest was studied using fluorescence spectroscopy, UV-visible absorption spectroscopy, 1H NMR, 2D NOESY, and theoretical calculations. The experimental results confirmed the formation of 1:2 inclusion complex with CB[7] and indicated a simple and sensitive competitive method for the fluorescence detection of MTX. It was found that the fluorescence intensities of CB[7]-palmatine, CB[7]-berberine and CB[7]-coptisine were quenched linearly upon the addition of MTX. The linear ranges obtained in the detection of MTX were 0.1-15 μg mL- 1, 0.2-15 μg mL- 1, and 0.4-15 μg mL- 1 with detection limits of 0.03 μg mL-1, 0.06 μg mL-1, and 0.13 μg mL-1, respectively. This method can be used for the determination of MTX in biological fluids. These results suggested that cucurbit[7]uril is a promising drug carrier for targeted MTX delivery and monitoring, with improved efficacy and reduced toxicity in normal tissues.

  3. FLOWERING LOCUS T protein may act as the long-distance florigenic signal in the cucurbits.

    Science.gov (United States)

    Lin, Ming-Kuem; Belanger, Helene; Lee, Young-Jin; Varkonyi-Gasic, Erika; Taoka, Ken-Ichiro; Miura, Eriko; Xoconostle-Cázares, Beatriz; Gendler, Karla; Jorgensen, Richard A; Phinney, Brett; Lough, Tony J; Lucas, William J

    2007-05-01

    Cucurbita moschata, a cucurbit species responsive to inductive short-day (SD) photoperiods, and Zucchini yellow mosaic virus (ZYMV) were used to test whether long-distance movement of FLOWERING LOCUS T (FT) mRNA or FT is required for floral induction. Ectopic expression of FT by ZYMV was highly effective in mediating floral induction of long-day (LD)-treated plants. Moreover, the infection zone of ZYMV was far removed from floral meristems, suggesting that FT transcripts do not function as the florigenic signal in this system. Heterografting demonstrated efficient transmission of a florigenic signal from flowering Cucurbita maxima stocks to LD-grown C. moschata scions. Real-time RT-PCR performed on phloem sap collected from C. maxima stocks detected no FT transcripts, whereas mass spectrometry of phloem sap proteins revealed the presence of Cm-FTL1 and Cm-FTL2. Importantly, studies on LD- and SD-treated C. moschata plants established that Cmo-FTL1 and Cmo-FTL2 are regulated by photoperiod at the level of movement into the phloem and not by transcription. Finally, mass spectrometry of florally induced heterografted C. moschata scions revealed that C. maxima FT, but not FT mRNA, crossed the graft union in the phloem translocation stream. Collectively, these studies are consistent with FT functioning as a component of the florigenic signaling system in the cucurbits.

  4. MODULATION OF GROWTH AND PROTON PUMPING ATPase ACTIVITY OF PROBIOTIC Lactobacilli BY DIETARY CUCURBITS

    Directory of Open Access Journals (Sweden)

    Irfan Ahmad

    2013-12-01

    Full Text Available Gastrointestinal tract predominantly harbor probiotic Lactobacilli which exert beneficial effects on human health. Aqueous extracts from fruits of Lagenaria siceraria (Ls, Luffa cylindrica (Lc and Cucurbita maxima (Cm were prepared and lyophilized. Fruit extracts were investigated for their effects on Lactobacillus rhamnosus (L. rhamnosus, Lactobacillus plantarum (L. plantarum and Lactobacillus acidophilus (L. acidophilus. Extracts were found to enhance growth of Lactobacilli without any toxic effect (up to 1000µg/mL concentration. Minimum concentration of extracts at which growth of probiotic strains were found to be enhanced significantly were determined (103.67 µg/mL-118µg/mL and considered as effective concentration (EC or growth stimulatory concentration (GSC. Proton pumping ATPase activity of Lactobacilli were examined and found to be enhanced significantly (29.89- 61.96% in extracts treated probiotics (Lactobacilli as compared to the normal control. Inulin used as positive control and found to enhance the proton efflux activity (28.06-37.72% with respect to the control. These dietary cucurbits enhance metabolic activity of probiotic Lactobacilli by modulating their proton pumping ATPase mechanism. This study suggested that the consumption of cucurbit fruits might be a natural source of enhancing the activities of probiotic Lactobacilli in the gut.

  5. Identification and mapping of two powdery mildew resistance genes in Triticum boeoticum L.

    Science.gov (United States)

    Chhuneja, Parveen; Kumar, Krishan; Stirnweis, Daniel; Hurni, Severine; Keller, Beat; Dhaliwal, Harcharan S; Singh, Kuldeep

    2012-04-01

    Powdery mildew (PM) caused by Blumeria graminis f. sp. tritici (Bgt), is one of the important foliar diseases of wheat that can cause serious yield losses. Breeding for cultivars with diverse resources of resistance is the most promising approach for combating this disease. The diploid A genome progenitor species of wheat are an important resource for new variability for disease resistance genes. An accession of Triticum boeoticum (A(b)A(b)) showed resistance against a number of Bgt isolates, when tested using detached leaf segments. Inheritance studies in a recombinant inbred line population (RIL), developed from crosses of PM resistant T. boeoticum acc. pau5088 with a PM susceptible T. monococcum acc. pau14087, indicated the presence of two powdery mildew resistance genes in T. boeoticum acc. pau5088. Analysis of powdery mildew infection and molecular marker data of the RIL population revealed that both powdery mildew resistance genes are located on the long arm of chromosome 7A. Mapping was conducted using an integrated linkage map of 7A consisting of SSR, RFLP, STS, and DArT markers. These powdery mildew resistance genes are tentatively designated as PmTb7A.1 and PmTb7A.2. The PmTb7A.2 is closely linked to STS markers MAG2185 and MAG1759 derived from RFLP probes which are linked to powdery mildew resistance gene Pm1. This indicated that PmTb7A.2 might be allelic to Pm1. The PmTb7A.1, flanked by a DArT marker wPt4553 and an SSR marker Xcfa2019 in a 4.3 cM interval, maps proximal to PmT7A.2. PmTb7A.1 is putatively a new powdery mildew resistance gene. The powdery mildew resistance genes from T. boeoticum are currently being transferred to cultivated wheat background through marker-assisted backcrossing, using T. durum as bridging species.

  6. Biological control mechanisms of D-pinitol against powdery mildew in cucumber

    OpenAIRE

    Chen, J; Fernandez, Diana; Wang, D. D.; Chen, Y. J.; Dai, G. H.

    2014-01-01

    D-pinitol is an effective agent for controlling powdery mildew (Podosphaera xanthii) in cucumber. In this study, we determined the mechanisms of D-pinitol in controlling powdery mildew in cucumber plants. We compared P. xanthii development on cucumber leaf surface treated with D-pinitol or water (2 mg ml(-1)) at different time points after inoculation. The germinating conidia, hyphae, and conidiophores of the pathogen were severely damaged by D-pinitol at any time of application tested. The h...

  7. Response of cucurbit rootstocks for grafted melon (Cucumis melo) to southern root-knot nematode, Meloidogyne incognita

    Science.gov (United States)

    Root-knot nematodes (RKN) are an important re-emerging pest of melon (Cucumis melo), due largely to the loss of methyl bromide as a pre-plant soil fumigant. Melon is highly susceptible to southern RKN, Meloidogyne incognita, which causes severe root galling and reduced melon fruit yields. Cucurbit...

  8. Transmission of Squash vein yellowing virus to and From Cucurbit Weeds and Effects on Sweetpotato Whitefly (Hemiptera: Aleyrodidae) Behavior

    Science.gov (United States)

    Several common cucurbit weed reservoirs for Squash vein yellowing virus (SqVYV) were compared with watermelons as sources of inoculum. Weed susceptibility to SqVYV was also analyzed. In addition, behavior of the whitefly vector of SqVYV was studied on infected and non-infected plants. This report...

  9. First report of the cucurbit yellow vine disease caused by Serratia marcescens in watermelon and yellow squash in Alabama

    Science.gov (United States)

    Symptoms typical of cucurbit yellow vine disease (CYVD) were first observed in a 2 ha watermelon field in Crawford, Russell County, Alabama on 8 June 2010. Watermelon plants, cv. 'Jubilee,' exhibited a yellow or chlorotic appearance and some plants were completely wilted. On 24 June plant samples ...

  10. Identification of viruses infecting cucurbits and determination of genetic diversity of Cucumber mosaic virus in Lorestan province, Iran

    Directory of Open Access Journals (Sweden)

    Hasanvand Vahid

    2017-06-01

    Full Text Available Various viral pathogens infect Cucurbitaceae and cause economic losses. The aim of the present study was to detect plant viral pathogens including Cucumber mosaic virus (CMV, Cucumber green mottle mosaic virus (CGMMV, Zucchini yellow mosaic virus (ZYMV, Cucurbit yellow stunting disorder virus (CYSDV and Cucurbit chlorotic yellows virus (CCYV in Lorestan province, in western Iran, and also to determine CMV genetic diversity in Iranian populations. A total of 569 symptomatic leaf samples were collected in 2013 and 2014 from cucurbits growing regions in Lorestan province. The collected samples were assessed for viral diseases by ELISA. The results showed virus incidences in most regions. Then, the infection of 40 samples to CMV was confirmed by RT-PCR. Moreover, to distinguish between the two groups (I and II of CMV, PCR products were digested by two restriction enzymes XhoI and EcoRI. Results of the digestion showed that the isolates of Lorestan belonged to group I. The CMV-coat protein gene of eight isolates from different regions and hosts was sequenced and phylogenetic analysis was performed. Subsequent analyses showed even more genetic variation among Lorestan isolates. The phylogenetic tree revealed that Lorestan province isolates belonged to two IA and IB subgroups and could be classified together with East Azerbaijan province isolates. The results of the present study indicate a wide distribution of CMV, ZYMV, CGMMV, CYSDV and CCYV viruses in cucurbits fields of Lorestan province and for the first time subgroup IB of CMV was reported on melon from Iran.

  11. Occurrence, Distribution and Biological variability of Zucchini Yellow Mosaic Virus in cucurbits of Khuzestan province, South west of Iran

    Directory of Open Access Journals (Sweden)

    Somayeh Safara

    2011-11-01

    Full Text Available ZYMV is one of the most important plant viruses that cause economical damage in cucurbits. The symptoms of ZYMV in different cucurbits include stunting, yellowing, mottling, severe mosaic, leaf and fruit deformation, blistering and shoe string. Investigation on occurrence of this virus, in Khuzestan province was carried out in November 2009, April and May 2010 by collecting cucurbits samples from different cucurbits fields. After DAS-ELISA test, ZYMV was maintained in squash. Then total RNA were extracted and were tested by RT-PCR. Using RT-PCR, fragments belonging to N-terminal of coat protein and C-terminal of nuclear inclusion bodies were replicated. PCR product for investigation of replication was loaded in 1% agarose gel. From seven regions in Khuzestan, 175 leaf samples showing different symptoms (yellowing, mosaic, deformation and blistering were collected. Seventy one samples out of total samples (175 samples showed ZYMV infection. Occurrence of Zucchini Yellow Mosaic Virus in Khuzestan province was confirmed, using serological and RT-PCR tests. Infection of ZYMV in Khuzestan province (40.5% is higher than the average of Iran’s infection (38%. This article is first report of occurrence ZYMV in different regions of Khuzestan province except Dezful.

  12. Hybridization of powdery mildew strains gives rise to pathogens on novel agricultural crop species.

    Science.gov (United States)

    Menardo, Fabrizio; Praz, Coraline R; Wyder, Stefan; Ben-David, Roi; Bourras, Salim; Matsumae, Hiromi; McNally, Kaitlin E; Parlange, Francis; Riba, Andrea; Roffler, Stefan; Schaefer, Luisa K; Shimizu, Kentaro K; Valenti, Luca; Zbinden, Helen; Wicker, Thomas; Keller, Beat

    2016-02-01

    Throughout the history of agriculture, many new crop species (polyploids or artificial hybrids) have been introduced to diversify products or to increase yield. However, little is known about how these new crops influence the evolution of new pathogens and diseases. Triticale is an artificial hybrid of wheat and rye, and it was resistant to the fungal pathogen powdery mildew (Blumeria graminis) until 2001 (refs. 1,2,3). We sequenced and compared the genomes of 46 powdery mildew isolates covering several formae speciales. We found that B. graminis f. sp. triticale, which grows on triticale and wheat, is a hybrid between wheat powdery mildew (B. graminis f. sp. tritici) and mildew specialized on rye (B. graminis f. sp. secalis). Our data show that the hybrid of the two mildews specialized on two different hosts can infect the hybrid plant species originating from those two hosts. We conclude that hybridization between mildews specialized on different species is a mechanism of adaptation to new crops introduced by agriculture.

  13. Bacillus sp. BS061 Suppresses Gray Mold and Powdery Mildew through the Secretion of Different Bioactive Substances.

    Science.gov (United States)

    Kim, Young-Sook; Song, Ja-Gyeong; Lee, In-Kyoung; Yeo, Woon-Hyung; Yun, Bong-Sik

    2013-09-01

    A Bacillus sp. BS061 significantly reduced disease incidence of gray mold and powdery mildew. To identify the active principle, the culture filtrate was partitioned between butanol and water. The antifungal activity against B. cinerea was evident in the butanol-soluble portion, and active substances were identified as cyclic lipopeptides, iturin A series, by nuclear magnetic resonance spectrometry (NMR) and mass analysis. Interestingly, antifungal activity against powdery mildew was observed in the water-soluble portion, suggesting that cyclic lipopeptides have no responsibility to suppress powdery mildew. This finding reveals that biocontrol agents of Bacillus origin suppress gray mold and powdery mildew through the secretion of different bioactive substances.

  14. Reasoned opinion on the modification of the existing MRLs for cyprodinil in radishes and cucurbits inedible peel

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2013-04-01

    Full Text Available In accordance with Article 6 of Regulation (EC No 396/2005, the Netherlands, hereafter referred to as the evaluating Member State (EMS-NL, received an application from LTO Groeiservice to modify the existing MRL for the active substance cyprodinil in radish; a second application from the company Syngenta AGRO S.A.S to modify the existing MRL for the active substance cyprodinil in cucurbits, inedible peel was submitted to France (EMS-FR. In order to accommodate the intended uses of cyprodinil, EMSs proposed to raise the existing MRLs from the limit of quantification to 0.07 mg/kg for radish and to 0.6 mg/kg for cucurbits inedible peel. EMS-NL and EMS-FR drafted two evaluation reports in accordance with Article 8 of Regulation (EC No 396/2005, which were submitted to the European Commission and forwarded to EFSA. According to EFSA the data are sufficient to derive MRL proposals of 0.08 mg/kg for radish and of 0.6 mg/kg for cucurbits, inedible peel. Adequate analytical enforcement methods are available to control the residues of cyprodinil in radishes and cucurbits at the validated LOQ of 0.01 mg/kg. Based on the risk assessment results, EFSA concludes that the proposed use of cyprodinil on radish and cucurbits inedible peel under consideration will not result in a consumer exposure exceeding the toxicological reference value and therefore is unlikely to pose a consumer health risk.

  15. MECHANISMS INVOLVED IN MYCORRHIZAL WHEAT PROTECTION AGAINST POWDERY MILDEW.

    Science.gov (United States)

    Mustafa, G; Tisserant, B; Randoux, B; Fontaine, J; Sahraoui, A Lounes-Hadj; Reignault, Ph

    2014-01-01

    In France, the Ecophyto 2018 national action plan will set out to reduce the use of pesticides by 50% by 2018, if possible. To achieve this goal, the use of arbuscular mycorrhizal (AM) fungi could be a potential alternative method allowing the control of crop diseases. The inoculation by AM fungi has been demonstrated to protect plants against soil-borne pathogens, but little is known about their effectiveness against aerial pathogens, such as the biotrophic fungus Blumeria graminis f.sp. tritici (Bgt) causing wheat (Triticum aestivum) powdery mildew. In the present study, wheat plants were grown in pots, under controlled conditions. Using various phosphorus (P) concentrations, the effectiveness of three AM inocula (Rhizophagus irregularis (Ri), Funneliformis mosseae (Fm)) and Solrize, a mixture of Ri and Fm) in Orvantis wheat cultivar, were tested. After 42 days of culture, mycorrhizal (M) and non-mycorrhizal (NM) wheat plants were infected by Bgt. A satisfactory mycorrhizal rate was obtained with the phosphorus concentration P/5 (P corresponding to the dose used in wheat fields in = 62 mg/L). Our work shows, for the first time, (i) a protective effect of AM inoculation against wheat powdery mildew, reaching up to 73% with Fm inocula, and (ii) its ability to induce a systemic resistance in wheat. Thereafter, we investigated mechanisms involved in this protection. Control plants, M plants, infected plants by Bgt, and M-infected plants were compared at: (i) cytological level, our results revealed that papillae and whole-fluorescent cells presence was induced, conversely fungal haustorium formation in epidermal cells was reduced within M plants leaves (ii) enzymatic level-by assessing defense enzyme activities (lipoxygenase, peroxidase) known as defense markers were measured 24, 48, 72 and 96 hours after infection (hai). The importance of these activities in the defense pathways induced in wheat by AM fungi will be discussed.

  16. Durable broad-spectrum powdery mildew resistance in pea er1 plants is conferred by natural loss-of-function mutations in PsMLO1

    NARCIS (Netherlands)

    Humphry, M.; Reinstädler, A.; Ivanov, S.; Bisseling, T.; Panstruga, R.

    2011-01-01

    Loss-of-function alleles of plant-specific MLO (Mildew Resistance Locus O) genes confer broad-spectrum powdery mildew resistance in monocot (barley) and dicot (Arabidopsis thaliana, tomato) plants. Recessively inherited powdery mildew resistance in pea (Pisum sativum) er1 plants is, in many aspects,

  17. IDENTIFICATION AND EFFECTS OF MIXED INFECTION OF Potyvirus ISOLATES WITH Cucumber mosaic virus IN CUCURBITS

    Directory of Open Access Journals (Sweden)

    GRAZIELA DA SILVA BARBOSA

    2016-01-01

    Full Text Available Mixed infections in cucurbits are frequently observed in natural conditions between viruses from the Potyvirus genus and Cucumber mosaic virus (CMV, which significantly decreases productivity. The objectives of the present study was to compare the host range of PRSV - W, WMV, and ZYMV isolates and evaluate the effects of mixed infections with CMV in zucchini plants ( Cucurbita pepo L.. Host range studies comprising 23 plant species confirmed some similarities and biological differences among the isolates of PRSV - W, ZYMV, and WMV. RT - PCR confirmed the amplification of DNA fragments of the PRSV - W, WMV, and ZYMV coat protein gene ( cp and cytoplasm inclusion gene ( ci . The virus interaction studies in zucchini Caserta plants indicated synergistic interactions, particularly among species from the Potyvirus genus, and some CMV interference with some virus combinations.

  18. Spectroscopy and laser characterization of synthesized supramolecular host cucurbit[7]uril using aqueous Rhodamine B dye

    Indian Academy of Sciences (India)

    Deepak R Boraste; Monika Gupta; Ganapati Shankarling; Alok K Ray; Sandip K Nayak

    2014-02-01

    Recent demonstration in augmenting the efficiency of aqueous Rhodamine dye lasers using cucurbit[7]uril (CB[7]), a deaggregating and photostabilizing host, has drawn interest in the synthesis and characterization of spectroscopic grade CB[7] in larger quantities. Synthesis of cucurbituril group of macrocycles always leads to the formation of various homologues of CB[n]s (n=5–7) with CB[7] as the minor product. The literature procedure has been optimized to get pure CB[7] in 12–14% yield by fractional crystallization and the purity was checked by NMR, MS and spectrophotometric titration. Laser performances of the synthesized and commercial CB[7] sample as an additive were evaluated using Nd-YAG (532 nm) pumped Rhodamine B aqueous dye lasers and comparable results were obtained.

  19. Supramolecular Encapsulation of Vitamin B6 by Macrocyclic Nanocontainer Cucurbit[7]uril

    Directory of Open Access Journals (Sweden)

    Wanying Li

    2015-01-01

    Full Text Available A pharmaceutically and biologically relevant molecule, pyridoxine hydrochloride (vitamin B6, was encapsulated inside the cavity of a molecular container, cucurbit[7]uril (CB[7], in aqueous solution. The CB[7] based “nanocapsule” of vitamin B6 has been investigated for the first time, via 1H NMR and UV-visible spectroscopic titrations (including Job’s plot and ab initio molecular modeling. The results have demonstrated that vitamin B6 forms stable host-guest complexes within CB[7] in 1 : 1 stoichiometry, with a binding affinity of (4.0±0.5×103 M−1. Such a nanocapsule could potentially find application in vitamin B6 formulation for the purpose of enhancing the stability, absorption, and delivery of this important vitamin.

  20. Electrostatic repulsion between cucurbit[7]urils can be overcome in [3]pseudorotaxane without adding salts.

    Science.gov (United States)

    Pessêgo, M; Moreira, J A; Rosa da Costa, A M; Corrochano, P; Poblete, F J; Garcia-Rio, L

    2013-04-19

    The host-guest chemistry between cucurbit[7]uril (CB7) and a series of bolaform (Bn) surfactants with different chain lengths, n = 12-22, was the target of our study. [3]Pseudorotaxanes are formed when the alkyl chain of the bolaform has more than 14 carbon atoms. In these cases, two CB7 molecules can be accommodated between the two head groups of the bolaform without addition of electrolytes to the medium. In the case of a bolaform with 12 carbon atoms, the electrostatic repulsion between the carbonyl groups of the CB7 molecules avoids the threading of a second CB7 molecule yielding a mixed structure formed by a [2]pseudorotaxane and an external host-guest complex. The assembly behavior was investigated using NMR spectroscopy, isothermal titration calorimetry (ITC), and kinetic measurements.

  1. Biodegradation of aliphatic hydrocarbons in the presence of hydroxy cucurbit[6]uril.

    Science.gov (United States)

    Pasumarthi, Rajesh; Kumar, Vikash; Chandrasekharan, Sivaraman; Ganguly, Anasuya; Banerjee, Mainak; Mutnuri, Srikanth

    2014-11-15

    Aliphatic hydrocarbons are one of the major environmental pollutants with reduced bioavailability. The present study focuses on the effect of hydroxy cucurbit[6]uril on the bioavailability of hydrocarbons. A bacterial consortium was used for biodegradation studies under saline and non-saline conditions. Based on denaturing gradient gel electrophoresis results it was found that the consortium under saline conditions had two different strains. The experiment was conducted in microcosms with tetradecane, hexadecane, octadecane and mixture of the mentioned hydrocarbons as the sole carbon source. The residual hydrocarbon was quantified using gas chromatography every 24h. It was found that biodegradation of tetradecane and hexadecane, as individual carbon source increased in the presence of hydroxy CB[6], probably due to the increase in their bioavailability. In case of octadecane this did not happen. Bioavailability of all three aliphatic hydrocarbons was increased when provided as a mixture to the consortium under saline conditions.

  2. Determination of L-phenylalanine by cucurbit[7]uril sensitized fluorescence quenching method

    Institute of Scientific and Technical Information of China (English)

    Chang Feng Li; Li Ming Du; Hao Wu; Ying Xia Chang

    2011-01-01

    The determination method of L-phenylalanine (LPA) by fluorescence quenching was developed. The assay was based on the combination of the cucurbit[7]uril (CB[7]) with palmatine hydrochloride (PAL) reaction. In the presence of CB[7], the fluorescence of PAL was quenched by LPA which can be employed to detect LPA. Under the optimal conditions, a linear range 3.63 × 10-8-9.68 × 10-6 mol/L and a detection limit 1.27 × 10-8 mol/L of LPA were obtained. The relative standard deviation (R.S.D) was 1.8% obtained from a series of11 standards each containing 6.05 × 10-6 mol/L oLPA. This paper also discusses the mechanism of fluorescence indicator probe.

  3. Applying imidacloprid via a precision banding system to control striped cucumber beetle (Coleoptera: Chrysomelidae) in cucurbits.

    Science.gov (United States)

    Jasinski, J; Darr, M; Ozkan, E; Precheur, R

    2009-12-01

    The striped cucumber beetle, Acalymma vittatum (F.) (Coleoptera: Chrysomelidae), is a key pest of cucurbit crops throughout its range. A novel precision band applicator was designed to inject a solid stream of imidacloprid solution in-furrow directly over the seed during planting to reduce beetle leaf feeding on pumpkin, zucchini, and cucumber crops. In 2004 and 2005, bioassays at the cotyledon through fifth leaf were conducted on striped cucumber beetles using seedling leaf tissue grown from seeds treated using both continuous and precision banded in-furrow imidacloprid solution applications. In 2004, 80% of bioassay trials had treatments with beetle mortality significantly higher than the check, whereas 70% of the bioassay trials showed no significant difference in mortality between continuous in-furrow and precision banded treatments. In 2005, 79% of bioassay trials had treatments with beetle mortality significantly higher than the check, whereas 100% of the bioassays showed no significant difference in beetle mortality between continuous in-furrow and precision banded treatments at the same insecticide rate. The environmental savings of precision banded treatments compared with continuous in-furrow treatment reduced imidacloprid up to 84.5% on a per hectare basis for all cucurbits tested in 2004 and 2005, translating into an economic savings up to $215/ha. In separate bioassay trials conducted in 2005 on pumpkin, where insecticide band length and injection volume were manipulated independently, several treatments had significantly higher beetle mortality than the check. There was a trend of increased beetle mortality in treatments using shorter band lengths combined with higher insecticide solution volumes.

  4. Studies on biological control of powdery mildew in cucumber (Sphaerotheca fuliginea) and rose (Sphaerotheca pannosa) by means of mycoparasites.

    NARCIS (Netherlands)

    Verhaar, M.A.

    1998-01-01

    Powdery mildew on rose ( Sphaerotheca pannosa ) and cucumber ( Sphaerotheca fuliginea ) are two serious diseases in glasshouses. Intensive control by fungicides is needed. The research presented here deals with biocontrol of powdery mildew on cucumber and rose by means of mycoparasites.The mycoparas

  5. Pea powdery mildew er1 resistance is associated to loss-of-function mutations at a MLO homologous locus

    NARCIS (Netherlands)

    Pavan, S.N.C.; Schiavulli, A.; Appiano, M.; Visser, R.G.F.; Bai, Y.

    2011-01-01

    The powdery mildew disease affects several crop species and is also one of the major threats for pea (Pisum sativum L.) cultivation all over the world. The recessive gene er1, first described over 60 years ago, is well known in pea breeding, as it still maintains its efficiency as a powdery mildew

  6. Application of Glycerol for Induced Powdery Mildew Resistance in Triticum aestivum L.

    Science.gov (United States)

    Li, Yinghui; Song, Na; Zhao, Chuanzhi; Li, Feng; Geng, Miaomiao; Wang, Yuhui; Liu, Wanhui; Xie, Chaojie; Sun, Qixin

    2016-01-01

    Previous work has demonstrated that glycerol-3-phosphate (G3P) and oleic acid (18:1) are two important signal molecules associated with plant resistance to fungi. In this article, we provide evidence that a 3% glycerol spray application 1-2 days before powdery mildew infection and subsequent applications once every 4 days was sufficient to stimulate the plant defense responses without causing any significant damage to wheat leaves. We found that G3P and oleic acid levels were markedly induced by powdery mildew infection. In addition, TaGLI1 (encoding a glycerol kinase) and TaSSI2 (encoding a stearoylacyl carrier protein fatty acid desaturase), two genes associated with the glycerol and fatty acid (FA) pathways, respectively, were induced by powdery mildew infection, and their promoter regions contain some fungal response elements. Moreover, exogenous application of glycerol increased the G3P level and decreased the level of oleic acid (18:1). Glycerol application induced the expression of pathogenesis-related (PR) genes (TaPR-1, TaPR-2, TaPR-3, TaPR-4, and TaPR-5), induced the generation of reactive oxygen species (ROS) before powdery mildew infection, and induced salicylic acid (SA) accumulation in wheat leaves. Further, we sprayed glycerol in a wheat field and found that it significantly (p powdery mildew disease and lessened disease-associated kernel weight loss, all without causing any noticeable degradation in wheat seed quality.

  7. Biotrophy at Its Best: Novel Findings and Unsolved Mysteries of the Arabidopsis-Powdery Mildew Pathosystem.

    Science.gov (United States)

    Kuhn, Hannah; Kwaaitaal, Mark; Kusch, Stefan; Acevedo-Garcia, Johanna; Wu, Hongpo; Panstruga, Ralph

    2016-01-01

    It is generally accepted in plant-microbe interactions research that disease is the exception rather than a common outcome of pathogen attack. However, in nature, plants with symptoms that signify colonization by obligate biotrophic powdery mildew fungi are omnipresent. The pervasiveness of the disease and the fact that many economically important plants are prone to infection by powdery mildew fungi drives research on this interaction. The competence of powdery mildew fungi to establish and maintain true biotrophic relationships renders the interaction a paramount example of a pathogenic plant-microbe biotrophy. However, molecular details underlying the interaction are in many respects still a mystery. Since its introduction in 1990, the Arabidopsis-powdery mildew pathosystem has become a popular model to study molecular processes governing powdery mildew infection. Due to the many advantages that the host Arabidopsis offers in terms of molecular and genetic tools this pathosystem has great capacity to answer some of the questions of how biotrophic pathogens overcome plant defense and establish a persistent interaction that nourishes the invader while in parallel maintaining viability of the plant host.

  8. Serine/threonine kinase gene Stpk-V, a key member of powdery mildew resistance gene Pm21, confers powdery mildew resistance in wheat.

    Science.gov (United States)

    Cao, Aizhong; Xing, Liping; Wang, Xiaoyun; Yang, Xueming; Wang, Wei; Sun, Yulei; Qian, Chen; Ni, Jinlong; Chen, Yaping; Liu, Dajun; Wang, Xiue; Chen, Peidu

    2011-05-10

    Powdery mildew resistance gene Pm21, located on the chromosome 6V short arm of Haynaldia villosa and transferred to wheat as a 6VS·6AL translocation (T6VS·6AL), confers durable and broad-spectrum resistance to wheat powdery mildew. Pm21 has become a key gene resource for powdery mildew resistance breeding all over the world. In China, 12 wheat varieties containing Pm21 have been planted on more than 3.4 million hectares since 2002. Pm21 has been intractable to molecular genetic mapping because the 6VS does not pair and recombine with the 6AS. Moreover, all known accessions of H. villosa are immune to powdery mildew fungus. Pm21 is still defined by cytogenetics as a locus. In the present study, a putative serine and threonine protein kinase gene Stpk-V was cloned and characterized with an integrative strategy of molecular and cytogenetic techniques. Stpk-V is located on the Pm21 locus. The results of a single cell transient expression assay showed that Stpk-V could decrease the haustorium index dramatically. After the Stpk-V was transformed into a susceptible wheat variety Yangmai158, the characterized transgenic plants showed high and broad-spectrum powdery mildew resistance similar to T6VS·6AL. Silencing of the Stpk-V by virus-induced gene silencing in both T6VS·6AL and H. villosa resulted in their increased susceptibility. Stpk-V could be induced by Bgt and exogenous H(2)O(2), but it also mediated the increase of endogenous H(2)O(2), leading to cell death and plant resistance when the plant was attacked by Bgt.

  9. Establishment of a Simple and Rapid Gene Delivery System for Cucurbits by Using Engineered of Zucchini yellow mosaic virus.

    Science.gov (United States)

    Kang, Minji; Seo, Jang-Kyun; Choi, Hoseong; Choi, Hong-Soo; Kim, Kook-Hyung

    2016-02-01

    The infectious full-length cDNA clone of zucchini yellow mosaic virus (ZYMV) isolate PA (pZYMV-PA), which was isolated from pumpkin, was constructed by utilizing viral transcription and processing signals to produce infectious in vivo transcripts. Simple rub-inoculation of plasmid DNAs of pZYMV-PA was successful to cause infection of zucchini plants (Cucurbita pepo L.). We further engineered this infectious cDNA clone of ZYMV as a viral vector for systemic expression of heterologous proteins in cucurbits. We successfully expressed two reporter genes including gfp and bar in zucchini plants by simple rub-inoculation of plasmid DNAs of the ZYMV-based expression constructs. Our method of the ZYMV-based viral vector in association with the simple rub-inoculation provides an easy and rapid approach for introduction and evaluation of heterologous genes in cucurbits.

  10. Reasoned opinion on the modification of the existing MRLs for proquinazid in tomatoes, aubergines and cucurbits with edible peel

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2012-09-01

    Full Text Available

    In accordance with Article 6 of Regulation (EC No 396/2005, Germany, hereafter referred to as the evaluating Member State (EMS, received two applications from Pflanzenschutzdienst der Landwirtschaftskammer Nordrhein-Westfalen to modify the existing MRLs for the active substance proquinazid in tomatoes and aubergines and in cucurbits (edible peel, respectively. In order to accommodate for the intended uses of proquinazid, Germany proposed to raise the existing MRLs from the limit of quantification (LOQ of 0.02 mg/kg to 0.15 mg/kg in tomatoes and aubergines and to 0.04 mg/kg in cucurbits with edible peel. Germany drafted two separate evaluation reports in accordance with Article 8 of Regulation (EC No 396/2005, which were submitted to the European Commission and forwarded to EFSA. For reasons of efficiency EFSA combined both applications in one reasoned opinion. According to EFSA the data are sufficient to derive MRL proposals of 0.15 mg/kg for the intended use on tomatoes and aubergines and of 0.05 mg/kg for the intended use on the whole group of cucurbits (edible peel. Adequate analytical enforcement methods are available to control the residues of proquinazid in the crops under consideration. Based on the risk assessment results, EFSA concludes that the proposed use of proquinazid on tomatoes, aubergines and cucurbits with edible peel will not result in a consumer exposure exceeding the toxicological reference values and therefore is unlikely to pose a consumer health risk.

  11. IDENTIFICATION OF RAPD MARKER LINKED TO POWDERY MILDEW RESISTANCE GENE Pm 12 IN WHEAT

    Institute of Scientific and Technical Information of China (English)

    GU Feng; ZHANG Qing-li; GUO Xiao-chun; LI Tao; WANG Hong-gang

    2004-01-01

    Powdery mildew is one of the most serious diseases of wheat in China. In this paper,bulked segregant analysis (BSA) was used to search for randomly amplified polymorphic DNA (RAPD) markers linked to the Pm12 gene,which confers resistance to the powdery mildew in wheat. 200 decamer primers were screened and one RAPD marker (S1071900) was identified to be linked to Pm 12 in coupling phase, and their genetic distance is 11.98 ±4.00cM. This marker can be used for marker - assisted selection in wheat breeding for the identification or pyramiding of Pm12 with other resistance genes.Key Words: Wheat, RAPD, Powdery mildew, resistance genes.

  12. NMR Spectroscopy Identifies Metabolites Translocated from Powdery Mildew Resistant Rootstocks to Susceptible Watermelon Scions.

    Science.gov (United States)

    Mahmud, Iqbal; Kousik, Chandrasekar; Hassell, Richard; Chowdhury, Kamal; Boroujerdi, Arezue F

    2015-09-16

    Powdery mildew (PM) disease causes significant loss in watermelon. Due to the unavailability of a commercial watermelon variety that is resistant to PM, grafting susceptible cultivars on wild resistant rootstocks is being explored as a short-term management strategy to combat this disease. Nuclear magnetic resonance-based metabolic profiles of susceptible and resistant rootstocks of watermelon and their corresponding susceptible scions (Mickey Lee) were compared to screen for potential metabolites related to PM resistance using multivariate principal component analysis. Significant score plot differences between the susceptible and resistant groups were revealed through Mahalanobis distance analysis. Significantly different spectral buckets and their corresponding metabolites (including choline, fumarate, 5-hydroxyindole-3-acetate, and melatonin) have been identified quantitatively using multivariate loading plots and verified by volcano plot analyses. The data suggest that these metabolites were translocated from the powdery mildew resistant rootstocks to their corresponding powdery mildew susceptible scions and can be related to PM disease resistance.

  13. Interaction of barley powdery mildew effector candidate CSEP0055 with the defence protein PR17c

    DEFF Research Database (Denmark)

    Zhang, Wen-Jing; Pedersen, Carsten; Kwaaitaal, Mark Adrianus Cornelis J

    2012-01-01

    A large number of effector candidates have been identified recently in powdery mildew fungi. However, their roles and how they perform their functions remain unresolved. In this study, we made use of host-induced gene silencing and confirmed that the secreted barley powdery mildew effector...... candidate, CSEP0055, contributes to the aggressiveness of the fungus. This result suggests that CSEP0055 is involved in the suppression of plant defence. A yeast two-hybrid screen indicated that CSEP0055 interacts with members of the barley pathogenesis-related protein families, PR1 and PR17. Interaction...... with PR17c was confirmed by bimolecular fluorescence complementation analyses. Down-regulation and over-expression of PR17c in epidermal cells of barley confirmed that this protein is important for penetration resistance against the powdery mildew fungus. In line with this, PR17c was found...

  14. Reasoned opinion on the modification of the existing MRLs for difenoconazole in raspberries, blackberries and cucurbits (edible peel

    Directory of Open Access Journals (Sweden)

    European Food Safety Authority

    2012-08-01

    Full Text Available

    In accordance with Article 6 of Regulation (EC No 396/2005, Germany, hereafter referred to as the evaluating Member State (EMS, received an application from TSGE Deutschland GmbH to modify the existing MRLs for difenoconazole in raspberries and blackberries. Germany also received an application from Landwirtschaftskammer NRW Pflanzenschutzdienst to modify the existing MRLs for difenoconazole in cucurbits with (edible peel. In order to accommodate the intended NEU outdoor use on raspberries and blackberries and the intended indoor use on cucurbits (edible peel, the EMS proposed to raise the existing MRLs in these berries from 0.3 mg/kg to 1.5 mg/kg and in cucurbits (edible peel from 0.1 mg/kg to 0.3 mg/kg. The EMS drafted two evaluation reports in accordance with Article 8 of Regulation (EC No 396/2005, which were submitted to the European Commission and forwarded to EFSA. According to EFSA, the applications are sufficiently supported by data and EFSA confirmed the MRL proposals made by the EMS. Adequate analytical enforcement methods are available to control the residues of difenoconazole in the crops under consideration. The risk assessment demonstrated that the intended use of difenoconazole on the crops under consideration will not result in a consumer exposure exceeding the toxicological reference values and therefore is unlikely to pose a public health concern.

  15. QTL Mapping for Adult Plant Resistance to Powdery Mildew in Italian Wheat cv. Strampelli

    Institute of Scientific and Technical Information of China (English)

    Asad Muhammad Azeem; BAI Bin; LAN Cai-xia; YAN Jun; XIA Xian-chun; ZHANG Yong; HE Zhong-hu

    2013-01-01

    The Italian wheat cv. Strampelli displays high resistance to powdery mildew caused by Blumeria graminis f. sp. tritici. The objective of this study was to map quantitative trait loci (QTLs) for resistance to powdery mildew in a population of 249 F2:3 lines from Strampelli/Huixianhong. Adult plant powdery mildew tests were conducted over 2 yr in Beijing and 1 yr in Anyang and simple sequence repeat (SSR) markers were used for genotyping. QTLs Qpm.caas-3BS, Qpm.caas-5BL.1, and Qpm.caas-7DS were consistent across environments whereas, Qpm.caas-2BS.1 found in two environments, explained 0.4-1.6, 5.5-6.9, 27.1-34.5, and 1.0-3.5%of the phenotypic variation respectively. Qpm.caas-7DS corresponded to the genomic location of Pm38/Lr34/Yr18. Qpm.caas-4BL was identified in Anyang 2010 and Beijing 2011, accounting for 1.9-3.5%of phenotypic variation. Qpm.caas-2BS.1 and Qpm.caas-5BL.1 contributed by Strampelli and Qpm.caas-3BS by Huixianhong, seem to be new QTL for powdery mildew resistance. Qpm.caas-4BL, Qpm.caas-5BL.3, and Qpm.caas-7DS contributed by Strampelli appeared to be in the same genomic regions as those mapped previously for stripe rust resistance in the same population, indicating that these loci conferred resistance to both stripe rust and powdery mildew. Strampelli could be a valuable genetic resource for improving durable resistance to both powdery mildew and stripe rust in wheat.

  16. PHOTOSYNTHETIC PIGMENTS IN HEVEA CLONES UNDER POWDERY MILDEW ATTACK

    Directory of Open Access Journals (Sweden)

    Gisely Cristina Gonzalez

    2013-08-01

    Full Text Available http://dx.doi.org/10.5902/1980509810561The rubber tree [Hevea brasiliensis (Willd. ex Adr. Of Juss. Muell. Arg.] can be affected by the occurrence of the fungus Oidium heveae, which causes one of the most important diseases of rubber trees, powdery mildew. This work studied meet changes in photosynthetic pigments, an indicator of oxidative stress, in seedlings of three Hevea brasiliensis clones, RRIM 600, GT1 and PR255, under infection in Oidium heveae. The experiment was conducted in an open environment under natural photoperiod conditions and at the beginning of the trial, the rubber plants would be inoculated were sprayed with an aqueous suspension containing O. heveae at a concentration of 16 x 104 conidia mL-1. On the day of inoculation and after 48, 96, 144 and 192 h leaf samples were collected for the determination of photosynthetic pigments. Degradation in photosynthetic pigments in the period of infection was observed in rubber tree clones studied; thus, there is oxidative stress in clones of rubber trees. No promising genetic material for genetic improvement work stress tolerance by Oidium heveae was identified.

  17. Localization of powdery mildew resistance gene Ml-ra on barley chromosome 5

    DEFF Research Database (Denmark)

    Doll, Hans; Jensen, Hans Peter

    1986-01-01

    Evidence is presented that the powdery mildew resistance gene called Ml-(41/145) represents a unique, unnamed locus, which we suggest to be designated Ml-ra with reference to variety 'Ragusa b' [Hordeum vulgare]. Ml-ra is located on the short arm of chormosome 5 near powdery mildew resistance locus...... Ml-a and the seed storage protein loci Hor1 and Hor2. The most likely order of the loci is Hor1, Ml-a, Ml-ra, and Hor2....

  18. Histo-chemical and biochemical analysis reveals association of er1 mediated powdery mildew resistance and redox balance in pea.

    Science.gov (United States)

    Mohapatra, Chinmayee; Chand, Ramesh; Navathe, Sudhir; Sharma, Sandeep

    2016-09-01

    Powdery mildew caused by Erysiphe pisi is one of the important diseases responsible for heavy yield losses in pea crop worldwide. The most effective method of controlling the disease is the use of resistant varieties. The resistance to powdery mildew in pea is recessive and governed by a single gene er1. The objective of present study is to investigate if er1 mediated powdery mildew resistance is associated with changes in the redox status of the pea plant. 16 pea genotypes were screened for powdery mildew resistance in field condition for two years and, also, analyzed for the presence/absence of er1 gene. Histochemical analysis with DAB and NBT staining indicates accumulation of reactive oxygen species (ROS) in surrounding area of powdery mildew infection which was higher in susceptible genotypes as compared to resistant genotypes. A biochemical study revealed that the activity of superoxide dismutase (SOD) and catalase, enzymes involved in scavenging ROS, was increased in, both, resistant and susceptible genotypes after powdery mildew infection. However, both enzymes level was always higher in resistant than susceptible genotypes throughout time course of infection. Moreover, irrespective of any treatment, the total phenol (TP) and malondialdehyde (MDA) content was significantly high and low in resistant genotypes, respectively. The powdery mildew infection elevated the MDA content but decreased the total phenol in pea genotypes. Statistical analysis showed a strong positive correlation between AUDPC and MDA; however, a negative correlation was observed between AUDPC and SOD, CAT and TP. Heritability of antioxidant was also high. The study identified few novel genotypes resistant to powdery mildew infection that carried the er1 gene and provided further clue that er1 mediated defense response utilizes antioxidant machinery to confer powdery mildew resistance in pea.

  19. Foreword: Special issue on fungal grapevine diseases

    Science.gov (United States)

    An impressively large proportion of fungicides applied in European, North American and Australian agriculture has been used to manage grapevine powdery mildew (Erysiphe necator), grapevine downy mildew (Plasmopara viticola), and botrytis bunch rot (Botrytis cinerea). These fungal and oomycetous plan...

  20. Antisense expression of peach mildew resistance locus O (PpMlo1) gene confers cross-species resistance to powdery mildew in Fragaria x ananassa.

    Science.gov (United States)

    Jiwan, Derick; Roalson, Eric H; Main, Dorrie; Dhingra, Amit

    2013-12-01

    Powdery mildew (PM) is one of the major plant pathogens. The conventional method of PM control includes frequent use of sulfur-based fungicides adding to production costs and potential harm to the environment. PM remains a major scourge for Rosaceae crops where breeding approaches mainly resort to gene-for-gene resistance. We have tested an alternate source of PM resistance in Rosaceae. Mildew resistance locus O (MLO) has been well studied in barley due to its role in imparting broad spectrum resistance to PM. We identified PpMlo1 (Prunus persica Mlo) in peach and characterized it further to test if a similar mechanism of resistance is conserved in Rosaceae. Due to its recalcitrance in tissue culture, reverse genetic studies involving PpMloI were not feasible in peach. Therefore, Fragaria x ananassa LF9 line, a taxonomic surrogate, was used for functional analysis of PpMlo1. Agrobacterium-mediated transformation yielded transgenic strawberry plants expressing PpMlo1 in sense and antisense orientation. Antisense expression of PpMlo1 in transgenic strawberry plants conferred resistance to Fragaria-specific powdery mildew, Podosphaera macularis. Phylogenetic analysis of 208 putative Mlo gene copies from 35 plant species suggests a large number of duplications of this gene family prior to the divergence of monocots and eudicots, early in eudicot diversification. Our results indicate that the Mlo-based resistance mechanism is functional in Rosaceae, and that Fragaria can be used as a host to test mechanistic function of genes derived from related tree species. To the best of our knowledge, this work is one of the first attempts at testing the potential of using a Mlo-based resistance strategy to combat powdery mildew in Rosaceae.

  1. Cucurbit[7]uril⋅guest pair with an attomolar dissociation constant.

    Science.gov (United States)

    Cao, Liping; Śekutor, Marina; Zavalij, Peter Y; Mlinarić-Majerski, Kata; Glaser, Robert; Isaacs, Lyle

    2014-01-20

    Host⋅guest complexes between cucurbit[7] (CB[7]) or CB[8] and diamantane diammonium ion guests 3 or 6 were studied by (1) H NMR spectroscopy and X-ray crystallography. (1) H NMR competition experiments revealed that CB[7]⋅6 is among the tightest monovalent non-covalent complexes ever reported in water with Ka =7.2×10(17)  M(-1) in pure D2 O and 1.9×10(15)  M(-1) in D2 O buffered with NaO2 CCD3 (50 mM). The crystal structure of CB[7]⋅6 allowed us to identify some of the structural features responsible for the ultratight binding, including the distance between the NMe3 (+) groups of 6 (7.78 Å), which allows it to establish 14 optimal ion-dipole interactions with CB[7], the complementarity of the convex van der Waals surface contours of 6 with the corresponding concave surfaces of CB[7], desolvation of the CO portals within the CB[7]⋅6 complex, and the co-linearity of the C7  axis of CB[7] with the N(+) ⋅⋅⋅N(+) line in 6. This work further blurs the lines of distinction between natural and synthetic receptors.

  2. Occurrence and molecular characterization of Cucumber green mottle mosaic virus in cucurbit crops of KPK, Pakistan

    Directory of Open Access Journals (Sweden)

    Asad Ali

    2014-12-01

    Full Text Available Field survey of the cucurbit crops revealed a high incidence of Cucumber green mottle mosaic virus (CGMMV in Khyber Pakhtunkhwa Province (KPK, Pakistan. Among the seven districts surveyed, average percent incidence of CGMMV was recorded up to 58.1% in district Nowshera, followed by 51.1% in district Charsada, 40.5% in district Swabi and 37.3% in district Mardan. In Swat and Dir districts average incidence CGMMV was recorded upto 31.2% and 29.4%, respectively. Among the different crops highest incidence in plain areas of KPK was recorded in bottle gourd (59.3% followed by 56.3% in Squash, 54.5% in Pumpkin, 45.5% in Melon, 41.7% in Cucumber and 29.9% in Sponge gourd. In Northern hilly areas highest incidence of CGMMV (52.9% was observed in pumpkin, followed by 49.6% in bottle gourd, 47.3% in squash, 45.1% in Melon 42.3% in cucumber and 41.6% in sponge gourd. Little variability was observed in the coat protein amino acid sequence identities of CGMMV Pakistan isolate, when compared with other reported isolates.

  3. Chemical composition of Apodanthera biflora, a Cucurbit of the dry forest in northwestern Peru

    Directory of Open Access Journals (Sweden)

    Daniel Clark

    2012-11-01

    Full Text Available The dry forest of northwestern Peru is the habitat of numerous native species that have received little attention beyond taxonomic purposes. Here we report the chemical composition of the roots and seeds of a set of accessions of Apondanthera biflora, a wild Cucurbit with potentialities as a food resource. The roots show features that are comparable to those from cassava roots and potato tubers: a high content of carbohydrates on a dry matter basis (77.5 – 84.9%, with starch representing around 20% of the total dry matter. The seeds’ fat content on a dry matter basis (22.22 – 39.37% falls within the percentages found in oily seeds such as safflower, whereas the protein content (21.37 – 29.06% is similar to that of flax and sunflower. The fatty acid profile of the seed’s oil shows a predominance of polyunsaturated acids, in particular linoleic acid (43.81%, making it comparable to that of cotton oil. Our results confirm the nutritional value of Apodanthera biflora and set the ground for its use in domestication and food security programs.

  4. Study on the inclusion interactions of berberine hydrochloride and cucurbit[7] by spectrofluorimetry

    Institute of Scientific and Technical Information of China (English)

    Yan Ping Li; Hao Wu; Li Ming Du

    2009-01-01

    The inclusion interaction between berberine hydrochloride (BRH) and cucurbit[7] (CB[7]) has been studied by spectro-fluorimetry. The result showed that CB[7] interaction with BRH to form a stable inclusion complex with an association constant of 9.57 x 104 L/tool and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself.Based on the significant enhancement of fluorescence intensity of BRH in inclusion complex, a spetrofluodmetric method with high sensitivity and selectivity was developed for the determination of BRH in aqueous solution. The linear range of the method was 3.2-2 x 103 ng]mL with a detection limit of 1.1 ng/mL. The proposed procedure could be applied successfully to determination of BRH remained in pharmaceutical dosage forms, spiked human plasma and urine with satisfactory results.(C) 2008 Li Ming Du. Published by Elsevier B.V. On behalf of Chinese Chemical Society. All rights reserved.

  5. Supramolecular Adducts of Cucurbit[7]uril and Amino Acids in the Gas Phase

    Science.gov (United States)

    Kovalenko, Ekaterina; Vilaseca, Marta; Díaz-Lobo, Mireia; Masliy, A. N.; Vicent, Cristian; Fedin, Vladimir P.

    2016-02-01

    The complexation of the macrocyclic cavitand cucurbit[7]uril (Q7) with a series of amino acids (AA) with different side chains (Asp, Asn, Gln, Ser, Ala, Val, and Ile) is investigated by ESI-MS techniques. The 1:1 [Q7 + AA + 2H]2+ adducts are observed as the base peak when equimolar Q7:AA solutions are electrosprayed, whereas the 1:2 [Q7 + 2AA + 2H]2+ dications are dominant when an excess of the amino acid is used. A combination of ion mobility mass spectrometry (IM-MS) and DFT calculations of the 1:1 [Q7 + AA + 2H]2+ (AA = Tyr, Val, and Ser) adducts is also reported and proven to be unsuccessful at discriminating between exclusion or inclusion-type conformations in the gas phase. Collision induced dissociation (CID) revealed that the preferred dissociation pathways of the 1:1 [Q7 + AA + 2H]2+ dications are strongly influenced by the identity of the amino acid side chain, whereas ion molecule reactions towards N-butylmethylamine displayed a common reactivity pattern comprising AA displacement. Special emphasis is given on the differences between the gas-phase behavior of the supramolecular adducts with amino acids (AA = Asp, Asn, Gln, Ser, Ala, Val, and Ile) and those featuring basic (Lys and Arg) and aromatic (Tyr and Phe) side chains.

  6. Encapsulation of the ethylene inhibitor 1-Methylcyclopropene by cucurbit[6]uril.

    Science.gov (United States)

    Zhang, Quan; Zhen, Zeng; Jiang, Hong; Li, Xue-Gang; Liu, Jun-An

    2011-10-12

    1-Methylcyclopropene (1-MCP) is an excellent safe and commercially available ethylene antagonist for the preservation of horticultural products. However 1-MCP has to be stored in absorbents due to its gaseous and unstable characteristics. In this paper cucurbit[6]uril (CB[6]) was used as the absorbent to encapsulate 1-MCP, and the resultant inclusion complex was characterized by IR, powder X-ray diffraction, thermal analysis, and fluorescent spectra. The effects of encapsulation conditions on the formation of inclusion complex were also investigated. The amount of 1-MCP encapsulated by CB[6] was about 4.5% by weight when the initial concentration of 1-MCP, encapsulation temperature, CB[6] concentration, and encapsulation time were set at 75 mL/L, 20 °C, 30 mM, and 8 h, respectively. Furthermore, the release of 1-MCP from the complex can be realized with different solutions such as sodium bicarbonate, benzoic acid, and distilled water. CB[6] can be used as an excellent absorbent for encapsulation of 1-MCP.

  7. Fluorescence detecting of paraquat using host-guest chemistry with cucurbit[8]uril

    Science.gov (United States)

    Sun, Shiguo; Li, Fusheng; Liu, Fengyu; Wang, Jitao; Peng, Xiaojun

    2014-01-01

    Paraquat (PQ) is one of the most widely used herbicides in the world, which has a good occupational safety record when used properly. While, it presents high mortality index after intentional exposure. Accidental deaths and suicides from PQ ingestion are relatively common in developing countries with an estimated 300,000 deaths occurring in the Asia-Pacific region alone each year, and there are no specific antidotes. Good predictors of outcome and prognosis may be plasma and urine testing within the first 24 h of intoxication. A fluorescence enhancement of approximately 30 times was seen following addition of PQ to a solution of the supramolecular compound 2MB@CB[8], which comprised two methylene blue (MB) molecules within one cucurbit[8]uril (CB[8]) host molecule. The fluorescence intensity was linearly proportional to the amount of PQ added over the concentration range 2.4 × 10-10 M-2.5 × 10-4 M. The reaction also occurred in living cells and within live mice.

  8. Resistance to Cucurbit aphid-borne yellows virus in Melon Accession TGR-1551.

    Science.gov (United States)

    Kassem, Mona A; Gosalvez, Blanca; Garzo, Elisa; Fereres, Alberto; Gómez-Guillamón, Maria Luisa; Aranda, Miguel A

    2015-10-01

    The genetic control of resistance to Cucurbit aphid-borne yellows virus (CABYV; genus Polerovirus, family Luteoviridae) in the TGR-1551 melon accession was studied through agroinoculation of a genetic family obtained from the cross between this accession and the susceptible Spanish cultivar 'Bola de Oro'. Segregation analyses were consistent with the hypothesis that one dominant gene and at least two more modifier genes confer resistance; one of these additional genes is likely present in the susceptible parent 'Bola de Oro'. Local and systemic accumulation of the virus was analyzed in a time course experiment, showing that TGR-1551 resistance was expressed systemically as a significant reduction of virus accumulation compared with susceptible controls, but not locally in agroinoculated cotyledons. In aphid transmission experiments, CABYV inoculation by aphids was significantly reduced in TGR-1551 plants, although the virus was acquired at a similar rate from TGR-1551 as from susceptible plants. Results of feeding behavior studies using the DC electrical penetration graph technique suggested that viruliferous aphids can salivate and feed from the phloem of TGR-1551 plants and that the observed reduction in virus transmission efficiency is not related to reduced salivation by Aphis gossypii in phloem sieve elements. Since the virus is able to accumulate to normal levels in agroinoculated tissues, our results suggest that resistance of TGR-1551 plants to CABYV is related to impairment of virus movement or translocation after it reaches the phloem sieve elements.

  9. Cucurbit[7]uril host-guest complexes of the histamine H2-receptor antagonist ranitidine.

    Science.gov (United States)

    Wang, Ruibing; Macartney, Donal H

    2008-06-07

    The macrocyclic host cucurbit[7]uril forms very stable complexes with the diprotonated (K(CB[7])(1) = 1.8 x 10(8) dm(3) mol(-1)), monoprotonated (K(CB[7])(2) = 1.0 x 10(7) dm(3) mol(-1)), and neutral (K(CB[7])(3) = 1.2 x 10(3) dm(3) mol(-1)) forms of the histamine H(2)-receptor antagonist ranitidine in aqueous solution. The complexation behaviour was investigated using (1)H NMR and UV-visible spectroscopy as a function of pH and the pK(a) values of the guest were observed to increase (DeltapK(a1) = 1.5 and DeltapK(a2) = 1.6) upon host-guest complex formation. The energy-minimized structures of the host-guest complexes with the cationic guests were determined and provide agreement with the NMR results indicating the location of the CB[7] over the central portion of the guest. The inclusion of the monoprotonated form of ranitidine slows the normally rapid (E)-(Z) exchange process and generates a preference for the (Z) isomer. The formation of the CB[7] host-guest complex greatly increases the thermal stability of ranitidine in acidic aqueous solution at 50 degrees C, but has no effect on its photochemical reactivity.

  10. Ketoprofen encapsulated cucurbit[6]uril nanoparticles: a new exploration of macrocycles for drug delivery

    Science.gov (United States)

    Hoai, Nguyen To; Tuyen Thi Dao, Phuong; Phu, Quoc Nam; Dam Le, Duy; Nguyen, Tuan Anh; Nguyen, Tai Chi; Chien Dang, Mau

    2012-12-01

    The aim of this study is (i) to fabricate a nanoparticle formulation of ketoprofen (Keto) using a relatively new family of macrocycles as the carrier for drug delivery: cucurbit[6]uril (CB[6]), (ii) to evaluate its in vitro dissolution and (iii) to investigate its in vivo pharmaceutical property. The CB[6]-Keto nanoparticles were prepared by emulsion solvent evaporation method. Morphology and size of the successfully prepared nanoparticles were then confirmed using a transmission electron microscope and dynamic light scattering. It was shown that they are spherical with hydrodynamic diameter of 200-300 nm. The in vitro dissolution studies of CB[6]-Keto nanoparticles were conducted at pH 1.2 and 7.4. The results indicated that there is a significant increase in Keto concentration at pH 7.4 compared to pH 1.2. For the in vivo assessment, CB[6]-Keto nanoparticles and referential profenid were administered by oral gavages to rabbits. The results implied that CB[6]-Keto nanoparticles remarkably increased area under the curve compared to profenid.

  11. Cucurbit[6]uril nanocavity as an enhanced spectrofluorimetric method for the determination of pyrene

    Energy Technology Data Exchange (ETDEWEB)

    Sueldo Occello, Valeria N. [Instituto de Investigaciones en Fisico Quimica de Cordoba (INFIQC), Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina); Veglia, Alicia V., E-mail: aveglia@fcq.unc.edu.ar [Instituto de Investigaciones en Fisico Quimica de Cordoba (INFIQC), Departamento de Quimica Organica, Facultad de Ciencias Quimicas, Universidad Nacional de Cordoba, Ciudad Universitaria, 5000 Cordoba (Argentina)

    2011-03-09

    The effect of the addition of macrocyclic host cucurbit[6]uril (CB6) on the photophysical properties of polycyclic aromatic hydrocarbon pyrene (PYR) was analyzed. The fluorescence emission spectra of the aromatic compound were determined at 25.0 {sup o}C in different acidic media (HCl 18%, w/v, or HCOOH 55%, w/v) with and without CB6. A significant enhancement in the fluorescence signals in the presence of CB6 was observed. The average values of the association constant (K{sub A}) for the 1:1 stoichiometry complex and the relative fluorescence quantum yield ratio between the complexed and free PYR ({phi}{sup PYR-CB6}/{phi}{sup PYR}) in acidic media were (4.0 {+-} 0.5) x 10{sup 2} M{sup -1} and (5.7 {+-} 0.2), respectively. The analytical parameters improved in the presence of CB6. The relative decrease in the limit of detection was 92%. The matrix effect was evaluated in fortified samples of tap water and tea extracts. Apparent recoveries obtained by the proposed method in tap water and tea extracts were (82-103)% and (89-99)%, respectively. Selectivity studies with inorganic and organic species were performed. The method is rapid, direct, selective and simple.

  12. Host-guest complexes and pseudorotaxanes of cucurbit[7]uril with acetylcholinesterase inhibitors.

    Science.gov (United States)

    Wyman, Ian W; Macartney, Donal H

    2009-11-06

    Pseudorotaxanes may be assembled in aqueous solution using dicationic acetylcholinesterase inhibitors, such as succinylcholine, BW284c51, and alpha,omega-bis(trialkylammonium)alkane dications (or their phosphonium analogues), as bolaform axles and cucurbit[7]uril (CB[7]) as the wheel. With the exceptions of the shorter [(CH(3))(3)N(CH(2))(n)N(CH(3))(3)](2+) (n = 6, 8) dications, the addition of a second CB[7] results in the translocation of the first CB[7], such that the hydrophobic -NR(3)(+) and -PR(3)(+) end groups (R = Me or Et) are located in the cavities of the wheels, while the central portion of the axles extend through the CB[7] portals into the bulk solvent. In the case of the [Quin(CH(2))(10)Quin](2+) (Quin = quinuclidinium) dication, the CB[7] host(s) resides only on the quinuclidinium end group(s). The 1:1 host-guest stability constants range from 8 x 10(6) to 3 x 10(10) M(-1) and are dependent on both the nature of the end group as well as the length and hydrophobicity of the central linker. The magnitude of the stability constants for the 2:1 complexes closely follow the trend observed previously for CB[7] binding with the NR(4)(+) and PR(4)(+) cations.

  13. Macrocyclic cavitands cucurbit[n]urils: prospects for application in biochemistry, medicine and nanotechnology

    Science.gov (United States)

    Gerasko, O. A.; Kovalenko, E. A.; Fedin, V. P.

    2016-08-01

    The prospects of using the organic macrocyclic cavitands cucurbit[n]urils (CB[n]) and their derivatives in biochemistry, medicine and nanotechnology are considered. A combination of CB[n] characteristics, such as a rigid highly symmetrical structure, polarized hydrophilic portals, a rather large intramolecular hydrophobic cavity, as well as high resistance to thermolysis and corrosive media and low toxicity, account for a wide range of unique opportunities for the deliberate design of new functional materials, which may find application in various areas of modern chemistry and new technologies. Inclusion compounds of CB[n] with biologically active molecules demonstrate a high potential for the design of a new generation of prolonged action pharmaceuticals. The review presents the prospects for the application of CB[n] to manufacture unique materials, such as CB[n]-containing vesicles, films and surfaces, suitable for immobilization of various molecules and nanoparticles on their surface and for the separation of complex mixtures. Potential applications of CB[n]-modified electrodes and hydrogels are analyzed, and the use of CB[n] in proton-conducting materials and materials for the gas sorption and separation are discussed. The bibliography includes 164 references.

  14. Spectroscopy and Dynamics of Cryptolepine in the Nanocavity of Cucurbit[7]uril and DNA.

    Science.gov (United States)

    Koninti, Raj Kumar; Sappati, Subrahmanyam; Satpathi, Sagar; Gavvala, Krishna; Hazra, Partha

    2016-02-16

    Herein, we explored the photophysical properties of the antimalarial, anticancer drug cryptolepine (CRYP) in the presence of the macrocyclic host cucurbit[7]uril (CB7) and DNA with the help of steady-state and time-resolved fluorescence techniques. Ground-state and excited-state calculations based on density functional theory were also performed to obtain insight into the shape, electron density distribution, and energetics of the molecular orbitals of CRYP. CRYP exists in two forms depending on the pH of the medium, namely, a cationic (charge transfer) form and a neutral form, which emit at λ=540 and 420 nm, respectively. In a buffer solution of pH 7, the drug exists in the cationic form, and upon encapsulation with CB7, it exhibits a huge enhancement in fluorescence intensity due to a decrement in nonradiative decay pathways of the emitting cryptolepine species. Furthermore, docking and quantum chemical calculations were employed to decipher the molecular orientation of the drug in the inclusion complex. Studies with natural DNA indicate that CRYP molecules intercalate into DNA, which leads to a huge quenching of the fluorescence of CRYP. Keeping this in mind, we studied the DNA-assisted release of CRYP molecules from the nanocavity of CB7. Strikingly, DNA alone could not remove the drug from the nanocavity of CB7. However, an external stimulus such as acetylcholine chloride was able to displace CRYP from the nanocavity, and subsequently, the displaced drug could bind to DNA.

  15. Knockdown of MLO genes reduces susceptibility to powdery mildew in grapevine

    NARCIS (Netherlands)

    Pessina, Stefano; Lenzi, Luisa; Perazzolli, Michele; Campa, Manuela; Costa, Dalla Lorenza; Urso, Simona; Valè, Giampiero; Salamini, Francesco; Velasco, Riccardo; Malnoy, Mickael

    2016-01-01

    Erysiphe necator is the causal agent of powdery mildew (PM), one of the most destructive diseases of grapevine. PM is controlled by sulfur-based and synthetic fungicides, which every year are dispersed into the environment. This is why PM-resistant varieties should become a priority for sustainable

  16. Suppression of cucumber powdery mildew by UV-B is affected by background light quality

    Science.gov (United States)

    Brief (5-10 min) exposure to UV-B radiation (280-300 nm) suppressed powdery mildew (Podosphaera xanthii) on Cucumis sativus. The effect was enhanced by red light (600-660 nm), but offset by blue light (420-500 nm) and UV-A (300-420 nm). Compared to untreated controls, 2 h red light from specific lig...

  17. Quantitative Analysis of the Early Powdery Mildew Infection Stages on Resistant Barley Genotypes

    DEFF Research Database (Denmark)

    Andersen, J. B.; Torp, J.

    1986-01-01

    A classification system was developed, that allowed quantification of the leaf surface development of the barley powdery mildew fungus on barley. An experiment with Manchuria and Pallas as susceptible controls and 4 resistance gene each represented by three lines with different gene backgrounds s...

  18. Strategies for durable resistance to the grapevine powdery mildew fungus, Erysiphe necator

    Science.gov (United States)

    Nearly all cultivars of Vitis vinifera are highly susceptible to the grapevine powdery mildew fungus, Erysiphe necator. Grape breeders around the world are working to introgress resistance from wild Vitis. Of the widely-used introgressions, most involve dominant, race-specific resistance phenotype...

  19. Powdery mildew suppresses herbivore-induced plant volatiles and interferes with parasitoid attraction in Brassica rapa

    Science.gov (United States)

    The co-occurrence of different antagonists on a plant can greatly affect infochemicals with ecological consequences for higher trophic levels. Here we investigated how the presence of a plant pathogen, the powdery mildew Erysiphe cruciferarum, on Brassica rapa affects 1) plant volatiles emitted in r...

  20. Evaluation of watermelon varieties for tolerance to powdery mildew and Phytophthora fruit rot, 2014

    Science.gov (United States)

    This experiment was conducted at the U.S. Vegetable Laboratory farm in Charleston, SC. The soil was Yonges loamy fine sand. This study was undertaken to determine the performance of seeded and seedless commercial watermelon varieties for tolerance to powdery mildew (PM) and Phytophthora fruit rot as...

  1. Effect of soil heating, severity of powdery mildew and nitrogen fertilization on yield of winter wheat

    Energy Technology Data Exchange (ETDEWEB)

    Buschhaus, H.; Werning, L.

    1981-01-01

    Field studies were conducted to determine the effect of different levels of nitrogen and severity of powdery mildew on yield of winter wheat grown in soil heated with waste heat from power plants. Soil heating reduced yield depending on efficiency of mildew control and nitrogen level from 12 to 37%. Disease severity showed a linear increase with intensity of heating corresponding with a decrease in yield reduction. In the non-heated plot, 0.8% of the flag leaves were diseases. Increase soil temperatures by 2-3/sup 0/C caused a 2% rise in mildew severity and at 5-6/sup 0/C 3%, respectively. Control of powdery mildew increased yield on the unheated plot about 5,2 dt/ha, on the moderately heated about 8,7 dt/ha and on the plots with highest temperature about 11,1 dt/ha over that of untreated plots. Nitrogen fertilizers increased yield on non-heated plots, in heated plots with diseased plants, only. Nitrogen did not increases yield of healthy plants on heated plots.

  2. Ozone and sulphur dioxide effects on the lilac powdery mildew fungus

    Energy Technology Data Exchange (ETDEWEB)

    Hibben, C.R.; Taylor, M.P.

    1975-01-01

    Colonisation of lilac (Syringa vulgaris) by the powdery mildew fungus (Microsphaera alni) is often sparse in sites exposed to urban air pollutants. The influence of ozone(O/sub 3/) and sulphur dioxide (SO/sub 2/) on conidial germination and the establishment of infection by M. alni was studied. Although tolerant of O/sub 3/, mildew infection was reduced by acute and chronic doses of SO/sub 2/. Conidial germination and the appressorium phase were the stages most sensitive to SO/sub 2/. Infection was unimpeded on leaves previously fumigated, thus confirming that these reactions were due more to the fungicidal, rather than the phytotoxic, properties of the pollutant. There was no synergism between the two gases that lowered the threshold of toxicity to conidia. A member of the Fungi Imperfecti, Hyalodendron album, sporulated on mildew colonies on lilac leaves. It was antagonistic to the mildew by reducing both conidial germination and the formation of appressoria. Conidia of H. album were more sensitive to O/sub 3/ and SO/sub 2/ than M. alni. These results suggest that the role of nonpathogenic microbial epiphytes should be considered when assessing the full impact of air pollutants on obligate parasites, and possibly on other foliar pathogens.

  3. Exogenous trehalose induces defenses in wheat before and during a biotic stress caused by powdery mildew.

    Science.gov (United States)

    Tayeh, Christine; Randoux, Béatrice; Vincent, Dorothée; Bourdon, Natacha; Reignault, Philippe

    2014-03-01

    Powdery mildew would be one of the most damaging wheat diseases without the extensive use of conventional fungicides. Some of the alternative control strategies currently emerging are based on the use of resistance inducers. The disacharride trehalose (TR) is classically described as an inducer of defenses in plants to abiotic stress. In this work, the elicitor or priming effect of TR was investigated in wheat both before and during a compatible wheat-powdery mildew interaction through molecular, biochemical, and cytological approaches. In noninoculated conditions, TR elicited the expression of genes encoding chitinase (chi, chi1, and chi4 precursor), pathogenesis-related protein 1, as well as oxalate oxidase (oxo). Moreover, lipid metabolism was shown to be altered by TR spraying via the upregulation of lipoxygenase (lox) and lipid-transfer protein (ltp)-encoding gene expression. On the other hand, the protection conferred by TR to wheat against powdery mildew is associated with the induction of two specific defense markers. Indeed, in infectious conditions following TR spraying, upregulations of chi4 precursor and lox gene expression as well as an induction of the LOX activity were observed. These results are also discussed with regard to the impact of TR on the fungal infectious process, which was shown to be stopped at the appressorial germ tube stage. Our findings strongly suggest that TR is a true inducer of wheat defense and resistance, at least toward powdery mildew.

  4. Functional Analysis of Barley Powdery Mildew Effector Candidates and Identification of their Barley Targets

    DEFF Research Database (Denmark)

    Ahmed, Ali Abdurehim

    The genome of barley powdery mildew fungus (Blumeria graminis f. sp. hordei, Bgh) encodes around 500 Candidate Secreted Effector Proteins (CSEPs), which are believed to be delivered to the barley cells either to interfere with plant defence and/or promote nutrient uptake. So far, little is known...

  5. Meta-analysis reveals a critical period for management of powdery mildew on Hop cones

    Science.gov (United States)

    Results of 28 field trials conducted over a 12-year period investigating management of hop powdery mildew caused by Podosphaera macularis were quantitatively summarized by meta-analysis to compare product efficacy and use patterns by mode of action as defined by Fungicide Resistance Action Committe...

  6. Adaptation to partial resistance to powdery mildew in the hop cultivar Cascade by Podosphaera macularis

    Science.gov (United States)

    The hop cultivar Cascade has been grown in the Pacific Northwestern U.S. with minimal input for management of powdery mildew (Podosphaera macularis) for nearly 20 years due to the putatively quantitative resistance in this cultivar. While partial resistance is generally thought to be more durable th...

  7. Registration of ‘Wyandot-14’ soybean with resistance to soybean aphid and powdery mildew

    Science.gov (United States)

    ‘Wyandot-14’ soybean [Glycine max (L.) Merr.] with resistance to soybean aphid biotypes 1 and 2 and resistance to powdery mildew was jointly released by the USDA-Agricultural Research Service and The Ohio Agricultural Research and Development Center (OARDC) as a late maturity group (MG) II (2.9) foo...

  8. Quantitative trait loci associated with resistance to powdery mildew in cornus florida

    Science.gov (United States)

    Powdery mildew of flowering dogwood (Cornus florida) caused by Erysiphe pulchra is one of the most destructive diseases in nursery production of flowering dogwood throughout the southeastern U.S. Since the mid-1990s, efforts to breed for resistance to the disease have been undertaken, but to-date on...

  9. Editorial: First report of powdery mildew (Oidium sp.) on Pincushion flowers (Scabiosa columbaria) in New York

    NARCIS (Netherlands)

    Jankovics, T.; Kiss, L.; Niks, R.E.; Daughtrey, M.L.

    2009-01-01

    Scabiosa columbaria (Dipsacaceae) is a popular perennial ornamental in the United States. It is native to Europe and was introduced to North America by nursery trade only recently. In the spring of 2006, symptoms of powdery mildew infection were observed on overwintered plants of S. columbaria cv.

  10. Transcriptional, microscopic and macroscopic investigations into monogenic and polygenic interactions of tomato and powdery mildew

    NARCIS (Netherlands)

    Li Chengwei,

    2005-01-01

    Powdery mildew ( Oidium neolycopersici) is a worldwide obligate fungal disease of tomato ( Solanum lycopersicum ). Six monogenic Ol genes and three major QTLs were identified and mapped on tomato genome. In this thesis, the mechanisms of both compatible and incompatible interactions of tomato and O.

  11. Morphological and phylogenetic comparisons amongst powdery mildews on Catalpa in the UK.

    Science.gov (United States)

    Cook, Roger T A; Henricot, Béatrice; Henrici, Alick; Beales, Paul

    2006-06-01

    Three species of powdery mildew, Erysiphe elevata, E. catalpae, and Neoerysiphe galeopsidis were identified on Catalpa species in England in 2004. A new disease record, N. galeopsidis was the first Catalpa mildew to appear (in June), but it was later out-competed by E. elevata that caused the most serious damage. Both mildews also attacked C. speciosa, C. xerubescens and a new host, xChitalpa tashkentensis, a Chilopsis xCatalpa hybrid. No powdery mildew was detected on C. bungei, C. ovata, or C. fargesii. Identifications of the pathogens using morphological data were fully supported by DNA analysis yielding characteristic rDNA ITS sequences. The sequences placed E. catalpae within the E. aquilegiae clade. The sequences for E. elevata from southern England and France closely matched those from Hungary and North America, confirming the recent spread of this pathogen from the USA. It eventually overran N. galeopsidis and its sudden appearance in the UK could be due to greater aggressiveness and to the production of more ascomata especially during autumns with delayed leaf fall as in 2001. A further species, Oidium hiratae (i.e. Podosphaera sp.), though described from a 1978 UK collection on C. bignonioides, was not detected in the field.

  12. Mapping of QTL for resistance to powdery mildew and resistance gene analogues in perennial ryegrass

    DEFF Research Database (Denmark)

    Schejbel, B; Jensen, L B; Asp, T;

    2008-01-01

    The objective of this study was to map resistance gene analogues (RGA) and quantitative trait loci (QTL) for powdery mildew resistance in perennial ryegrass (Lolium perenne L.). The mapping population consisted of 184 F2 genotypes produced from a cross between one genotype of a synthetic perennial...

  13. Identification of genes affecting the response of tomato and Arabidopsis upon powdery mildew infection

    NARCIS (Netherlands)

    Gao, D.

    2014-01-01

      Many plant species are hosts of powdery mildew fungi, including Arabidopsis and economically important crops such as wheat, barley and tomato. Resistance has been explored using induced mutagenesis and natural variation in the plant species. The isolated genes encompass loss-of-function susc

  14. Golovinomyces spadaceus causing powdery mildew on Coreopsis hybrid 'Full Moon' (Heliantheae, Asteraceae) in Washington State

    Science.gov (United States)

    Symptoms of powdery mildew were observed on a Coreopsis cultivar in the Horticulture and Landscape Architecture Garden on the Washington State University campus, Pullman, Whitman County, Washington. White to off-white sporulating mycelial areas were ~5mm in diam to confluent and confined to adaxial...

  15. Susceptibility pays off: insights into the mlo-based powdery mildew resistance

    NARCIS (Netherlands)

    Appiano, Michela

    2016-01-01

    Powdery mildew (PM) is a worldwide-occurring plant disease caused by ascomycete fungi of the order Erysiphales. A conspicuous number of plant species are susceptible to this disease, the occurrence of which is increasing due to the influence of climate change. Symptoms are easy to recognize by the p

  16. Potassium Bicarbonate as a Potential Sulphur Substitute in Protected Organic Cropping

    OpenAIRE

    Koller, Martin

    2011-01-01

    Powdery mildew attacks several important crops in greenhouses (e.g. tomatoes, cucumbers). Compared to other airborne pathogens, such as downy mildews (e.g. Pseudoperonospora cubensis or Phytophthora infestans) or Botrytis, the damage is often not very severe. However, an effective control of powdery mildew with organic fungicides gives the possibility to optimize climate conditions to also prevent downy mildews and gray mold. Sulphur, a well established fungicide, is rated as slightly to very...

  17. Assessment of Lipid Transfer Protein (LTP1) Gene in Wheat Powdery Mildew Resistance

    Institute of Scientific and Technical Information of China (English)

    LI Ai-li; MENG Cheng-sheng; ZHOU Rong-hua; MA Zhi-ying; JIA Ji-zeng

    2006-01-01

    This study is to investigate the role of lipid transfer protein (LTP1) gene of wheat (Triticum aestivum L.) in powdery mildew (Blumeria graminis f. sp. tritici, Bgt) resistance. A pair of primers based on the full length cDNA of wheat LTP1was used for amplifying the coding regions of LTP in hexaploid (AABBDD) wheat and its diploid donors T. urartu (AA),Ae. speltoides ssp speltoide (SS) and Ae. tauchii ssp strangulate (DD). LTP1 and LTP2 of wheat were isolated from the tested two hexaploid (ABD) materials: powdery mildew resistance near isogenic line (NIL) Mardler/7 x B ainong 3217 and its susceptible parent Bainong 3217 at the same time, while only one kind of LTP gene was found in the tested three diploid materials respectively by using the above PCR primer pairs. Two peaks of the expression of LTP1 and LTP2 induced by powdery mildew were observed [one occurred at 3 h after inoculation (hai); the other occurred at 10 hai] in resistant NIL Mardler/7 x Bainong3217 in comparison with a steady transcript level of LTP1 and LTP2 in susceptible Bainong3217.Transient over-expression result showed that LTP1 reduced the penetration efficiency (PE) of powdery mildew in susceptible cultivar by about 28.3%. This result indicated an obvious effectiveness of LTP1 in powdery mildew resistance. Expression analysis also showed that LTP1 and LTP2 of wheat are generally involved in salt/drought, but not in low temperature stress early responses.

  18. Elevated early callose deposition results in complete penetration resistance to powdery mildew in Arabidopsis.

    Science.gov (United States)

    Ellinger, Dorothea; Naumann, Marcel; Falter, Christian; Zwikowics, Claudia; Jamrow, Torsten; Manisseri, Chithra; Somerville, Shauna C; Voigt, Christian A

    2013-03-01

    A common response by plants to fungal attack is deposition of callose, a (1,3)-β-glucan polymer, in the form of cell wall thickenings called papillae, at site of wall penetration. While it has been generally believed that the papillae provide a structural barrier to slow fungal penetration, this idea has been challenged in recent studies of Arabidopsis (Arabidopsis thaliana), where fungal resistance was found to be independent of callose deposition. To the contrary, we show that callose can strongly support penetration resistance when deposited in elevated amounts at early time points of infection. We generated transgenic Arabidopsis lines that express POWDERY MILDEW RESISTANT4 (PMR4), which encodes a stress-induced callose synthase, under the control of the constitutive 35S promoter. In these lines, we detected callose synthase activity that was four times higher than that in wild-type plants 6 h post inoculation with the virulent powdery mildew Golovinomyces cichoracearum. The callose synthase activity was correlated with enlarged callose deposits and the focal accumulation of green fluorescent protein-tagged PMR4 at sites of attempted fungal penetration. We observed similar results from infection studies with the nonadapted powdery mildew Blumeria graminis f. sp. hordei. Haustoria formation was prevented in resistant transgenic lines during both types of powdery mildew infection, and neither the salicylic acid-dependent nor jasmonate-dependent pathways were induced. We present a schematic model that highlights the differences in callose deposition between the resistant transgenic lines and the susceptible wild-type plants during compatible and incompatible interactions between Arabidopsis and powdery mildew.

  19. Sequence and phylogenetic analyses of novel totivirus-like double-stranded RNAs from field-collected powdery mildew fungi.

    Science.gov (United States)

    Kondo, Hideki; Hisano, Sakae; Chiba, Sotaro; Maruyama, Kazuyuki; Andika, Ida Bagus; Toyoda, Kazuhiro; Fujimori, Fumihiro; Suzuki, Nobuhiro

    2016-02-02

    The identification of mycoviruses contributes greatly to understanding of the diversity and evolutionary aspects of viruses. Powdery mildew fungi are important and widely studied obligate phytopathogenic agents, but there has been no report on mycoviruses infecting these fungi. In this study, we used a deep sequencing approach to analyze the double-stranded RNA (dsRNA) segments isolated from field-collected samples of powdery mildew fungus-infected red clover plants in Japan. Database searches identified the presence of at least ten totivirus (genus Totivirus)-like sequences, termed red clover powdery mildew-associated totiviruses (RPaTVs). The majority of these sequences shared moderate amino acid sequence identity with each other (powdery mildew fungus populations infecting red clover plants in the field.

  20. Complexation of Eu(III) with cucurbit[n]uril, n = 5 and 7: a thermodynamic and structural study.

    Science.gov (United States)

    Rawat, Neetika; Kar, Aishwarya; Bhattacharyya, A; Rao, Ankita; Nayak, S K; Nayak, C; Jha, S N; Bhattacharyya, D; Tomar, B S

    2015-03-07

    Cucurbit[n]urils (CBn) are a new class of macrocyclic cage compounds capable of binding organic and inorganic species, owing to their unique pumpkin like structure comprising of both a hydrophobic cavity and a hydrophilic portal. The thermodynamics of the complexation of Eu(III) with CBn of a different cavity size viz. cucurbit[5]uril (CB5) and cucurbit[7]uril (CB7) has been studied by UV-Vis spectroscopy and calorimetry at 25 °C whereas the structure of the complexes was investigated using time resolved fluorescence spectroscopy (TRFS) and extended X-ray absorption fine structure spectroscopy (EXAFS) in a formic acid-water mixture (50 wt%). This is the first report on the structural investigation of Eu-CBn complexes in solution. The thermodynamic data (ΔG, ΔH and ΔS) for Eu(III) complexation with CBn reveal the formation of a 1 : 1 complex with CB5, while both 1 : 1 and 1 : 2 complexes are observed with CB7. The signatures of these species are observed in ESI-MS measurements, which corroborates with the species postulated in thermodynamic studies. The complexation reactions are found to be driven by ΔS as ΔH is either small negative or positive indicating the formation of inner sphere complexes, which is in line with TRFS and EXAFS results. These studies show that Eu(III) caps one of the CB5 portals by binding with all the carbonyl groups in the 1 : 1 Eu-CB5 complex, whereas in the 1 : 1 Eu-CB7 complex, Eu(III) interacts with only a few of the carbonyl groups of CB7. The computational studies (DFT calculations) on Eu-CB5 and Eu-CB7 complexes further support the experimental data.

  1. In vivo detection of cucurbit[6]uril, a hyperpolarized xenon contrast agent for a xenon magnetic resonance imaging biosensor

    Science.gov (United States)

    Hane, Francis T.; Li, Tao; Smylie, Peter; Pellizzari, Raiili M.; Plata, Jennifer A.; DeBoef, Brenton; Albert, Mitchell S.

    2017-01-01

    The Hyperpolarized gas Chemical Exchange Saturation Transfer (HyperCEST) Magnetic Resonance (MR) technique has the potential to increase the sensitivity of a hyperpolarized xenon-129 MRI contrast agent. Signal enhancement is accomplished by selectively depolarizing the xenon within a cage molecule which, upon exchange, reduces the signal in the dissolved phase pool. Herein we demonstrate the in vivo detection of the cucurbit[6]uril (CB6) contrast agent within the vasculature of a living rat. Our work may be used as a stepping stone towards using the HyperCEST technique as a molecular imaging modality. PMID:28106110

  2. Natural Occurrence of Tomato leaf curl New Delhi virus in Iranian Cucurbit Crops

    Directory of Open Access Journals (Sweden)

    Sara Yazdani-Khameneh

    2016-06-01

    Full Text Available The main areas for field-grown vegetable production in Iran were surveyed during the years of 2012–2014 to determine the occurrence of begomoviruses infecting these crops. A total of 787 leaf samples were collected from vegetables and some other host plants showing virus-like symptoms and tested by an enzyme-linked immunosorbent assay (ELISA using polyclonal antibodies produced against Tomato yellow leaf curl virus (TYLCV. According to the ELISA results, 81 samples (10.3% positively reacted with the virus antibodies. Begomovirus infections were confirmed by polymerase chain reaction (PCR using previously described TYLCV-specific primer pair TYLCV-Sar/TYLCV-Isr or universal primer pair Begomo-F/Begomo-R. The PCR tests using the primer pair TYLCV-Sar/TYLCV-Isr resulted in the amplification of the expected fragments of ca. 0.67-kb in size for ELISA-positive samples tested from alfalfa, pepper, spinach and tomato plants, confirming the presence of TYLCV. For one melon sample, having a week reaction in ELISA and no reaction in PCR using TYLCV-specific primers, the PCR reaction using the primer pair Begomo-F/Begomo-R resulted in the amplification fragments of the expected size of ca. 2.8 kb. The nucleotide sequences of the DNA amplicons derived from the isolate, Kz-Me198, were determined and compared with other sequences available in GenBank. BLASTN analysis confirmed the begomovirus infection of the sample and showed 99% identities with Tomato leaf curl New Delhi virus (ToLCNDV; phylogenetic analysis supported the results of the database searches. This study reports the natural occurrence of TYLCV in different hosts in Iran. Our results also reveal the emergence of ToLCNDV in Iranian cucurbit crops.

  3. SYNTHESIS AND PROPERTIES OF COPOLYMERS CONTAINING CUCURBIT[6]URIL-BASED PSEUDOROTAXANE STRUCTURE

    Institute of Scientific and Technical Information of China (English)

    Qiang Ma; Hui Yang; Kimoon Kim; Ye-bang Tan

    2012-01-01

    Novel copolymers based on acrylamide (AM) and complex pseudorotaxane monomer N'-(3-vinylbenzyl)-l,4-diaminobutane dihydrochloride with cucurbit[6]uril (CB[6]) (3VBCB) were prepared via free-radical polymerization in aqueous solution,and characterized by 1H-NMR,FT-IR,elemental analysis and static light scattering.The compositions of the copolymers (PAM3VBCB) with pseudorotaxane units were determined by 1H-NMR and elemental analysis.Thermal properties of the copolymers were studied by TGA,and the effects of the copolymer concentration and pH on the average hydrodynamic radius (Rh) of the copolymer molecules were studied by dynamic light scattering (DLS).The experiment data show that CB[6] beads are localized on 1,4-diaminobutane units in side chains of the copolymers.TGA results show that thermal stability of the copolymer increases with increasing the content of pseudorotaxane unit because of the enhanced rigidity and the bulky steric hindrance of 3VBCB in side chains of PAM3VBCB.DLS data show that the average hydrodynamic radius of copolymer molecules increases with the increase in the copolymer concentration,and both the pH and electrical conductivity of PAM3VBCB solutions demonstrate an acute change with addition of NaOH because of CB[6]dethreading from the side chains of PAM3VBCB.CB[6] threading and dethreading of PAM3VBCB could be controlled by addition of BaCl2 and Na2SO4.

  4. Differential Life History Trait Associations of Aphids with Nonpersistent Viruses in Cucurbits.

    Science.gov (United States)

    Angelella, G M; Egel, D S; Holland, J D; Nemacheck, J A; Williams, C E; Kaplan, I

    2015-06-01

    The diversity of vectors and fleeting nature of virus acquisition and transmission renders nonpersistent viruses a challenge to manage. We assessed the importance of noncolonizing versus colonizing vectors with a 2-yr survey of aphids and nonpersistent viruses on commercial pumpkin farms. We quantified aphid alightment using pan traps, while testing leaf samples with multiplex RT-PCR targeting cucumber mosaic virus (CMV), zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV), and papaya ringspot virus (PRSV). Overall, we identified 53 aphid species (3,899 individuals), from which the melon aphid, Aphis gossypii Glover, a pumpkin-colonizing species, predominated (76 and 37% of samples in 2010 and 2011, respectively). CMV and ZYMV were not detected, but WMV and PRSV were prevalent, both regionally (WMV: 28/29 fields, PRSV: 21/29 fields) and within fields (infection rates = 69 and 55% for WMV in 2010 and 2011; 28 and 25% for PRSV in 2010 and 2011). However, early-season samples showed extremely low infection levels, suggesting cucurbit viruses are not seed-transmitted and implicating aphid activity as a causal factor driving virus spread. Interestingly, neither noncolonizer and colonizer alightment nor total aphid alightment were good predictors of virus presence, but community analyses revealed species-specific relationships. For example, cowpea aphid (Aphis craccivora Koch) and spotted alfalfa aphid (Therioaphis trifolii Monell f. maculata) were associated with PRSV infection, whereas the oleander aphid (Aphis nerii Bover de Fonscolombe) was associated with WMV spread within fields. These outcomes highlight the need for tailored management plans targeting key vectors of nonpersistent viruses in agricultural systems.

  5. Genetic and virulence variability among Erwinia tracheiphila strains recovered from different cucurbit hosts.

    Science.gov (United States)

    Rojas, E Saalau; Dixon, P M; Batzer, J C; Gleason, M L

    2013-09-01

    The causal agent of cucurbit bacterial wilt, Erwinia tracheiphila, has a wide host range in the family Cucurbitaceae, including economically important crops such as muskmelon (Cucumis melo), cucumber (C. sativus), and squash (Cucurbita spp.). Genetic variability of 69 E. tracheiphila strains was investigated by repetitive-element polymerase chain reaction (rep-PCR) using BOXA1R and ERIC1-2 primers. Fingerprint profiles revealed significant variability associated with crop host; strains isolated from Cucumis spp. were clearly distinguishable from Cucurbita spp.-isolated strains regardless of geographic origin. Twelve E. tracheiphila strains isolated from muskmelon, cucumber, or summer squash were inoculated onto muskmelon and summer squash seedlings, followed by incubation in a growth chamber. Wilt symptoms were assessed over 3 weeks, strains were reisolated, and rep-PCR profiles were compared with the inoculated strains. Wilting occurred significantly faster when seedlings were inoculated with strains that originated from the same crop host genus (P<0.001). In the first run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon seedlings at a median of 7.8 and 5.6 days after inoculation (dai), respectively. Summer squash seedlings wilted 18.0, 15.7, and 5.7 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. In a second run of the experiment, cucumber and muskmelon strains caused wilting on muskmelon at 7.0 and 6.9 dai, respectively, whereas summer squash seedlings wilted at 23.6, 29.0 and 9.0 dai when inoculated with muskmelon-, cucumber-, and squash-origin strains, respectively. Our results provide the first evidence of genetic diversity within E. tracheiphila and suggest that strain specificity is associated with plant host. This advance is a first step toward understanding the genetic and population structure of E. tracheiphila.

  6. U-shaped conformation of alkyl chains bound to a synthetic receptor cucurbit[8]uril.

    Science.gov (United States)

    Ko, Young Ho; Kim, Youngkook; Kim, Hyunuk; Kim, Kimoon

    2011-02-01

    The behavior of a series of alkanes bound to the molecular host cucurbit[8]uril (CB[8]) has been systematically studied by 2D (1)H NMR spectroscopy and isothermal titration calorimetry (ITC). CB[8] and alkyltrimethylammonium (C(m) TA(+), (CH(3))(3)N(+)C(m)H(2m+1), m=6-16) form 1:1 host-guest complexes with a high binding constant (K≈10(6) m(-1)). The shortest hexyl chain of C(6)TA(+) can be fully encapsulated in an extended conformation inside the CB[8] cavity, which is driven by both enthalpy and entropy. However, for the longer aliphatic chains, C(8)-C(16), the long alkyl tails take a U-shaped conformation inside the cavity, and their complexation is dominantly or almost exclusively enthalpy-driven, owing to the increased van der Waals contact between the folded aliphatic chain and the inner wall of the host cavity. As the chain length increases from C(8) to C(16), the ammonium head group of the guests moves away from the portal of CB[8] while the long aliphatic tails maintain the U-shaped conformation inside the cavity. The complexation of C(m)TA(+) with CB[8] follows the enthalpy-entropy compensation rule commonly observed in molecular recognition systems. For example, among the guest molecules, C(12)TA(+) shows the highest enthalpic gain (most favorable), owing to the large van der Waals contact between the guest and the host cavity, and at the same time the most unfavorable entropic contribution, owing to the severe conformational restriction of the U-shaped alkyl chain inside the host. The enthalpy-entropy compensation plot for the complexation suggests large conformational changes of the long alkyl chains and extensive dehydration associated with the inclusion complex formation.

  7. Examination of cucurbit[7]uril and its host-guest complexes by diffusion nuclear magnetic resonance.

    Science.gov (United States)

    Wheate, Nial J; Kumar, P G Anil; Torres, Allan M; Aldrich-Wright, Janice R; Price, William S

    2008-02-28

    The self-diffusion of cucurbit[7]uril (CB[7]) and its host-guest complexes in D2O has been examined using pulsed gradient spin-echo nuclear magnetic resonance spectroscopy. CB[7] diffuses freely at a concentration of 2 mM with a diffusion coefficient (D) of 3.07 x 10(-10) m(2) s(-1). At saturation (3.7 mM), CB[7] diffuses more slowly (D = 2.82 x 10(-10) m(2) s(-1)) indicating that it partially self-associates. At concentrations between 2 and 200 mM, CsCl has no effect on the diffusion coefficient of CB[7] (1 mM). Conversely, CB[7] (2 mM) significantly affects the diffusion of 133Cs+ (1 mM), decreasing its diffusion coefficient from 1.86 to 0.83 x 10(-9) m(2) s(-1). Similar changes in the rate of diffusion of other alkali earth metal cations are observed upon the addition of CB[7]. The diffusion coefficient of 23Na+ changes from 1.26 to 0.90 x 10(-9) m(2) s(-1) and 7Li+ changes from 3.40 to 3.07 x 10(-9) m(2) s(-1). In most cases, encapsulation of a variety of inorganic and organic guests within CB[7] decreases their rates of diffusion in D2O. For instance, the diffusion coefficient of the dinuclear platinum complex trans-[[PtCl(NH3)2}2mu-dpzm](2+) (where dpzm is 4,4'-dipyrazolylmethane) decreases from 4.88 to 2.95 x 10(-10) m(2) s(-1) upon encapsulation with an equimolar concentration of CB[7].

  8. Selección de rizobacterias por su antagonismo frente a microorganismos patógenos de cucurbitáceas /Screening of rhizobacteria for their antagonism against microbial pathogens of cucurbits.

    Directory of Open Access Journals (Sweden)

    Gilda Jiménez Montejo

    2014-04-01

    Full Text Available Resumen:El desarrollo de inoculantes microbianos a partir de aislamientos de rizobacterias con potencial para el control biológico de enfermedades de los cultivos agrícolas requiere de una rigurosa selección. Se obtuvieron aislamientos bacterianos de la rizosfera de papa (Solanum tuberosum L. y de maíz (Zea mays L. y de semillas de frijol (Phaseolus vulgaris L.. Las colonias que mostraron in vitro halos de inhibición de los patógenos de cucurbitáceas: Xanthomonas cucurbitae, Acidovorax avenae subsp. citrull y Fusarium oxysporum, se seleccionaron como antagonistas. A partir de las características morfológicas, fisiológicas y bioquímicas las cepas antagonistas F16/95 y Xph se identificaron con la especie Bacillus subtilis y la cepa 14A como Pseudomonas putida. Las pruebas presuntivas de producción de antibiocinas in vitro sugirieron modos de acción de las rizobacterias relacionados con antibiosis y competencia por el hierro mediante la producción de sideróforos. Los resultados indicaron el potencial de las cepas de rizobacterias antagonistas Bacillus subtilis (F16/95, Xph y Pesudomonas putida 14A para el control biológico de enfermedades de las cucurbitáceas./Abstract:

  9. Recognition of Cucumber Downy Mildew Disease Based on Visual Saliency Map%基于视觉显著性图的黄瓜霜霉病识别方法

    Institute of Scientific and Technical Information of China (English)

    叶海建; 郎睿; 刘成启; 李民赞

    2016-01-01

    为提高黄瓜霜霉病叶部病害机器自动识别的准确性和鲁棒性,提出了一种基于视觉显著性图的黄瓜叶部霜霉病识别方法.首先将图像从RGB色彩空间变换到HSV色彩空间中进行色彩修正,再变换回RGB空间利用R、G、B分量的线性组合生成视觉显著性图,最后通过对生成的视觉显著性图进行阈值分割以识别病害区域.利用从北京市北部郊区日光温室采集到的50幅具有典型霜霉病特征的黄瓜叶片原始图像进行实验,结果表明,该方法能较为准确地从叶部彩色图像中识别出霜霉病病斑区域,平均误分率为6.98%,优于K-means法(11.38%)和OTSU法(15.98%);平均运行时间0.661 4s,少于K-means法的1.424 9 s;运行时间的均方根误差为0.051 5 s,鲁棒性优于K-means硬聚类算法.

  10. Preventive Effect of 20 Plant Extracts against Cucumber Downy Mildew%20种植物提取液对黄瓜霜霉病的预防作用研究

    Institute of Scientific and Technical Information of China (English)

    赵杰; 代光辉; 顾振芳; 陈晓斌; 孙兴全

    2005-01-01

    用叶圆盘生测法测定了20种植物不同组织部位的甲醇提取液对黄瓜霜霉病菌(Pseudoperonospora cubehsis)的抑茵效果,其中水蓼(Polygonum hydropiper L.)全草,合欢(Albizia julibrissin Durazz.)叶和石楠(Photinia serrulata Lindl.)枝的甲醇提取液在离体叶圆盘的防效分别为98.33%,100.00%和100.00%,其它植物提取液均无明显抑茵效果.上述3种植物提取液的室内盆栽试验结果表明,7天后对黄瓜霜霉病的预防效果分别为54.19%,62.00%和78.93%,田间试验的防效则分别为25.57%,27.91%和48.84%.对防效较好的石楠枝甲醇提取物用石油醚、乙酸乙酯、水饱和正丁醇依次进行萃取,并对各萃取物进行叶圆盘测定,结果表明,有效活性成分存在于正丁醇相和水相中;当浓度为30mg·ml-1时,两相萃取物对黄瓜霜霉病的抑制率分别为100.00%和87.87%.

  11. 6种候选杀菌剂对黄瓜霜霉病的防治效果%Control Efficacy of Six Candidate Fungicides against Cucumber Downy Mildew

    Institute of Scientific and Technical Information of China (English)

    乔桂双; 王文桥; 韩秀英; 李淼; 孟润杰; 刘长令; 刘颖超

    2009-01-01

    室内及田间试验结果表明:20%SYP-3399 SC、20%SYP-4155 EC、20%SYP-3343 SC对黄瓜霜霉病的防效较为突出.20%SYP-4155 EC(150 g a.i./hm 2)、20%SYP-3343 SC(150 g a.i./hm2)、20%SYP-3399 SC(900 g a.i./hm2)的防效与25%嘧菌脂SC(100 g a.i./hm2)、72%霜脲氰·代森锰锌WP(1 440 g a.i./hm2)防效相当,高于68%精甲霜灵·代森锰锌WG(675 g a.i./hm2)、25%吡唑醚菌酯EC(100 g a.i./hm2)的防效.3种候选杀菌剂在试验剂最范同内对作物安全.

  12. Characterization of endophytic bacteria from cucurbit fruits with potential benefits to agriculture in melons (Cucumis melo L.).

    Science.gov (United States)

    Glassner, Hanoch; Zchori-Fein, Einat; Compant, Stéphane; Sessitsch, Angela; Katzir, Nurit; Portnoy, Vitaly; Yaron, Sima

    2015-07-01

    Endophytes are microorganisms that mainly colonize vegetative parts, but are also found in reproductive and disseminating organs, and may have beneficial characteristics. To identify microorganisms associated with the agriculturally important family, Cucurbitaceae, endophytes were initially determined in fruits of Cucumis melo Reticulatus Group 'Dulce' by a cultivation-independent approach based on fluorescence in situ hybridization using double labeling of oligonucleotide probes. Alpha-, Beta-, Gammaproteobacteria, Firmicutes and Actinobacteria were localized inside the fruits. Culturable bacteria were further isolated and identified from fruit tissues of 'Dulce', from fruits of other cultivated and wild-field-grown Cucurbitaceae, and from wild fruits growing under natural conditions. Low densities of culturable bacteria were detected in the investigated fruits, especially in four out of the five wild species, regardless of their growing environment. Substantial differences were observed between the wild and cultivated cucurbit taxa in regard to the number of colonized fruits as well as the type of endophytes. Bacillus was the most dominant genus of endophytes colonizing fruits of Cucurbitaceae. The antagonistic effects of isolated endophytes were assessed against cucurbit disease agents in dual-culture assays. Several bacterial isolates exhibited antagonistic properties against the tested plant pathogens. The identified bacteria may be useful for protecting plants not only in the field, but also for post-harvest.

  13. Aniline-containing guests recognized by α,α’,δ,δ’-tetramethyl-cucurbit[6]uril host

    Science.gov (United States)

    Lin, Rui-Lian; Fang, Guo-Sheng; Sun, Wen-Qi; Liu, Jing-Xin

    2016-12-01

    The host-guest complexation of symmetrical α,α’,δ,δ’-tetramethyl-cucurbit[6]uril (TMeQ[6]) and cucurbit[7]uril (Q[7]) with a series of aniline-containing guests has been investigated by various experimental techniques including NMR, ITC, and X-ray crystallography. Experimental results indicate that both TMeQ[6] and Q[7] hosts can encapsulate aniline-containing guests to form stable inclusion complexes. However, the oval cavity of TMeQ[6] is more complementary in size and shape to the aromatic ring of the guests than the spherical cavity of Q[7]. Shielding and deshielding effects of the aromatic ring on guests lead to the remarkable chemical shifts of the TMeQ[6] host protons. The rotational restriction of the guests in the oval cavity of TMeQ[6] results in the large negative values of entropy. The X-ray crystal structure of the 1:1 inclusion complex between TMeQ[6] and N,N‧-diethyl-benzene-1,4-diamine unambiguously reveals that the aromatic ring of the guest resides in the oval cavity of TMeQ[6].

  14. Monitoring and Varietal Screening Cucurbit Fruit Fly, Bactrocera cucurbitae Coquillett (Diptera: Tephritidae on Cucumber in Bhaktapur and Kathmandu, Nepal

    Directory of Open Access Journals (Sweden)

    Ranju Maharjan

    2015-12-01

    Full Text Available Monitoring of cucurbit fruit fly by using four different types of traps was conducted in Sipadole VDC of Bhaktapur district during 2012 to observe the population dynamics. Three different types of fruit flies were recorded, in which the number of B. cucurbitae dominated to other species. Only B. cucurbitae damaged the cucumber, which was trapped 92.68%, 87.05%, 90.61%, and 69.38% in cue-lure, banana pulp bait, sticky traps and fly catcher, respectively. The highest number of fruit flies (167.5 male fruit flies/3traps was recorded in cue-lure trap during the first week of September, which coincided with 85.45% RH and 21.67°C and 25.04°C minimum and maximum temperature, respectively. Positive relation of temperature, relative humidity and fruit fly catches was observed. Thus, cue-lure was the most effective traps for monitoring of fruit fly population. In varietal screening, among the six different varieties of cucumber, i.e. Kathmandu local, Kusle, Kamini, Malini, Kasinda and Mahyco Green Long, they were highly significant difference in yield. Kamini gave the highest marketable fruit 26.66 mt/ha yield and the lowest by Kusle (5.05 mt/ha. All the varieties were affected by cucurbit fruit fly. The highest number of unmarketable fruit set was observed in Kamini (22.29 fruits/plant.

  15. Differential gene expression in individual papilla-resistant and powdery mildew-infected barley epidermal cells

    DEFF Research Database (Denmark)

    Gjetting, T.; Carver, Timothy L. W.; Skøt, Leif

    2004-01-01

    Resistance and susceptibility in barley to the powdery mildew fungus (Blumeria graminis f. sp. hordei) is determined at the single-cell level. Even in genetically compatible interactions, attacked plant epidermal cells defend themselves against attempted fungal penetration by localized responses...... leading to papilla deposition and reinforcement of their cell wall. This conveys a race-nonspecific form of resistance. However, this defense is not complete, and a proportion of penetration attempts succeed in infection. The resultant mixture of infected and uninfected leaf cells makes it impossible...... to relate powdery mildew-induced gene expression in whole leaves or even dissected epidermal tissues to resistance or susceptibility. A method for generating transcript profiles from individual barley epidermal cells was established and proven useful for analyzing resistant and successfully infected cells...

  16. The enhanced callose deposition in barley with ml-o powdery mildew resistance genes

    DEFF Research Database (Denmark)

    Skou, Jens-Peder

    1985-01-01

    Carborundum treatment of barley leaves induced a callose deposition which was detected as diffuse blotches in the epidermal cells of susceptible barleys and as deeply stained tracks along the scratches in barleys with the ml-o powdery mildew resistance gene. Subsequent inoculation with powdery...... mildew resulted in appositions that enlarged inversely to their size in the respective varieties when inoculated without carborundum treatment. Aphids sucking the leaves resulted in rows of callose containing spots along the anticlinal cell walls. The spots were larger in the ml-o mutant than...... in the mother variety. Callose was deposited in connection with the pleiotropic necrotic spotting in barleys with the ml-o gene. Modification of the necrotic spotting by crossing the ml-o gene into other gene backgrounds did not result in any change in the size of appositions upon inoculation with powdery...

  17. Inheritance of resistance to powdery mildew in pea and pathogenesis-related aspects

    Directory of Open Access Journals (Sweden)

    Ricardo Lima dos Santos

    2012-06-01

    Full Text Available The inheritance of resistance to powdery mildew in the pea cultivar MK-10 and some histological aspects of infection were assessed. For the inheritance study, F1, F2, backcrosses and F3 generations of MK-10 crossed with two susceptible populations were evaluated. Histological evaluations included percentage of germinated conidia, percentage of conidia that formed appresoria, percentage of conidia that established colonies, and number of haustoria per colony. Segregation ratios obtained in the resistance inheritance study were compared by Chi-square (ײ test and the histological data were analyzed by Tukey's test at 5% probability. It was concluded that resistance of MK-10 to powdery mildew is due to a pair of recessive alleles since it is expressed in the pre-penetration stage and completed by post-penetration localized cellular death, characteristic of the presence of the pair of recessive alleles er1er1.

  18. The value of powdery mildew resistance in grapes: Evidence from California

    Directory of Open Access Journals (Sweden)

    Kate Binzen Fuller

    2014-12-01

    Full Text Available Powdery mildew (PM is a fungal disease that damages many crops, including grapes. In California, wine, raisin, and table grapes contributed over $3.9 billion to the value of farm production in 2011. Grape varieties with resistance to powdery mildew are currently being developed, using either conventional or transgenic approaches, each of which has associated advantages and disadvantages. PM-resistant varieties of grapes could yield large economic benefits to California grape growers—potentially allowing cost savings as high as $48 million per year in the subset of the industry covered by our analysis (Crimson Seedless table grapes, all raisin grapes, and Central Coast Chardonnay wine grapes, but benefits range widely across the different grape production systems.

  19. Inhibitive Mechanisms of Two Silicon Compounds on Powdery Mildew of Melon

    Institute of Scientific and Technical Information of China (English)

    GUO Yu-rong; LIU Lei; ZHAO Hua; CHEN De-rong; BI Yang

    2005-01-01

    Seedlings of Yujinxiang melon were used to investigate the effect and inhibitive mechanism of sodium silicate and nanosized silicon oxide on powdery mildew. The results showed that the severity of powdery mildew on melon seedlings was lowered significantly by treatment with either of the two silicon compounds, although the effect of sodium silicate was more powerful than silicon oxide. Application of sodium silicate to the seedlings caused significant increases in the activity of peroxidase (POD) and of 3-1,3-glucosidase (GLU), both enzymes are known to be associated with the disease defence systems of plants. SEM-EDX analysis of sodium silicate-treated leaves of the melon seedlings showed an elevated level of silicon deposit at stomata and epidermis. Treatment with nanosized silicon oxide also resulted in a similar increase in silicon deposit, but the treatment did not cause a significant increase in POD activity.

  20. Arabidopsis phospholipase Dδ is involved in basal defense and nonhost resistance to powdery mildew fungi

    DEFF Research Database (Denmark)

    Pinosa, Francesco; Buhot, Nathalie; Kwaaitaal, Mark Adrianus Cornelis J

    2013-01-01

    Plants have evolved a complex array of defensive responses against pathogenic microorganisms. Recognition of microbes initiates signaling cascades that activate plant defenses. The membrane lipid phosphatidic acid, produced by phospholipase D (PLD), has been shown to take part in both abiotic...... and biotic stress signaling. In this study, the involvement of PLD in the interaction between Arabidopsis (Arabidopsis thaliana) and the barley powdery mildew fungus Blumeria graminis f. sp. hordei (Bgh) was investigated. This nonadapted pathogen is normally resisted by a cell wall-based defense, which stops....... In conclusion, we propose that PLD is involved in defense signaling in nonhost resistance against powdery mildew fungi and put PLDδ forward as the main isoform participating in this process....

  1. The enhanced callose deposition in barley with ml-o powdery mildew resistance genes

    DEFF Research Database (Denmark)

    Skou, Jens-Peder

    1985-01-01

    Carborundum treatment of barley leaves induced a callose deposition which was detected as diffuse blotches in the epidermal cells of susceptible barleys and as deeply stained tracks along the scratches in barleys with the ml-o powdery mildew resistance gene. Subsequent inoculation with powdery...... mildew resulted in appositions that enlarged inversely to their size in the respective varieties when inoculated without carborundum treatment. Aphids sucking the leaves resulted in rows of callose containing spots along the anticlinal cell walls. The spots were larger in the ml-o mutant than...... in the mother variety. Callose was deposited in connection with the pleiotropic necrotic spotting in barleys with the ml-o gene. Modification of the necrotic spotting by crossing the ml-o gene into other gene backgrounds did not result in any change in the size of appositions upon inoculation with powdery...

  2. A Japanese powdery mildew isolate with exceptionally large infection efficience on Mlo-resistant barley

    DEFF Research Database (Denmark)

    Lyngkjær, M.F.; Jensen, H.P.; Østergård, Hanne

    1995-01-01

    A Japanese field isolate (Race I) of Erysiphe graminis f,sp. hordei was tested on 17 barley lines carrying the mlo powdery mildew resistance gene. Race I produced many successful infections with infection type larger than or equal to 2 on six lines (M66, MC20, SR1, SR7, Atem and Totem). On the re......A Japanese field isolate (Race I) of Erysiphe graminis f,sp. hordei was tested on 17 barley lines carrying the mlo powdery mildew resistance gene. Race I produced many successful infections with infection type larger than or equal to 2 on six lines (M66, MC20, SR1, SR7, Atem and Totem...

  3. Infestation of transgenic powdery mildew-resistant wheat by naturally occurring insect herbivores under different environmental conditions.

    Directory of Open Access Journals (Sweden)

    Fernando Álvarez-Alfageme

    Full Text Available A concern associated with the growing of genetically modified (GM crops is that they could adversely affect non-target organisms. We assessed the impact of several transgenic powdery mildew-resistant spring wheat lines on insect herbivores. The GM lines carried either the Pm3b gene from hexaploid wheat, which confers race-specific resistance to powdery mildew, or the less specific anti-fungal barley seed chitinase and β-1,3-glucanase. In addition to the non-transformed control lines, several conventional spring wheat varieties and barley and triticale were included for comparison. During two consecutive growing seasons, powdery mildew infection and the abundance of and damage by naturally occurring herbivores were estimated under semi-field conditions in a convertible glasshouse and in the field. Mildew was reduced on the Pm3b-transgenic lines but not on the chitinase/glucanase-expressing lines. Abundance of aphids was negatively correlated with powdery mildew in the convertible glasshouse, with Pm3b wheat plants hosting significantly more aphids than their mildew-susceptible controls. In contrast, aphid densities did not differ between GM plants and their non-transformed controls in the field, probably because of low mildew and aphid pressure at this location. Likewise, the GM wheat lines did not affect the abundance of or damage by the herbivores Oulema melanopus (L. and Chlorops pumilionis Bjerk. Although a previous study has revealed that some of the GM wheat lines show pleiotropic effects under field conditions, their effect on herbivorous insects appears to be low.

  4. Hot pepper (Capsicum chinense, Jacq. inheritance of reaction to powdery mildew

    Directory of Open Access Journals (Sweden)

    Blat Sally Ferreira

    2006-01-01

    Full Text Available The pepper species C. chinense has been considered one of the most important resistance sources to powdery mildew Capsicum spp. However, the inheritance in this species was unknown. The purpose of this work was to study its reaction inheritance. Two powdery mildew resistant parents, 'Pimenta Cheiro' 1 and PI 152225 and two moderately susceptible ones, 'Pimenta Doce' IH-1761 and 'Pimenta Índio', were used to obtain three F1 and their respective F2 generations: 'Pimenta Doce' IH-1761 'Pimenta Cheiro' 1, 'Pimenta Índio' PI 152225 and 'Pimenta Doce' IH-1761 PI 152225. The powdery mildew epidemy was natural using inoculum from a highly-sporulating susceptible pepper host. Powdery mildew host reaction evaluations were carried out during the fruiting stage using a rating system based on disease severity scales varying from 1 (resistant to 5 (highly susceptible. The experimental design was completely randomized. The following genetic parameters were estimated: gene action, heritability coefficient and expected selection gain in the F3 generation. The transgressive segregation in F2 indicated oligogenic inheritance. Results show the presence of additive, dominant, and epistatic gene action. The dominant and epistatic effects detected in crosses presented negative values, tending towards susceptibility. The heritability and selection gain estimates were moderate, with values of 35.5% and 1.7% for 'Pimenta Doce' IH 1761 'Pimenta Cheiro' 1, from 50.4% to 3.5% for 'Pimenta Índio' PI 152225, and 49% and 2.7% for the 'Pimenta Doce' IH 1761 PI 152225 crosses, respectively. These gene action results are favorable for breeding programs and exploration of hybrids.

  5. Multiple Evolutionary Events Involved in Maintaining Homologs of Resistance to Powdery Mildew 8 in Brassica napus

    Science.gov (United States)

    Li, Qin; Li, Jing; Sun, Jin-Long; Ma, Xian-Feng; Wang, Ting-Ting; Berkey, Robert; Yang, Hui; Niu, Ying-Ze; Fan, Jing; Li, Yan; Xiao, Shunyuan; Wang, Wen-Ming

    2016-01-01

    The Resistance to Powdery Mildew 8 (RPW8) locus confers broad-spectrum resistance to powdery mildew in Arabidopsis thaliana. There are four Homologous to RPW8s (BrHRs) in Brassica rapa and three in Brassica oleracea (BoHRs). Brassica napus (Bn) is derived from diploidization of a hybrid between B. rapa and B. oleracea, thus should have seven homologs of RPW8 (BnHRs). It is unclear whether these genes are still maintained or lost in B. napus after diploidization and how they might have been evolved. Here, we reported the identification and sequence polymorphisms of BnHRs from a set of B. napus accessions. Our data indicated that while the BoHR copy from B. oleracea is highly conserved, the BrHR copy from B. rapa is relatively variable in the B. napus genome owing to multiple evolutionary events, such as gene loss, point mutation, insertion, deletion, and intragenic recombination. Given the overall high sequence homology of BnHR genes, it is not surprising that both intragenic recombination between two orthologs and two paralogs were detected in B. napus, which may explain the loss of BoHR genes in some B. napus accessions. When ectopically expressed in Arabidopsis, a C-terminally truncated version of BnHRa and BnHRb, as well as the full length BnHRd fused with YFP at their C-termini could trigger cell death in the absence of pathogens and enhanced resistance to powdery mildew disease. Moreover, subcellular localization analysis showed that both BnHRa-YFP and BnHRb-YFP were mainly localized to the extra-haustorial membrane encasing the haustorium of powdery mildew. Taken together, our data suggest that the duplicated BnHR genes might have been subjected to differential selection and at least some may play a role in defense and could serve as resistance resource in engineering disease-resistant plants. PMID:27493652

  6. Grapevine powdery mildew resistance and susceptibility loci identified on a high-resolution SNP map.

    Science.gov (United States)

    Barba, Paola; Cadle-Davidson, Lance; Harriman, James; Glaubitz, Jeffrey C; Brooks, Siraprapa; Hyma, Katie; Reisch, Bruce

    2014-01-01

    Improved efficacy and durability of powdery mildew resistance can be enhanced via knowledge of the genetics of resistance and susceptibility coupled with the development of high-resolution maps to facilitate the stacking of multiple resistance genes and other desirable traits. We studied the inheritance of powdery mildew (Erysiphe necator) resistance and susceptibility of wild Vitis rupestris B38 and cultivated V. vinifera 'Chardonnay', finding evidence for quantitative variation. Molecular markers were identified using genotyping-by-sequencing, resulting in 16,833 single nucleotide polymorphisms (SNPs) based on alignment to the V. vinifera 'PN40024' reference genome sequence. With an average density of 36 SNPs/Mbp and uniform coverage of the genome, this 17K set was used to identify 11 SNPs on chromosome 7 associated with a resistance locus from V. rupestris B38 and ten SNPs on chromosome 9 associated with a locus for susceptibility from 'Chardonnay' using single marker association and linkage disequilibrium analysis. Linkage maps for V. rupestris B38 (1,146 SNPs) and 'Chardonnay' (1,215 SNPs) were constructed and used to corroborate the 'Chardonnay' locus named Sen1 (Susceptibility to Erysiphe necator 1), providing the first insight into the genetics of susceptibility to powdery mildew from V. vinifera. The identification of markers associated with a susceptibility locus in a V. vinifera background can be used for negative selection among breeding progenies. This work improves our understanding of the nature of powdery mildew resistance in V. rupestris B38 and 'Chardonnay', while applying next-generation sequencing tools to advance grapevine genomics and breeding.

  7. Multiple Evolutionary Events Involved in Maintaining Homologs of Resistance to Powdery Mildew 8 in Brassica napus.

    Science.gov (United States)

    Li, Qin; Li, Jing; Sun, Jin-Long; Ma, Xian-Feng; Wang, Ting-Ting; Berkey, Robert; Yang, Hui; Niu, Ying-Ze; Fan, Jing; Li, Yan; Xiao, Shunyuan; Wang, Wen-Ming

    2016-01-01

    The Resistance to Powdery Mildew 8 (RPW8) locus confers broad-spectrum resistance to powdery mildew in Arabidopsis thaliana. There are four Homologous to RPW8s (BrHRs) in Brassica rapa and three in Brassica oleracea (BoHRs). Brassica napus (Bn) is derived from diploidization of a hybrid between B. rapa and B. oleracea, thus should have seven homologs of RPW8 (BnHRs). It is unclear whether these genes are still maintained or lost in B. napus after diploidization and how they might have been evolved. Here, we reported the identification and sequence polymorphisms of BnHRs from a set of B. napus accessions. Our data indicated that while the BoHR copy from B. oleracea is highly conserved, the BrHR copy from B. rapa is relatively variable in the B. napus genome owing to multiple evolutionary events, such as gene loss, point mutation, insertion, deletion, and intragenic recombination. Given the overall high sequence homology of BnHR genes, it is not surprising that both intragenic recombination between two orthologs and two paralogs were detected in B. napus, which may explain the loss of BoHR genes in some B. napus accessions. When ectopically expressed in Arabidopsis, a C-terminally truncated version of BnHRa and BnHRb, as well as the full length BnHRd fused with YFP at their C-termini could trigger cell death in the absence of pathogens and enhanced resistance to powdery mildew disease. Moreover, subcellular localization analysis showed that both BnHRa-YFP and BnHRb-YFP were mainly localized to the extra-haustorial membrane encasing the haustorium of powdery mildew. Taken together, our data suggest that the duplicated BnHR genes might have been subjected to differential selection and at least some may play a role in defense and could serve as resistance resource in engineering disease-resistant plants.

  8. Development of partial ontogenic resistance to powdery mildew in hop cones and its management implications.

    Science.gov (United States)

    Twomey, Megan C; Wolfenbarger, Sierra N; Woods, Joanna L; Gent, David H

    2015-01-01

    Knowledge of processes leading to crop damage is central to devising rational approaches to disease management. Multiple experiments established that infection of hop cones by Podosphaera macularis was most severe if inoculation occurred within 15 to 21 days after bloom. This period of infection was associated with the most pronounced reductions in alpha acids, cone color, and accelerated maturation of cones. Susceptibility of cones to powdery mildew decreased progressively after the transition from bloom to cone development, although complete immunity to the disease failed to develop. Maturation of cone tissues was associated with multiple significant affects on the pathogen manifested as reduced germination of conidia, diminished frequency of penetration of bracts, lengthening of the latent period, and decreased sporulation. Cones challenged with P. macularis in juvenile developmental stages also led to greater frequency of colonization by a complex of saprophytic, secondary fungi. Since no developmental stage of cones was immune to powdery mildew, the incidence of powdery mildew continued to increase over time and exceeded 86% by late summer. In field experiments with a moderately susceptible cultivar, the incidence of cones with powdery mildew was statistically similar when fungicide applications were made season-long or targeted only to the juvenile stages of cone development. These studies establish that partial ontogenic resistance develops in hop cones and may influence multiple phases of the infection process and pathogen reproduction. The results further reinforce the concept that the efficacy of a fungicide program may depend largely on timing of a small number of sprays during a relatively brief period of cone development. However in practice, targeting fungicide and other management tactics to periods of enhanced juvenile susceptibility may be complicated by a high degree of asynchrony in cone development and other factors that are situation-dependent.

  9. Occurrence of a black mildew in Santalum album plantation at Anakulam, Thiruvananthapuram, Kerala, India

    Directory of Open Access Journals (Sweden)

    V.B. Hosagoudar

    2013-06-01

    Full Text Available The Anakulam sub-unit of the Trivandrum Division of the Kerala Forest Development Corporation has planted 7.84 ha of sandal wood trees in Block V, including the plantation of 5200 plants in the year 2010 and 3000 plants during the year 2011 at a spacing of 3x3m. This area is located at an altitude of 300m. The entire sandal wood plantation is being affected with a black mildew fungus, identified as Asterina congesta.

  10. Development of partial ontogenic resistance to powdery mildew in hop cones and its management implications.

    Directory of Open Access Journals (Sweden)

    Megan C Twomey

    Full Text Available Knowledge of processes leading to crop damage is central to devising rational approaches to disease management. Multiple experiments established that infection of hop cones by Podosphaera macularis was most severe if inoculation occurred within 15 to 21 days after bloom. This period of infection was associated with the most pronounced reductions in alpha acids, cone color, and accelerated maturation of cones. Susceptibility of cones to powdery mildew decreased progressively after the transition from bloom to cone development, although complete immunity to the disease failed to develop. Maturation of cone tissues was associated with multiple significant affects on the pathogen manifested as reduced germination of conidia, diminished frequency of penetration of bracts, lengthening of the latent period, and decreased sporulation. Cones challenged with P. macularis in juvenile developmental stages also led to greater frequency of colonization by a complex of saprophytic, secondary fungi. Since no developmental stage of cones was immune to powdery mildew, the incidence of powdery mildew continued to increase over time and exceeded 86% by late summer. In field experiments with a moderately susceptible cultivar, the incidence of cones with powdery mildew was statistically similar when fungicide applications were made season-long or targeted only to the juvenile stages of cone development. These studies establish that partial ontogenic resistance develops in hop cones and may influence multiple phases of the infection process and pathogen reproduction. The results further reinforce the concept that the efficacy of a fungicide program may depend largely on timing of a small number of sprays during a relatively brief period of cone development. However in practice, targeting fungicide and other management tactics to periods of enhanced juvenile susceptibility may be complicated by a high degree of asynchrony in cone development and other factors that are

  11. Effects of bunch rot (Botrytis cinerea) and powdery mildew (Erysiphe necator) fungal diseases on wine aroma

    Science.gov (United States)

    Lopez Pinar, Angela; Rauhut, Doris; Ruehl, Ernst; Buettner, Andrea

    2017-03-01

    This study aimed to characterize the effects of bunch rot and powdery mildew on the primary quality parameter of wine, the aroma. The influence of these fungal diseases was studied by comparative Aroma Extract Dilution Analyses (AEDA) and sensory tests. The effect of bunch rot was investigated on three grape varieties, namely White Riesling, Red Riesling and Gewürztraminer and that of powdery mildew on the hybrid Gm 8622-3; thereby, samples were selected that showed pronounced cases of infection to elaborate potential currently unknown effects. Both infections revealed aromatic differences induced by these fungi. The sensory changes were not associated with one specific compound only, but were due to quantitative variations of diverse substances. Bunch rot predominantly induced an increase in the intensities of peach-like/fruity, floral and liquor-like/toasty aroma notes. These effects were found to be related to variations in aroma substance composition as monitored via AEDA, mainly an increase in the FD factors of lactones and a general moderate increase of esters and alcohols. On the other hand, powdery mildew decreased the vanilla-like character of the wine while the remaining sensory attributes were rather unaffected. Correspondingly, FD factors of the main aroma constituents were either the same or only slightly modified by this disease. Moreover, bunch rot influenced the aroma profiles of the three varieties studied to a different degree. In hedonic evaluation, bunch rot-affected samples were rated as being more pleasant in comparison to their healthy controls in all three varieties while the powdery mildew-affected sample was rated as being less pleasant than its healthy control.

  12. Wheat protection against powdery mildew by arbuscular mycorrhizal fungi : mechanisms and optimization

    OpenAIRE

    Mustafa, Ghalia

    2015-01-01

    The use of arbuscular mycorrhizal fungi (AMF) could be an innovative alternative to chemicals against fungal plant diseases. Our work aimed at studying the possible protective effect of arbuscular mycorrhization in the bread wheat (Triticum aestivum L.) against Blumeria graminis f. sp. tritici (Bgt), a biotrophic fungi responsible of wheat powdery mildew, a disease affecting the aerial plant organs. Wheat mycorrhizal inoculation by Funneliformis mosseae (Fm), under controlled and optimized co...

  13. Occurrence of a black mildew in Santalum album plantation at Anakulam, Thiruvananthapuram, Kerala, India

    Directory of Open Access Journals (Sweden)

    V.B. Hosagoudar

    2013-06-01

    Full Text Available The Anakulam sub-unit of the Trivandrum Division of the Kerala Forest Development Corporation has planted 7.84 ha of sandal wood trees in Block V, including the plantation of 5200 plants in the year 2010 and 3000 plants during the year 2011 at a spacing of 3x3m. This area is located at an altitude of 300m. The entire sandal wood plantation is being affected with a black mildew fungus, identified as Asterina congesta.

  14. Multiple evolutionary events involved in maintaining homologs of Resistance to Powdery Mildew 8 in Brassica napus

    Directory of Open Access Journals (Sweden)

    Qin Li

    2016-07-01

    Full Text Available The Resistance to Powdery Mildew 8 (RPW8 locus confers broad-spectrum resistance to powdery mildew in Arabidopsis thaliana. There are four Homologous to RPW8s (BrHRs in Brassica rapa and three in B. oleracea (BoHRs. B. napus (Bn is derived from diploidization of a hybrid between B. rapa and B. oleracea, thus should have seven homologs of RPW8 (BnHRs. It is unclear whether these genes are still maintained or lost in B. napus after diploidization and how they might have been evolved. Here we reported the identification and sequence polymorphisms of BnHRs from a set of B. napus accessions. Our data indicated that while the BoHR copy from B. oleracea is highly conserved, the BrHR copy from B. rapa is relatively variable in the B. napus genome owing to multiple evolutionary events, such as gene loss, point mutation, insertion, deletion and intragenic recombination. Given the overall high sequence homology of BnHR genes, it is not surprising that both intragenic recombination between two orthologs and two paralogs were detected in B. napus, which may explain the loss of BoHR genes in some B. napus accessions. When ectopically expressed in Arabidopsis, a C-terminally truncated version of BnHRa and BnHRb, as well as the full length BnHRd fused with YFP at their C-termini could trigger cell death in the absence of pathogens and enhanced resistance to powdery mildew disease. Moreover, subcellular localization analysis showed that both BnHRa-YFP and BnHRb-YFP were mainly localized to the extra-haustorial membrane (EHM encasing the haustorium of powdery mildew. Taken together, our data suggest that the duplicated BnHR genes might have been subjected to differential selection and at least some may play a role in defense and could serve as resistance resource in engineering disease-resistant plants.

  15. Powdery mildew fungal effector candidates share N-terminal Y/F/WxC-motif

    Directory of Open Access Journals (Sweden)

    Emmersen Jeppe

    2010-05-01

    Full Text Available Abstract Background Powdery mildew and rust fungi are widespread, serious pathogens that depend on developing haustoria in the living plant cells. Haustoria are separated from the host cytoplasm by a plant cell-derived extrahaustorial membrane. They secrete effector proteins, some of which are subsequently transferred across this membrane to the plant cell to suppress defense. Results In a cDNA library from barley epidermis containing powdery mildew haustoria, two-thirds of the sequenced ESTs were fungal and represented ~3,000 genes. Many of the most highly expressed genes encoded small proteins with N-terminal signal peptides. While these proteins are novel and poorly related, they do share a three-amino acid motif, which we named "Y/F/WxC", in the N-terminal of the mature proteins. The first amino acid of this motif is aromatic: tyrosine, phenylalanine or tryptophan, and the last is always cysteine. In total, we identified 107 such proteins, for which the ESTs represent 19% of the fungal clones in our library, suggesting fundamental roles in haustoria function. While overall sequence similarity between the powdery mildew Y/F/WxC-proteins is low, they do have a highly similar exon-intron structure, suggesting they have a common origin. Interestingly, searches of public fungal genome and EST databases revealed that haustoria-producing rust fungi also encode large numbers of novel, short proteins with signal peptides and the Y/F/WxC-motif. No significant numbers of such proteins were identified from genome and EST sequences from either fungi which do not produce haustoria or from haustoria-producing Oomycetes. Conclusion In total, we identified 107, 178 and 57 such Y/F/WxC-proteins from the barley powdery mildew, the wheat stem rust and the wheat leaf rust fungi, respectively. All together, our findings suggest the Y/F/WxC-proteins to be a new class of effectors from haustoria-producing pathogenic fungi.

  16. mRNA-Seq analysis of the Pseudoperonospora cubensis transcriptome during cucumber (Cucumis sativus L. infection.

    Directory of Open Access Journals (Sweden)

    Elizabeth A Savory

    Full Text Available Pseudoperonospora cubensis, an oomycete, is the causal agent of cucurbit downy mildew, and is responsible for significant losses on cucurbit crops worldwide. While other oomycete plant pathogens have been extensively studied at the molecular level, Ps. cubensis and the molecular basis of its interaction with cucurbit hosts has not been well examined. Here, we present the first large-scale global gene expression analysis of Ps. cubensis infection of a susceptible Cucumis sativus cultivar, 'Vlaspik', and identification of genes with putative roles in infection, growth, and pathogenicity. Using high throughput whole transcriptome sequencing, we captured differential expression of 2383 Ps. cubensis genes in sporangia and at 1, 2, 3, 4, 6, and 8 days post-inoculation (dpi. Additionally, comparison of Ps. cubensis expression profiles with expression profiles from an infection time course of the oomycete pathogen Phytophthora infestans on Solanum tuberosum revealed similarities in expression patterns of 1,576-6,806 orthologous genes suggesting a substantial degree of overlap in molecular events in virulence between the biotrophic Ps. cubensis and the hemi-biotrophic P. infestans. Co-expression analyses identified distinct modules of Ps. cubensis genes that were representative of early, intermediate, and late infection stages. Collectively, these expression data have advanced our understanding of key molecular and genetic events in the virulence of Ps. cubensis and thus, provides a foundation for identifying mechanism(s by which to engineer or effect resistance in the host.

  17. Airborne hyperspectral imaging for the detection of powdery mildew in wheat

    Science.gov (United States)

    Franke, Jonas; Mewes, Thorsten; Menz, Gunter

    2008-08-01

    Plant stresses, in particular fungal diseases, show a high variability in spatial and temporal dimension with respect to their impact on the host. Recent "Precision Agriculture"-techniques allow for a spatially and temporally adjusted pest control that might reduce the amount of cost-intensive and ecologically harmful agrochemicals. Conventional stressdetection techniques such as random monitoring do not meet demands of such optimally placed management actions. The prerequisite is an accurate sensor-based detection of stress symptoms. The present study focuses on a remotely sensed detection of the fungal disease powdery mildew (Blumeria graminis) in wheat, Europe's main crop. In a field experiment, the potential of hyperspectral data for an early detection of stress symptoms was tested. A sophisticated endmember selection procedure was used and, additionally, a linear spectral mixture model was applied to a pixel spectrum with known characteristics, in order to derive an endmember representing 100% powdery mildew-infected wheat. Regression analyses of matched fraction estimates of this endmember and in-field-observed powdery mildew severities showed promising results (r=0.82 and r2=0.67).

  18. Identification of Powdery Mildew Responsive Genes in Hevea brasiliensis through mRNA Differential Display.

    Science.gov (United States)

    Li, Xiang; Bi, Zhenghong; Di, Rong; Liang, Peng; He, Qiguang; Liu, Wenbo; Miao, Weiguo; Zheng, Fucong

    2016-01-29

    Powdery mildew is an important disease of rubber trees caused by Oidium heveae B. A. Steinmann. As far as we know, none of the resistance genes related to powdery mildew have been isolated from the rubber tree. There is little information available at the molecular level regarding how a rubber tree develops defense mechanisms against this pathogen. We have studied rubber tree mRNA transcripts from the resistant RRIC52 cultivar by differential display analysis. Leaves inoculated with the spores of O. heveae were collected from 0 to 120 hpi in order to identify pathogen-regulated genes at different infection stages. We identified 78 rubber tree genes that were differentially expressed during the plant-pathogen interaction. BLAST analysis for these 78 ESTs classified them into seven functional groups: cell wall and membrane pathways, transcription factor and regulatory proteins, transporters, signal transduction, phytoalexin biosynthesis, other metabolism functions, and unknown functions. The gene expression for eight of these genes was validated by qRT-PCR in both RRIC52 and the partially susceptible Reyan 7-33-97 cultivars, revealing the similar or differential changes of gene expressions between these two cultivars. This study has improved our overall understanding of the molecular mechanisms of rubber tree resistance to powdery mildew.

  19. Breeding and molecular cytogenetic identification of wheat-Thinopyrum intermedium addition lines resistant to powdery mildew

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Wheat-related species Th. intermedium was used to cross with common wheat Yannong 15. In the self progenies of the hybrid, two addition lines, Ⅱ-1-7-1 and Ⅱ-3-3-2, stable in cytology, were developed by cytology and powdery mildew resistance identification. Their chromosome number were 2n = 44 and formed 22 bivalents at PMC MI. In F1 of the two addition lines crossing with Yannong 15, there appeared about one univalent at PMC MI, respectively. Resistance identification in greenhouse and field using the No. 15 and mixed strains of E. gramnis f. sp. tritici showed that they were immune to powdery mildew. Chromosome number and resistance identification using the F2 single plants of the addition line crossing with Yannong 15 indicated that the resistant gene was located on the alien chromosomes. In situ hybridization using St and E genomic DNA as probe showed that the added chromosome in the two addition lines probably came from the E genome of Th. intermedium, which indicated that a pair of E genome chromosomes carried a new resistant gene to powdery mildew.

  20. Simultaneous editing of three homoeoalleles in hexaploid bread wheat confers heritable resistance to powdery mildew.

    Science.gov (United States)

    Wang, Yanpeng; Cheng, Xi; Shan, Qiwei; Zhang, Yi; Liu, Jinxing; Gao, Caixia; Qiu, Jin-Long

    2014-09-01

    Sequence-specific nucleases have been applied to engineer targeted modifications in polyploid genomes, but simultaneous modification of multiple homoeoalleles has not been reported. Here we use transcription activator-like effector nuclease (TALEN) and clustered, regularly interspaced, short palindromic repeats (CRISPR)-Cas9 (refs. 4,5) technologies in hexaploid bread wheat to introduce targeted mutations in the three homoeoalleles that encode MILDEW-RESISTANCE LOCUS (MLO) proteins. Genetic redundancy has prevented evaluation of whether mutation of all three MLO alleles in bread wheat might confer resistance to powdery mildew, a trait not found in natural populations. We show that TALEN-induced mutation of all three TaMLO homoeologs in the same plant confers heritable broad-spectrum resistance to powdery mildew. We further use CRISPR-Cas9 technology to generate transgenic wheat plants that carry mutations in the TaMLO-A1 allele. We also demonstrate the feasibility of engineering targeted DNA insertion in bread wheat through nonhomologous end joining of the double-strand breaks caused by TALENs. Our findings provide a methodological framework to improve polyploid crops.

  1. Effects of silicates from scaps of photovoltaic industries on powdery mildew of zucchini.

    Science.gov (United States)

    Pugliese, M; Alvarez, M T Moreno; Gullino, M L; Garibaldi, A

    2012-01-01

    Silicon is the second most abundant element on earth's surface and its use can stimulate natural defense mechanisms in plants. The effect of silicate from scraps of photovoltaic industries against powdery mildew on zucchini (Cucurbita pepo) was evaluated under greenhouse conditions. Potted plants were inoculated with a spore suspension containing 1 x 10(5) cfu/ml. The following treatments have been carried out, 3 and 10 days after pathogen inoculation: chemical fungicide (propiconazole, TILT 25 EC, Syngenta); Bacillus subtilis (250 g/hl, Serenade, Intrachem); 1% and 0.1% sodium silicate (r = 1); 1% and 0.1% sodium silicate (r = 2); tap water as control. Disease incidence and severity were assessed 7, 14 and 21days after pathogen inoculation. Results showed that the application of 1% sodium silicate (r = 1) significantly reduced the powdery mildew to a level similar to chemical control. The other treatments, including Bacillus subtilis, reduced disease severity compared to water control, but were less efficient. The use of silicates from photovoltaic industries is a valid alternative for the control of powdery mildew on zucchini, in particular in organic farming. However, silicates might not be sufficient at higher disease incidence levels, and their use is more suitable within an integrated disease control strategy.

  2. Grid inhomogeneous solvation theory: hydration structure and thermodynamics of the miniature receptor cucurbit[7]uril.

    Science.gov (United States)

    Nguyen, Crystal N; Young, Tom Kurtzman; Gilson, Michael K

    2012-07-28

    The displacement of perturbed water upon binding is believed to play a critical role in the thermodynamics of biomolecular recognition, but it is nontrivial to unambiguously define and answer questions about this process. We address this issue by introducing grid inhomogeneous solvation theory (GIST), which discretizes the equations of inhomogeneous solvation theory (IST) onto a three-dimensional grid situated in the region of interest around a solute molecule or complex. Snapshots from explicit solvent simulations are used to estimate localized solvation entropies, energies, and free energies associated with the grid boxes, or voxels, and properly summing these thermodynamic quantities over voxels yields information about hydration thermodynamics. GIST thus provides a smoothly varying representation of water properties as a function of position, rather than focusing on hydration sites where solvent is present at high density. It therefore accounts for full or partial displacement of water from sites that are highly occupied by water, as well as for partly occupied and water-depleted regions around the solute. GIST can also provide a well-defined estimate of the solvation free energy and therefore enables a rigorous end-states analysis of binding. For example, one may not only use a first GIST calculation to project the thermodynamic consequences of displacing water from the surface of a receptor by a ligand, but also account, in a second GIST calculation, for the thermodynamics of subsequent solvent reorganization around the bound complex. In the present study, a first GIST analysis of the molecular host cucurbit[7]uril is found to yield a rich picture of hydration structure and thermodynamics in and around this miniature receptor. One of the most striking results is the observation of a toroidal region of high water density at the center of the host's nonpolar cavity. Despite its high density, the water in this toroidal region is disfavored energetically and

  3. The Novel Gene VpPR4-1 from Vitis pseudoreticulata Increases Powdery Mildew Resistance in Transgenic Vitis vinifera L.

    Science.gov (United States)

    Dai, Lingmin; Wang, Dan; Xie, Xiaoqing; Zhang, Chaohong; Wang, Xiping; Xu, Yan; Wang, Yuejin; Zhang, Jianxia

    2016-01-01

    Pathogenesis-related proteins (PRs) can lead to increased resistance of the whole plant to pathogen attack. Here, we isolate and characterize a PR-4 protein (VpPR4-1) from a wild Chinese grape Vitis pseudoreticulata which shows greatly elevated transcription following powdery mildew infection. Its expression profiles under a number of abiotic stresses were also investigated. Powdery mildew, salicylic acid, and jasmonic acid methyl ester significantly increased the VpPR4-1 induction while NaCl and heat treatments just slightly induced VpPR4-1 expression. Abscisic acid and cold treatment slightly affected the expression level of VpPR4-1. The VpPR4-1 gene was overexpressed in 30 regenerated V. vinifera cv. Red Globe via Agrobacterium tumefaciens-mediated transformation and verified by the Western blot. The 26 transgenic grapevines exhibited higher expression levels of PR-4 protein content than wild-type vines and six of them were inoculated with powdery mildew which showed that the growth of powdery mildew was repressed. The powdery mildew-resistance of Red Globe transformed with VpPR4-1 was enhanced inoculated with powdery mildew. Moreover, other powdery mildew resistant genes were associated with feedback regulation since VpPR4-1 is in abundance. This study demonstrates that PR-4 protein in grapes plays a vital role in defense against powdery mildew invasion.

  4. Strategies for RUN1 deployment using RUN2 and REN2 to manage grapevine powdery mildew informed by studies of race-specificity

    Science.gov (United States)

    The TIR-NB-LRR gene, Resistance to Uncinula necator 1 (RUN1), from Vitis rotundifolia was recently identified and confirmed to confer resistance to the grapevine powdery mildew fungus Erysiphe necator (syn. U. necator) in transgenic Vitis vinifera cultivars. However, powdery mildew cleistothecia ha...

  5. Powdery mildew outbreaks caused by Podosphaera macularis on Hop cultivars possessing the resistance gene R6 in the Pacific Northwestern United States

    Science.gov (United States)

    Resistant cultivars of hop (Humulus lupulus) have been grown, with the aim of helping to manage powdery mildew in the Pacific Northwest since the first report of the disease in the field in 1997 (4). A major objective of many breeding programs is development of resistance to powdery mildew, and thi...

  6. Dynamic evolution of resistance gene analogs in the orthologous genomic regions of powdery mildew resistance gene MlIW170 in Triticum dicoccoides and Aegilops tauschii

    Science.gov (United States)

    Wheat is one of the most important staple grain crops in the world. Powdery mildew disease caused by Blumeria graminis f.sp. tritici can result in significant losses in both grain yield and quality in wheat. In this study, the wheat powdery mildew resistance gene MlIW170 locus located on the short ...

  7. Fine physical and genetic mapping of powdery mildew resistance gene MlIW172 originating from wild emmer(Triticum dicoccoides)

    Science.gov (United States)

    Powdery mildew, caused by Blumeria graminis f. sp. tritici, is one of the most important wheat diseases in the world. In this study, a single dominant powdery mildew resistance gene MlIW172 was identified in the IW172 wild emmer accession and mapped to the distal region of chromosome arm 7AL (bin7A...

  8. Identification and genetic mapping of the putative Thinopyrum intermedium-derived dominant powdery mildew resistance gene PmL962 on wheat chromosome arm 2BS

    Science.gov (United States)

    Powdery mildew, caused by Blumeria graminis f. sp. tritici (Bgt), is a destructive disease affecting the production of wheat (Triticum aestivum). Powdery mildew resistance was putatively transferred from Thinopyrum intermedium to the common wheat line L962, which conferred resistance to multiple Ch...

  9. Molecular Cytogenetic Identification of a Wheat-Thinopyron intermedium (Host) Barkworth & DR Dewey Partial Amphiploid Resistant to Powdery Mildew

    Institute of Scientific and Technical Information of China (English)

    Shu-Bing LIU; Hong-Gang WANG; Xue-Yong ZHANG; Xing-Feng LI; Da-Yong LI; Xia-Yu DUAN; Yi-Lin ZHOU

    2005-01-01

    Wide cross and molecular cytogenetic methods were used to transfer the powdery mildew resistance gene from Thinopyron intermedium (Host) Barkworth & DR Dewey to wheat. Among the progeny of crossing common wheat (Triticum aestivum L.) Yannong 15 with Th. intermedium, a partial amphiploid E990256, with resistance to powdery mildew, was developed. It had 56 chromosomes and could form 28bivalents in pollen mother cells at metaphase I of meiosis. Resistance verification by race 15 at the seedling stage and by mixed strains of Erysiphales gramnis DC. f. sp. tritici Em. Marchal at the adult stage showed it was immune to powdery mildew at both stages. Gene postulation via 21 isolates of E. gramnis f. sp. tritici and 29 differential hosts showed it was nearly immune to all the isolates used, and its resistance pattem was different from all the mildew resistance genes used, which indicated it probably contained a new resistance gene to powdery mildew. Biochemical verification showed it might convey different Th. intermedium chromosomes from those of the wheat-Th. intermedium partial amphiploids Zhong 1-5. Genomic in situ hybridization analysis by using St genomic DNA as the probe showed E990256 contained a recombination genome of St and E.

  10. Cytological and molecular analysis of nonhost resistance in rice to wheat powdery mildew and leaf rust pathogens.

    Science.gov (United States)

    Cheng, Yulin; Yao, Juanni; Zhang, Hongchang; Huang, Lili; Kang, Zhensheng

    2015-07-01

    Cereal powdery mildews caused by Blumeria graminis and cereal rusts caused by Puccinia spp. are constant disease threats that limit the production of almost all important cereal crops. Rice is an intensively grown agricultural cereal that is atypical because of its immunity to all powdery mildew and rust fungi. We analyzed the nonhost interactions between rice and the wheat powdery mildew fungus B. graminis f. sp. tritici (Bgt) and the wheat leaf rust fungus Puccinia triticina (Ptr) to identify the basis of nonhost resistance (NHR) in rice against cereal powdery mildew and rust fungi at cytological and molecular levels. No visible symptoms were observed on rice leaves inoculated with Bgt or Ptr. Microscopic observations showed that both pathogens exhibited aberrant differentiation and significantly reduced penetration frequencies on rice compared to wheat. The development of Bgt and Ptr was also completely arrested at early infection stages in cases of successful penetration into rice leaves. Attempted infection of rice by Bgt and Ptr induced similar defense responses, including callose deposition, accumulation of reactive oxygen species, and hypersensitive response in rice epidermal and mesophyll cells, respectively. Furthermore, a set of defense-related genes were upregulated in rice against Bgt and Ptr infection. Rice is an excellent monocot model for genetic and molecular studies. Therefore, our results demonstrate that rice is a useful model to study the mechanisms of NHR to cereal powdery mildew and rust fungi, which provides useful information for the development of novel and durable strategies to control these important pathogens.

  11. Rye Pm8 and wheat Pm3 are orthologous genes and show evolutionary conservation of resistance function against powdery mildew.

    Science.gov (United States)

    Hurni, Severine; Brunner, Susanne; Buchmann, Gabriele; Herren, Gerhard; Jordan, Tina; Krukowski, Patricia; Wicker, Thomas; Yahiaoui, Nabila; Mago, Rohit; Keller, Beat

    2013-12-01

    The improvement of wheat through breeding has relied strongly on the use of genetic material from related wild and domesticated grass species. The 1RS chromosome arm from rye was introgressed into wheat and crossed into many wheat lines, as it improves yield and fungal disease resistance. Pm8 is a powdery mildew resistance gene on 1RS which, after widespread agricultural cultivation, is now widely overcome by adapted mildew races. Here we show by homology-based cloning and subsequent physical and genetic mapping that Pm8 is the rye orthologue of the Pm3 allelic series of mildew resistance genes in wheat. The cloned gene was functionally validated as Pm8 by transient, single-cell expression analysis and stable transformation. Sequence analysis revealed a complex mosaic of ancient haplotypes among Pm3- and Pm8-like genes from different members of the Triticeae. These results show that the two genes have evolved independently after the divergence of the species 7.5 million years ago and kept their function in mildew resistance. During this long time span the co-evolving pathogens have not overcome these genes, which is in strong contrast to the breakdown of Pm8 resistance since its introduction into commercial wheat 70 years ago. Sequence comparison revealed that evolutionary pressure acted on the same subdomains and sequence features of the two orthologous genes. This suggests that they recognize directly or indirectly the same pathogen effectors that have been conserved in the powdery mildews of wheat and rye.

  12. Contribuição das folhas cotiledonares para o crescimento e estabelecimento de plântulas de cucurbitáceas Cotyledonary leaf contribution for growth and establishment of cucurbit seedlings

    Directory of Open Access Journals (Sweden)

    Dilson Antônio Bisognin

    2004-06-01

    Full Text Available As cucurbitáceas apresentam germinação epigeal, cujos cotilédones têm a dupla função de fornecer substâncias de reserva e fotoassimilados para o crescimento e o estabelecimento da plântula. O objetivo deste trabalho foi quantificar o nível de dependência de plântulas de abóbora híbrida (Cucurbita maxima x C. moschata, melancia (Citrullus lanatus, pepino (Cucumis sativus e porongo (Lagenaria siceraria em relação às folhas cotiledonares para o crescimento e estabelecimento inicial. Foi efetuada a remoção de um ou dois cotilédones aos 3; 6; 9 e 12 dias após a emergência (DAE, comparando-se o crescimento das plântulas com o de plântulas controle (sem remoção. O crescimento inicial foi avaliado a cada três dias, da emergência até 21 DAE, determinando-se a taxa de expansão das folhas cotiledonares, o período de tempo até a equivalência entre área foliar e cotiledonar e a produção de matéria seca. A abóbora apresentou a maior taxa de expansão das folhas cotiledonares, o menor período até a emissão e expansão das folhas verdadeiras e a maior produção de matéria seca. As plântulas de abóbora e pepino apresentaram a maior dependência em relação às folhas cotiledonares. Os resultados obtidos mostram que danos às folhas cotiledonares, dependendo da espécie, da intensidade e da idade da plântula, podem afetar drasticamente o crescimento inicial e o estabelecimento das plântulas, com reflexos evidentes no rendimento de frutos em cucurbitáceas.Cucurbit species have epigeal cotyledons adapted for both storage and photoassimilation functions. Seedling dependence on cotyledonary leaves for initial growth and establishment was quantified for hybrid squash (Cucurbita maxima x C. moschata, watermelon (Citrullus lanatus, cucumber (Cucumis sativus, and bottlegourd (Lagenaria siceraria. One or both cotyledons were excised at 3; 6; 9; and 12 days after emergence (DAE and initial growth was compared to control

  13. Host cell entry of powdery mildew is correlated with endosomal transport of antagonistically acting VvPEN1 and VvMLO to the papilla.

    Science.gov (United States)

    Feechan, A; Jermakow, A M; Ivancevic, A; Godfrey, D; Pak, H; Panstruga, R; Dry, I B

    2013-10-01

    Challenge by a nonadapted powdery mildew fungal pathogen leads to the formation of a local cell-wall apposition (papilla) beneath the point of attempted penetration. Several plasma membrane (PM) proteins with opposing roles in powdery mildew infection, including Arabidopsis thaliana PENETRATION1 (PEN1) and barley (Hordeum vulgare) MILDEW RESISTANCE LOCUS O (MLO), are localized to the site of powdery mildew attack. PEN1 contributes to penetration resistance to nonadapted powdery mildews, whereas MLO is a susceptibility factor required by adapted powdery mildew pathogens for host cell entry. Our previous studies have demonstrated that the vesicle and endosomal trafficking inhibitors, brefeldin A and wortmannin, have opposite effects on the penetration rates of adapted and nonadapted powdery mildews on grapevine. These findings prompted us to study the pathogen-induced intracellular trafficking of grapevine variants of MLO and PEN1. We first identified grapevine (Vitis vinifera) VvPEN1 and VvMLO orthologs that rescue Arabidopsis Atpen1 and Atmlo2 mlo6 mlo12 null mutants, respectively. By using endomembrane trafficking inhibitors in combination with fluorescence microscopy, we demonstrate that VvMLO3/VvMLO4 and VvPEN1 are co-trafficked together from the PM to the site of powdery mildew challenge. This focal accumulation of VvMLO3/VvMLO4 and VvPEN1 to the site of attack seems to be required for their opposing functions during powdery mildew attack, because their subcellular localization is correlated with the outcome of attempted powdery mildew penetration.

  14. Use of potassium bicarbonate (Armicarb) on the control of powdery mildew (Sphaerotheca mors-uvae) of gooseberry (Ribes uva-crispa).

    Science.gov (United States)

    Wenneker, M; Kanne, J

    2010-01-01

    Powdery mildew (Sphaerotheca mors-uvae) severely infects young shoots, stems and fruits of gooseberry (Ribes uva-crispa). Environmental friendly and biological control measures are being sought throughout the world. Especially in organic gooseberry growing effective control measures are needed, because powdery mildew infections may result in a total loss of the crop. In organic currant growing the number of adequate control methods is very limited. Sulphur as a fungicide against powdery mildew in e.g. gooseberry or table grape growing is not recommendable due to possible bleaching of berries and scorching of tender shoots. Various bicarbonate salts are suggested as a good option to control powdery mildew. In a field trial the effect of potassium bicarbonate (Armicarb) on the on the control of powdery mildew of gooseberry was evaluated. Four treatments; i.e. two preventive strategies and two curative strategies, were applied. PLants were sprayed until runoff. The percent of infected fruits and disease severity were assessed. In the unsprayed control plots very high disease incidences were observed; on average more than 90% of the berries were infected with powdery mildew. The weekly (preventive) spray applications with potassium carbonate reduced the disease incidences on fruits significantly. On average approximately 10% of the fruits were affected by powdery mildew. However, the number of spray applications was high. In conclusion, our results indicate that applications of potassium bicarbonate (as Armicarb) are effective in reducing the incidence and severity of American powdery mildew in gooseberry. Early spray applications are necessary to protect berries against powdery mildew infections. Future research will focus on reducing the number of applications, e.g. warning models based on powdery mildew of rose (Sphaerotheca pannosa).

  15. A highly luminescent tetramer from a weakly emitting monomer: acid- and redox-controlled multiple complexation by cucurbit[7]uril.

    Science.gov (United States)

    Bergamini, Giacomo; Fermi, Andrea; Marchini, Marianna; Locritani, Mirko; Credi, Alberto; Venturi, Margherita; Negri, Fabrizia; Ceroni, Paola; Baroncini, Massimo

    2014-06-01

    The tetrahedral, shape-persistent molecule 1(4+), containing four pyridylpyridinium units connected through a central carbon atom, exhibits unexpected photophysical properties including a substantially redshifted absorption (2350 cm(-1)) and a very strong fluorescence (Φem = 40 %), compared with the monomer 2(+) (Φem = 0.4 %). Density functional theory calculations on the structure and spectroscopic properties of 1(4+) and 2(+) show that exciton interactions, homoconjugation, and orbital nature account for the observed differences in their photophysical properties. The protonated tetramer binds four cucurbit[7]uril molecules and the host/guest interactions can be controlled by chemical (acid/base) as well as redox stimuli.

  16. TaqMan real-time PCR for detection and quantitation of squash leaf curl virus in cucurbits.

    Science.gov (United States)

    Kuan, Cheng-Ping; Huang, Hung-Chang; Chang, Chia-Che; Lu, Yi-Lin

    2012-02-01

    A real-time PCR assay based on the TaqMan chemistry was developed for reliable detection and quantitation of the squash leaf curl virus (SLCV) in melon and squash plants. This method was highly specific to SLCV and it was about one thousand times more sensitive than the conventional PCR method. The protocol of the real-time PCR established in this study enabled detection of as little as 10(2) copies of SLCV DNA with CP gene as the target. This TaqMan real-time PCR assay for detection and quantitation of SLCV would be a useful tool for application in quarantine and certification of SLCV in cucurbits as well as in the research of disease resistance and epidemiology.

  17. Virus symptoms and viruses associated with two cucurbit crops grown in a derived savannah agro-ecology in Nigeria

    Directory of Open Access Journals (Sweden)

    AYO-JOHN

    2014-06-01

    Full Text Available Five watermelon varieties, Sugar Baby, Charleston Grey, Kaolak, Crimson Sweet and Oranaise and three cucumber varieties, Poinsett, Ashley and Royal hybrid were grown on the field in two trials (i late season between August and October 2008 and (ii early season between April and June 2012 in Abeokuta, Ogun State to evaluate the cultivars for virus symptoms and viruses under natural tropical conditions. Symptomatic leaf samples were collected from each crop variety and indexed for Cucumber mosaic virus (CMV, Melon necrotic spot virus (MNSV, Papaya ringspot virus (PRSV, Watermelon mosaic virus (WMV, Zucchini yellow mosaic virus (ZYMV and Cucumber green mottle mosaic virus (CGMMV in Double Antibody Sandwich (DAS Enzyme-linked immunosorbent assay (ELISA. The disease incidence was 100.0% at 6 weeks after planting (WAP for all the cucurbits crops for both seasons while the highest symptom severity score at 10 WAP was 4 and 5 for watermelon and 3.6 and 4 for cucumber in the 1st and 2nd trials. The viruses detected in late season were CMV, CGMMV and MNSV which occurred in all the cucumber and watermelon varieties. In addition PRSV, WMV and ZYMV occurred in mixed infection in the cucumber varieties Pointsett and Royal Hybrid. In the early season, PRSV was the most prevalent virus infection in the cucumber and watermelon varieties. Also CMV+PRSV, PRSV+WMV, and MNSV+PRSV occurred in mixed infection in Charleston Grey, Oranaise and Sugar Baby respectively. The viruses detected are among the viruses reported to limit the production of cucurbit crops world-wide.

  18. Patterns of species richness and diversity of insects associated with cucurbit fruits in the southern part of Cameroon.

    Science.gov (United States)

    Mokam, Didi Gaëlle; Djiéto-Lordon, Champlain; Bilong Bilong, Charles-Félix

    2014-01-01

    Patterns of species diversity and community structure of insects associated with fruits of domesticated cucurbits were investigated from January 2009 to 2011 in three localities from two agroecological zones in the southern part of Cameroon. Rarefaction curves combined with nonparametric estimators of species richness were used to extrapolate species richness beyond our own data. Sampling efforts of over 92% were reached in each of the three study localities. Data collected revealed a total of 66 insect morphospecies belonging to 37 families and five orders, identified from a set of 57,510 insects. The orders Diptera (especially Tephritidae and Lonchaeidae) and Hymenoptera (mainly Braconidae and Eulophidae) were the most important, in terms of both abundance and species richness on the one hand, and effects on agronomic performance on the other. Values for both the species diversity (Shannon and Simpson) and the species richness indices (Margalef and Berger-Parker) calculated showed that the insect communities were species-rich but dominated, all to a similar extent, by five main species (including four fruit fly species and one parasitoid). Species abundance distributions in these communities ranged from the Zipf-Mandelbrot to Mandelbrot models. The communities are structured as tritrophic networks, including cucurbit fruits, fruit-feeding species (fruit flies) and carnivorous species (parasitoids). Within the guild of the parasitoids, about 30% of species, despite their low abundance, may potentially be of use in biological control of important pests. Our field data contribute in important ways to basic knowledge of biodiversity patterns in agrosystems and constitute baseline data for the planned implementation of biological control in Integrated Pest Management. © The Author 2014. Published by Oxford University Press on behalf of the Entomological Society of America.

  19. Insights into the recent emergence of powdery mildew on its 'new' host triticale: from origin to disease control.

    Science.gov (United States)

    Troch, Veronique; Audenaert, Kris; Bekaert, Boris; Höfte, Monica; Haesaert, Geert

    2014-01-01

    The development of new crop species and their associated agro-ecosystems led simultaneously to the emergence of new pathogens (Stukenbrock and McDonald, 2008). This research focused on the recent emergence of powdery mildew (Blumeria graminis) on triticale (x Triticosecale Wittmack). In a first part, we aimed to gain insights into the evolutionary origin of this pathogen on its new host. A secondary aim was to investigate the presence of powdery mildew resistance in current commercial triticale cultivars, including its cellular basis of resistance. To address these research goals, we have pursued a molecular, pathological and cytological approach. This discussion will reflect on the experimental findings described in this research and their impact for future management of powdery mildew on triticale and other cereals.

  20. Adult plant and seedling resistance to powdery mildew in a Triticum aestivum x Triticum militinae hybrid line.

    Science.gov (United States)

    Jakobson, Irena; Peusha, Hilma; Timofejeva, Ljudmilla; Järve, Kadri

    2006-02-01

    In the progeny of a cross between the common wheat cultivar Tähti and Triticum militinae, a member of the timopheevii group of tetraploid wheats, several hybrid lines were selected that are characterized by improved seedling and adult plant resistance (APR) to powdery mildew. An F2 single-seed descendant mapping population segregating for seedling resistance and APR to powdery mildew was analysed for the identification of quantitative trait loci (QTL). The main QTL responsible for APR was detected on the long arm of chromosome 4A tightly linked to the Xgwm160 locus on a T. militinae translocation explaining up to 54% of phenotypic variance. The same translocation influenced seedling resistance to powdery mildew upon inoculation of plants with a synthetic population of Blumeria graminis DC. f. sp. tritici, and explained 28-33% of the phenotypic variance.

  1. Field susceptibility of 13 scab-resistant apple cultivars to apple powdery mildew [Podosphaera leucotricha (Ell. et Ev. Salmon

    Directory of Open Access Journals (Sweden)

    Zbigniew Borecki

    2013-12-01

    Full Text Available Field susceptibility of 13 scab-resistant apple cultivars to apple powdery mildew was evaluated in 1983-1986. Four groups of susceptibility were distinguished. None of the 13 tested scab-resistant apple trees exhibited complete field immunity to apple powdery mildew. Two cultivars, 'Prima' and 'Primula', were practically resistant. 'Liberty' and two numbered selections, NY-140-9 and NY-158-2, belonged to the group of lower susceptibility. Moderate susceptibility was shown by: 'Novamac', 'Freedom', 'Gavin', 'Prima' and 'Florina'. The group of apple trees most susceptible to Podosphaera leucotricha included: 'Macfree', 'Priscilla' and 'Nova Easygro'. It is not necessary to use chemical sprays to control powdery mildew on 'Prima' and 'Primula'. A reduced spraying program may be recommended only under high disease pressure on less susceptible apple cultivars. A regular spray schedule is needed on moderately susceptible apple trees, but improved chemical control is necessary on the most susceptible ones.

  2. Differences in early callose deposition during adapted and non-adapted powdery mildew infection of resistant Arabidopsis lines.

    Science.gov (United States)

    Naumann, Marcel; Somerville, Shauna; Voigt, Christian

    2013-06-01

    The deposition of callose, a (1,3)-β-glucan cell wall polymer, can play an essential role in the defense response to invading pathogens. We could recently show that Arabidopsis thaliana lines with an overexpression of the callose synthase gene PMR4 gained complete penetration resistance to the adapted powdery mildew Golovinomyces cichoracearum and the non-adapted powdery mildew Blumeria graminis f. sp hordei. The penetration resistance is based on the transport of the callose synthase PMR4 to the site of attempted fungal penetration and the subsequent formation of enlarged callose deposits. The deposits differed in their total diameter comparing both types of powdery mildew infection. In this study, further characterization of these callose deposits revealed that size differences were especially pronounced in the core region of the deposits. This suggests that specific, pathogen-dependent factors exist, which might regulate callose synthase transport to the core region of forming deposits.

  3. Preliminary research on the identification system for anthracnose and powdery mildew of sandalwood leaf based on image processing.

    Science.gov (United States)

    Wu, Chunyan; Wang, Xuefeng

    2017-01-01

    This paper presents a survey on a system that uses digital image processing techniques to identify anthracnose and powdery mildew diseases of sandalwood from digital images. Our main objective is researching the most suitable identification technology for the anthracnose and powdery mildew diseases of the sandalwood leaf, which provides algorithmic support for the real-time machine judgment of the health status and disease level of sandalwood. We conducted real-time monitoring of Hainan sandalwood leaves with varying severity levels of anthracnose and powdery mildew beginning in March 2014. We used image segmentation, feature extraction and digital image classification and recognition technology to carry out a comparative experimental study for the image analysis of powdery mildew, anthracnose disease and healthy leaves in the field. Performing the actual test for a large number of diseased leaves pointed to three conclusions: (1) Distinguishing effects of BP (Back Propagation) neural network method, in all kinds of classical methods, for sandalwood leaf anthracnose and powdery mildew disease are relatively good; the size of the lesion areas were closest to the actual. (2) The differences between two diseases can be shown well by the shape feature, color feature and texture feature of the disease image. (3) Identifying and diagnosing the diseased leaves have ideal results by SVM, which is based on radial basis kernel function. The identification rate of the anthracnose and healthy leaves was 92% respectively, and that of powdery mildew was 84%. Disease identification technology lays the foundation for remote monitoring disease diagnosis, preparing for remote transmission of the disease images, which is a very good guide and reference for further research of the disease identification and diagnosis system in sandalwood and other species of trees.

  4. Allelic barley MLA immune receptors recognize sequence-unrelated avirulence effectors of the powdery mildew pathogen.

    Science.gov (United States)

    Lu, Xunli; Kracher, Barbara; Saur, Isabel M L; Bauer, Saskia; Ellwood, Simon R; Wise, Roger; Yaeno, Takashi; Maekawa, Takaki; Schulze-Lefert, Paul

    2016-10-18

    Disease-resistance genes encoding intracellular nucleotide-binding domain and leucine-rich repeat proteins (NLRs) are key components of the plant innate immune system and typically detect the presence of isolate-specific avirulence (AVR) effectors from pathogens. NLR genes define the fastest-evolving gene family of flowering plants and are often arranged in gene clusters containing multiple paralogs, contributing to copy number and allele-specific NLR variation within a host species. Barley mildew resistance locus a (Mla) has been subject to extensive functional diversification, resulting in allelic resistance specificities each recognizing a cognate, but largely unidentified, AVRa gene of the powdery mildew fungus, Blumeria graminis f. sp. hordei (Bgh). We applied a transcriptome-wide association study among 17 Bgh isolates containing different AVRa genes and identified AVRa1 and AVRa13, encoding candidate-secreted effectors recognized by Mla1 and Mla13 alleles, respectively. Transient expression of the effector genes in barley leaves or protoplasts was sufficient to trigger Mla1 or Mla13 allele-specific cell death, a hallmark of NLR receptor-mediated immunity. AVRa1 and AVRa13 are phylogenetically unrelated, demonstrating that certain allelic MLA receptors evolved to recognize sequence-unrelated effectors. They are ancient effectors because corresponding loci are present in wheat powdery mildew. AVRA1 recognition by barley MLA1 is retained in transgenic Arabidopsis, indicating that AVRA1 directly binds MLA1 or that its recognition involves an evolutionarily conserved host target of AVRA1 Furthermore, analysis of transcriptome-wide sequence variation among the Bgh isolates provides evidence for Bgh population structure that is partially linked to geographic isolation.

  5. Olfactory cues from plants infected by powdery mildew guide foraging by a mycophagous ladybird beetle.

    Science.gov (United States)

    Tabata, Jun; De Moraes, Consuelo M; Mescher, Mark C

    2011-01-01

    Powdery mildews (Erysiphales) are economically important plant pathogens that attack many agricultural crops. Conventional management strategies involving fungicide application face challenges, including the evolution of resistance and concerns over impacts on non-target organisms, that call for investigation of more sustainable alternatives. Mycophagous ladybird beetles (Coleoptera: Coccinellidae) feed on powdery mildew and have considerable potential as biological control agents; however, the foraging ecology and behavior of these beetles is not well understood. Here we document the olfactory cues presented by squash plants (Cucurbita moschata) infected by powdery mildew (Podosphaera sp.) and the behavioral responses of twenty-spotted ladybird beetles (Psyllobora vigintimaculata) to these cues. Volatile analyses through gas chromatography revealed a number of volatile compounds characteristic of infected plants, including 3-octanol and its analogues 1-octen-3-ol and 3-octanone. These compounds are typical "moldy" odorants previously reported in volatiles collected from other fungi. In addition, infected plants exhibited elevated emissions of several compounds also observed in collections from healthy leaves, including linalool and benzyl alcohol, which are reported to have anti-fungal properties. In Y-tube choice assays, P. vigintimaculata beetles displayed a significant preference for the odors of infected plants compared to those of healthy plants. Moreover, beetles exhibited strong attraction to one individual compound, 1-octen-3-ol, which was the most abundant of the characteristic fungal compounds identified. These results enhance our understanding of the olfactory cues that guide foraging by mycophagous insects and may facilitate the development of integrated disease-management strategies informed by an understanding of underlying ecological mechanisms.

  6. Monitoring powdery mildew of winter wheat by using moderate resolution multi-temporal satellite imagery.

    Directory of Open Access Journals (Sweden)

    Jingcheng Zhang

    Full Text Available Powdery mildew is one of the most serious diseases that have a significant impact on the production of winter wheat. As an effective alternative to traditional sampling methods, remote sensing can be a useful tool in disease detection. This study attempted to use multi-temporal moderate resolution satellite-based data of surface reflectances in blue (B, green (G, red (R and near infrared (NIR bands from HJ-CCD (CCD sensor on Huanjing satellite to monitor disease at a regional scale. In a suburban area in Beijing, China, an extensive field campaign for disease intensity survey was conducted at key growth stages of winter wheat in 2010. Meanwhile, corresponding time series of HJ-CCD images were acquired over the study area. In this study, a number of single-stage and multi-stage spectral features, which were sensitive to powdery mildew, were selected by using an independent t-test. With the selected spectral features, four advanced methods: mahalanobis distance, maximum likelihood classifier, partial least square regression and mixture tuned matched filtering were tested and evaluated for their performances in disease mapping. The experimental results showed that all four algorithms could generate disease maps with a generally correct distribution pattern of powdery mildew at the grain filling stage (Zadoks 72. However, by comparing these disease maps with ground survey data (validation samples, all of the four algorithms also produced a variable degree of error in estimating the disease occurrence and severity. Further, we found that the integration of MTMF and PLSR algorithms could result in a significant accuracy improvement of identifying and determining the disease intensity (overall accuracy of 72% increased to 78% and kappa coefficient of 0.49 increased to 0.59. The experimental results also demonstrated that the multi-temporal satellite images have a great potential in crop diseases mapping at a regional scale.

  7. Preventative and Curative Effects of Several Plant Derived Agents Against Powdery Mildew Disease of Okra

    Directory of Open Access Journals (Sweden)

    Moustafa Hemdan Ahmed MOHARAM

    2012-08-01

    Full Text Available The preventative and curative effects of some plant derived agents based on plant extracts or essential oils were studied at different concentrations against Erysiphe cichoracearum DC. ex Merat, the causal pathogen of okra powdery mildew by the detached leaf-disk and potted plants bioassays. Through detached leaf-disk assay, the highest mean preventative effect (97.74% was recorded by neem seed oil followed by jojoba oil (89.82% and extract of Rynoutria sachalinensis (82.77%. Neem seed oil at 1% was the most effective agent followed by jojoba oil and extract of R. sachalinensis at 1.5% and 2%, respectively, where they suppressed E. cichoracearum completely. Potted plants assay revealed that neem seed oil, jojoba oil and extract of R. sachalinensis as well as the fungicide (active ingredient dinocap showed higher preventative efficacy at all leaf olds treated after 7 and 14 days of inoculation as compared with extracts of henna and garlic. Moreover, the preventative efficacy partly remained apparent after 14 days of inoculation at all leaf olds tested. In field trials through 2010 and 2011 growing seasons, when the first symptoms of powdery mildew appeared naturally, 1.5% jojoba oil, 2% extract of R. sachalinensis and 1% neem seed oil were sprayed individually twice on grown plants to evaluate their efficacy on controlling powdery mildew, growth and yield of okra. Resulted showed that neem seed oil was the most effective agent and highly decreased the disease severity to 29.92%, recorded the highly curative effect (68.15% and also improved plant growth and pods yield.

  8. Olfactory cues from plants infected by powdery mildew guide foraging by a mycophagous ladybird beetle.

    Directory of Open Access Journals (Sweden)

    Jun Tabata

    Full Text Available Powdery mildews (Erysiphales are economically important plant pathogens that attack many agricultural crops. Conventional management strategies involving fungicide application face challenges, including the evolution of resistance and concerns over impacts on non-target organisms, that call for investigation of more sustainable alternatives. Mycophagous ladybird beetles (Coleoptera: Coccinellidae feed on powdery mildew and have considerable potential as biological control agents; however, the foraging ecology and behavior of these beetles is not well understood. Here we document the olfactory cues presented by squash plants (Cucurbita moschata infected by powdery mildew (Podosphaera sp. and the behavioral responses of twenty-spotted ladybird beetles (Psyllobora vigintimaculata to these cues. Volatile analyses through gas chromatography revealed a number of volatile compounds characteristic of infected plants, including 3-octanol and its analogues 1-octen-3-ol and 3-octanone. These compounds are typical "moldy" odorants previously reported in volatiles collected from other fungi. In addition, infected plants exhibited elevated emissions of several compounds also observed in collections from healthy leaves, including linalool and benzyl alcohol, which are reported to have anti-fungal properties. In Y-tube choice assays, P. vigintimaculata beetles displayed a significant preference for the odors of infected plants compared to those of healthy plants. Moreover, beetles exhibited strong attraction to one individual compound, 1-octen-3-ol, which was the most abundant of the characteristic fungal compounds identified. These results enhance our understanding of the olfactory cues that guide foraging by mycophagous insects and may facilitate the development of integrated disease-management strategies informed by an understanding of underlying ecological mechanisms.

  9. Immigration of the barley mildew pathogen into field plots of barley

    DEFF Research Database (Denmark)

    O'Hara, R.B.; Brown, J.K.M.

    1996-01-01

    Immigration of the barley powdery mildew pathogen (Erysiphe graminis f.sp. hordei) into field plots of the spring barley variety Tyra (carrying the resistance allele Mla1) was investigated. Spores were trapped from the top of the plot canopies, as well as from control plots of wheat with no barley...... nearby. Comparison of the frequencies of virulent and avirulent single-colony isolates showed that the amount of immigration, relative to the amount of inoculum being produced within the plot, reduced very rapidly, until it could not be detected in the middle of the growing season (mid-June)....

  10. Uncinula necator (Schow Burr., the Causal Agent of Grape Powdery Mildew: Economic Impact, Epidemiology and Control

    Directory of Open Access Journals (Sweden)

    Zoran Miladinović

    2007-01-01

    Full Text Available The article is an overview of what we know at present about the patogen Uncinula necator and the disease powdery mildew of grapevine, i.e. its economic status, inoculum source, microclimate conditions, vine susceptibility and principles of its protection.Powdery mildew is a major grapevine disease in terms of losses. It infects the plant’s green parts, reducing its fertility, spoiling the quality of grapes and wine and ruining plant vitality. The process additionally affects subsequent vegetation seasons. The disease occursevery year and its intensity depends on a number of factors.It had long been assumed that overwintering mycelium was the primary source of inoculum. More recent research, however, has revealed a crucial role of cleistothecia in many vineyards. They were found in our vine-growing regions long ago but their true role in the epidemiology of disease has been explained only recently.Microclimate conditions considerably affect the abundance and vitality of cleistothecia and the pathogen’s infection potential. Outbreaks and intensity of disease both depend on them, while vine susceptibility plays another important role, depending on cultivarand plant ontogenesis. Grapevine is most sensitive during flowering and bunch formation when conditions are generally good for the disease to appear and spread.Temperature, precipitation and relative air humidity may limit the occurrence of powdery mildew, but extreme values in that respect are a rarity. Their normal scope is more or less favourable for the disease, especially in Podgorica vineyards.Knowing the pathogen, especially its infection potential, environmental conditions, dynamics of host development and timely and good quality protection of vines, both preventive and chemical, is crucial for grapevine protection.Prevention is important but treatments with fungicides are crucial for U. necator control, and they can either focus on destroying the inoculum and delaying mildew outbreaks

  11. RFLP Tagging of a Gene Pm12 for Powdery Mildew Resistance in Wheat (Triticum aestivum L. )

    Institute of Scientific and Technical Information of China (English)

    贾继增; T.E.Miller; S.M.Reader; M.D.Gale

    1994-01-01

    A dominant gene, Pml2, conferring the resistance to powdery mildew (Erysiphe graminis) has been transferred to wheat from Aegilops speltoides. Sixteen RFLP probes were used to test Line 31 and its parents, showing that Line 31 is a 6B/6S translocation lines. The linkage analysis by five probes indicates that Pm12 is located on the chromosome 6B/6S, and tightly flanked by an RFLP marker α-Amy-1 (1.1 cM), identified by RFLP and isozyme analysis. This approach is equally applicable to the identification of other transferred alien genes and the segments of alien chromosome introgressed into wheat.

  12. A transgenic wheat with a stilbene synthase gene resistant to powdery mildew obtained by biolistic method

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Stilbene, a kind of phytoalexin, plays an important role in resistance to fungal and bacterial infection in plants. It strongly inhibits the growth of fungi and sprout of spore. Stilbene synthase gene (Vst1) obtained from grapevine has been transferred into common spring wheat Jinghong 5 by using the biolistic transformation method. Five transgenic plants (T0) were obtained from the bombarded 2014 immature embryos. One immune plantlet and 3 plantlets with mid-resistance to powdery mildew were identified from the transgenic plants of T3 generation which came from 2 T0 transgenic plants.

  13. In Vitro Synthesized RNA Generated from cDNA Clones of Both Genomic Components of Cucurbit yellow stunting disorder virus Replicates in Cucumber Protoplasts

    Science.gov (United States)

    Owen, Carolyn A.; Moukarzel, Romy; Huang, Xiao; Kassem, Mona A.; Eliasco, Eleonora; Aranda, Miguel A.; Coutts, Robert H. A.; Livieratos, Ioannis C.

    2016-01-01

    Cucurbit yellow stunting disorder virus (CYSDV), a bipartite whitefly-transmitted virus, constitutes a major threat to commercial cucurbit production worldwide. Here, construction of full-length CYSDV RNA1 and RNA2 cDNA clones allowed the in vitro synthesis of RNA transcripts able to replicate in cucumber protoplasts. CYSDV RNA1 proved competent for replication; transcription of both polarities of the genomic RNA was detectable 24 h post inoculation. Hybridization of total RNA extracted from transfected protoplasts or from naturally CYSDV-infected cucurbits revealed high-level transcription of the p22 subgenomic RNA species. Replication of CYSDV RNA2 following co-transfection with RNA1 was also observed, with similar transcription kinetics. A CYSDV RNA2 cDNA clone (T3CM8Δ) comprising the 5′- and 3′-UTRs plus the 3′-terminal gene, generated a 2.8 kb RNA able to replicate to high levels in protoplasts in the presence of CYSDV RNA1. The clone T3CM8Δ will facilitate reverse genetics studies of CYSDV gene function and RNA replication determinants. PMID:27314380

  14. In Vitro Synthesized RNA Generated from cDNA Clones of Both Genomic Components of Cucurbit yellow stunting disorder virus Replicates in Cucumber Protoplasts

    Directory of Open Access Journals (Sweden)

    Carolyn A. Owen

    2016-06-01

    Full Text Available Cucurbit yellow stunting disorder virus (CYSDV, a bipartite whitefly-transmitted virus, constitutes a major threat to commercial cucurbit production worldwide. Here, construction of full-length CYSDV RNA1 and RNA2 cDNA clones allowed the in vitro synthesis of RNA transcripts able to replicate in cucumber protoplasts. CYSDV RNA1 proved competent for replication; transcription of both polarities of the genomic RNA was detectable 24 h post inoculation. Hybridization of total RNA extracted from transfected protoplasts or from naturally CYSDV-infected cucurbits revealed high-level transcription of the p22 subgenomic RNA species. Replication of CYSDV RNA2 following co-transfection with RNA1 was also observed, with similar transcription kinetics. A CYSDV RNA2 cDNA clone (T3CM8Δ comprising the 5′- and 3′-UTRs plus the 3′-terminal gene, generated a 2.8 kb RNA able to replicate to high levels in protoplasts in the presence of CYSDV RNA1. The clone T3CM8Δ will facilitate reverse genetics studies of CYSDV gene function and RNA replication determinants.

  15. In Vitro Synthesized RNA Generated from cDNA Clones of Both Genomic Components of Cucurbit yellow stunting disorder virus Replicates in Cucumber Protoplasts.

    Science.gov (United States)

    Owen, Carolyn A; Moukarzel, Romy; Huang, Xiao; Kassem, Mona A; Eliasco, Eleonora; Aranda, Miguel A; Coutts, Robert H A; Livieratos, Ioannis C

    2016-06-14

    Cucurbit yellow stunting disorder virus (CYSDV), a bipartite whitefly-transmitted virus, constitutes a major threat to commercial cucurbit production worldwide. Here, construction of full-length CYSDV RNA1 and RNA2 cDNA clones allowed the in vitro synthesis of RNA transcripts able to replicate in cucumber protoplasts. CYSDV RNA1 proved competent for replication; transcription of both polarities of the genomic RNA was detectable 24 h post inoculation. Hybridization of total RNA extracted from transfected protoplasts or from naturally CYSDV-infected cucurbits revealed high-level transcription of the p22 subgenomic RNA species. Replication of CYSDV RNA2 following co-transfection with RNA1 was also observed, with similar transcription kinetics. A CYSDV RNA2 cDNA clone (T3CM8Δ) comprising the 5'- and 3'-UTRs plus the 3'-terminal gene, generated a 2.8 kb RNA able to replicate to high levels in protoplasts in the presence of CYSDV RNA1. The clone T3CM8Δ will facilitate reverse genetics studies of CYSDV gene function and RNA replication determinants.

  16. 植物白粉病的化学防治进展%Development of Chemical Control for Powdery Mildew on Plants

    Institute of Scientific and Technical Information of China (English)

    周益林; 段霞瑜; 盛宝钦

    2001-01-01

    Powdery mildew is a type of important disease on plants, and fungicides is a main mean for controlling powdery mildew. The development and history of chemical control for powdery mildew was briefly reviewed, and some important fungicides and the mechanism of their action were introduced.%对植物白粉病的化学防治历史和发展进行了综述,同时介绍了一些重要的药剂及其作用机制,并讨论了白粉病化学防治中存在的问题。

  17. Identification and translocation of metabolites from powdery mildew resistant rootstocks to susceptible watermelon scions using nuclear magnetic resonance spectroscopy

    Science.gov (United States)

    Watermelon (Citrullus lanatus), an important commercial crop, and nutritious fruit, is high in antioxidants, vitamins, and lycopene. Powdery mildew (PM) is a serious disease caused by Podosphaera xanthii, which significantly reduces watermelon production in the U.S. and other parts of the world. C...

  18. Distribution and characterization of Podosphaera macularis virulent on hop cultivars possessing R6-based resistance to powdery mildew

    Science.gov (United States)

    In 2012, an epidemic of powdery mildew occurred in Washington and Idaho on previously resistant cultivars whose resistance was putatively based on the gene designated R6. In 2013, isolates capable of causing severe disease on cultivars with R6-based resistance were confirmed in Oregon and became wid...

  19. Genomic identification, phylogeny, and expression analysis of MLO genes involved in susceptibility to powdery mildew in Fragaria vesca.

    Science.gov (United States)

    Miao, L X; Jiang, M; Zhang, Y C; Yang, X F; Zhang, H Q; Zhang, Z F; Wang, Y Z; Jiang, G H

    2016-08-05

    The MLO (powdery mildew locus O) gene family is important in resistance to powdery mildew (PM). In this study, all of the members of the MLO family were identified and analyzed in the strawberry (Fragaria vesca) genome. The strawberry contains at least 20 members of the MLO family, and the protein sequence contained between 171 and 1485 amino acids, with 0-34 introns. Chromosomal localization showed that the MLOs were unevenly distributed on each of the chromosomes, except for chromosome 4. The greatest number of MLOs (seven) was found on chromosome 3. A phylogenetic tree showed that the MLOs were divided into seven groups (I-VII), four of which consisted of MLOs from strawberry, Arabidopsis thaliana, rice, and maize, suggesting that these genes may have evolved after the divergence of monocots and dicots. Multiple sequence alignment showed that strawberry MLO candidates related to powdery mildew resistance possessed seven highly conserved transmembrane domains, a calmodulin-binding domain, and two conserved regions, all of which are important domains for powdery mildew resistance genes. Expressed sequence tag analysis revealed that the MLOs were induced by multiple abiotic stressors, including low and high temperature, drought, and high salinity. These findings will contribute to the functional characterization of MLOs related to PM susceptibility, and will assist in the development of disease resistance in strawberries.

  20. ‘Appalachian Joy’ is a supernumery, white-bracted cultivar of cornus florida resistant to powdery mildew

    Science.gov (United States)

    The wholesale nursery industry in Tennessee contributes more than $200 million to the annual economy of the state and are in excess of $50 million annually for flowering dogwood (Cornus florida). Two fungal diseases, dogwood anthracnose and powdery mildew (Discula destructiva and Erysiphe pulchra, r...

  1. Detection of pre-symptomatic rose powdery-mildew and gray-mold diseases based on thermal vision

    Science.gov (United States)

    Jafari, M.; Minaei, S.; Safaie, N.

    2017-09-01

    Roses are the most important plants in ornamental horticulture. Roses are susceptible to a number of phytopathogenic diseases. Among the most serious diseases of rose, powdery mildew (Podosphaera pannosa var. rosae) and gray mold (Botrytis cinerea) are widespread which require considerable attention. In this study, the potential of implementing thermal imaging to detect the pre-symptomatic appearance of these fungal diseases was investigated. Effects of powdery mildew and gray mold diseases on rose plants (Rosa hybrida L.) were examined by two experiments conducted in a growth chamber. To classify the healthy and infected plants, feature selection was carried out and the best extracted thermal features with the largest linguistic hedge values were chosen. Two neuro-fuzzy classifiers were trained to distinguish between the healthy and infected plants. Best estimation rates of 92.55% and 92.3% were achieved in training and testing the classifier with 8 clusters in order to identify the leaves infected with powdery mildew. In addition, the best estimation rates of 97.5% and 92.59% were achieved in training and testing the classifier with 4 clusters to identify the gray mold disease on flowers. Performance of the designed neuro-fuzzy classifiers were evaluated with the thermal images captured using an automatic imaging setup. Best correct estimation rates of 69% and 80% were achieved (on the second day post-inoculation) for pre-symptomatic appearance detection of powdery mildew and gray mold diseases, respectively.

  2. Studies in plant pathogenic fungi—II. On some powdery mildews (Erysiphales) recently recorded from the Netherlands

    NARCIS (Netherlands)

    Noordeloos, M.E.; Loerakker, W.M.

    1989-01-01

    Full descriptions and notes on their pathogenous properties are given of the anamorphs of four powdery mildews recently recorded as new from the Netherlands. Two are described as new species, viz. Oidium longipes on Solarium melongena and O. limnanthis on Limnanthes alba. Oidium lycopersicum Cooke &

  3. A disulphide isomerase gene (PDI-V) from Haynaldia villosa contributes to powdery mildew resistance in common wheat.

    Science.gov (United States)

    Faheem, Muhammad; Li, Yingbo; Arshad, Muhammad; Jiangyue, Cheng; Jia, Zhao; Wang, Zongkuan; Xiao, Jin; Wang, Haiyan; Cao, Aizhong; Xing, Liping; Yu, Feifei; Zhang, Ruiqi; Xie, Qi; Wang, Xiue

    2016-04-13

    In this study, we report the contribution of a PDI-like gene from wheat wild relative Haynaldia villosa in combating powdery mildew. PDI-V protein contains two conserved thioredoxin (TRX) active domains (a and a') and an inactive domain (b). PDI-V interacted with E3 ligase CMPG1-V protein, which is a positive regulator of powdery mildew response. PDI-V was mono-ubiquitinated by CMPG1-V without degradation being detected. PDI-V was located on H. villosa chromosome 5V and encoded for a protein located in the endoplasmic reticulum. Bgt infection in leaves of H. villosa induced PDI-V expression. Virus induced gene silencing of PDIs in a T. durum-H. villosa amphiploid compromised the resistance. Single cell transient over-expression of PDI-V or a truncated version containing the active TXR domain a decreased the haustorial index in moderately susceptible wheat cultivar Yangmai 158. Stable transgenic lines over-expressing PDI-V in Yangmai 158 displayed improved powdery mildew resistance at both the seedling and adult stages. By contrast over-expression of point-mutated PDI-V(C57A) did not increase the level of resistance in Yangmai 158. The above results indicate a pivotal role of PDI-V in powdery mildew resistance and showed that conserved TRX domain a is critical for its function.

  4. Map - vs. homology - based cloning for the recessive gene ol-2 conferring resistance to tomato powdery mildew

    NARCIS (Netherlands)

    Pavan, S.N.C.; Zheng, Z.; Borisova, M.; Berg, van den P.M.M.M.; Lotti, C.; Giovanni, de C.; Lindhout, P.; Jong, de J.H.; Ricciardi, L.; Visser, R.G.F.; Bai, Y.

    2008-01-01

    The recessive gene ol-2 confers papilla-associated and race-non-specific resistance to tomato powdery mildew caused by Oidium neolycopersici. In order to facilitate marker assisted selection (MAS) in practical breeding programmes, we identified two simple sequence repeat (SSR) markers and one

  5. Pea powdery mildew er1 resistance is associated to loss-of-function mutations at a MLO homologous locus.

    Science.gov (United States)

    Pavan, Stefano; Schiavulli, Adalgisa; Appiano, Michela; Marcotrigiano, Angelo R; Cillo, Fabrizio; Visser, Richard G F; Bai, Yuling; Lotti, Concetta; Ricciardi, Luigi

    2011-12-01

    The powdery mildew disease affects several crop species and is also one of the major threats for pea (Pisum sativum L.) cultivation all over the world. The recessive gene er1, first described over 60 years ago, is well known in pea breeding, as it still maintains its efficiency as a powdery mildew resistance source. Genetic and phytopathological features of er1 resistance are similar to those of barley, Arabidopsis, and tomato mlo powdery mildew resistance, which is caused by the loss of function of specific members of the MLO gene family. Here, we describe the obtainment of a novel er1 resistant line by experimental mutagenesis with the alkylating agent diethyl sulfate. This line was found to carry a single nucleotide polymorphism in the PsMLO1 gene sequence, predicted to result in premature termination of translation and a non-functional protein. A cleaved amplified polymorphic sequence (CAPS) marker was developed on the mutation site and shown to be fully co-segregating with resistance in F(2) individuals. Sequencing of PsMLO1 from three powdery mildew resistant cultivars also revealed the presence of loss-of-function mutations. Taken together, results reported in this study strongly indicate the identity between er1 and mlo resistances and are expected to be of great breeding importance for the development of resistant cultivars via marker-assisted selection.

  6. Mapping of novel powdery mildew resistance gene Pm53 introgressed from Aegilops speltoides into soft red winter wheat

    Science.gov (United States)

    Powdery mildew of wheat (Triticum aestivum L.) is a major fungal disease in many areas of the world, caused by Blumeria graminis f.sp. tritici (Bgt). Host plant resistance is the preferred form of disease prevention because it is both economical and environmentally benign. Identification of new resi...

  7. Genetic mapping of MlUM15: an Aegilops neglecta-derived powdery mildew resistance gene in common wheat

    Science.gov (United States)

    Powdery mildew, caused by Blumeria graminis DC f. sp. tritici, is a major fungal disease of wheat (Triticum aestivum L.) in cool and humid climates. Race-specific host plant resistance is a reliable, economical, and environmentally benign form of disease prevention. The identification of molecular m...

  8. Preliminary evaluation of resistance to powdery mildew (Podosphaera xanthii) in AVRDC collections of bitter gourd (Momordica charantia L.)

    Science.gov (United States)

    Bitter gourd (Momordica charantia L.) is an important market vegetable in Asia, where it is also used in folk medicine to manage type 2 diabetes. Powdery mildew caused by Podosphaera xanthii is a serious fungal disease of bitter gourd and yield losses of up to 50% have been reported. After observi...

  9. On-farm and on-station evaluations of three orchard management approaches against apple scab and apple powdery mildew

    NARCIS (Netherlands)

    Holb, I.J.; Abonyi, F.; Buurma, J.; Heijne, B.

    2017-01-01

    In a three-year study (from 2012 to 2014), the efficacy of three apple management approaches (conventional, standard and advanced Integrated Pest Management - CON, IPM1 and IPM2, respectively) was aimed to investigate against apple scab and apple powdery mildew in on-station (small research scale)

  10. Development of Random Amplified Polymorphism DNA Markers Linked to Powdery Mildew Resistance Gene in Melon

    Directory of Open Access Journals (Sweden)

    Budi Setiadi Daryono

    2015-11-01

    Full Text Available A random amplified polymorphic DNA (RAPD marker linked to powdery mildew resistance gene (Pm-I in melon PI 371795 was reported. However, the RAPD marker has problem in scoring. To detect powdery mildew resistance gene (Pm-I in melon accurately, the RAPD marker was cloned and sequenced to design sequence characterized amplified region (SCAR markers. SCAPMAR5 marker derived from pUBC411 primer yielded a single DNA band at 1061 bp. Segregation of SCAPMAR5 marker in bulk of F2 plants demonstrated that the marker was co-segregated with RAPD marker from which the SCAR marker was originated. Moreover, results of SCAR analysis in diverse melons showed SCAPMAR5 primers obtained a single 1061 bp linked to Pm-I in resistant melon PI 371795 and PMAR5. On the other hand, SCAPMAR5 failed to detect Pm-I in susceptible melons. Results of this study revealed that SCAR analysis not only confirmed melons that had been clearly scored for resistance to Pm-I evaluated by RAPD markers, but also clarified the ambiguous resistance results obtained by the RAPD markers.   Key words: Cucumis melo L., Pm-I, RAPD, SCAPMAR5

  11. Essential oils and whole milk in the control of soybean powdery mildew

    Directory of Open Access Journals (Sweden)

    Fabiano José Perina

    2013-11-01

    Full Text Available This research aimed to evaluate the potential of essential oils (EOs and cow's whole milk (CWM in order to control soybean powdery mildew and to estimate the most effective concentrations of these natural products in reducing the disease severity on soybean plants. Three experiments were carried out: The first experiment evaluated and selected the most effective treatments to reduce the severity of soybean powdery mildew under greenhouse conditions; the second experiment evaluated the effect of CWM and EOs of citronella, lemongrass, eucalyptus, cinnamon and tea tree on the pathogen through the ultrastructure analysis of soybean leaflets infected by Erysiphe diffusa using the scanning electron microscope (SEM and light microscope (LM technology. In the third experiment, the most effective products were tested at several concentrations in order to define the most effective concentrations to reduce disease severity under greenhouse conditions. The treatments CWM (100mL L-1 and EOs of citronella, lemongrass and eucalyptus (1.0mL L-1, reduced the disease severity from 67 to 74%. Direct effects from all natural products tested on the structures of E. diffusa were demonstrated through the SEM and LM analysis. Concentrations at 1.5mL L-1 for EOs of citronella, lemongrass and eucalyptus and also at 180mL L-1 for the treatment CWM were the most effective against E. diffusa on soybean.

  12. Proteomic analysis of the compatible interaction of wheat and powdery mildew (Blumeria graminis f. sp. tritici).

    Science.gov (United States)

    Li, Jie; Yang, Xiwen; Liu, Xinhao; Yu, Haibo; Du, Congyang; Li, Mengda; He, Dexian

    2017-02-01

    Proteome characteristics of wheat leaves with the powdery mildew pathogen Blumeria graminis f. sp. tritici (Bgt) infection were investigated by two-dimensional electrophoresis and tandem MALDI-TOF/TOF-MS. We identified 46 unique proteins which were differentially expressed at 24, 48, and 72 h post-inoculation. The functional classification of these proteins showed that most of them were involved in photosynthesis, carbohydrate and nitrogen metabolism, defense responses, and signal transduction. Upregulated proteins included primary metabolism pathways and defense responses, while proteins related to photosynthesis and signal transduction were mostly downregulated. As expected, more antioxidative proteins were activated at the later infection stage than the earlier stage, suggesting that the antioxidative system of host plays a role in maintaining the compatible interaction between wheat and powdery mildew. A high accumulation of 6-phosphogluconate dehydrogenase and isocitrate dehydrogenase in infected leaves indicated the regulation of the TCA cycle and pentose phosphate pathway in parallel to the activation of host defenses. The downregulation of MAPK5 could be facilitated for the compatible interaction of wheat plants and Bgt. qRT-PCR analysis supported the data of protein expression profiles. Our results reveal the relevance of primary plant metabolism and defense responses during compatible interaction, and provide new insights into the biology of susceptible wheat in response to Bgt infection.

  13. Application of Osthol Induces a Resistance Response Against Powdery Mildew in Pumpkin Leave

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    Yong Jian Fan

    2007-09-01

    Full Text Available Plants can defend themselves against fungal infection by natural means inducedby biotic and abiotic elicitors. Osthol is a natural compound extracted from dried fruits ofCnidii Monnieri Fructus. In this study, it has been shown to not only be a fungicide withacceptable curative properties (control efficacy of 68.72, but it also showed a significantprophylactic effect (with control efficacy of 77.36 against pumpkin powdery mildew at aconcentration of 100 μg·mL-1. In pumpkin leaves with/or without inoculation ofSphaerotheca fuliginea, osthol treatment induced the accumulation of chitinase andperoxidase and enhanced the transcription of chitinase gene in non-inoculated leaves. Thepotentiation of phenylalanine amonia-lyase activity in leaves by osthol application andfollowing inoculation was absent in that with inoculation or osthol treatment, indicatingthat induced PAL in osthol-pretreated plants was inoculation-mediated. In conclusion, thisnatural compound could induce resistance response in the plant against powdery mildew.

  14. CEPF Western Ghats Special Series: Black mildews of Kodagu, Karnataka, India

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    C. Jagath Thimmaiah

    2013-12-01

    Full Text Available The systematic survey of the foliicolous fungi of Kodagu was initiated by one of the authors (VBH in the year 2002, conducted four field tours to the area and subsequently taken over by the other authors (CJT & MCJ. Of these, only black mildews are presented here. More than 400 collections of black mildews are collected from Kodagu recorded on 265 host plants belonging to 65 families of flowering plants represented three fungal groups: Meliolales, Asterinales and Schiffnerulaceae belonging to 20 fungal genera: Amazonia - 4, Appendiculella - 1, Armatella - 4, Asterdiella - 21, Asterina - 61, Asterolibertia - 2, Asterostomella - 5, Cirsosia - 2, Echidnodella - 2, Eupelte - 1, Irenopsis - 11, Ishwaramyces - 1, Lembosia - 4, Mahanteshamyces - 1, Meliola - 82, Meliolaster - 1, Prillieuxina - 2, Questieriella - 3, Sarcinella - 6, Schiffnerula - 9. Of these, Asteridiella kodavae, Meliola coorgiana, Meliola kodaguensis, Meliola madhucae, Meliola cauveriana and Meliola goniothalami are new species. The area forms type locality for several taxa. This is the first of its kind for the area and forms a base for the subsequent work.

  15. Transcriptomes That Confer to Plant Defense against Powdery Mildew Disease in Lagerstroemia indica

    Directory of Open Access Journals (Sweden)

    Xinwang Wang

    2015-01-01

    Full Text Available Transcriptome analysis was conducted in two popular Lagerstroemia cultivars: “Natchez” (NAT, a white flower and powdery mildew resistant interspecific hybrid and “Carolina Beauty” (CAB, a red flower and powdery mildew susceptible L. indica cultivar. RNA-seq reads were generated from Erysiphe australiana infected leaves and de novo assembled. A total of 37,035 unigenes from 224,443 assembled contigs in both genotypes were identified. Approximately 85% of these unigenes have known function. Of them, 475 KEGG genes were found significantly different between the two genotypes. Five of the top ten differentially expressed genes (DEGs involved in the biosynthesis of secondary metabolites (plant defense and four in flavonoid biosynthesis pathway (antioxidant activities or flower coloration. Furthermore, 5 of the 12 assembled unigenes in benzoxazinoid biosynthesis and 7 of 11 in flavonoid biosynthesis showed higher transcript abundance in NAT. The relative abundance of transcripts for 16 candidate DEGs (9 from CAB and 7 from NAT detected by qRT-PCR showed general agreement with the abundances of the assembled transcripts in NAT. This study provided the first transcriptome analyses in L. indica. The differential transcript abundance between two genotypes indicates that it is possible to identify candidate genes that are associated with the plant defenses or flower coloration.

  16. Inheritance of Powdery Mildew Resistance in Cucumber (Cucumis sativus L.) and Development of an AFLP Marker for Resistance Detection

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Cucumber powdery mildew is one of the most destructive diseases of cucumber throughout the world. In the present study, inheritance of powdery mildew resistance in three crosses, and linkage of resistance with amplified fragment length polymorphism (AFLP) markers are studied to formulate efficient strategies for breeding cultivars resistant to powdery mildew. The joint analysis of multiple generations and AFLP technique has been applied in this study. The best model is the one with two major genes, additive, dominant, and epistatic effects, plus polygenes with additive, dominant, and epistatic effects (E-1-0 model). The heritabilities of the major genes varied from 64.26% to 97.82%, and susceptibility was incompletely dominant for the two major genes in the three crosses studied. The additive effects of the two major genes and the dominant effect of the second major gene were high, and the epistatic effect of the additive-dominant between the two major genes was the highest in cross Ⅰ. In cross Ⅱ, the absolute value of the additive effect, dominant effect, and potential ratio of the first major gene were far higher than those of the second major gene, and the epistatic effect of the additive-additive was the highest. The genetic parameters of the two major genes in cross Ⅲ were similar to those in cross Ⅱ. Correlation and regression analyses showed that marker E25/M63-103 was linked to a susceptible gene controlling powdery mildew resistance. The marker could account for 19.98% of the phenotypic variation. When the marker was tested on a diverse set of 29 cucumber lines, the correlation between phenotype and genotype was not significant, which suggested cultivar specialty of gene expression or different methods of resistance to powdery mildew. The target DNA fragment was 103 bp in length, and only a small part was found to be homologous to DNA in the other species evaluated,which indicated that it was unique to the cucumber genome.

  17. mlo-based powdery mildew resistance in hexaploid bread wheat generated by a non-transgenic TILLING approach.

    Science.gov (United States)

    Acevedo-Garcia, Johanna; Spencer, David; Thieron, Hannah; Reinstädler, Anja; Hammond-Kosack, Kim; Phillips, Andrew L; Panstruga, Ralph

    2017-03-01

    Wheat is one of the most widely grown cereal crops in the world and is an important food grain source for humans. However, wheat yields can be reduced by many abiotic and biotic stress factors, including powdery mildew disease caused by Blumeria graminis f.sp. tritici (Bgt). Generating resistant varieties is thus a major effort in plant breeding. Here, we took advantage of the non-transgenic Targeting Induced Lesions IN Genomes (TILLING) technology to select partial loss-of-function alleles of TaMlo, the orthologue of the barley Mlo (Mildew resistance locus o) gene. Natural and induced loss-of-function alleles (mlo) of barley Mlo are known to confer durable broad-spectrum powdery mildew resistance, typically at the expense of pleiotropic phenotypes such as premature leaf senescence. We identified 16 missense mutations in the three wheat TaMlo homoeologues, TaMlo-A1, TaMlo-B1 and TaMlo-D1 that each lead to single amino acid exchanges. Using transient gene expression assays in barley single cells, we functionally analysed the different missense mutants and identified the most promising candidates affecting powdery mildew susceptibility. By stacking of selected mutant alleles we generated four independent lines with non-conservative mutations in each of the three TaMlo homoeologues. Homozygous triple mutant lines and surprisingly also some of the homozygous double mutant lines showed enhanced, yet incomplete, Bgt resistance without the occurrence of discernible pleiotropic phenotypes. These lines thus represent an important step towards the production of commercial non-transgenic, powdery mildew-resistant bread wheat varieties.

  18. Two major er1 alleles confer powdery mildew resistance in three pea cultivars bred in Yunnan Province, China

    Institute of Scientific and Technical Information of China (English)

    Suli Sun; Yuhua He; Cheng Dai; Canxing Duan; Zhendong Zhu

    2016-01-01

    Powdery mildew, caused by Erysiphe pisi D.C., is an important disease of pea (Pisum sativum L.). The use of cultivars carrying powdery mildew resistance alleles at the er1 locus is the most effective and economical means of controlling this disease. The objectives of this study were to screen Chinese elite pea cultivars for resistance to E. pisi and to identify the responsible gene at the er1 locus. Among the 37 pea cultivars tested, three (Yunwan 8, Yunwan 21, and Yunwan 23) were immune to E. pisi infection in phenotypic evaluations. The full-length cDNA sequences of the er1 candidate gene, PsMLO1, from the three resistant cultivars and control plants were analyzed. Comparison of the cDNA sequences of 10 clones revealed differences among the powdery mildew-resistant cultivars, susceptible controls, and wild-type cultivar Sprinter. The observed resistance in Yunwan 8 plants resulted from a point mutation (C→G) at position 680 of PsMLO1 that introduced a stop codon, leading to premature termination of protein synthesis. The responsible resistance allele was identified as er1–1. Powdery mildew resistance in Yunwan 21 and Yunwan 23 plants was caused by identical insertions or deletions in PsMLO1. Three distinct PsMLO1 transcripts were observed in Yunwan 21 and Yunwan 23 plants. These transcripts were characterized by a 129-bp deletion and 155-and 220-bp insertions, respectively. The responsible resistance allele was identified as er1–2. We have characterized two important er1 alleles in three E. pisi-resistant pea cultivars bred in Yunnan Province, China. These cultivars represent important genetic resources for the breeding of powdery mildew-resistant pea cultivars.

  19. Identification of QTL for adult-plant resistance to powdery mildew in Chinese wheat landrace Pingyuan 50

    Institute of Scientific and Technical Information of China (English)

    Muhammad; Azeem; Asad; Bin; Bai; Caixia; Lan; Jun; Yan; Xianchun; Xia; Yong; Zhang; Zhonghu; He

    2014-01-01

    Powdery mildew caused by Blumeria graminis f. sp. tritici is one of the major wheat diseases worldwide. The Chinese wheat landrace Pingyuan 50 has shown adult-plant resistance(APR)to powdery mildew in the field for over 60 years. To dissect the genetic basis of APR to powdery mildew in this cultivar, a mapping population of 137 double haploid(DH) lines derived from Pingyuan 50/Mingxian 169 was evaluated in replicated field trials for two years in Beijing(2009–2010 and 2010–2011) and one year in Anyang(2009–2010). A total of 540 polymorphic SSR markers were genotyped on the entire population for construction of a linkage map and QTL analysis. Three QTL were mapped on chromosomes 2BS(QPm.caas-2BS.2), 3BS(QPm.caas-3BS),and 5AL(QPm.caas-5AL) with the resistance alleles contributed by Pingyuan 50 explaining 5.3%,10.2%, and 9.1% of the phenotypic variances, respectively, and one QTL on chromosome 3BL(QPm.caas-3BL) derived from Mingxian 169 accounting for 18.1% of the phenotypic variance.QPm.caas-3BS, QPm.caas-3BL, and QPm.caas-5AL appear to be new powdery mildew APR loci.QPm.caas-2BS.2 and QPm.caas-5AL are possibly pleiotropic or closely linked resistance loci to stripe rust resistance QTL. Pingyuan 50 could be a potential genetic resource to facilitate breeding for improved APR to both powdery mildew and stripe rust.

  20. Loss of function in Mlo orthologs reduces susceptibility of pepper and tomato to powdery mildew disease caused by Leveillula taurica.

    Directory of Open Access Journals (Sweden)

    Zheng Zheng

    Full Text Available Powdery mildew disease caused by Leveillula taurica is a serious fungal threat to greenhouse tomato and pepper production. In contrast to most powdery mildew species which are epiphytic, L. taurica is an endophytic fungus colonizing the mesophyll tissues of the leaf. In barley, Arabidopsis, tomato and pea, the correct functioning of specific homologues of the plant Mlo gene family has been found to be required for pathogenesis of epiphytic powdery mildew fungi. The aim of this study was to investigate the involvement of the Mlo genes in susceptibility to the endophytic fungus L. taurica. In tomato (Solanum lycopersicum, a loss-of-function mutation in the SlMlo1 gene results in resistance to powdery mildew disease caused by Oidium neolycopersici. When the tomato Slmlo1 mutant was inoculated with L. taurica in this study, it proved to be less susceptible compared to the control, S. lycopersicum cv. Moneymaker. Further, overexpression of SlMlo1 in the tomato Slmlo1 mutant enhanced susceptibility to L. taurica. In pepper, the CaMlo2 gene was isolated by applying a homology-based cloning approach. Compared to the previously identified CaMlo1 gene, the CaMlo2 gene is more similar to SlMlo1 as shown by phylogenetic analysis, and the expression of CaMlo2 is up-regulated at an earlier time point upon L. taurica infection. However, results of virus-induced gene silencing suggest that both CaMlo1 and CaMlo2 may be involved in the susceptibility of pepper to L. taurica. The fact that overexpression of CaMlo2 restored the susceptibility of the tomato Slmlo1 mutant to O. neolycopersici and increased its susceptibility to L. taurica confirmed the role of CaMlo2 acting as a susceptibility factor to different powdery mildews, though the role of CaMlo1 as a co-factor for susceptibility cannot be excluded.

  1. Identification of QTL for adult-plant resistance to powdery mildew in Chinese wheat landrace Pingyuan 50

    Directory of Open Access Journals (Sweden)

    Muhammad Azeem Asad

    2014-10-01

    Full Text Available Powdery mildew caused by Blumeria graminis f. sp. tritici is one of the major wheat diseases worldwide. The Chinese wheat landrace Pingyuan 50 has shown adult-plant resistance (APR to powdery mildew in the field for over 60 years. To dissect the genetic basis of APR to powdery mildew in this cultivar, a mapping population of 137 double haploid (DH lines derived from Pingyuan 50/Mingxian 169 was evaluated in replicated field trials for two years in Beijing (2009–2010 and 2010–2011 and one year in Anyang (2009–2010. A total of 540 polymorphic SSR markers were genotyped on the entire population for construction of a linkage map and QTL analysis. Three QTL were mapped on chromosomes 2BS (QPm.caas-2BS.2, 3BS (QPm.caas-3BS, and 5AL (QPm.caas-5AL with the resistance alleles contributed by Pingyuan 50 explaining 5.3%, 10.2%, and 9.1% of the phenotypic variances, respectively, and one QTL on chromosome 3BL (QPm.caas-3BL derived from Mingxian 169 accounting for 18.1% of the phenotypic variance. QPm.caas-3BS, QPm.caas-3BL, and QPm.caas-5AL appear to be new powdery mildew APR loci. QPm.caas-2BS.2 and QPm.caas-5AL are possibly pleiotropic or closely linked resistance loci to stripe rust resistance QTL. Pingyuan 50 could be a potential genetic resource to facilitate breeding for improved APR to both powdery mildew and stripe rust.

  2. Two major er1 alleles confer powdery mildew resistance in three pea cultivars bred in Yunnan Province, China

    Directory of Open Access Journals (Sweden)

    Suli Sun

    2016-10-01

    Full Text Available Powdery mildew, caused by Erysiphe pisi D.C., is an important disease of pea (Pisum sativum L.. The use of cultivars carrying powdery mildew resistance alleles at the er1 locus is the most effective and economical means of controlling this disease. The objectives of this study were to screen Chinese elite pea cultivars for resistance to E. pisi and to identify the responsible gene at the er1 locus. Among the 37 pea cultivars tested, three (Yunwan 8, Yunwan 21, and Yunwan 23 were immune to E. pisi infection in phenotypic evaluations. The full-length cDNA sequences of the er1 candidate gene, PsMLO1, from the three resistant cultivars and control plants were analyzed. Comparison of the cDNA sequences of 10 clones revealed differences among the powdery mildew-resistant cultivars, susceptible controls, and wild-type cultivar Sprinter. The observed resistance in Yunwan 8 plants resulted from a point mutation (C → G at position 680 of PsMLO1 that introduced a stop codon, leading to premature termination of protein synthesis. The responsible resistance allele was identified as er1–1. Powdery mildew resistance in Yunwan 21 and Yunwan 23 plants was caused by identical insertions or deletions in PsMLO1. Three distinct PsMLO1 transcripts were observed in Yunwan 21 and Yunwan 23 plants. These transcripts were characterized by a 129-bp deletion and 155- and 220-bp insertions, respectively. The responsible resistance allele was identified as er1–2. We have characterized two important er1 alleles in three E. pisi-resistant pea cultivars bred in Yunnan Province, China. These cultivars represent important genetic resources for the breeding of powdery mildew-resistant pea cultivars.

  3. Reprint of "Sequence and phylogenetic analyses of novel totivirus-like double-stranded RNAs from field-collected powdery mildew fungi".

    Science.gov (United States)

    Kondo, Hideki; Hisano, Sakae; Chiba, Sotaro; Maruyama, Kazuyuki; Andika, Ida Bagus; Toyoda, Kazuhiro; Fujimori, Fumihiro; Suzuki, Nobuhiro

    2016-07-02

    The identification of mycoviruses contributes greatly to understanding of the diversity and evolutionary aspects of viruses. Powdery mildew fungi are important and widely studied obligate phytopathogenic agents, but there has been no report on mycoviruses infecting these fungi. In this study, we used a deep sequencing approach to analyze the double-stranded RNA (dsRNA) segments isolated from field-collected samples of powdery mildew fungus-infected red clover plants in Japan. Database searches identified the presence of at least ten totivirus (genus Totivirus)-like sequences, termed red clover powdery mildew-associated totiviruses (RPaTVs). The majority of these sequences shared moderate amino acid sequence identity with each other (powdery mildew fungus populations infecting red clover plants in the field.

  4. Separation performance of cucurbit[8]uril and its coordination complex with cadmium (II) in capillary gas chromatography.

    Science.gov (United States)

    Sun, Tao; Ji, Ningning; Qi, Meiling; Tao, Zhu; Fu, Ruonong

    2014-05-23

    Here we report the investigation of using cucurbit[8]uril (CB8) and its coordination complex with cadmium (II) (CB8-Cd) as stationary phases for capillary gas chromatography (GC). The prepared capillary columns of CB8 and CB8-Cd stationary phases achieved column efficiency of 2200plates/m and 1508plates/m, respectively, and showed weak polarity based on the measured McReynolds constants. Their separation performance was investigated by GC separation of mixtures of different types while a commercial column was used for comparison. The CB8 stationary phase achieved high resolution for a wide range of analytes from nonpolar to polar while the CB8-Cd stationary phase exhibited good separation mainly for nonpolar to weak polar analytes. The CB stationary phases differ from the commercial one in terms of retention behaviors and resolving ability due to their different molecular interactions with analytes. Moreover, energy effect on the retention of analytes on CB8 and CB8-Cd stationary phases was examined, showing that retention on CB8 column was determined mainly by enthalpy change for polar analytes and by both enthalpy change and entropy change for weak polar analytes whereas retention on CB8-Cd column was mainly controlled by entropy change. This work demonstrates the great potential of CB8 and CB8-Cd stationary phases as a new type of GC stationary phases in GC analysis.

  5. Preparation and characterization of inclusion complexes of antitumor camptothecin with cucurbit[n=7,8]urils

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    The slightly water-soluble anticancer drug camptothecin(CPT) and its inclusion complexes with cucurbit[n = 7,8]uril(Q[n](n = 7,8)) were investigated.The formation of 1:2 complexes with Q[n](n = 7,8) in aqueous solution was confirmed by fluorescence spectroscopy and the apparent stability constants were determined to be higher than 3.01 × 1012 L2/mol2.The solid inclusion complexes of CPT and Q[n](n = 7,8) were also prepared by the co-evaporation method and characterized by Fourier transformation-infrared spectroscopy,differential scanning calorimetry and powder X-ray diffraction.Aqueous solubility and dissolution studies indicate that the complexes exhibited significantly increased dissolution rates compared with the pure drug and physical mixtures.The potential of Q[7] or Q[8] for stabilizing lactone modality of CPT was investigated by the High Performance Liquid Chromatography(HPLC) method.The results reveal more than 63% CPT lactone form(active form) in CPT-Q[7] or Q[8] complexes compared to only 36% CPT lactone form in the absence of Q[7] or Q[8] after being incubated in the phosphate buffer solution(pH 7.4 at 37 °C) for 5h.

  6. Yellowing disease in zucchini squash produced by mixed infections of Cucurbit yellow stunting disorder virus and Cucumber vein yellowing virus.

    Science.gov (United States)

    Gil-Salas, Francisco M; Peters, Jeff; Boonham, Neil; Cuadrado, Isabel M; Janssen, Dirk

    2011-11-01

    Zucchini squash is host to Cucurbit yellow stunting disorder virus (CYSDV), a member of the genus Crinivirus, and Cucumber vein yellowing virus (CVYV), a member of the genus Ipomovirus, both transmitted by the whitefly Bemisia tabaci. Field observations suggest the appearance of new symptoms observed on leaves of zucchini squash crops when both viruses were present. When infected during controlled experiments with CYSDV only, zucchini plants showed no obvious symptoms and the virus titer decreased between 15 and 45 days postinoculation (dpi), after which it was no longer detected. CVYV caused inconspicuous symptoms restricted to vein clearing on some of the apical leaves and the virus accumulated progressively between 15 and 60 dpi. Similar accumulations of virus followed single inoculations with the potyvirus Zucchini yellow mosaic virus (ZYMV) and plants showed severe stunting, leaf deformation, and mosaic yellowing. However, in mixed infections with CYSDV and CVYV, intermediate leaves showed chlorotic mottling which evolved later to rolling, brittleness, and complete yellowing of the leaf lamina, with exception of the veins. No consistent alteration of CVYV accumulation was detected but the amounts of CYSDV increased ≈100-fold and remained detectable at 60 dpi. Such synergistic effects on the titer of the crinivirus and symptom expression were not observed when co-infected with ZYMV.

  7. A Binary Bivalent Supramolecular Assembly Platform Based on Cucurbit[8]uril and Dimeric Adapter Protein 14-3-3.

    Science.gov (United States)

    de Vink, Pim J; Briels, Jeroen M; Schrader, Thomas; Milroy, Lech-Gustav; Brunsveld, Luc; Ottmann, Christian

    2017-07-24

    Interactions between proteins frequently involve recognition sequences based on multivalent binding events. Dimeric 14-3-3 adapter proteins are a prominent example and typically bind partner proteins in a phosphorylation-dependent mono- or bivalent manner. Herein we describe the development of a cucurbit[8]uril (Q8)-based supramolecular system, which in conjunction with the 14-3-3 protein dimer acts as a binary and bivalent protein assembly platform. We fused the phenylalanine-glycine-glycine (FGG) tripeptide motif to the N-terminus of the 14-3-3-binding epitope of the estrogen receptor α (ERα) for selective binding to Q8. Q8-induced dimerization of the ERα epitope augmented its affinity towards 14-3-3 through a binary bivalent binding mode. The crystal structure of the Q8-induced ternary complex revealed molecular insight into the multiple supramolecular interactions between the protein, the peptide, and Q8. © 2017 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA.

  8. A competitive strategy based on cucurbit[7]uril supramolecular interaction for simple and sensitive detection of dibucaine.

    Science.gov (United States)

    Li, Yan; Li, Chang-Feng; Du, Li-Ming; Feng, Jian-Xia; Liu, Hai-Long; Fu, Yun-Long

    2015-01-01

    In this work, the competitive interaction between dibucaine and three fluorescent probes (i.e., berberine, palmatine, and coptisine) for occupancy of the cucurbit[7]uril (CB[7]) cavity was studied by fluorescence spectra, UV-visible absorption spectra, (1)H NMR spectra, and theoretical calculations in acidic aqueous solution. Based on the fluorescence enhancement of berberine, palmatine, and coptisine upon binding with CB[7], respectively, a series of fluorescence detection methods for dibucaine were proposed. At the optimized conditions, the fluorescence intensity of berberine-CB[7], palmatine-CB[7], and coptisine-CB[7] complexes showed negative correlation to the concentration of dibucaine, which led to a series of simple and sensitive fluorescence methods for the determination of dibucaine for the first time. Linear ranges obtained in the detection of the dibucaine were 0.018-3.34 μmol L(-1), 0.032-4.47 μmol L(-1), and 0.079-4.42 μmol L(-1) with detection limits of 6.0 nmol L(-1), 12.0 nmol L(-1), and 25.0 nmol L(-1), respectively. Moreover, the proposed method was successfully applied for the determination of the drug in biological fluids. The competitive mode based on CB[7] superstructure provided a promising assay strategy for fluorescence detection in various potential applications.

  9. Controlled gelation kinetics of cucurbit[7]uril-adamantane cross-linked supramolecular hydrogels with competing guest molecules

    Science.gov (United States)

    Chen, Hao; Hou, Shengzhen; Ma, Haili; Li, Xu; Tan, Yebang

    2016-02-01

    Gelation kinetics of hydrogels is closely linked to many applications such as the development of injectable and printable hydrogels. However, the control of gelation kinetics without compromising the structure and other properties of the hydrogels, remains a challenge. Here, we demonstrate a method to control the gelation kinetics of cucurbit[7]uril-adamantane (CB[7]-AD) cross-linked supramolecular hydrogels by using competing guest molecules. The association between CB[7] and AD moieties on the polymer backbone was impeded by pre-occupying the CB[7] cavity with competing guest molecules. By using various guest molecules and concentrations, the gelation of the hydrogels could be varied from seconds to hours. The strong interaction of CB[7]-AD pair endue the hydrogels good mechanical properties and stability. Moreover, the binding of functionalized guest molecules of CB[7] moieties offers a facile approach for tailoring of the hydrogels’ scaffold. Combined with hydrogel injection and printing technology, this method offers an approach for the development of hydrogels with advanced temporal and spatial complexity.

  10. Laser Induced breakdown spectroscopy: A rapid tool for the identification and quantification of minerals in cucurbit seeds.

    Science.gov (United States)

    Singh, Jyotsana; Kumar, Rohit; Awasthi, Shikha; Singh, Vinti; Rai, A K

    2017-04-15

    Laser-induced breakdown spectroscopy (LIBS) was investigated to estimate the viability as a simple and rapid method for analysis of nutrient elements in seed kernels of cucurbits. LIBS spectra were recorded in the range of 200-975nm by using Q-switched Nd:YAG laser at 532nm (4ns, 10Hz) attached to echelle spectrometer with intensified charged coupled device (ICCD). The spectral analysis revealed the presence of several elements like C, O, N, Mg, Ca, Na and K in seeds. The quantification of elements (Mg, Ca, Na and K) through LIBS was done using calibration curve method in which all calibration curve shows good linearity (r>0.95). The result obtained through LIBS was in reasonable agreement with that obtained through atomic absorption spectroscopy (AAS). Principal Component Analysis (PCA) was also applied to the LIBS data for rapid categorization of seed samples belonging to same species although samples have similar nutrient elements. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. PH responsive self-assembly of cucurbit[7]urils and polystyrene-block- polyvinylpyridine micelles for hydrophobic drug delivery

    KAUST Repository

    Moosa, B.A.

    2013-01-01

    Polystyrene-block-polyvinylpyridine (PS-b-P4VP) polypseudorotaxanes with cucurbit[7]urils (CB[7]) were prepared from water soluble PS-b-P4VPH+ polymer and CB[7] in aqueous solution at room temperature. At acidic and neutral pH, the pyridinium block of PS-b-P4VP is protonated (PS-b-P4VPH +) pushing CB[7] to preferably host the P4VP block. At basic pH (pH 8), P4VP is not charged and thus is not able to strongly complex CB[7]. This phenomenon was verified further by monitoring the release of pyrene, a hydrophobic cargo model, from a PS-b-P4VPH+/CB[7] micellar membrane. Release study of UV active pyrene from the membrane at different pH values revealed that the system is only operational under basic conditions and that the host-guest interaction of CB[7] with P4VPH+ significantly slows down cargo release.

  12. Lagged association between powdery mildew leaf severity, airborne inoculum, weather, and crop losses in strawberry.

    Science.gov (United States)

    Carisse, O; Morissette-Thomas, V; Van der Heyden, H

    2013-08-01

    Knowledge about epidemiology and the impact of disease on yield is fundamental for establishing effective management strategies. The purpose of this study was to investigate the relationship between foliar strawberry mildew severity, Podosphaera aphanis airborne inoculum concentration, weather, and subsequent crop losses for day-neutral strawberry. The experiment was conducted at three, five, and four sites in 2006, 2007, and 2008, respectively, for a total of 12 epidemics. At each site, data were collected on 25 plants at 2-day intervals from the end of May to early October for a total of 60 to 62 samplings annually. First, seasonal crop losses were statistically described; then, a lagged regression model was developed to describe crop losses from the parameters that were significantly associated with losses. There was a strong positive linear relationship between seasonal crop losses and the area under the leaf disease progress curve (R(2) = 0.90) and daily mean airborne conidia concentration (R(2) = 0.86), and a negative linear relationship between crop losses and time to 5% loss (R(2) = 0.76) and time to 5% leaf area diseased (R(2) = 0.61). Among the 53 monitoring- and weather-based variables analyzed, percent leaf area diseased, log10-transformed airborne inoculum concentration, and weather variables related to temperature were significantly associated with crop losses. However, polynomial distributed lag regression models built with weather variables were not accurate in predicting losses, with the exception of a model based on a combined temperature and humidity variable, which provided accurate prediction of the data used to construct the model but not of independent data. Overall, the model based on log10-transformed airborne inoculum concentration did not provide accurate crop loss predictions. The model built using percent leaf area diseased with a time lag of 8 days (n = 4) and a polynomial degree of 2 provided a good description of the crop-loss data

  13. Characterization of resistance mechanisms to powdery mildew (Erysiphe betae) in beet (Beta vulgaris).

    Science.gov (United States)

    Fernández-Aparicio, Mónica; Prats, Elena; Emeran, Amero A; Rubiales, Diego

    2009-04-01

    Beet powdery mildew incited by Erysiphe betae is a serious foliar fungal disease of worldwide distribution causing losses of up to 30%. In the present work, we searched for resistance in a germplasm collection of 184 genotypes of Beta vulgaris including fodder (51 genotypes), garden (60 genotypes), leaf (51 genotypes), and sugar (22 genotypes) beet types. Resistant genotypes were identified in the four beet types under study. In addition, mechanisms underlying resistance were dissected through histological studies. These revealed different resistance mechanisms acting at different fungal developmental stages, i.e., penetration resistance, early and late cell death, or posthaustorial resistance. Most genotypes were able to hamper fungal development at several stages. The later are interesting for breeding aiming to resistance durability. Furthermore, characterization of defense mechanisms will be useful for further cellular and molecular studies to unravel the bases of resistance in this species.

  14. Single-cell transcript profiling of barley attacked by the powdery mildew fungus

    DEFF Research Database (Denmark)

    Gjetting, Torben; Hagedorn, Peter; Schweizer, Patrick

    2007-01-01

    attacked at the same time may resist fungal penetration. To date, the mixed cellular responses seen even in susceptible host leaves have made it difficult to relate induced changes in gene expression to resistance or susceptibility in bulk leaf samples. By microextraction of cell-specific m......RNA and subsequent cDNA array analysis, we have successfully obtained separate gene expression profiles for specific mildew-resistant and -infected barley cells. Thus, for the first time, it is possible to identify genes that are specifically regulated in infected cells and, presumably, involved in fungal...... establishment. Further, although much is understood about the genetic basis of effective papilla resistance associated with mutant mlo barley, we provide here the first evidence for gene regulation associated with effective papilla-based nonspecific resistance expressed in nominally "susceptible" wild...

  15. Messages from Powdery Mildew DNA:How the Interplay with a Host Moulds Pathogen Genomes

    Institute of Scientific and Technical Information of China (English)

    Pietro D. Spanu

    2014-01-01

    The genomes of the barley,Arabidopsis and pea powdery mildew are signiifcantly larger than those of related fungi. This is due to an extraordinary expansion of retro-trasposons that are evident as repetitive elements in the sequence. The protein coding genes are fewer than expected due to an overall reduction in the size of gene families, a reduction in the number of paralogs and because of the loss of certain metabolic pathways. Many of these changes have also been observed in the genomes of other taxonomically unrelated obligate biotrophic pathogens. The only group of genes that bucks the trend of gene loss, are those encoding small secreted proteins that bear the hall marks of effectors.

  16. Chemical control of pepper mildew Phytophthora capsici (Leon, on early peppers in Tunisia

    Directory of Open Access Journals (Sweden)

    Moens, M.

    1986-01-01

    Full Text Available Peper mildew, caused by Phytophthora capsici, is a serious problem in the intensive early cultures of the Tunisian Nebhana region. In experiments done in very severe conditions of contamination, the best control was obtained by a weekly soil drench (100 ml per plant with the commercial metalaxyl + maneb mixture (40 g + 192g. hh1. The protection continued up to 5 weeks after the end of the treatment. The action of foliar sprayings was slower and not remanant. The effectiveness of captafol and phosethylaluminium soil drenches (0.2g and 0.4 g per plant was poor. An improvement of the control was obtained by diluting a dose of 0, 4g captafol per plant in a greater quantity of water (500 ml. Phytotoxic symptoms appeared on the leaves ofthe pepper plants after all metalaxyl + maneb treatments, but not after the other fungicide applications.

  17. Effects of elevated CO2 and temperature on interactions of zucchini and powdery mildew

    Directory of Open Access Journals (Sweden)

    Massimo PUGLIESE

    2013-01-01

    Full Text Available Effects of increased CO2 and temperature on powdery mildew (Podosphaera xanthii of zucchini (Cucurbita pepo, were evaluated under controlled conditions. Zucchini plants were grown in phytotrons under four different simulated climatic conditions: 450 ppm of CO2 at standard (18°C night, 24°C day and elevated temperatures (22°C night, 28°C day, elevated CO2 (800 ppm with standard temperature and elevated CO2 (800 ppm with elevated temperature (4°C higher than standard. Physiological responses of zucchini and pathogen development were studied. Under elevated CO2 both healthy and infected zucchini plants grew better when temperature was lower. Elevated CO2 generally caused no significant differences in pathogen development or disease severity, whereas elevated temperature stimulated the development of the pathogen. A combination of elevated CO2 and temperature always stimulated the development of the pathogen and disease severity compared to standard conditions.

  18. Synthesis of honeycomb-like palladium nanostructures by using cucurbit[7]uril and their catalytic activities for reduction of 4-nitrophenol

    Energy Technology Data Exchange (ETDEWEB)

    Premkumar, Thathan [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); The University College/Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Geckeler, Kurt E., E-mail: keg@gist.ac.kr [Department of Materials Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of); Department of Nanobio Materials and Electronics (WCU), Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju 500-712 (Korea, Republic of)

    2014-12-15

    An eco-friendly one-pot method to synthesize self-assembled palladium nanoclusters using a macrocycle, namely cucurbit[7]uril, in the alkaline medium without employing any special reducing or capping agents and/or external energy at room temperature is described. This greener approach, which utilizes water as a benign solvent and biocompatible cucurbit[7]uril as both reducing and protecting agents, can be applied to synthesize other noble metal nanoparticles such as gold, silver, and platinum. Owing to unique structural arrangement of cucurbit[7]uril, it was possible to prepare palladium nanoclusters of honeycomb-like structure irrespective of the reaction conditions. The honeycomb-like palladium nanoclusters were characterized using transmission electron microscopy (TEM), higher-resolution TEM (HR-TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), UV–vis, and FT-IR spectroscopy. Significantly, the synthesized palladium nanoclusters exhibited catalytic activity for the reduction reaction of 4-nitrophenol at room temperature. The approach launched here is easy, green, and user-friendly in contrast to the conventional techniques using polymers or surfactants and harsh reductants. - Highlights: • A simple and one-pot method to synthesis palladium nanostructures with honey-comb like structure. • The strategy established here does not require any harsh and toxic reducing agents. • It has a potential to be a general method for the synthesis of metal nanoparticles in water medium. • Palladium nanoclusters can be used as catalyst for the reduction reaction of 4-nitrophenol. • This system makes a novel platform for industrial and biomedical applications.

  19. A combined molecular dynamics simulation and quantum mechanics study on mercaptopurine interaction with the cucurbit [6,7] urils: Analysis of electronic structure.

    Science.gov (United States)

    Zaboli, Maryam; Raissi, Heidar

    2018-01-05

    In the current study, the probability of complex formation between mercaptopurine drug with cucurbit[6]urils and cucurbit[7]urils has been investigated. The calculations for geometry optimization of complexes have been carried out by means of DFT (B3LYP), DFT-D (B3LYP-D) and M06-2X methods. The Atoms In Molecules (AIM), Natural Bond Orbital (NBO), NMR, the density of states (DOSs) and frontier molecular orbital (MO) analyses have been done on the inclusion complexes. In addition, the UV-Vis spectra of the first eight states have been obtained by CAM-B3LYP/TD-DFT calculation. The obtained results of the complexation process reveal that CB[7]-DRG complexes are more favorable than that of CB[6]-DRG interactions. Furthermore, our theoretical results show that configurations III and I are the most stable configurations related to the CB[6]/DRG and CB[7]/DRG interactions, respectively. The positive ∇(2)ρ(r) and HC values at the bond critical points indicate that exist the weak H-bonds between CB[6] and CB[7] with H atoms of the drug molecule. The obtained negative binding energy values of CB[7]-DRG interaction in solution phase show the stability of these complexes in the aqueous medium. Also, all of the observed parameters of molecular dynamics simulation such as the number of contacts, hydrogen bonding, center-of-mass distance and van der Waals energy values confirm the encapsulation of mercaptopurine molecule inside the cucurbit[7]urils cavity at about 3.2ns. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. Powdery Mildew Decreases the Radial Growth of Oak Trees with Cumulative and Delayed Effects over Years

    Science.gov (United States)

    Bert, Didier; Lasnier, Jean-Baptiste; Capdevielle, Xavier; Dugravot, Aline; Desprez-Loustau, Marie-Laure

    2016-01-01

    Quercus robur and Q. petraea are major European forest tree species. They have been affected by powdery mildew caused by Erysiphe alphitoides for more than a century. This fungus is a biotrophic foliar pathogen that diverts photosynthetate from the plant for its own nutrition. We used a dendrochronological approach to investigate the effects of different levels of infection severity on the radial growth of young oak trees. Oak infection was monitored at individual tree level, at two sites in southwestern France, over a five-year period (2001–2005). Mean infection severity was almost 75% (infected leaf area) at the end of the 2001 growing season, at both sites, but only about 40% in 2002, and 8%, 5% and 2% in 2003, 2004 and 2005, respectively. Infection levels varied considerably between trees and were positively related between 2001 and 2002. Increment cores were taken from each tree to assess annual ring widths and increases in basal area. Annual radial growth was standardised to take the effect of tree size into account. Annual standardised radial growth was significantly and negatively correlated with infection severity in the same year, for both 2001 and 2002, and at both sites. The decrease in growth reached 70–90% for highly infected trees. The earlywood width was poorly correlated with infection severity, but the proportion of latewood in tree rings was lower in highly infected trees (60%) than in less heavily infected trees (85%). Infection in 2001 and 2002 was found to have a cumulative effect on radial growth in these years, together with a delayed effect detectable in 2003. Thus, even non-lethal pathogens like powdery mildew can have a significant impact on tree functioning. This impact should be taken into account in growth and yield models, to improve predictions of forest net primary production. PMID:27177029

  1. QTL mapping of powdery mildew resistance in WI 2757 cucumber (Cucumis sativus L.).

    Science.gov (United States)

    He, Xiaoming; Li, Yuhong; Pandey, Sudhakar; Yandell, Brain S; Pathak, Mamta; Weng, Yiqun

    2013-08-01

    Powdery mildew (PM) is a very important disease of cucumber (Cucumis sativus L.). Resistant cultivars have been deployed in production for a long time, but the genetic mechanisms of PM resistance in cucumber are not well understood. A 3-year QTL mapping study of PM resistance was conducted with 132 F2:3 families derived from two cucumber inbred lines WI 2757 (resistant) and True Lemon (susceptible). A genetic map covering 610.4 cM in seven linkage groups was developed with 240 SSR marker loci. Multiple QTL mapping analysis of molecular marker data and disease index of the hypocotyl, cotyledon and true leaf for responses to PM inoculation identified six genomic regions in four chromosomes harboring QTL for PM resistance in WI 2757. Among the six QTL, pm1.1 and pm1.2 in chromosome 1 conferred leaf resistance. Minor QTL pm3.1 (chromosome 3) and pm4.1 (chromosome 4) contributed to disease susceptibility. The two major QTL, pm5.1 and pm5.2 were located in an interval of ~40 cM in chromosome 5 with each explaining 21.0-74.5 % phenotypic variations. Data presented herein support two recessively inherited, linked major QTL in chromosome 5 plus minor QTL in other chromosomes that control the PM resistance in WI 2757. The QTL pm5.2 for hypocotyl resistance plays the most important role in host resistance. Multiple observations in the same year revealed the importance of scoring time in the detection of PM resistance QTL. Results of this study provided new insights into phenotypic and genetic mechanisms of powdery mildew resistance in cucumber.

  2. Phylogeography and population structure of the grape powdery mildew fungus, Erysiphe necator, from diverse Vitis species

    Directory of Open Access Journals (Sweden)

    Brewer Marin

    2010-09-01

    Full Text Available Abstract Background The grape powdery mildew fungus, Erysiphe necator, was introduced into Europe more than 160 years ago and is now distributed everywhere that grapes are grown. To understand the invasion history of this pathogen we investigated the evolutionary relationships between introduced populations of Europe, Australia and the western United States (US and populations in the eastern US, where E. necator is thought to be native. Additionally, we tested the hypothesis that populations of E. necator in the eastern US are structured based on geography and Vitis host species. Results We sequenced three nuclear gene regions covering 1803 nucleotides from 146 isolates of E. necator collected from the eastern US, Europe, Australia, and the western US. Phylogeographic analyses show that the two genetic groups in Europe represent two separate introductions and that the genetic groups may be derived from eastern US ancestors. Populations from the western US and Europe share haplotypes, suggesting that the western US population was introduced from Europe. Populations in Australia are derived from European populations. Haplotype richness and nucleotide diversity were significantly greater in the eastern US populations than in the introduced populations. Populations within the eastern US are geographically differentiated; however, no structure was detected with respect to host habitat (i.e., wild or cultivated. Populations from muscadine grapes, V. rotundifolia, are genetically distinct from populations from other Vitis host species, yet no differentiation was detected among populations from other Vitis species. Conclusions Multilocus sequencing analysis of the grape powdery mildew fungus is consistent with the hypothesis that populations in Europe, Australia and the western US are derived from two separate introductions and their ancestors were likely from native populations in the eastern US. The invasion history of E. necator follows a pattern

  3. Identification of molecular markers linked to the mildew resistance gene Pl-d in apple.

    Science.gov (United States)

    James, C M; Clarke, J B; Evans, K M

    2004-12-01

    Powdery mildew poses a serious problem for apple growers, and resistance to the disease is a major objective in breeding programmes for cultivar improvement. As selective pressure allows pathogens to overcome previously reliable resistances, there is a need for the introduction of novel resistance genes into new breeding lines. This investigation is concerned with the identification of the first set of molecular markers linked to the gene for mildew resistance, Pl-d, from the accession 'D12'. As no prior information on the map position or markers for Pl-d were available, a bulked-segregant approach was used to test 49 microsatellite primers, 176 amplified fragment length polymorphism (AFLP) primers and 80 random amplified polymorphic DNA (RAPD) primers in a progeny segregating for Pl-d resistance, 'Fiesta' (susceptible) x A871-14 ('Worcester Pearmain' x 'D12'). The segregations of the markers identified in the resistant and susceptible bulks were scored in the progeny, then the recombination fractions between Pl-d and the most tightly linked markers were calculated and a map prepared. Three AFLP, one RAPD and two microsatellite markers were identified. One AFLP was developed into a sequence-characterised amplified region marker, while the microsatellites CH03C02 and CH01D03 were flanking markers, 7 and 11 recombination units, respectively, from Pl-d. Two more distant microsatellites on the same linkage group, CH01D09 and CH01G12, confirmed the orientation of the markers on the linkage group. These microsatellites place Pl-d on the bottom of linkage group 12 in published apple maps, a region where a number of other disease resistance genes have been identified.

  4. Powdery Mildew Decreases the Radial Growth of Oak Trees with Cumulative and Delayed Effects over Years.

    Directory of Open Access Journals (Sweden)

    Didier Bert

    Full Text Available Quercus robur and Q. petraea are major European forest tree species. They have been affected by powdery mildew caused by Erysiphe alphitoides for more than a century. This fungus is a biotrophic foliar pathogen that diverts photosynthetate from the plant for its own nutrition. We used a dendrochronological approach to investigate the effects of different levels of infection severity on the radial growth of young oak trees. Oak infection was monitored at individual tree level, at two sites in southwestern France, over a five-year period (2001-2005. Mean infection severity was almost 75% (infected leaf area at the end of the 2001 growing season, at both sites, but only about 40% in 2002, and 8%, 5% and 2% in 2003, 2004 and 2005, respectively. Infection levels varied considerably between trees and were positively related between 2001 and 2002. Increment cores were taken from each tree to assess annual ring widths and increases in basal area. Annual radial growth was standardised to take the effect of tree size into account. Annual standardised radial growth was significantly and negatively correlated with infection severity in the same year, for both 2001 and 2002, and at both sites. The decrease in growth reached 70-90% for highly infected trees. The earlywood width was poorly correlated with infection severity, but the proportion of latewood in tree rings was lower in highly infected trees (60% than in less heavily infected trees (85%. Infection in 2001 and 2002 was found to have a cumulative effect on radial growth in these years, together with a delayed effect detectable in 2003. Thus, even non-lethal pathogens like powdery mildew can have a significant impact on tree functioning. This impact should be taken into account in growth and yield models, to improve predictions of forest net primary production.

  5. Molecular mapping of powdery mildew resistance gene Eg-3 in cultivated oat (Avena sativa L. cv. Rollo).

    Science.gov (United States)

    Mohler, Volker; Zeller, Friedrich J; Hsam, Sai L K

    2012-05-01

    Powdery mildew is a prevalent fungal disease affecting oat (Avena sativa L.) production in Europe. Common oat cultivar Rollo was previously shown to carry the powdery mildew resistance gene Eg-3 in common with cultivar Mostyn. The resistance gene was mapped with restriction fragment length polymorphism (RFLP) markers from Triticeae group-1 chromosomes using a population of F(3) lines from a cross between A. byzantina cv. Kanota and A. sativa cv. Rollo. This comparative mapping approach positioned Eg-3 between cDNA-RFLP marker loci cmwg706 and cmwg733. Since both marker loci were derived from the long arm of barley chromosome 1H, the subchromosomal location of Eg-3 was assumed to be on the long arm of oat chromosome 17. Amplified fragment length polymorphism (AFLP) marker technology featured as an efficient means for obtaining markers closely linked to Eg-3.

  6. A rapid inoculation technique for assessing pathogenicity of Fusarium oxysporum f. sp. niveum and F. o. melonis on Cucurbits

    Science.gov (United States)

    Freeman, S.; Rodriguez, R.J.

    1993-01-01

    A continuous-dip inoculation technique for rapid assessment of pathogenicity of Fusarium oxysporum f. sp. niveum and F. o. melonis was developed. The method, adapted from a similar procedure for determining pathogenicity of Colletotrichum magna (causal agent of anthracnose of cucurbits), involves constant exposure of seedlings and cuttings (seedlings with root systems excised) of watermelon and muskmelon to conidial suspensions contained in small scintillation vials. Disease development in intact seedlings corresponded well to disease responses observed with the standard root-dip inoculation/pot assay. The continuous-dip inoculation technique resulted in rapid disease development, with 50% of watermelon cuttings dying after 4–6 days of exposure to F. o. niveum. A mortality of 30% also was observed in watermelon cuttings exposed to conidia of F. o. melonis, as opposed to only a 0–2.5% mortality in seedlings with intact roots. Disease response was similar with muskmelon seedlings and cuttings continuously dip-inoculated with F. o. melonis isolates. However, no disease symptoms were observed in muskmelon seedlings or cuttings inoculated with F. o. niveum. Four nonpathogenic isolates of F. oxysporum did not cause disease symptoms in either watermelon or muskmelon cuttings and seedlings when assayed by this technique. The proposed method enables a rapid screening of pathogenicity and requires less time, labor, and greenhouse space than the standard root-dip inoculation/pot assay. The reliability of the continuous-dip inoculation technique is limited, however, to exposure of intact seedlings at a concentration of 1 × 106conidia per milliliter; the method is not accurate at this range for excised seedlings.

  7. Sequence-specific, nanomolar peptide binding via cucurbit[8]uril-induced folding and inclusion of neighboring side chains.

    Science.gov (United States)

    Smith, Lauren C; Leach, David G; Blaylock, Brittney E; Ali, Omar A; Urbach, Adam R

    2015-03-18

    This paper describes the molecular recognition of the tripeptide Tyr-Leu-Ala by the synthetic receptor cucurbit[8]uril (Q8) in aqueous buffer with nanomolar affinity and exceptional specificity. This combination of characteristics, which also applies to antibodies, is desirable for applications in biochemistry and biotechnology but has eluded supramolecular chemists for decades. Building on prior knowledge that Q8 binds to peptides with N-terminal aromatic residues, a library screen of 105 peptides was designed to test the effects of residues adjacent to N-terminal Trp, Phe, or Tyr. The screen used tetramethylbenzobis(imidazolium) (MBBI) as a fluorescent indicator and resulted in the unexpected discovery that MBBI can serve not only as a turn-off sensor via the simultaneous inclusion of a Trp residue but also as a turn-on sensor via the competitive displacement of MBBI upon binding of Phe- or Tyr-terminated peptides. The unusual fluorescence response of the Tyr series prompted further investigation by (1)H NMR spectroscopy, electrospray ionization mass spectrometry, and isothermal titration calorimetry. From these studies, a novel binding motif was discovered in which only 1 equiv of peptide binds to Q8, and the side chains of both the N-terminal Tyr residue and its immediate neighbor bind within the Q8 cavity. For the peptide Tyr-Leu-Ala, the equilibrium dissociation constant value is 7.2 nM, whereas that of its sequence isomer Tyr-Ala-Leu is 34 μM. The high stability, recyclability, and low cost of Q8 combined with the straightforward incorporation of Tyr-Leu-Ala into recombinant proteins should make this system attractive for the development of biological applications.

  8. Biomass, virus concentration, and symptomatology of cucurbits infected by mild and severe strains of Papaya ringspot virus

    Directory of Open Access Journals (Sweden)

    Pacheco Davi Andrade

    2003-01-01

    Full Text Available Pre-immunization with mild strains of Papaya ringspot virus - type W (PRWV-W has allowed the mosaic disease to be controlled in different cucurbit species, with increases in marketable fruit yield. The objective of this study was to compare virus concentration, biomass and symptomatology of 'Caserta' zucchini squash, 'Menina Brasileira' long-neck squash and 'Crimson Sweet' watermelon plants infected by three mild strains and one severe strain of PRSV-W. Plants were inoculated at the cotyledonary stage, under greenhouse conditions, sampled at 7, 14, 21, 28 and 35 days after inoculation (DAI, and analyzed by PTA-ELISA. The severity of the symptoms was scored according to a scale from 1 to 5, and the fresh and dry biomass of the aerial part of the plants were evaluated at 40 DAI. Concentrations of the mild strains, based on absorbance values of the PTA-ELISA, were lower than the concentration of the severe strain for all species. The mild strains did not cause mosaic in infected plants of all species. Plants of zucchini squash and watermelon infected by the severe strain exhibited severe mosaic symptoms, but the same was not noticed for infected long-neck squash plants. Biomass values from zucchini squash and watermelon plants infected by the mild strains were 1.7 % to 12.4 % lower as compared to healthy plants. Biomass values of zucchini squash and watermelon plants infected by the severe strain presented greater reduction, varying from 29 % to 74 %. However, biomass values of long-neck squash plants infected by the mild and severe strains were similar for all treatments.

  9. Transmission of Squash vein yellowing virus to and From Cucurbit Weeds and Effects on Sweetpotato Whitefly (Hemiptera: Aleyrodidae) Behavior.

    Science.gov (United States)

    Shrestha, D; McAuslane, H J; Adkins, S T; Smith, H A; Dufault, N; Webb, S E

    2016-08-01

    Since 2003, growers of Florida watermelon [Citrullus lanatus (Thunb.) Matsum. and Nakai] have periodically suffered large losses from a disease caused by Squash vein yellowing virus (SqVYV), which is transmitted by the whitefly Middle East-Asia Minor 1 (MEAM1), formerly Bemisia tabaci (Gennadius) biotype B. Common cucurbit weeds like balsam apple (Momordica charantia L.) and smellmelon [Cucumis melo var. dudaim (L.) Naud.] are natural hosts of SqVYV, and creeping cucumber (Melothria pendula L.) is an experimental host. Study objectives were to compare these weeds and 'Mickylee' watermelon as sources of inoculum for SqVYV via MEAM1 transmission, to determine weed susceptibility to SqVYV, and to evaluate whitefly settling and oviposition behaviors on infected vs. mock-inoculated (inoculated with buffer only) creeping cucumber leaves. We found that the lowest percentage of watermelon recipient plants was infected when balsam apple was used as a source of inoculum. Watermelon was more susceptible to infection than balsam apple or smellmelon. However, all weed species were equally susceptible to SqVYV when inoculated by whitefly. For the first 5 h after release, whiteflies had no preference to settle on infected vs. mock-inoculated creeping cucumber leaves. After 24 h, whiteflies preferred to settle on mock-inoculated leaves, and more eggs were laid on mock-inoculated creeping cucumber leaves than on SqVYV-infected leaves. The transmission experiments (source of inoculum and susceptibility) show these weed species as potential inoculum sources of the virus. The changing settling preference of whiteflies from infected to mock-inoculated plants could lead to rapid spread of virus in the agroecosystem.

  10. Characterization of a synergistic interaction between two cucurbit-infecting begomoviruses: Squash leaf curl virus and Watermelon chlorotic stunt virus.

    Science.gov (United States)

    Sufrin-Ringwald, Tali; Lapidot, Moshe

    2011-02-01

    Squash leaf curl virus (SLCV) and Watermelon chlorotic stunt virus (WmCSV) are cucurbit-infecting bipartite begomoviruses. Both viruses are found in the eastern Mediterranean basin but the effects of dual infection of both viruses on melon (Cucumis melo L.) have not been described. 'Arava' melon plants were inoculated in the greenhouse, using whiteflies, with either SLCV, WmCSV, or both. Control plants were exposed to nonviruliferous whiteflies or not exposed at all. Following inoculation, plants were transplanted to a 50-mesh insect-proof nethouse and grown until fruit maturity. The experiment was performed in two melon-growing seasons: spring, transplant in May and harvest in July; and summer, transplant in August and harvest in October. Following inoculation, SLCV-infected melon plants showed mild symptoms that disappeared with time, and there was no effect on plant height. WmCSV-infected plants developed disease symptoms that became more obvious with time, and plants were somewhat shorter than control plants in the spring but not in the summer. SLCV had no effect on yield, regardless of season. WmCSV had no statistically significant effect on yield in the spring but, in the summer, reduced yield by 22%, on average. Dual-inoculated plants showed a synergistic interaction between the two viruses. They developed disease symptoms that were more pronounced than WmCSV alone, with plants being shorter than control plants by 20 to 25% regardless of season. Moreover, the yield of dual-inoculated plants was reduced on average by 21% in the spring and 54% in the summer, and fruit appearance was adversely affected. Dual inoculation did not affect WmCSV DNA level but SLCV DNA level was increased several-fold by the presence of WmCSV.

  11. 平榛白粉病药剂防治试验%Corylus heterophylla Powdery Mildew Test

    Institute of Scientific and Technical Information of China (English)

    王尧; 孙冬伟

    2012-01-01

      Powdery mildew is an important disease with hazelnut ,rapid onset ,spread fast ,serious harm characteristics of .The hazelnut powdery mildew testing found ,Corylus heterophylla pow-dery mildew in Fushun city starting period for June to early July ,flourishing period in the middle of July to late September ,stage of 10 month to month l1 .Effect of chemical control of powdery mildew of Corylus heterophylla effective best is 12 .5% myclobutanil 1000 times liquid ,use 7 days later to investigate its control effect reached 57 .6% ,45% and 15% 200 times solution LSSS three Triadimefon 400 times fluid control effect were 51 .2% ,51 .7% .%  白粉病是榛子的重要病害,具有发病快、传播快、危害严重的特点.通过对平榛白粉病药剂防治试验发现,平榛白粉病在抚顺市始发期为6月上旬至7月上旬,盛发期为7月中旬至9月下旬,末期为10月上旬至11月.平榛白粉病有效药剂防治效果最好的是12.5%腈菌唑1000倍液,施用7天后调查其防治效果达到57.6%,45%石硫合剂200倍液和15%三唑酮400倍液防治效果分别为51.2%、51.7%.

  12. Whole Genome Re-Sequencing and Characterization of Powdery Mildew Disease-Associated Allelic Variation in Melon.

    Directory of Open Access Journals (Sweden)

    Sathishkumar Natarajan

    Full Text Available Powdery mildew is one of the most common fungal diseases in the world. This disease frequently affects melon (Cucumis melo L. and other Cucurbitaceous family crops in both open field and greenhouse cultivation. One of the goals of genomics is to identify the polymorphic loci responsible for variation in phenotypic traits. In this study, powdery mildew disease assessment scores were calculated for four melon accessions, 'SCNU1154', 'Edisto47', 'MR-1', and 'PMR5'. To investigate the genetic variation of these accessions, whole genome re-sequencing using the Illumina HiSeq 2000 platform was performed. A total of 754,759,704 quality-filtered reads were generated, with an average of 82.64% coverage relative to the reference genome. Comparisons of the sequences for the melon accessions revealed around 7.4 million single nucleotide polymorphisms (SNPs, 1.9 million InDels, and 182,398 putative structural variations (SVs. Functional enrichment analysis of detected variations classified them into biological process, cellular component and molecular function categories. Further, a disease-associated QTL map was constructed for 390 SNPs and 45 InDels identified as related to defense-response genes. Among them 112 SNPs and 12 InDels were observed in powdery mildew responsive chromosomes. Accordingly, this whole genome re-sequencing study identified SNPs and InDels associated with defense genes that will serve as candidate polymorphisms in the search for sources of resistance against powdery mildew disease and could accelerate marker-assisted breeding in melon.

  13. Genetic dissection of powdery mildew resistance in interspecific half-sib grapevine families using SNP-based maps.

    Science.gov (United States)

    Teh, Soon Li; Fresnedo-Ramírez, Jonathan; Clark, Matthew D; Gadoury, David M; Sun, Qi; Cadle-Davidson, Lance; Luby, James J

    2017-01-01

    Quantitative trait locus (QTL) identification in perennial fruit crops is impeded largely by their lengthy generation time, resulting in costly and labor-intensive maintenance of breeding programs. In a grapevine (genus Vitis) breeding program, although experimental families are typically unreplicated, the genetic backgrounds may contain similar progenitors previously selected due to their contribution of favorable alleles. In this study, we investigated the utility of joint QTL identification provided by analyzing half-sib families. The genetic control of powdery mildew was studied using two half-sib F1 families, namely GE0711/1009 (MN1264 × MN1214; N = 147) and GE1025 (MN1264 × MN1246; N = 125) with multiple species in their ancestry. Maternal genetic maps consisting of 1077 and 1641 single nucleotide polymorphism (SNP) markers, respectively, were constructed using a pseudo-testcross strategy. Ratings of field resistance to powdery mildew were obtained based on whole-plant evaluation of disease severity. This 2-year analysis uncovered two QTLs that were validated on a consensus map in these half-sib families with improved precision relative to the parental maps. Examination of haplotype combinations based on the two QTL regions identified strong association of haplotypes inherited from 'Seyval blanc', through MN1264, with powdery mildew resistance. This investigation also encompassed the use of microsatellite markers to establish a correlation between 206-bp (UDV-015b) and 357-bp (VViv67) fragment sizes with resistance-carrying haplotypes. Our work is one of the first reports in grapevine demonstrating the use of SNP-based maps and haplotypes for QTL identification and tagging of powdery mildew resistance in half-sib families.

  14. Whole Genome Re-Sequencing and Characterization of Powdery Mildew Disease-Associated Allelic Variation in Melon.

    Science.gov (United States)

    Natarajan, Sathishkumar; Kim, Hoy-Taek; Thamilarasan, Senthil Kumar; Veerappan, Karpagam; Park, Jong-In; Nou, Ill-Sup

    2016-01-01

    Powdery mildew is one of the most common fungal diseases in the world. This disease frequently affects melon (Cucumis melo L.) and other Cucurbitaceous family crops in both open field and greenhouse cultivation. One of the goals of genomics is to identify the polymorphic loci responsible for variation in phenotypic traits. In this study, powdery mildew disease assessment scores were calculated for four melon accessions, 'SCNU1154', 'Edisto47', 'MR-1', and 'PMR5'. To investigate the genetic variation of these accessions, whole genome re-sequencing using the Illumina HiSeq 2000 platform was performed. A total of 754,759,704 quality-filtered reads were generated, with an average of 82.64% coverage relative to the reference genome. Comparisons of the sequences for the melon accessions revealed around 7.4 million single nucleotide polymorphisms (SNPs), 1.9 million InDels, and 182,398 putative structural variations (SVs). Functional enrichment analysis of detected variations classified them into biological process, cellular component and molecular function categories. Further, a disease-associated QTL map was constructed for 390 SNPs and 45 InDels identified as related to defense-response genes. Among them 112 SNPs and 12 InDels were observed in powdery mildew responsive chromosomes. Accordingly, this whole genome re-sequencing study identified SNPs and InDels associated with defense genes that will serve as candidate polymorphisms in the search for sources of resistance against powdery mildew disease and could accelerate marker-assisted breeding in melon.

  15. Allocation of the S-genome chromosomes of Aegilops variabilis Eig. carrying powdery mildew resistance in triticale (× Triticosecale Wittmack).

    Science.gov (United States)

    Kwiatek, M; Belter, J; Majka, M; Wiśniewska, H

    2016-03-01

    It has been hypothesized that the powdery mildew adult plant resistance (APR) controlled by the Pm13 gene in Aegilops longissima Schweinf. & Muschl. (S(l)S(l)) has been evolutionary transferred to Aegilops variabilis Eig. (UUSS). The molecular marker analysis and the visual evaluation of powdery mildew symptoms in Ae. variabilis and the Ae. variabilis × Secale cereale amphiploid forms (2n = 6x = 42, UUSSRR) showed the presence of product that corresponded to Pm13 marker and the lower infection level compared to susceptible model, respectively. This study also describes the transfer of Ae. variabilis Eig. (2n = 4x = 28, U(v)U(v)S(v)S(v)) chromosomes, carrying powdery mildew resistance, into triticale (× Triticosecale Wittm., 2n = 6x = 42, AABBRR) using Ae. variabilis × S. cereale amphiploid forms. The individual chromosomes of Ae. variabilis, triticale 'Lamberto' and hybrids were characterized by genomic and fluorescence in situ hybridization (GISH/FISH). The chromosome configurations of obtained hybrid forms were studied at first metaphase of meiosis of pollen mother cells (PMCs) using GISH. The statistical analysis showed that the way of S-genome chromosome pairing and transmission to subsequent hybrid generations was diploid-like and had no influence on chromosome pairing of triticale chromosomes. The cytogenetic study of hybrid forms were supported by the marker-assisted selection using Pm13 marker and visual evaluation of natural infection by Blumeria graminis, that allowed to select the addition or substitution lines of hybrids carrying chromosome 3S(v) which were tolerant to the powdery mildew infection.

  16. A complex protein derivative acts as biogenic elicitor of grapevine resistance against powdery mildew under field conditions.

    Science.gov (United States)

    Nesler, Andrea; Perazzolli, Michele; Puopolo, Gerardo; Giovannini, Oscar; Elad, Yigal; Pertot, Ilaria

    2015-01-01

    Powdery mildew caused by Erysiphe necator is one of the most important grapevine diseases in several viticulture areas, and high fungicide input is required to control it. However, numerous synthetic chemical pesticides are under scrutiny due to concerns about their impact on human health and the environment. Biopesticides, such as biogenic elicitors, are a promising alternative to chemical fungicides. Although several studies have reported on effective elicitors against grapevine diseases, their efficacy under field conditions has not been investigated extensively or has occurred at rather limited levels. Our goal was to examine the efficacy of a protein-based composition, namely nutrient broth (NB), against powdery mildew under field conditions and to characterize its mechanism of action. Weekly treatments with NB was highly effective in controlling powdery mildew on grapevine across seasons with different disease pressures. The level of disease control achieved with NB was comparable to standard fungicide treatments both on leaves and bunches across three different years. NB has no direct toxic effect on the germination of E. necator conidia, and it activates plant resistance with both systemic and translaminar effect in experiments with artificial inoculation under controlled conditions. NB induced the expression of defense-related genes in grapevine, demonstrating stimulation of plant defense mechanisms, prior to and in the early stages of pathogen infection. NB is a natural derivative from meat and yeast, substances that tend not to raise concerns about toxicological and ecotoxicological properties. NB represents a valid control tool for integrated plant protection programs against powdery mildew, to reduce the use of synthetic pesticides on grapevine.

  17. Studies in plant pathogenic fungi—II. On some powdery mildews (Erysiphales) recently recorded from the Netherlands

    OpenAIRE

    Noordeloos, M.E.; Loerakker, W.M.

    1989-01-01

    Full descriptions and notes on their pathogenous properties are given of the anamorphs of four powdery mildews recently recorded as new from the Netherlands. Two are described as new species, viz. Oidium longipes on Solarium melongena and O. limnanthis on Limnanthes alba. Oidium lycopersicum Cooke & Massee is redescribed on account of the study of the holotype and recently collected material, and an Oidium sp. occurring on Chrysanthemum morifolium is critically compared with the existing desc...

  18. A complex protein derivative acts as biogenic elicitor of grapevine resistance against powdery mildew under field conditions

    Directory of Open Access Journals (Sweden)

    Andrea eNesler

    2015-09-01

    Full Text Available Powdery mildew caused by Erysiphe necator is one of the most important grapevine diseases in several viticulture areas, and high fungicide input is required to control it. However, numerous synthetic chemical pesticides are under scrutiny due to concerns about their impact on human health and the environment. Biopesticides, such as biogenic elicitors, are a promising alternative to chemical fungicides. Although several studies have reported on effective elicitors against grapevine diseases, their efficacy under field conditions has not been investigated extensively or has occurred at rather limited levels. Our goal was to examine the efficacy of a protein-based composition, namely nutrient broth (NB, against powdery mildew under field conditions and to characterize its mechanism of action. Weekly treatments with NB was highly effective in controlling powdery mildew on grapevine across seasons with different disease pressures. The level of disease control achieved with NB was comparable to standard fungicide treatments both on leaves and bunches across three different years. NB has no direct toxic effect on the germination of E. necator conidia, and it activates plant resistance with both systemic and translaminar effect in experiments with artificial inoculation under controlled conditions. NB induced the expression of defense-related genes in grapevine, demonstrating stimulation of plant defense mechanisms, prior to and in the early stages of pathogen infection. NB is a natural derivative from meat and yeast, substances that tend not to raise concerns about toxicological and ecotoxicological properties. NB represents a valid control tool for integrated plant protection programs against powdery mildew, to reduce the use of synthetic pesticides on grapevine.

  19. Map - vs. homology - based cloning for the recessive gene ol-2 conferring resistance to tomato powdery mildew

    OpenAIRE

    Pavan, S.N.C.; Zheng, Z.; Borisova, M.; Berg, van den, G.J.; Lotti, C.; Giovanni, , da Bergamo; Lindhout, P.; de Jong; Ricciardi, L.; Visser, R.G.F.; Bai, Y.

    2008-01-01

    The recessive gene ol-2 confers papilla-associated and race-non-specific resistance to tomato powdery mildew caused by Oidium neolycopersici. In order to facilitate marker assisted selection (MAS) in practical breeding programmes, we identified two simple sequence repeat (SSR) markers and one cleaved amplified polymorphic sequence (CAPS) marker which are linked to the resistance locus and co-dominantly inherited. Aiming to provide a base for ol-2 positional cloning, we used a large segregatin...

  20. Gene expression profiling related to powdery mildew resistance in wheat with the method of suppression subtractive hybridization

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    "Bainong 3217×Mardler" BC5F4 wheat line at the initial stage of inoculation with powdery mildew pathogen (Erysiphe graminis DC) was used to construct a suppression subtractive hybridization (SSH) cDNA library. Totally 760 ESTs were obtained through sequencing. Similarity analysis of ESTs based on BLASTn and BLASTx with the sequences in GenBank, in combination with macroarray differential screening, revealed that 199 ESTs of 65 kinds were known to be functionally disease resistance related. Based on the gene expression profiling in the present study, it is postulated that salicylic acid (SA) and MAP-related signal transduction pathways were involved in powdery mildew resistance in wheat. System acquired resistance genes were predominant in terms of kinds and quantity. With the initiation of cell defense reaction, the genes conferring anti-oxida- tion substances were largely expressed and thus cell protection mechanism was activated. Much evidence revealed that phenylpropanes metabolic pathway was involved in phytoalexin synthesis in wheat powdery mildew resistance. Genes conferring some enzymes of structural modification of cell walls and proteinase inhibitors inhibiting pathogen growth were also detected. The genes controlling a few proteinases (mainly cysteine proteinase) had a considerable redundancy of expression.

  1. Mutation of the Glucosinolate Biosynthesis Enzyme Cytochrome P450 83A1 Monooxygenase Increases Camalexin Accumulation and Powdery Mildew Resistance.

    Science.gov (United States)

    Liu, Simu; Bartnikas, Lisa M; Volko, Sigrid M; Ausubel, Frederick M; Tang, Dingzhong

    2016-01-01

    Small secondary metabolites, including glucosinolates and the major phytoalexin camalexin, play important roles in immunity in Arabidopsis thaliana. We isolated an Arabidopsis mutant with increased resistance to the powdery mildew fungus Golovinomyces cichoracearum and identified a mutation in the gene encoding cytochrome P450 83A1 monooxygenase (CYP83A1), which functions in glucosinolate biosynthesis. The cyp83a1-3 mutant exhibited enhanced defense responses to G. cichoracearum and double mutant analysis showed that this enhanced resistance requires NPR1, EDS1, and PAD4, but not SID2 or EDS5. In cyp83a1-3 mutants, the expression of genes related to camalexin synthesis increased upon G. cichoracearum infection. Significantly, the cyp83a1-3 mutant also accumulated higher levels of camalexin. Decreasing camalexin levels by mutation of the camalexin synthetase gene PAD3 or the camalexin synthesis regulator AtWRKY33 compromised the powdery mildew resistance in these mutants. Consistent with these observations, overexpression of PAD3 increased camalexin levels and enhanced resistance to G. cichoracearum. Taken together, our data indicate that accumulation of higher levels of camalexin contributes to increased resistance to powdery mildew.

  2. Powdery Mildew Resistance in Wheat Cultivar Mv Hombár is Conferred by a New Gene, PmHo.

    Science.gov (United States)

    Komáromi, Judit; Jankovics, Tünde; Fábián, Attila; Puskás, Katalin; Zhang, Zengyan; Zhang, Miao; Li, Hongjie; Jäger, Katalin; Láng, László; Vida, Gyula

    2016-11-01

    A new powdery mildew resistance gene designated as PmHo was identified in 'Mv Hombár' winter wheat, bred in Martonvásár, Hungary. It has exhibited a high level of resistance over the last two decades. Genetic mapping of recombinant inbred lines derived from the cross 'Ukrainka'/Mv Hombár located this gene on chromosome 2AL. The segregation ratio and consistent effect in all environments indicated that PmHo is a major dominant powdery mildew resistance gene. The race-specific nature of resistance in Mv Hombár was shown by the emergence of a single virulent pathotype designated as 51-Ho. This pathotype was, to some extent, able to infect Mv Hombár, developing visible symptoms with sporulating colonies. Microscopic studies revealed that, in incompatible interactions, posthaustorial hypersensitivity reaction was the most prevalent but not exclusive plant defense response in Mv Hombár, and fungal growth was mostly arrested during haustorium formation or in the early stages of colony development. The delayed fungal development of the virulent pathotype 51-Ho may be explained by additional effects of other loci that were also involved in the powdery mildew resistance of Mv Hombár.

  3. Mutation of the glucosinolate biosynthesis enzyme cytochrome P450 83A1 monooxygenase increases camalexin accumulation and powdery mildew resistance

    Directory of Open Access Journals (Sweden)

    Simu eLiu

    2016-03-01

    Full Text Available Small secondary metabolites, including glucosinolates and the major phytoalexin camalexin, play important roles in immunity in Arabidopsis thaliana. We isolated an Arabidopsis mutant with increased resistance to the powdery mildew fungus Golovinomyces cichoracearum and identified a mutation in the gene encoding cytochrome P450 83A1 monooxygenase (CYP83A1, which functions in glucosinolate biosynthesis. The cyp83a1-3 mutant exhibited enhanced defense responses to G. cichoracearum and double mutant analysis showed that this enhanced resistance requires NPR1, EDS1, and PAD4, but not SID2 or EDS5. In cyp83a1-3 mutants, the expression of genes related to camalexin synthesis increased upon G. cichoracearum infection. Significantly, the cyp83a1-3 mutant also accumulated higher levels of camalexin. Decreasing camalexin levels by mutation of the camalexin synthetase gene PAD3 or the camalexin synthesis regulator AtWRKY33 compromised the powdery mildew resistance in these mutants. Consistent with these observations, overexpression of PAD3 increased camalexin levels and enhanced resistance to G. cichoracearum. Taken together, our data indicate that accumulation of higher levels of camalexin contributes to increased resistance to powdery mildew.

  4. Daily light integral and day light quality: Potentials and pitfalls of nighttime UV treatments on cucumber powdery mildew.

    Science.gov (United States)

    Suthaparan, Aruppillai; Solhaug, Knut Asbjørn; Stensvand, Arne; Gislerød, Hans Ragnar

    2017-10-01

    Nighttime ultraviolet (UV) radiation, if applied properly, has a significant potential for management of powdery mildews in many crop species. In this study, the role of growth light duration, irradiance, a combination of both (daily light integral) and light spectral quality (blue or red) on the efficacy of UV treatments against powdery mildew caused by Podosphaera xanthii and the growth performance of cucumber plants was studied in growth chambers. Increasing daily light integral provided by high-pressure sodium lamps (HPS) decreased efficacy of nighttime UV treatments against P. xanthii, but it increased plant growth. Furthermore, the efficacy of nighttime UV decreased when day length was increased from 16 to 20h at a constant daily light integral. The efficacy of nighttime UV increased if red light was applied after UV treatment, showing the possibility of day length extension without reducing the effect of UV. Increasing the dose of blue light during daytime reduced the efficacy of nighttime UV in controlling the disease, whereas blue deficient growth light (<6% of blue) caused UV mediated curling of young leaves. Furthermore, application of blue light after nighttime UV reduced its disease control efficacy. This showed the importance of maintaining a minimum of blue light in the growth light before nighttime UV treatment. Findings from this study showed that optimization of nighttime UV for management of powdery mildew is dependent on the spectral composition of the photosynthetically active radiation. Copyright © 2017 Elsevier B.V. All rights reserved.

  5. Mla- and Rom1-mediated control of microRNA398 and chloroplast copper/zinc superoxide dismutase regulates cell death in response to the barley powdery mildew fungus

    Science.gov (United States)

    Barley Mla (Mildew resistance locus a) confers allele-specific interactions with natural variants of the ascomycete fungus, Blumeria graminis f. sp. hordei (Bgh), causal agent of powdery mildew disease. Significant reprogramming of host gene expression occurs upon infection by this obligate biotrop...

  6. The Property and Subject Classification of China Cucurbits and Vegetables%《中国瓜菜》性质及学科分类

    Institute of Scientific and Technical Information of China (English)

    李杨; 朱安; 房威; 张志转; 朱永和

    2012-01-01

    Classify China Cucurbits and Vegetables according to property and subject of journal based on quantity of literatures. 61.24% of itspapers in 2010 are relate to academic research and the literatures about horticulture account for 75. 13% of summation. The literatures of othersubject failed to obtain adequate influence as a result of small quantity. So China Cucurbits and Vegetables belongs to scholarly journal abouthorticulture.%根据期刊性质和学科分类方法,以文献数量为依据对《中国瓜菜》进行分类结果发现,《中国瓜菜》2010年刊登的论文61.24%属研究性论文,园艺类文献占当年发表文献总量的75.13%,其余学科文献均较少,不能划入相应学科,因此应将该刊归类为园艺类专业学术期刊.

  7. Seletividade de inseticidas, recomendados para cucurbitáceas para Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae em condições de laboratório

    Directory of Open Access Journals (Sweden)

    Dirceu Pratissoli

    2011-10-01

    Full Text Available As brocas-das-cucurbitáceas Diaphania spp. são as principais pragas das cucurbitáceas, podendo ocasionar perdas de até 100% na produção. A fim de reduzir o uso de inseticidas, o controle biológico, aplicado com parasitoides do gênero Trichogramma, tem-se destacado. Objetivou-se avaliar a seletividade dos ingredientes ativos abamectina, tiacloprido e clorfenapir, para Trichogramma atopovirilia Oatman & Platner (Hymenoptera: Trichogrammatidae. Para isso, 20 fêmeas recém-emergidas de T. atopovirilla foram individualizadas, em tubos de vidro (2,5 cm de diâmetro x 8,5 cm de comprimento, e oferecidas cartelas com 30 ovos de Diaphania hyalinata (Linnaeus (Lepidoptera: Pyralidae, previamente imersas por cinco segundos em calda química. Os ingredientes ativos abamectina, tiacloprido e clorfenapir não afetaram o parasitismo de T. atopovirilia. Clorfenapir reduziu a emergência. Abamectina e tiacloprido são os mais recomendados no manejo integrado de pragas, pois foram os que se mostraram mais seletivos a T. atopovirilia em ovos de D. hyalinata.

  8. Key Components of Different Plant Defense Pathways Are Dispensable for Powdery Mildew Resistance of the Arabidopsis mlo2 mlo6 mlo12 Triple Mutant

    Directory of Open Access Journals (Sweden)

    Hannah Kuhn

    2017-06-01

    Full Text Available Loss of function mutations of particular plant MILDEW RESISTANCE LOCUS O (MLO genes confer durable and broad-spectrum penetration resistance against powdery mildew fungi. Here, we combined genetic, transcriptomic and metabolomic analyses to explore the defense mechanisms in the fully resistant Arabidopsis thaliana mlo2 mlo6 mlo12 triple mutant. We found that this genotype unexpectedly overcomes the requirement for indolic antimicrobials and defense-related secretion, which are critical for incomplete resistance of mlo2 single mutants. Comparative microarray-based transcriptome analysis of mlo2 mlo6 mlo12 mutants and wild type plants upon Golovinomyces orontii inoculation revealed an increased and accelerated accumulation of many defense-related transcripts. Despite the biotrophic nature of the interaction, this included the non-canonical activation of a jasmonic acid/ethylene-dependent transcriptional program. In contrast to a non-adapted powdery mildew pathogen, the adapted powdery mildew fungus is able to defeat the accumulation of defense-relevant indolic metabolites in a MLO protein-dependent manner. We suggest that a broad and fast activation of immune responses in mlo2 mlo6 mlo12 plants can compensate for the lack of single or few defense pathways. In addition, our results point to a role of Arabidopsis MLO2, MLO6, and MLO12 in enabling defense suppression during invasion by adapted powdery mildew fungi.

  9. An LRR/Malectin Receptor-Like Kinase Mediates Resistance to Non-adapted and Adapted Powdery Mildew Fungi in Barley and Wheat.

    Science.gov (United States)

    Rajaraman, Jeyaraman; Douchkov, Dimitar; Hensel, Götz; Stefanato, Francesca L; Gordon, Anna; Ereful, Nelzo; Caldararu, Octav F; Petrescu, Andrei-Jose; Kumlehn, Jochen; Boyd, Lesley A; Schweizer, Patrick

    2016-01-01

    Pattern recognition receptors (PRRs) belonging to the multigene family of receptor-like kinases (RLKs) are the sensing devices of plants for microbe- or pathogen-associated molecular patterns released from microbial organisms. Here we describe Rnr8 (for Required for non-host resistance 8) encoding HvLEMK1, a LRR-malectin domain-containing transmembrane RLK that mediates non-host resistance of barley to the non-adapted wheat powdery mildew fungus Blumeria graminis f.sp. tritici. Transgenic barley lines with silenced HvLEMK1 allow entry and colony growth of the non-adapted pathogen, although sporulation was reduced and final colony size did not reach that of the adapted barley powdery mildew fungus B. graminis f.sp. hordei. Transient expression of the barley or wheat LEMK1 genes enhanced resistance in wheat to the adapted wheat powdery mildew fungus while expression of the same genes did not protect barley from attack by the barley powdery mildew fungus. The results suggest that HvLEMK1 is a factor mediating non-host resistance in barley and quantitative host resistance in wheat to the wheat powdery mildew fungus.

  10. An LRR/malectin receptor-like kinase mediates resistance to non-adapted and adapted powdery mildew fungi in barley and wheat

    Directory of Open Access Journals (Sweden)

    Jeyaraman Rajaraman

    2016-12-01

    Full Text Available Pattern recognition receptors (PRRs belonging to the multigene family of receptor-like kinases (RLKs are the sensing devices of plants for microbe- or pathogen-associated molecular patterns released from microbial organisms. Here we describe Rnr8 (for required for nonhost resistance 8 encoding HvLEMK1, a LRR-malectin domain-containing transmembrane RLK that mediates nonhost resistance of barley to the non-adapted wheat powdery mildew fungus Blumeria graminis f.sp. tritici. Transgenic barley lines with silenced HvLEMK1 allow entry and colony growth of the non-adapted pathogen, although sporulation was reduced and final colony size did not reach that of the adapted barley powdery mildew fungus Blumeria graminis f.sp. hordei. Transient expression of the barley or wheat LEMK1 genes enhanced resistance in wheat to the adapted wheat powdery mildew fungus while expression of the same genes did not protect barley from attack by the barley powdery mildew fungus. The results suggest that HvLEMK1 is a factor mediating nonhost resistance in barley and quantitative host resistance in wheat to the wheat powdery mildew fungus.

  11. The composition, anti-mildew and anti-wood-decay fungal activities of the leaf and fruit oils of Juniperus formosana from Taiwan.

    Science.gov (United States)

    Su, Yu-Chang; Hsu, Kuan-Ping; Wang, Eugene I-Chen; Ho, Chen-Lung

    2013-09-01

    In this study, anti-mildew and anti-wood-decay fungal activities of the leaf and fruits essential oil and its constituents from Juniperus formosana were evaluated in vitro against seven mildew fungi and four wood decay fungi, respectively. The main compounds responsible for the anti-mildew and anti-wood-decay fungal activities were also identified. The essential oil from the fresh leaves and fruits of J. formosana were isolated using hydrodistillation in a Clevenger-type apparatus, and characterized by GC-FID and GC-MS, respectively. The leaf oil mainly consisted of alpha-pinene (41.0%), limonene (11.5%), alpha-cadinol (11.0%), elemol (6.3%), and beta-myrcene (5.8%); the fruit oil was mostly alpha-pinene (40.9%), beta-myrcene (32.4%), alpha-thujene (5.9%) and limonene (5.9%). Comparing the anti-mildew and anti-wood-decay fungal activities of the oils suggested that the leaf oil was the most effective. For the anti-mildew and anti-wood-decay fungal activities of the leaf oil, the active source compounds were determined to be alpha-cadinol and elemol.

  12. Quaternary IPM (integrated pest management)--concept for the control of powdery mildew in sugar beets.

    Science.gov (United States)

    Wolf, P F J; Verreet, A

    2008-01-01

    Powdery mildew, caused by Erysiphe betae (Vanha) Weltzien, may be assumed as an important leaf disease in sugar beet growing areas of central Europe. Although the causal agent is mainly adapted to arid climatic zones, the disease is appearing every year, where the extent of infection is mainly dependent on weather conditions and susceptibility of cultivar. The losses caused by powdery mildew seldom exceed 10% of sugar yield; moreover, losses are likely only under the condition that the epidemic onset occurs before end-August. Nevertheless, the epidemic onset varies in a wide range, as there are years with high incidence followed by growing periods without severe infection. Therefore, in order to have a flexible control of the disease, where the use of fungicides could be minimised to an essential amount, a quaternary IPM (Integrated Pest Management) -concept was developed. The development is based on epidemiological field studies (Germany, 1993-2004, n = 76) of sugar beet leaf diseases under variation of year, site and cultivar. Efficacy of fungicide treatment timing was assessed in relation to the epidemic development. Comparison of treatments comprised fungicide sprays carried out from disease initiation till later stages of the epidemic. Additionally, the assessments were performed in relation to an untreated and a healthy control--the latter was three times treated according to a treatment regime with three to four week intervals. The effect of different application timings was measured by the potential of disease and yield loss control. The quaternary concept combines the advantages of four elements in order to compensate the constraints of the single tools: The period without disease risk is determined by a so-called negative-prognosis (i). First symptoms appear in the period from mid-July till the beginning of September. If disease initiation cannot be excluded, field observations by a sample of 100 leaves are advised. The disease scores enable the appliance

  13. Genetic mapping of two genes conferring resistance to powdery mildew in common bean (Phaseolus vulgaris L.).

    Science.gov (United States)

    Pérez-Vega, Elena; Trabanco, Noemí; Campa, Ana; Ferreira, Juan José

    2013-06-01

    Powdery mildew (PM) is a serious disease in many legume species, including the common bean (Phaseolus vulgaris L.). This study investigated the genetic control behind resistance reaction to PM in the bean genotype, Cornell 49242. The results revealed evidence supporting a qualitative mode of inheritance for resistance and the involvement of two independent genes in the resistance reaction. The location of these resistance genes was investigated in a linkage genetic map developed for the XC RIL population. Contingency tests revealed significant associations for 28 loci out of a total of 329 mapped loci. Fifteen were isolated or formed groups with less than two loci. The thirteen remaining loci were located at three regions in linkage groups Pv04, Pv09, and Pv11. The involvement of Pv09 was discarded due to the observed segregation in the subpopulation obtained from the Xana genotype for the loci located in this region. In contrast, the two subpopulations obtained from the Xana genotype for the BM161 locus, linked to the Co-3/9 anthracnose resistance gene (Pv04), and from the Xana genotype for the SCAReoli locus, linked to the Co-2 anthracnose resistance gene (Pv11), exhibited monogenic segregations, suggesting that both regions were involved in the genetic control of resistance. A genetic dissection was carried out to verify the involvement of both regions in the reaction to PM. Two resistant recombinant lines were selected, according to their genotypes, for the block of loci included in the Co-2 and Co-3/9 regions, and they were crossed with the susceptible parent, Xana. Linkage analysis in the respective F2 populations supported the hypothesis that a dominant gene (Pm1) was located in the linkage group Pv11 and another gene (Pm2) was located in the linkage group Pv04. This is the first report showing the localization of resistance genes against powdery mildew in Phaseolus vulgaris and the results offer the opportunity to increase the efficiency of breeding

  14. Detection, differentiation and phylogenetic analysis of cucumber mosaic virus isolates from cucurbits in the northwest region of Iran.

    Science.gov (United States)

    Bashir, Nemat Sokhandan; Kalhor, Mohammad Rasaei; Zarghani, Shaheen Nourinejhad

    2006-06-01

    One hundred and twenty three cucurbit samples with one or more symptoms of leaf mosaic, leaf distortion, fruit mosaic, stunting, mottling and yellowing were collected from several locations in the northwest region of Iran. Screening by double-antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) with a cucumber mosaic virus (CMV) polyclonal antibody, produced positive reactions from 13 samples. However, none of these positive samples reacted with a CMV subgroup-II (S-II)-specific monoclonal antibody in a triple antibody sandwich (TAS)-ELSIA. When total RNA from the CMV-infected samples was subjected to reverse transcription polymerase chain reaction (RT-PCR) with a pair of primers corresponding to the flanking regions of the virus coat protein (CP) gene, an expected DNA fragment of about 872 bp was amplified from 10 of the 13 isolates. This fragment covered the CP open reading frame (ORF) plus 92 and 123 bp of the 5' and 3' flanking regions, respectively. Restriction analysis with MspI (HpaII) was done on 9 of the PCR products and revealed a previously described CMV subgroup I (S-I) specific profile (537 and 335 bp fragments) for the isolates B13, B23, B5, SH5, SH17, S342 and S337, and an additional fragment, suggestive of combined profiles, was present for B13, SH5 and S342. Two other isolates, SH12 and B7 had a CMV S-II MspI profile (four visible fragments and a predicted non-visible 28-bp fragment on 2% agarose). Also, BsuRI (HaeIII) did not cut the PCR products characteristic of the CMV S-I specific MspI profile, whereas for the S-II isolates, BsuRI gave two fragments with sizes of approximately 559 and 313 bp. Nucleotide (nt) sequences of clones from the isolates B13, B23, SH5, SH17, S337 and SH12 were determined and aligned with those of previously published CMV strains and isolates. Consensus parsimonious trees constructed on the basis of the whole amplified region (841 nt excluding the primer sequences), CP ORF (nt or deduced amino acid data), or

  15. 亚麻种质对白粉病的抗性评价%Resistance Evaluation of Flax Varieties to Powdery Mildew

    Institute of Scientific and Technical Information of China (English)

    乔红霞; 陈娟

    2012-01-01

    The resistance evaluation of 53 flax varieties to powdery mildew in Qingyang region were conducted, the results showed that there were nearly no flax varieties with immune to powdery mildew, except for Xiji variety. There are very short of flax germplasm resources which are resistance to powdery mildew in Qingyang region.%对收集的53个亚麻种质进行了白粉病田间抗性评价,结果表明所调查的亚麻种质均无免疫(M)植株,仅西吉胡麻为抗(R)病品种,庆阳市抗白粉病亚麻资源材料较为匮乏.

  16. The novel gene VpPR4-1 from Vitis pseudoreticulata increases powdery mildew resistance in transgenic Vitis vinifera L.

    Directory of Open Access Journals (Sweden)

    Lingmin eDai

    2016-05-01

    Full Text Available Pathogenesis-related proteins (PRs can lead to increased resistance of the whole plant to pathogen attack. Here, we isolate and characterize a PR-4 protein from a wild Chinese grape Vitis pseudoreticulata which shows greatly elevated transcription following powdery mildew infection. Its expression profiles under a number of abiotic stresses were also investigated. The PR-4 gene was overexpressed in regenerated V. vinifera cv. Red Globe via Agrobacterium tumefaciens-mediated transformation and verified by the Western blot. The transgenic grapevines exhibited higher expression levels of PR-4 protein content than wild-type vines and also repressed the growth of powdery mildew. The PR gene responds differently to different stresses in the PR-4 transformants. This study demonstrates that PR-4 protein in grapes plays a vital role in defense against powdery mildew invasion.

  17. 芍药白粉病的空间分布型及抽样技术∗%Spatial Distribution Pattern and Sampling Method of Peony Powdery Mildew

    Institute of Scientific and Technical Information of China (English)

    何玉会; 马海霞; 瞿小杰; 李茜; 杨信东

    2014-01-01

    对芍药白粉病的空间分布型进行研究,结果表明:芍药白粉病的空间分布型为聚集分布。芍药白粉病的理论抽样数研究结果表明:若想获得精确的调查结果,在常见的发病条件下(每个植株的病级数为1~5),大约需要调查200~700个植株。如果想获得较为精确的调查结果,在常见的发病条件下(每个植株的病级数为1~5),大约需要调查50~170个植株。另外还制定了指导防治工作的序贯抽样检索表。%Peony samples with powdery mildew were collected in Changchun, Jilin province in this study. The spatial distribution of the peony powdery mildew was found to be in a pattern of aggrega⁃ted distribution. In addition, optimum sample number for analyzing peony powdery mildew was de⁃termined. The field survey results showed that, under normal disease condition, 200—700 plant samples ( 1—5 disease grade of peony powdery mildew per plant) were required to analyze data with high precision; while 50—170 plant samples ( 1—5 disease grade of peony powdery mildew per plant) were required to analyze data with moderate precision. A sequential sampling search table was established, which can be used for directing peony powdery mildew disease control.

  18. The Wheat Mediator Subunit TaMED25 Interacts with the Transcription Factor TaEIL1 to Negatively Regulate Disease Resistance against Powdery Mildew.

    Science.gov (United States)

    Liu, Jie; Zhang, Tianren; Jia, Jizeng; Sun, Jiaqiang

    2016-03-01

    Powdery mildew, caused by the biotrophic fungal pathogen Blumeria graminis f. sp. tritici, is a major limitation for the production of bread wheat (Triticum aestivum). However, to date, the transcriptional regulation of bread wheat defense against powdery mildew remains largely unknown. Here, we report the function and molecular mechanism of the bread wheat Mediator subunit 25 (TaMED25) in regulating the bread wheat immune response signaling pathway. Three homoalleles of TaMED25 from bread wheat were identified and mapped to chromosomes 5A, 5B, and 5D, respectively. We show that knockdown of TaMED25 by barley stripe mosaic virus-induced gene silencing reduced bread wheat susceptibility to the powdery mildew fungus during the compatible plant-pathogen interaction. Moreover, our results indicate that MED25 may play a conserved role in regulating bread wheat and barley (Hordeum vulgare) susceptibility to powdery mildew. Similarly, bread wheat ETHYLENE INSENSITIVE3-LIKE1 (TaEIL1), an ortholog of Arabidopsis (Arabidopsis thaliana) ETHYLENE INSENSITIVE3, negatively regulates bread wheat resistance against powdery mildew. Using various approaches, we demonstrate that the conserved activator-interacting domain of TaMED25 interacts physically with the separate amino- and carboxyl-terminal regions of TaEIL1, contributing to the transcriptional activation activity of TaEIL1. Furthermore, we show that TaMED25 and TaEIL1 synergistically activate ETHYLENE RESPONSE FACTOR1 (TaERF1) transcription to modulate bread wheat basal disease resistance to B. graminis f. sp. tritici by repressing the expression of pathogenesis-related genes and deterring the accumulation of reactive oxygen species. Collectively, we identify the TaMED25-TaEIL1-TaERF1 signaling module as a negative regulator of bread wheat resistance to powdery mildew.

  19. No indication of strict host associations in a widespread mycoparasite: grapevine powdery mildew (Erysiphe necator) is attacked by phylogenetically distant Ampelomyces strains in the field.

    Science.gov (United States)

    Pintye, Alexandra; Bereczky, Zsolt; Kovács, Gábor M; Nagy, László G; Xu, Xiangming; Legler, Sara Elisabetta; Váczy, Zsuzsanna; Váczy, Kálmán Zoltán; Caffi, Tito; Rossi, Vittorio; Kiss, Levente

    2012-07-01

    Pycnidial fungi belonging to the genus Ampelomyces are common intracellular mycoparasites of powdery mildews worldwide. Some strains have already been developed as commercial biocontrol agents (BCAs) of Erysiphe necator and other powdery mildew species infecting important crops. One of the basic, and still debated, questions concerning the tritrophic relationships between host plants, powdery mildew fungi, and Ampelomyces mycoparasites is whether Ampelomyces strains isolated from certain species of the Erysiphales are narrowly specialized to their original mycohosts or are generalist mycoparasites of many powdery mildew fungi. This is also important for the use of Ampelomyces strains as BCAs. To understand this relationship, the nuclear ribosomal DNA internal transcribed spacer (ITS) and partial actin gene (act1) sequences of 55 Ampelomyces strains from E. necator were analyzed together with those of 47 strains isolated from other powdery mildew species. These phylogenetic analyses distinguished five major clades and strains from E. necator that were present in all but one clade. This work was supplemented with the selection of nine inter-simple sequence repeat (ISSR) markers for strain-specific identification of Ampelomyces mycoparasites to monitor the environmental fate of strains applied as BCAs. The genetic distances among strains calculated based on ISSR patterns have also highlighted the genetic diversity of Ampelomyces mycoparasites naturally occurring in grapevine powdery mildew. Overall, this work showed that Ampelomyces strains isolated from E. necator are genetically diverse and there is no indication of strict mycohost associations in these strains. However, these results cannot rule out a certain degree of quantitative association between at least some of the Ampelomyces lineages identified in this work and their original mycohosts.

  20. The Effect of Different Cucurbit Rootstocks on Some Morphological and Physiological Traits of Cucumber (Cucumis sativus cv. Super Dominus

    Directory of Open Access Journals (Sweden)

    reihane Mesgari

    2017-02-01

    Full Text Available Introduction: Cucumber is one of the most important vegetable crops for the local consumption and exportation. The use of grafted vegetable seedlings has been popular in many countries during recent years. Growing fruit-bearing vegetables, chiefly tomato, cucumber and watermelon through grafted seedlings become a widespread practice worldwide. Grafting is a valuable technique to avoid soil-borne diseases, provide biotic and abiotic stress tolerance, enhance nutrient uptake, optimize water use, and increase fruit yield and quality. Vegetable grafting is a new topic in Iran and there are a limited number of studies on grafted vegetable production. However, attention to grafting by researchers has recently increased. Suitable rootstocks should be identified and characterized for the effective utilization of grafting. The rootstock's vigorous root system increases the efficiency of water and nutrient absorption, and may also serve as a source of endogenous plant hormones, thus leading to increased growth and yield in addition to disease control. In the present study, we investigated the response of two Cucurbita sp. and an Iranian melon as rootstocks for cucumber. Materials and methods: In order to study the effect of cucurbit rootstocks and grafting method on growth, yield and fruit quality of cucumber (Cucumis sativus cv. Super Dominus, an experiment was conducted as a factorial design in the base of RCBD with three replications in the greenhouse and research farm, University of Zanjan. Treatments were included three rootstocks (Cucurbita moschata L., Lagenaria siceraria and Cucumis melo L. and ungrafted plants (control and two grafting method (hole insertion and splice grafting. Seeds were sown simultaneously in plastic pots. For obtaining the same stem diameter of scion and rootstocks, cucumber seeds were planted four days earlier than rootstocks seeds. The seedlings were grown in an environment-controlled greenhouse with 25/20 day