Vasyl P. Heluta
Full Text Available Information is provided on Erysiphe platani, a newly invasive fungus in Ukraine. The anamorph of this North American powdery mildew was first recorded in Ukraine in 1986 on Platanus orientalis in the Nikita Botanical Garden (Crimea. Later, it was found in other localities of the Crimean peninsula, and in Odessa and Odessa region on three species of plane, namely P. × hispanica, P. occidentalis and P. orientalis. Spread of the fungus was epiphytotic. This mildew significantly reduces the ornamental value of plane trees, which are often planted in public open spaces within urban areas of southern Ukraine. Recently, E. platani has formed the teleomorph in this region. Morphologically, the Ukrainian material is slightly different from the species description, viz. appendages are longer (up to 3 times the chasmothecial diam., often with less compact apices.
Full Text Available This paper includes 53 species of Erysiphales collected on the Masurian Lakeland (North-East of Poland. Most of them are common in our country. Erysiphe lythri on Lythrum salicaria are seldom met. Some other powdery mildews were found on host plants, where they appear rarely or are found only in some regions of Poland.
Full Text Available Fungi of the genus Ampelomyces are the major antagonists of Erysiphales fungi being a significant group of phytopathogens. The hyperparasites attack various developmental stages of powdery mildews. As a result the infested ascomata do not reach the stage of maturity, do not form appendages nor ascospores, which is linked with a reduction of the source of primary infections. Studies conducted so far have mainly been devoted to Ampelomyces fungi application in the biological control of powdery mildews on crops, whilst a few only have been focused on the ecology of these mycoparasites on Erysiphales fungi infecting plants, especially in the urban environment. The present study addresses the natural occurrence and effect of Ampelomyces fungi on the development of ascomata of powdery mildews species. The material was collected in 2005–2009 in several cities of the northeastern Poland. First time ever Ampelomyces spores are reported in mature ascomata of Erysiphales with fully developed appendages. This phenomenon has been observed in the case of two species, viz.: Erysiphe flexuosa on Aesculus spp. and E. vanbruntiana var. sambuci-racemosae on Sambucus racemosa and is presumably linked with improved implementation, propagation and probably better survival during winter months.
Full Text Available This paper continues the presentation of results of a 3-year investigation on the occurrence of fungi of the order Erysiphales in the Drawski Landscape Park (north-western Poland. The list of occurrence of members of Erysiphales presented includes 31 next species and 15 species found on plants not mentioned in the previous paper. Additionally, the occurrence of the powdery mildew fungi in 12 permanent plots with nine plant associations was presented and compared.
Mori, Y.; Sato, Y.; Takamatsu, S.
Phylogenetic relationships of Erysiphales within Ascomycota were inferred from the newly determined sequences of the 18S rDNA and partial sequences of the 28S rDNA including the D1 and D2 regions of 10 Erysiphales taxa. Phylogenetic analyses revealed that the Erysiphales form a distinct clade among ascomycetous fungi suggesting that the Erysiphales diverged from a single ancestral taxon. The Myxotrichaceae of the Onygenales was distantly related to the other onygenalean families and was the sister group to the Erysiphales calde, with which it combined to form a clade. The Erysiphales/Myxotrichaceae clade was also closely related to some discomycetous fungi (Leotiales, Cyttariales and Thelebolaceae) including taxa that form cleistothecial ascomata. The present molecular analyses as well as previously reported morphological observations suggest the possible existence of a novel evolutionary pathway from cleistothecial discomycetous fungi to Erysiphales and Myxotrichaceae. However, since most of these fungi, except for the Erysiphales, are saprophytic on dung and/or plant materials, the questions of how and why an obligate biotroph like the Erysiphales radiated from the saprophytic fungi remain to be addressed. We also estimated the radiation time of the Erysiphales using the 18S rDNA sequences and the two molecular clockes that have been previously reported. The calculation showed that the Erysiphales split from the Myxotrichaceae 190–127 myr ago. Since the radiation time of the Erysiphales does not exceed 230 myr ago, even when allowance is made for the uncertainty of the molecular clocks, it is possible to consider that the Erysiphales evolved after the radiation of angiosperms. The results of our calculation also showed that the first radiation within the Erysiphales (138–92 myr ago) coincided with the date of a major diversification of angiosperms (130–90 myr ago). These results may support our early assumption that the radiation of the Erysiphales
Abundant production of conidia is a driving factor for epidemics of grape powdery mildew (Erysiphe necator (syn. Uncinula necator). Previous investigations revealed evidence for a signal that coordinates the onset of asexual reproduction. The genetic basis for this signal in powdery mildews had not ...
Torp, J.; Andersen, Brian
Conidial proteins from barley powdery mildew, Erysiphe graminis f. sp. hordei, were separated by 2-dimensional electrophoresis in polyacrylamide slab gels. Isoelectric focusing was used in the first dimension and separation according to molecular weight in a gel containing sodium dodecyl sulphate...
Rezende Viviane Ferreira
Full Text Available Genetic control of common bean (Phaseolus vulgaris resistance to powdery mildew (Erysiphe polygoni was studied using segregating populations from the bean variety crosses Jalo x ESAL 686 and ESAL 550 x ESAL 686. F2 plants, together with the parents, were inoculated and evaluated using a scale of values from one (plant without symptoms to nine (completely infected plant. F2 plants were harvested individually, and F2:3 families were obtained. These families were evaluated in an 11 x 11 and 12 x 12 simple lattice statistical design for the Jalo x ESAL 686 and ESAL 550 x ESAL 686 crosses, respectively, using the same value scale as the F2 generation. The segregation observed in F2 plants and F2:3 families indicated that two genes are involved in genetic control, due to a double recessive epistasis. The high linear regression coefficient (b between F2 plants and their F2:3 family, 0.66 for ESAL 550 x ESAL 686 cross, and 0.71 for Jalo x ESAL 686 cross, showed that the trait is highly heritable.
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
Cirulli, M.; Montemurro, G.; Ciccarese, F.; Smilari, F.
The infection of pea by Erysiphe polygoni was investigated. The susceptible cultivar ''Sprinter'' and the resistant varieties ''Stratagem Resistant'' (er 1 er 1 Er 2 Er 2 ) and ''Mexique-4'' (er 1 er 1 er 2 er 2 ) were used. Observations of germination of conidia, formation of primary appressoria, differentiation of secondary hyphae, number of secondary hyphae per conidium, and number of branches on the longest hyphae per conidium were made at different times from inoculation. The rate of conidial germination was not affected by the host genotypes. The formation of short germ tubes with primary appressoria were found to be similar on the susceptible ''Sprinter'' as well as on the ''Stratagem Resistant'' and ''Mexique-4''. No statistical difference in the growth of germ tubes with appressorium between susceptible and resistant peas was observed at 2, 4, 6, 10 and 12 hrs after inoculation. In resistant peas formation of primary appressoria was not followed by further mycelial growth. Conversely, in the susceptible pea, germinating conidia produced multiple germ tubes and branching hyphae. The establishment of a compatible relationship between host and pathogen appears to occur at or near the stage of formation of the primary appressorium. Most conidia on the leaves formed primary appressoria as early as 2 hrs after inoculation. The Course of the host/pathogen relationship is apparently decided at a very early stage after pathogen contact with the host, such as the length of the longest hyphae, number of germ tubes per conidium and branching of the longest, and the difference in the macroscopic fungal fructification. E. polygoni activity in susceptible pea is evidently influenced by temperature whereas the gene action of the genetic factors remains unaffected in resistant pea
Damgaard, C.; Giese, Nanna Henriette
Genetic variation of the barley powdery mildew fungus (Erysiphe graminis f.sp. hordei) was estimated in three Danish local populations. Genetic variation was estimated from the variation amongst clones of Egh, and was therefore an estimate of the maximum genetic variation in the local populations...
Full Text Available In this study, we cloned a new chitinase gene, EuCHIT2, from Eucommia ulmoides Oliver (E. ulmoides using rapid amplification of cDNA ends (RACE technology and constructed an overexpression vector, pSH-35S-EuCHIT2, to introduce it into tobacco (Nicotiana tabacum cv. Xanthi. Resistance to Erysiphe cichoracearum de Candolle (E.cichoracearum DC and molecular mechanisms in the transgenic tobacco were determined by drop inoculation, spore counting, determination of physicochemical indicators, and analysis of gene expression. The chitinase activity and resistance to E. cichoracearum DC were significantly higher in the transgenic tobacco than in wild-type tobacco (p < 0.05. The activities of peroxidase (POD and catalase (CAT, after inoculation with E. cichoracearum DC, were higher in the transgenic tobacco than in the wild-type. Conversely, the malondialdehyde (MDA content was significantly lower in the transgenic tobacco than the wild-type before and after inoculation. In addition, our study also indicated that the resistance to E. cichoracearum DC might involve the salicylic acid (SA and jasmonic acid (JA pathways, because the expression levels of pathogenesis-related gene 1 (PR-1a and coronatine-insensitive 1 (COI1 were significantly increased and decreased, respectively, after inoculation with E. cichoracearum DC. The present study supports the notion that PR-1a and POD participate in resistance to E. cichoracearum DC in the transgenic tobacco plants.
Schlicht, Markus; Kombrink, Erich
Powdery mildews are a diverse group of pathogenic fungi that can infect a large number of plant species, including many economically important crops. However, basic and applied research on these devastating diseases has been hampered by the obligate biotrophic lifestyle of the pathogens, which require living host cells for growth and reproduction, and lacking genetic and molecular tools for important host plants. The establishment of Arabidopsis thaliana as a host of different powdery mildew species allowed pursuing new strategies to study the molecular mechanisms governing these complex plant–pathogen interactions. Nitric oxide (NO) has emerged as an important signaling molecule in plants, which is produced upon infection and involved in activation of plant immune responses. However, the source and pathway of NO production and its precise function in the regulatory network of reactions leading to resistance is still unknown. We studied the response of Arabidopsis thaliana to infection with the adapted powdery mildew, Golovinomyces orontii (compatible interaction) and the non-adapted, Erysiphe pisi (incompatible interaction). We observed that NO accumulated rapidly and transiently at infection sites and we established a correlation between the resistance phenotype and the amount and timing of NO production. Arabidopsis mutants with defective immune response accumulated lower NO levels compared to wild type. Conversely, increased NO levels, generated by treatment with chemicals or expression of a NO-synthesizing enzyme, resulted in enhanced resistance, but only sustained NO production prevented excessive leaf colonization by the fungus, which was not achieved by a short NO burst although this reduced the initial penetration success. By contrast, lowered NO levels did not impair the ultimate resistance phenotype. Although our results suggest a function of NO in mediating plant immune responses, a direct impact on pathogen growth and development cannot be excluded
Gao, Yu-Rong; Han, Yong-Tao; Zhao, Feng-Li; Li, Ya-Juan; Cheng, Yuan; Ding, Qin; Wang, Yue-Jin; Wen, Ying-Qiang
The most economically important disease of cultivated grapevines worldwide is powdery mildew caused by the biotrophic fungal pathogen Erysiphe necator. To integrate effective genetic resistance into cultivated grapevines, numerous disease resistance screens of diverse Vitis germplasm, including wild species, have been conducted to identify powdery mildew resistance, but the results have been inconsistent. Here, a new powdery mildew isolate that is infectious on grapevines, designated Erysiphe necator NAFU1 (En. NAFU1), was identified and characterized by phylogeny inferred from the internal transcribed spacer (ITS) of pathogen ribosomal DNA sequences. Three classical methods were compared for the maintenance of En. NAFU1, and the most convenient method was maintenance on detached leaves and propagation by contact with infected leaves. Furthermore, controlled inoculations of En. NAFU1 were performed using detached leaves from 57 wild Chinese grapevine accessions to quickly evaluate powdery mildew resistance based on trypan blue staining of leaf sections. The results were compared with previous natural epidemics in the field. Among the screened accessions inoculated with En. NAFU1, 22.8% were resistant, 33.3% were moderately resistant, and 43.9% were susceptible. None of the accessions assessed herein were immune from infection. These results support previous findings documenting the presence of race-specific resistance to E. necator in wild Chinese grapevine. The resistance of wild Chinese grapevine to En. NAFU1 could be due to programmed cell death. The present results suggest that En. NAFU1 isolate could be used for future large-scale screens of resistance to powdery mildew in diverse Vitis germplasms and investigations of the interaction between grapevines and pathogens. Copyright © 2015 Elsevier Masson SAS. All rights reserved.
Ellis, Christine; Karafyllidis, Ioannis; Turner, John G
In Arabidopsis spp., the jasmonate (JA) response pathway generally is required for defenses against necrotrophic pathogens and chewing insects, while the salicylic acid (SA) response pathway is generally required for specific, resistance (R) gene-mediated defenses against both biotrophic and necrotrophic pathogens. For example, SA-dependent defenses are required for resistance to the biotrophic fungal pathogen Erysiphe cichoracearum UCSC1 and the bacterial pathogen Pseudomonas syringae pv. maculicola, and also are expressed during response to the green peach aphid Myzus persicae. However, recent evidence indicates that the expression of JA-dependent defenses also may confer resistance to E. cichoracearum. To confirm and to extend this observation, we have compared the disease and pest resistance of wild-type Arabidopsis plants with that of the mutants coil, which is insensitive to JA, and cev1, which has constitutive JA signaling. Measurements of the colonization of these plants by E. cichoracearum, P. syringae pv. maculicola, and M. persicae indicated that activation of the JA signal pathway enhanced resistance, and was associated with the activation of JA-dependent defense genes and the suppression of SA-dependent defense genes. We conclude that JA and SA induce alternative defense pathways that can confer resistance to the same pathogens and pests.
Agurto, Mario; Schlechter, Rudolf O.; Armijo, Grace; Solano, Esteban; Serrano, Carolina; Contreras, Rodrigo A.; Zúñiga, Gustavo E.; Arce-Johnson, Patricio
Fungal pathogens are the cause of the most common diseases in grapevine and among them powdery mildew represents a major focus for disease management. Different strategies for introgression of resistance in grapevine are currently undertaken in breeding programs. For example, introgression of several resistance genes (R) from different sources for making it more durable and also strengthening the plant defense response. Taking this into account, we cross-pollinated P09-105/34, a grapevine plant carrying both RUN1 and REN1 pyramided loci of resistance to Erysiphe necator inherited from a pseudo-backcrossing scheme with Muscadinia rotundifolia and Vitis vinifera ‘Dzhandzhal Kara,’ respectively, with the susceptible commercial table grape cv. ‘Crimson Seedless.’ We developed RUN1REN1 resistant genotypes through conventional breeding and identified them by marker assisted selection. The characterization of defense response showed a highly effective defense mechanism against powdery mildew in these plants. Our results reveal that RUN1REN1 grapevine plants display a robust defense response against E. necator, leading to unsuccessful fungal establishment with low penetration rate and poor hypha development. This resistance mechanism includes reactive oxygen species production, callose accumulation, programmed cell death induction and mainly VvSTS36 and VvPEN1 gene activation. RUN1REN1 plants have a great potential as new table grape cultivars with durable complete resistance to E. necator, and are valuable germplasm to be included in grape breeding programs to continue pyramiding with other sources of resistance to grapevine diseases. PMID:28553300
Full Text Available In 2002, the occurrence of fungi of the order Erysiphales on plants of the Słowiański Park located in Goorzów Wielkopolski was investigated. Plant samples were collected once a month, from August to November. The samples examined were above ground plant parts colonized by powdery mildew fungi. A total of 78 samples were collected. Apart from 14 species of the order Erysiphales, Ampelomyces quisqualis parasitizing on Erysiphe cichoracearum var. cichoracearum, Phyllactinia mali and Podosphaera tridactyl var. tridactyla was found. Ampelomyces quisqualis affected hyphae, oidia, and young cleistothecia of P. mali. In contrast, in E. cichoracearum var. cichoracearum, Po. tridactyle var. tridactyla, this hyperparasite colonized only hyphae and oidia. This paper for the first trime informs of A. quisqualis parasitizing on P. mali and Po. tridactyla var. tridactyla.
Uwe Braun; S. Krishna Mohan
In the course of routine examinations of powdery mildews collected in Idaho and Oregon, USA, some of the identified species proved to be new to North America, in some cases on new host plants. Leveillula papilionacearum and L. picridis are first records from the USA. Astragalus filipes, Dalea ornata and D. searlsiae are new hosts for Leveillula papilionacearum....
Jun 19, 2012 ... In this study, a novel bZIP-like gene was isolated from Chinese wild Vitis ... Results reveal that it was in lower lever in flower than in leaf, stem, tendril and fruit. .... First-strand cDNA was synthesized from 1 µg of DNase treated.
Christiansen, S.K.; Justesen, A.F.; Giese, H.
to be similar for all four genes. The results of the codon-usage analysis suggest that Egh is more flexible than other fungi in the choice of nucleotides at the wobble position. Codon-usage preferences in Egh and barley genes indicate a level of difference which may be exploited to discriminate between fungal...
Lopez Pinar, Angela; Rauhut, Doris; Ruehl, Ernst; Buettner, Andrea
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.
Torp, J.; Jensen, H.P.
Full text: Seedlings of 4 barley lines possessing resistance genes M1-a6, M1-a12 or M1-g were inoculated with powdery mildew culture CR3, which is a-virulent to the 4 host lines. In total, 50 million conidia were screened for the occurrence of virulent mutants, 43 putative virulent mutants were found. They could be grouped into 5 genotypes according to the virulence spectrum. They might have originated by one of the following events: 1. admixture, 2. physiological events that allow a few conidia to establish colonies in spite of the presence of a functional gene for resistance, 3. mutation in a gene for specificity, 4. deletion or mutation in some kind of suppressing element in which case more than one virulence may be affected. Based upon the virulence spectra, mating type, biochemical tests and analysis of test crosses, 3 of the genotypes were clearly classified as not being of mutational origin. Of the two remaining genotypes one differed in 4 virulences, the other by two virulences and one avirulence. Based upon expectations from the gene-for-gene concept, it is concluded that both were not of mutational origin. If in fact there are derived from a mutation, the concept of gene-for-gene interactions would have to be revised. Assuming that no mutations for virulence were found in this experiment, the spontaneous mutation frequency from avirulence to virulence would be below 2x10 -8 . (author)
In the last three decades, plant disease control has become heavily dependent on fungicides. This practice increased yield significantly but had also negative side-effects on the environment. In many countries, integrated control programs have been initiated in order to reduce pesticide use
Christiansen, S.K.; Knudsen, S.; Giese, H.
Particle gun acceleration appears to be a possible way to transform mycelium cells of obligate plant parasites growing on host surfaces, GUS expression was obtained in E. graminis f.sp. hordei cells after bombardment with the GUS gene under the control of the E. graminis f.sp. hordei beta...
Lopez Pinar, Angela; Rauhut, Doris; Ruehl, Ernst; Buettner, Andrea
Fungal infections are detrimental for viticulture since they may reduce harvest yield and wine quality. This study aimed to characterize the effects of bunch rot and powdery mildew on wine aroma by quantification of representative aroma compounds using Stable Isotope Dilution Analysis (SIDA). For this purpose, samples affected to a high degree by each fungus were compared with a healthy sample in each case; to this aim, the respective samples were collected and processed applying identical conditions. Thereby, the effects of bunch rot were studied in three different grape varieties: White Riesling, Red Riesling and Gewürztraminer whereas the influence of powdery mildew was studied on the hybrid Gm 8622-3. Analyses revealed that both fungal diseases caused significant changes in the concentration of most target compounds. Thereby, the greatest effects were increases in the concentration of phenylacetic acid, acetic acid and γ-decalactone for both fungi and all grape varieties. Regarding other compounds, however, inconsistent effects of bunch rot were observed for the three varieties studied.
Angela Lopez Pinar
Full Text Available Fungal infections are detrimental for viticulture since they may reduce harvest yield and wine quality. This study aimed to characterize the effects of bunch rot and powdery mildew on wine aroma by quantification of representative aroma compounds using Stable Isotope Dilution Analysis (SIDA. For this purpose, samples affected to a high degree by each fungus were compared with a healthy sample in each case; to this aim, the respective samples were collected and processed applying identical conditions. Thereby, the effects of bunch rot were studied in three different grape varieties: White Riesling, Red Riesling and Gewürztraminer whereas the influence of powdery mildew was studied on the hybrid Gm 8622-3. Analyses revealed that both fungal diseases caused significant changes in the concentration of most target compounds. Thereby, the greatest effects were increases in the concentration of phenylacetic acid, acetic acid and γ-decalactone for both fungi and all grape varieties. Regarding other compounds, however, inconsistent effects of bunch rot were observed for the three varieties studied.
Valdés-Gómez, Héctor; Araya-Alman, Miguel; Pañitrur-De la Fuente, Carolina; Verdugo-Vásquez, Nicolás; Lolas, Mauricio; Acevedo-Opazo, César; Gary, Christian; Calonnec, Agnès
The primary strategy to control powdery mildew in Chilean vineyards involves periodic fungicide spraying, which may lead to many environmental and human health risks. This study aimed to implement and evaluate the effectiveness and economic feasibility of a novel decision support strategy (DSS) to limit the number of treatments against this pathogen. An experiment was conducted between the 2010 and 2013 seasons in two irrigated vine fields, one containing a cultivar of Cabernet Sauvignon (CS) and the other a cultivar of Chardonnay (CH). The results showed that the DSS effectively controlled powdery mildew in CS and CH vine fields, as evidenced by a disease severity lower than 3%, which was lower than that observed in untreated vines (approximately 10 and 40% for CS and CH respectively). The DS strategy required the application of only 2-3 fungicide treatments per season in key vine phenological stages, and the cost fluctuated between $US 322 and 415 ha -1 , which was 40-60% cheaper than the traditional strategy employed by vine growers. The decision support strategy evaluated in this trial allows a good control of powdery mildew for various types of epidemic with an early and late initiation. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.
Jørgensen, Jørgen Helms; Mortensen, K.
by the hosts. An average of about 60% of the germinated conidia formed haustoria, 50% formed hyphae, and 40% formed mildew colonies on the susceptible hosts. In contrast, only about 0.7% formed haustoria, 0.4% formed hyphae, and 0.2% formed colonies on the resistant hosts, on which the great majority...
Full Text Available Morphogenesis of cleistothecia in Microsphaera alphitoides Griff. et Maubl. (Erysiphales, Ascomycetes on naturally infected leaf of oak was investigated with the scanning electron microscope. All phases of the life cycle of this specks have been described. Some comparisons between methods of preparation of the material have been made.
N. R. Fonseca; L. M. S. Guimaraes; R. P. Pires; Ned Klopfenstein; M. -S. Kim; A. C. Alfenas
Powdery mildew diseases are caused by biotrophic fungi in the Erysiphales. These fungal pathogens are easily observed by the whitish powdery appearance caused by their colonization of the aerial surfaces on living plants (Stadnik & Rivera, 2001) (Figure 1). In Brazil, powdery mildew of Eucalyptus spp is increasing under the current nursery production...
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
DYNAMICS OFCercospora zeina POPULATIONS IN MAIZE-BASED AGRO- ..... Population differentiation of Cercospora zeina in three districts of Uganda based on analysis of molecular variance ..... interactions: The example of the Erysiphe.
Laurence Veronique Bindschedler
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.
Cécile Robin; Amira Mougou-Hamdane; Jean-Marc Gion; Antoine Kremer; Marie-Laure. Desprez-Loustau
Powdery mildew, caused by Erysiphe alphitoides (Ascomycete), is the most frequent disease of oaks, which are also known to be host plants for Phytophthora cinnamomi (Oomycete), the causal agent of ink disease. Components of genetic resistance to these two pathogens, infecting either leaves or root and collar, were...
Lyngkjær, M.F.; Jensen, H.P.; Østergård, Hanne
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...
Hovmøller, M.S.; Munk, L.; Østergård, Hanne
Gene frequencies in samples of aerial populations of barley powdery mildew (Erysiphe graminis f.sp. hordei), which were collected in adjacent barley areas and in successive periods of time, were compared using mobile and stationary sampling techniques. Stationary samples were collected from trap ...
Wheat powdery mildew, causal agent Erysiphe graminis f. sp. tritici , has been a serious disease in central China since the late 1970s.
The wheat growing area in central China can be divided into three zones defined by altitude.
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...
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...
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...
Powdery mildew is a serious disease of pea worldwide, and it could be caused by two fungal species Erysiphe pisi and E. trifolii. White powdery patches on leaves, stems and pods are characteristics of the disease. The pathogen may form black fruiting bodies called chasmothecia near the end of the gr...
Powdery mildew of pea, caused by Erysiphe pisi DC, is a serious production constraint to pea (Pisum sativum L.) production in the U.S. and elsewhere. Utilization of genetic resistance to powdery mildew using er1 has been an effective strategy to manage this disease. This gene, er1, conferring powde...
O'Hara, R.B.; Brown, J.K.M.
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...
The two most economically important diseases of grapevine cultivation worldwide are caused by the fungal pathogen powdery mildew (Erysiphe necator syn. Uncinula necator) and the oomycete, downy mildew (Plasmopara viticola). These pathogens, endemic to North America, were introduced into Europe in t...
Jiang, W.M.; Jørgensen, Jørgen Helms; Torp, J
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...
Schwarz, G.; Michalek, W.; Mohler, V.
The complex Mla locus of barley determines resistance to the powdery mildew pathogen Erysiphe graminis f. sp. hol dei. With a view towards gene isolation, a population consisting of 950 F-2 individuals derived from a cross between the near-isogenic lines 'P01' (Mla1) and 'P10' (Mla12) was used to...
Pedersen, L.H.; Jacobsen, S.; Hejgaard, J.
The plasma membrane bound beta-1,3-D-glucan (callose) synthase. assumed to be involved in the resistance to the powdery mildew fungus (Erysiphe graminis f.sp. hordei), was partially purified from a microsomal fraction of green barley leaves (Hordeum vulgare L.). Plasma membranes were enriched...
Centrum voor genetische bronnen (CGN) in Nederland- -,
By 2014-14-07 data on experiments was available for the following traits. / Annuality 2120 observations on 1905 accessions / Awnedness - hoodedness 2570 observations on 2099 accessions / Early growth tendency 1717 observations on 1425 accessions / Erysiphe graminis 3832 observations on 1794
Full Text Available In Romania the most important pathogens on tomatoes crops are Alternaria porri f.sp. solani, Botrytis cinerea, Fulvia fulva, Phytophthora infestans and Erysiphe sp. During period of vegetation, the attack of mentioned pathogens are frequently overlapping. For simultaneously control of pathogenswere used some combination with different active substances (chlorothalonil 500g/l, iprodione 500 g/l, fenhexamid 500 g/l, thiophanate methyl 500g/l, metiram 80%, dimethomorph 9%, mancozeb 60%, difenoconazole 250 g/l , fenamidone 75g/l, propamocarb HCL 375 g/l. The best results for controlling Alternaria porri f.sp. solani, Botrytis cinerea and Fulvia fulva are metiram 80% 0.2% + thiophanate methyl 500g/l 0.14% with 93.5% efficacy. In the untreated check the degree of attack was 78.6% (44.3% A.solani, 7.0% B.cinerea and 27.3% F. Fulva. For controlling Phytophthora infestans, Erysiphe sp. and Fulvia fulva (fenamidone 75g/l + propamocarb HCL 375 g/lÂ Â Â 0.2% +Â difenoconazole 250 g/l 0.05% with 94.5% efficacy. In the untreated check the degree of attack is 81.2% (38.4% P. infestans, 27.4% Erysiphe sp. , 15.4% F. fulva.
Ewa Dorota Zalewska
Full Text Available The largest participation in causing the disease of herbal plants have fungi. Studies on their occurrence on plants of the family Apiaceae are conducted in the Lublin region since 2001. The observations of plant healthiness are carried out directly on the plantations. Plants with symptoms of disease are studied in the laboratory. Identification of the fungi is performed based on etiological symptoms and on the base of fungal cultures isolated from plants. Among the many species of fungi obtained from diseased plants to the particularly harmful belong: Septoria carvi, Colletotrichum gloeosporioidesand C. dematium, Sclerotinia sclerotiorum, Passalora puncta(Cercosporidium punctum and Erysiphe umbelliferarum.
Pinosa, Francesco; Buhot, Nathalie; Kwaaitaal, Mark Adrianus Cornelis J
resistance against Bgh, and chemical inhibition of PLDs in plants mutated in PLDδ indicated that this isoform alone is involved in Bgh resistance. In addition, we confirmed the involvement of PLDδ in penetration resistance against another nonadapted pea powdery mildew fungus, Erysiphe pisi. A green...... fluorescent protein fusion of PLDδ localized to the plasma membrane at the Bgh attack site, where it surrounded the cell wall reinforcement. Furthermore, in the pldδ mutant, transcriptional up-regulation of early microbe-associated molecular pattern response genes was delayed after chitin stimulation...
Torp, J.; Joergensen, J.H.
Full text: The barley line Sultan 5 carries resistance gene M1-a12. Seeds were treated with EMS or NaN 3 . Among 10381 M 1 -spike progenies inoculated with M1-a12 a-virulent isolates of Erysiphe graminis, 25 segregated for less resistant infection type. Among 10 mutants analyzed, 9 had mutant allels of M1-a12 and one had a recessive mutant gene in a different locus acting as a ''suppressor'' of M1-a12. (author)
Almacellas Gort, Jaume
La cendrosa de l'ordi, causada pel fong Blumeria graminis (D.C.) E. O. Speer f. sp. hordei Em. Marchal, sin. Erysiphe graminis D.C.: Fr. f. sp. hordei Em. Marchal, anamorf: Oidium monilioides (Nees) Link, és la malaltia aèria més important en aquest conreu a Catalunya. El 1987 es van iniciar les investigacions sobre l'etiologia de les principals malalties dels cereals. Es realitzà una prospecció per tota la l’àrea cerealícola de la geografia catalana, que va permetre estimar la distribuci...
Liyanage, K K; Khan, Sehroon; Brooks, Siraprapa; Mortimer, Peter E; Karunarathna, Samantha C; Xu, Jianchu; Hyde, Kevin D
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. Copyright © 2017 Elsevier Ltd. All rights reserved.
Ale-Agha, N; Feige, G B; Dachowski, M
Forty-three microfungi have been observed on thirty species of the Compositae occurring in several locations in the Ruhr Basin in North Rhine-Westphalia. Many fungi belong to the Ascomycetes (Erysiphales, Diaporthales, Dothideales, Leotiales and Pleosporales) and to the Deuteromycetes (Melanconiales, Moniliales and Sphaeropsidales). Other fungi wich were found in our investigation belong to the Basidiomycetes (Uredinales) and to the Oomycetes (Peronosporales). Some recorded microfungi have been discovered on new hosts in North Rhine-Westphalia and also in Germany for the first time. New for North Rhine-Westphalia are Ascochyta spec. Libert on Matricaria recutita L., Phoma exigua var. linicola (Naumov & Vassilevski) Maas on Tripleurospermum maritimum (L.) W. D. J. Koch, Phomopsis achillea (Sacc.) Höhn. on Achillea ageratum L., Diaporthe aff. arctii (Lasch) Nitschke on Solidago canadensis L. and on Achillea ageratum L., Lophiostoma caulium (Fr.) Ces. & De Not. on Anthemis tinctoria L. and Ophiobolus fructicum (Rob. ex Desm.) on Serratula tinctoria L. New for Germany are Ophiobolus cirsii (P. Karst.) Sacc. on Cichorium intybus L., Phomopsis cirsii Grove on Cirsium vulgare (Savi) Ten., Pleospora kansensis J. P. Ellis & M. B. Ellis and Pleospora phaeocomoides cf. var. infectoria on Centaurea jacea L.
The symposium "One fungus = Which name" held in Amsterdam 12-13 April 2012, addressed the drastic changes in the naming of pleomorphic fungi adopted by the 18(th) International Botanical Congress in Melbourne in 2011. Possible solutions and ways to face resulting problems were suggested. The fundamental change is that under the new rules fungi in future will be treated nomenclaturally like plants and all other groups of organisms ruled by the ICN, i.e. with one correct name for each species. Numerous discussions and statements during the Symposium reflected widespread anxieties that these rules could negatively influence taxonomic work on pleomorphic fungi. However, they are groundless, being based on misunderstandings and confusion of nomenclature and taxonomy. With pleomorphic fungi, taxonomists will in future have to answer the question whether different morphs can represent one fungus (taxon), but this remains a taxonomic decision and has nothing to do with nomenclature. Furthermore, the ICN does not and cannot rule on how this decision is made. Thus it cannot provide rules based solely on methods involving morphology in vivo or in vitro, molecular analyses, physiological and biochemical data, inoculation experiments in pathogenic groups or any other methods or combinations of them. It is up to the taxonomist to select appropriate methods and to decide which data are sufficient to introduce new taxa. Some future problems and strategies around the application of anamorph- and teleomoph-typified taxon names (genera and species), are discussed here, using the recently monographed powdery mildews (Erysiphales) as an example.
Full Text Available Parasites are able to evolve rapidly and overcome host defense mechanisms, but the molecular basis of this adaptation is poorly understood. Powdery mildew fungi (Erysiphales, Ascomycota are obligate biotrophic parasites infecting nearly 10,000 plant genera. They obtain their nutrients from host plants through specialized feeding structures known as haustoria. We previously identified the AVR(k1 powdery mildew-specific gene family encoding effectors that contribute to the successful establishment of haustoria. Here, we report the extensive proliferation of the AVR(k1 gene family throughout the genome of B. graminis, with sequences diverging in formae speciales adapted to infect different hosts. Also, importantly, we have discovered that the effectors have coevolved with a particular family of LINE-1 retrotransposons, named TE1a. The coevolution of these two entities indicates a mutual benefit to the association, which could ultimately contribute to parasite adaptation and success. We propose that the association would benefit 1 the powdery mildew fungus, by providing a mechanism for amplifying and diversifying effectors and 2 the associated retrotransposons, by providing a basis for their maintenance through selection in the fungal genome.
GLAUBER HENRIQUE DE SOUSA NUNES
Full Text Available O objetivo do trabalho foi selecionar famílias de feijão adaptadas às condições de inverno do sul de Minas Gerais. A partir das populações segregantes L3272 x (Carioca x TU e L3272 x ESAL 601 foram selecionadas 230 famílias que foram previamente avaliadas no cultivo de inverno no sul de Minas Gerais. Foram mantidas 103 famílias, sendo 79 de ciclo normal e 24 precoces. Esses dois grupos de famílias foram avaliados independentemente, em dois locais, no inverno de 1995. As famílias selecionadas foram avaliadas em um único experimento, no inverno de 1996. Em todos os experimentos foram avaliados os caracteres produtividade de grãos, número de dias para o florescimento, e reação ao patógeno Erysiphe polygoni. Os resultados mostraram heterogeneidade entre as famílias no que tange a todos os caracteres estudados, permitindo a seleção de famílias adaptadas às condições de inverno. A correlação genética entre o número de dias para o florescimento e a reação ao patógeno Erysiphe poligoni foi baixa e negativa. As estimativas das herdabilidades no sentido amplo foram relativamente elevadas quanto a todos os caracteres, nos dois grupos de famílias avaliados. A herdabilidade no sentido amplo, referente a famílias de ciclo normal, foi semelhante à estimativa da herdabilidade realizada.The purpose of the present work was to select common bean families adapted to the winter conditions of South of Minas Gerais State, Brazil. 230 families were selected from segregant populations L3272 x (Carioca x TU and L3272 x ESAL 601. They were evaluated in the winter crops in the South of Minas Gerais, and the 103 most promising ones were selected. The families selected were divided in two sets. The first, with 79 normal cycle families, and the second, with 24 precocious families, which were assessed in two locations, in 1995. The best 24 families were evaluated in the winter of 1996. The traits considered were grain yield, number of the days
Oerke, E.C.; Schoenbeck, F.
Shorttime changes of environmental conditions stressed barley and bean and affected plant growth and their predisposition for various pathogens. Moderate stress intensities as low or high temperatures, water or light deficits, increased the susceptibility to Erysiphe graminis var. hordei or Uromyces phaseoli and reduced disease level of spot blotch caused by Cochliobolus sativus, respectively. There was only little effect on plant growth in that case. Intensive stress as a result of combinations of unfavorable environmental conditions or longtime continuance of moderate stress reduced the plant growth and turned the predisposing effect to the opposite: after the treatment, plants were more resistent to diseases caused by biotrophic fungi, whereas there was increased susceptibility to the perthotrophic fungus. High intensities of fertilization acted as an additional stress and intensified the plant reaction to environmental alterations. The variation of the predisposition is discussed in relation to stress intensity.
Carver, T.L.W.; Lyngkjær, M.F.; Neyron, L.
graminis DC.). Successful penetration and haustorium formation by the inducer rendered living epidermal cells highly accessible to later challenge attack as judged by increased frequency of challenge penetration success compared to controls. Conversely, where failure of inducer attack on living epidermal......First-formed (seedling) and later-formed leaves of oat cvs Selma (susceptible) and Maldwyn (adult plant resistance under complex genetic control) were subjected to a double inoculation procedure ('inducer' followed by 'challenger') with conidia of Blumeria graminis (DC.) Speer (Syn. Erysiphe......, suggesting that induced changes in (in)accessibility may be a common consequence of B. graminis attack in cereals. As expected, in Maldwyn, cell death was a consistent but infrequent response to attack (5-20%, of attacks caused cell death in controls). Here, the successful formation of an inducer haustorium...
Sun, Man; Yang, Hui-Hui; Tian, Lei; Li, Jian-Qiang; Zhao, Wei-Guang
The novel imino diacid analogs of valine amides were synthesized via several steps, including the protection, amidation, deprotection, and amino alkylation of valine, with the resulting structures confirmed by (1)H and (13)C NMR and HRMS. Bioassays showed that some of these compounds exhibited good fungicidal activity. Notably, isopropyl 2-((1-((1-(3-fluorophenyl)ethyl)amino)-3-methyl-1-oxobutan-2-yl)amino)propanoate 5i displayed significant levels of control, at 50%, against Erysiphe graminis at 3.9μM as well as a level of potency very similar to the reference azoxystrobin, which gave 60% activity at this concentration. The present work demonstrates that imino diacid analogs of valine amides could be potentially useful key compounds for the development of novel fungicides against wheat powdery mildew. Copyright © 2015 Elsevier Ltd. All rights reserved.
Full Text Available A survey of phytopathogenic fungi and Oomyceteswas conducted in Riyadh, Kingdom of Saudi Arabia duringOctober 2008 – May 2009. Total of 223 samples were collectedfrom four regions; Al-Kharj, Oyaynah, Old Diriyah, and Al Amariyah. Isolation was done using Potato Dextrose Agar(PDA. Infected parts were cut then sterilized in chlorox(10%, then were put in petridish that contain PDA andincubated at 25-27 °C. A total twelve genera of fungi andsingle genera of Oomycetes were isolated from the infectedplants and identifi ed as Fusarium spp., Alternaria spp.,Helmintosphorium (Bipolaris spp., Sclerotium spp., Rhizoctoniaspp., Cladosporium spp., Mauginiella scattae, Erysiphe spp.,Leveillula spp., Macrophomina phaseolina, Ustilago spp.,Ulocladium spp., and Phytium spp.
Borojevic, K.; Worland, A.J.
Full text: The existence of genes suppressing resistance to leaf rust, stem rust and yellow rust in hexaploid wheat has been suggested. If such genes are deleted or inactivated, a more resistant variety may be obtained. In mutant lines of the wheat variety San Pastore, selected after treatment with 20,000 rad of gamma-rays, resistance to leaf rust, yellow rust, stem rust, and to some extent to Erysiphe graminis was determined. The mutants responded to infection by producing necrotic flecks in the presence of high level of disease inoculum. Similar flecks develop under stress condition. It is likely that the mother variety San Pastore carries genes for resistance which are masked by suppressor genes. Irradiation inactivates suppressors so that resistance genes which were previously masked are expressed. The first results of monosomic analysis indicate that chromosomes of groups 4 and 5 or possibly 7 may be critical for expression of resistance in the mutant lines. (author)
Llugany, M; Martin, S R; Barceló, J; Poschenrieder, C
Sensitivity to Erysiphe in Noccaea praecox with low metal supply is related to the failure in enhancing SA. Cadmium protects against fungal-infection by direct toxicity and/or enhanced fungal-induced JA signaling. Metal-based defense against biotic stress is an attractive hypothesis on evolutionary advantages of plant metal hyperaccumulation. Metals may compensate for a defect in biotic stress signaling in hyperaccumulators (metal-therapy) by either or both direct toxicity to pathogens and by metal-induced alternative signaling pathways. Jasmonic acid (JA) and salicylic acid (SA) are well-established components of stress signaling pathways. However, few studies evaluate the influence of metals on endogenous concentrations of these defense-related hormones. Even less data are available for metal hyperaccumulators. To further test the metal-therapy hypothesis we analyzed endogenous SA and JA concentrations in Noccaea praecox, a cadmium (Cd) hyperaccumulator. Plants treated or not with Cd, were exposed to mechanical wounding, expected to enhance JA signaling, and/or to infection by biotrophic fungus Erysiphe cruciferarum for triggering SA. JA and SA were analyzed in leaf extracts using LC-ESI(-)-MS/MS. Plants without Cd were more susceptible to fungal attack than plants receiving Cd. Cadmium alone tended to increase leaf SA but not JA. Either or both fungal attack and mechanical wounding decreased SA levels and enhanced JA in the Cd-rich leaves of plants exposed to Cd. High leaf Cd in N. praecox seems to hamper biotic-stress-induced SA, while triggering JA signaling in response to fungal attack and wounding. To the best of our knowledge, this is the first report on the endogenous JA and SA levels in a Cd-hyperaccumulator exposed to different biotic and abiotic stresses. Our results support the view of a defect in SA stress signaling in Cd hyperaccumulating N. praecox.
Bradshaw, Michael; Braun, Uwe; Götz, Monika; Meeboon, Jamjan; Takamatsu, Susumu
The taxonomic history of the common powdery mildew of Chrysanthemum × morifolium (chrysanthemum, florist's daisy), originally described in Germany as Oidium chrysanthemi, is discussed. The position of O. chrysanthemi was investigated on the basis of morphological traits and molecular phylogenetic analyses. Based on the results of this study, this species, which is closely related to Golovinomyces artemisae, was reassessed and reallocated to Golovinomyces. The phylogenetic analysis and taxonomic reassessment of the chrysanthemum powdery mildew is supplemented by a morphological description, a summary of its worldwide distribution data, and a brief discussion of the introduction of this fungus to North America. G. chrysanthemi differs from true G. artemisiae in that it has much longer conidiophores, is not constricted at the base, and has much larger and most importantly longer conidia. The close affinity of Golovinomyces to Artemisia and Chrysanthemum species signifies a coevolutionary event between the powdery mildews concerned and their host species in the subtribe Artemisiinae (Asteraceae tribe Anthemideae). This conclusion is fully supported by the current phylogeny and taxonomy of the host plant genera and the coevolution that occurred with the host and pathogen. The following powdery mildew species, which are associated with hosts belonging to the tribe Anthemideae of the Asteraceae, are epitypified: Alphitomorpha depressa β artemisiae (≡ Alphitomorpha artemisiae), Erysiphe artemisiae, and Oidium chrysanthemi. Erysiphe macrocarpa is neotypified. Their sequences were retrieved from the epitype collections and have been added to the phylogenetic tree. Golovinomyces orontii, an additional powdery mildew species on Chrysanthemum ×morifolium, is reported. This species is rarely found as a spontaneous infection and was obtained from inoculation experiments.
Tabata, Jun; De Moraes, Consuelo M; Mescher, Mark C
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.
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.
Rogério F. Vieira
Full Text Available Dentre várias linhagens introduzidas do "Asian Vegetable Research and Development Center" (AVRDC, sobressaiu a linhagem VC 3984-B-2-B-4-1-B, que recebeu o nome de Ouro Verde MG 2. Suas sementes são verde-brilhantes e o peso de 1000 unidades varia de 43 a 51 g. O início da floração ocorre em torno de 33 dias após a emergência e a primeira vagem madura surge entre 23 e 33 dias. Por se tratar de espécie de maturação desuniforme, podem ser necessárias duas a quatro colheitas. As plantas podem atingir 95 cm de altura. As vagens são marrom-escuras e concentram-se na parte superior da planta. É suscetível a duas doenças que geralmente aparecem no final do ciclo de vida do mungo-verde: míldio-pulverulento (Erysiphe polygoni e mancha-foliar-de-cercospora (Cercospora canescens. A 'Ouro Verde MG 2' é resistente ao acamamento, e o seu rendimento, em três ensaios instalados em dezembro, janeiro e fevereiro, variou de 1,5 a 2,0 t/ha. Esses rendimentos foram, em média, 12% superior ao da cultivar Ouro Verde.Among many accessions introduced from Asian Vegetable Research and Development Center (AVRDC, the VC 3984-B-2-B-4-1-B stood out and was named 'Ouro Verde MG 2'. The seeds are bright green and 1000-seed weight ranges from 43 to 51 g. Flowering starts approximately 33 days after emergence and the first pod ripens between 23 and 33 days later. As mungbean is a non-uniform maturation species, two to four harvests could be necessary. The plant can reach 95 cm high. The pods are dark brown and concentrated in the upper canopy. This cv. is susceptible to two diseases which generally appear late in the crop: powdery mildew (Erysiphe polygoni and cercospora leaf spot (Cercospora canescens. 'Ouro Verde MG 2' is resistant to lodging. The yield measured in three experiments carried out in December, January, and February, ranged from 1.5 to 2.0 t/ha. In average, these yields were 12% superior than the achieved by the cultivar 'Ouro Verde'.
Full Text Available O oídio da soja, causado por Erysiphe diffusa, é considerado uma doença esporádica podendo ocasionar perdas quando atinge proporções epidêmicas. O trabalho teve por objetivo avaliar a eficiência de bicarbonato de potássio (Kaligreen® no controle do oídio da soja. As pulverizações do bicarbonato de potássio nas concentrações de 0; 0,25%, 0,5%, 0,75% e 1,0% e do fungicida (piraclostrobina + epoxiconazole e as avaliações foram semanais. Folhas foram coletadas para análise ultraestrutural através da microscopia eletrônica de varredura. O bicarbonato de potássio controlou a doença em todas as concentrações, mas causou fitotoxicidade a partir de 0,5%. Na analise ultraestrutural pode-se observar que o produto apresentou ação direta sobre o patógeno ocasionando murchamento e redução na germinação dos conídios. O produto apresenta potencial para controlar a doença, porém deve ser adequada a concentração a ser recomenda, bem como a frequência de aplicação para evitar os problemas de fitotoxicidade.The soybean powdery mildew, caused by Erysiphe diffusa, is considered a sporadic disease which can cause losses when it reaches epidemic proportions. This study aimed to evaluate the efficiency of potassium bicarbonate (Kaligreen® in controlling soybean powdery mildew. Sprays of both potassium bicarbonate at concentrations of 0, 0.25%, 0.5%, 0.75% and 1.0% and fungicide (pyraclostrobin + epoxiconazole, as well as assessments, were weekly carried out. Leaves were collected for ultrastructural analysis by scanning electron microscopy. Potassium bicarbonate controlled the disease at all concentrations but caused phytotoxicity from 0.5%. In the ultrastructural analysis, the product had a direct action on the pathogen, causing wilting and reduction in conidium germination. The product has the potential to control the disease, but the concentration to be recommended should be adequate, as well as the frequency of application to
Full Text Available The distribution and life cycle of wild radish (Raphanus raphanistrum L. and a survey of the pathogens of this plant are reported for the northern regions of Tunisia. Wild radish is a common weed of cereal crops and legumes. It germinates in early autumn (October, develops a rosette stage in November to December after which stem growth, fl owering and pod production occur through to May, with pod maturity completed in June. Fungus isolation from the foliar tissues exhibiting disease symptoms showed that wild radish was infected with the fungi Albugo candida, Alternaria spp. including A. brassicicola, and A. raphani, Erysiphe cruciferarum, Stemphylium herbarum, Peronospora parasitica and Phoma lingam. Ascochyta spp., Cercospora armoraciae, Cladosporium cladosporioides and Colletotrichum higginsianum are here reported from wild radish for the first time. Inoculation tests of pathogens on wild radish plants showed that the most injurious fungi were Alternaria raphani and Phoma lingam. The remaining pathogens were weakly to moderately aggressive on this weed. To access the pathogenic effect of fungi spontaneously infecting natural populations of wild radish, the weed was grown in a field experiment with and without the broad-spectrum systemic fungicide Carbendazim. Results showed a statistically significant two-fold decrease in the number and weight of seed pods in the non-treated plants, indicating that the reproductive potential of wild radish was naturally reduced by fungal infection. Foliar pathogenic fungi have a potential in the integrated weed management of wild radish, this role merits further investigations.
Guo, Chunlei; Guo, Rongrong; Xu, Xiaozhao; Gao, Min; Li, Xiaoqin; Song, Junyang; Zheng, Yi; Wang, Xiping
WRKY proteins comprise a large family of transcription factors that play important roles in plant defence regulatory networks, including responses to various biotic and abiotic stresses. To date, no large-scale study of WRKY genes has been undertaken in grape (Vitis vinifera L.). In this study, a total of 59 putative grape WRKY genes (VvWRKY) were identified and renamed on the basis of their respective chromosome distribution. A multiple sequence alignment analysis using all predicted grape WRKY genes coding sequences, together with those from Arabidopsis thaliana and tomato (Solanum lycopersicum), indicated that the 59 VvWRKY genes can be classified into three main groups (I-III). An evaluation of the duplication events suggested that several WRKY genes arose before the divergence of the grape and Arabidopsis lineages. Moreover, expression profiles derived from semiquantitative PCR and real-time quantitative PCR analyses showed distinct expression patterns in various tissues and in response to different treatments. Four VvWRKY genes showed a significantly higher expression in roots or leaves, 55 responded to varying degrees to at least one abiotic stress treatment, and the expression of 38 were altered following powdery mildew (Erysiphe necator) infection. Most VvWRKY genes were downregulated in response to abscisic acid or salicylic acid treatments, while the expression of a subset was upregulated by methyl jasmonate or ethylene treatments.
Vanacker, Helene; Carver, Tim L.W.; Foyer, Christine H.
H2O2 production and changes in glutathione, catalase, and peroxidase were followed in whole-leaf extracts from the susceptible (AlgS [Algerian/4* (F14) Man.(S)]; ml-a1 allele) and resistant (AlgR [Algerian/4* (F14) Man.(R)]; Ml-a1 allele) barley (Hordeum vulgare) isolines between 12 and 24 h after inoculation with powdery mildew (Blumeria graminis [DC]. Speer [syn. Erysiphe graminis DC] f.sp hordei Marchal). Localized papilla responses and cell death hypersensitive responses were not observed within the same cell. In hypersensitive response sites, H2O2 accumulation first occurred in the mesophyll underlying the attacked epidermal cell. Subsequently, H2O2 disappeared from the mesophyll and accumulated around attacked epidermal cells. In AlgR, transient glutathione oxidation coincided with H2O2 accumulation in the mesophyll. Subsequently, total foliar glutathione and catalase activities transiently increased in AlgR. These changes, absent from AlgS, preceded inoculation-dependent increases in peroxidase activity that were observed in both AlgR and AlgS at 18 h. An early intercellular signal precedes H2O2, and this elicits anti-oxidant responses in leaves prior to events leading to death of attacked cells. PMID:10938348
Parodi, P.C.; Nebreda, I.M.
Seed from six genotypes of spring wheat: Huelquen, Collafen, Yafen, PLA771 and Bluebird No.3 (Triticum aestivum L.), and also Quilafen (Triticum durum Desf.) was exposed to gamma radiation in doses of 10 and 25 krad. The aim of the research is to produce cultivars resistant to the main diseases, with a high protein content and grain yield, for the north-central region of Chile (29-35 0 latitude south). The selection process up to the generation M 5 has made it possible to identify mutants with a higher level of resistance to Puccinia graminis, Puccinia recondita and Puccinia striiformis than the original genotypes. Progress made in improving resistance to a fungal complex attacking the spikelets of the mutant cultivars Huelquen and Yafen, to Erysiphe graminis, and to the yellow dwarf virus in barley (BYDV), has been slighter. The yield of grain and protein per unit surface of the mutants studied during repeated experiments has been greater than for the controls. If this trend continues, there should be a number of mutants that could be used for commercial cultivation. (author)
Weinstein, L. H.; Osmeloski, J. F.; Wettlaufer, S. H.; Galston, A. W.
In higher plants, polyamines arise from arginine by one of two pathways: via ornithine and ornithine decarboxylase or via agmatine and arginine decarboxylase but in fungi, only the ornithine decarboxylase pathway is present. Since polyamines are required for normal growth of microorganisms and plants and since the ornithine pathway can be irreversibly blocked by alpha-difluoromethylornithine (DFMO) which has no effect on arginine decarboxylase, fungal infection of green plants might be controlled by the site-directed use of such a specific metabolic inhibitor. DFMO at relatively low concentrations provided effective control of the three biotrophic fungal pathogens studied, Puccinia recondita (leaf rust), P. graminis f. sp. tritici (stem rust), and Erysiphe graminis (powdery mildew) on wheat (Triticum aestivum L.) Effective control of infection by leaf or stem rust fungi was obtained with sprays of DFMO that ranged from about 0.01 to 0.20 mM in experiments where the inhibitor was applied after spore inoculation. The powdery mildew fungus was somewhat more tolerant of DFMO, but good control of the pathogen was obtained at less than 1.0 mM. In general, application of DFMO after spore inoculation was more effective than application before inoculation. Less control was obtained following treatment with alpha-difluoromethylarginine (DFMA) but the relatively high degree of control obtained raises the possibility of a DFMA to DFMO conversion by arginase.
Full Text Available Wheat cv. Grana grown under field conditions, in the early phase of the first node formation, was sprayed with Ethrel (0.35 ml/m2 and with the fungicides: Sportak 45 EC (0.1 ml/m2 and Bayleton Triple (0.2 g/m2 - separately and in conjunction with Ethrel. It was found that Ethrel reduced the plant's susceptibility to infection by Cercosporella herpotrichoides and by species of the genus Fusarium. The fungicides were more active and also reduced the susceptibility to infection by Erysiphe graminis and Puccinia triticina. The fungistatic effect of Ethrel and Sportak was synergistic only in the case of Cercosporella herpotrichoides. Other interactions between Ethrel and fungicides were not found. Ethrel and fungicides only slightly affected the mycoflora of the root but they completely eliminated the fungi of the genus Mucor from the rhizosphere and reduced the participation of isolates of the genus Alternaria and Cladosporium in the rhizosphere and rhizoplane of wheat. The fungicides were more active than Ethrel. An interaction between Ethrel and fungicides in the reduction of fungi of the genus Fusarium in the rhizosphere was shown.
Soliman, Mona H; El-Mohamedy, Riad S R
Foliar sprays of three plant resistance inducers, including chitosan (CH), potassium sorbate (PS) (C 6 H 7 kO 2 ), and potassium bicarbonates (PB) (KHCO 3 ), were used for resistance inducing against Erysiphe cichoracearum DC (powdery mildew) infecting okra plants. Experiments under green house and field conditions showed that, the powdery mildew disease severity was significantly reduced with all tested treatments of CH, PS, and PB in comparison with untreated control. CH at 0.5% and 0.75% (w/v) plus PS at 1.0% and 2.0% and/or PB at 2.0% or 3.0% recorded as the most effective treatments. Moreover, the highest values of vegetative studies and yield were observed with such treatments. CH and potassium salts treatments reflected many compounds of defense singles which leading to the activation power defense system in okra plant. The highest records of reduction in powdery mildew were accompanied with increasing in total phenolic, protein content and increased the activity of polyphenol oxidase, peroxidase, chitinase, and β-1,3-glucanase in okra plants. Meanwhile, single treatments of CH, PS, and PB at high concentration (0.75%, 2.0%, and/or 3.0%) caused considerable effects. Therefore, application of CH and potassium salts as natural and chemical inducers by foliar methods can be used to control of powdery mildew disease at early stages of growth and led to a maximum fruit yield in okra plants.
The ml-o genes in barley are important sources in breeding for resistance against the barley powdery mildew fungus (Erysiphe graminis). The resistance mechanism is a rapid formation of a large callose containing cell wall apposition at the site of the pathogen's infection attempt. This reduces the chances of infection to almost nil in all epidermal cells, except in the small subsidiary cells, in which appositions are rarely formed. Small mildew colonies from infections in subsidiary cells may be seen on the otherwise resistant leaf. This is described by the infection type 0/(4). Mildew isolate HL 3 selected by SCHWARZBACH has increased aggressiveness. No ml-o-virulent isolates are known. However, ml-o-resistant varieties when grown extensively in Europe, will introduce field selection for mildew pathotypes with aggressiveness or virulence to ml-o resistance. Studies on increased aggressiveness require new methods. The material comprises two powdery mildew isolates: GE 3 without ml-o aggressiveness and the aggressive HL 3/5; and two near-isogenic barley lines in Carlsberg II: Riso 5678(R) with the recessive mutant resistance gene ml-o5 and Riso 5678(S) with the wild-type gene for susceptibility. Latent period and disease efficiency show no significant differences between the two isolates on the susceptible barley line (S) but the isolates differ from each other on the resistant barley line
Sharma, R.; Kant, A.; Kaushal, R.P.
To induce resistance in pea against Ascochyta blight and powdery mildew through mutagenesis, two locally grown cultivars Lincoln and Palam Priya were subjected to three doses each of gamma rays (10, 15 and 20 kR) and chemical mutagen ethylmethane sulfonate (0.1, 0.2 and 0.3%). Reduced germination was observed in response to mutagen treatment in both cultivars. Phenotypic changes were observed in M1 and M2 generations of both the cultivars. In M2 generation twenty-seven mutants of Lincoln and sixteen of Palam Priya were found resistant to Ascochyta blight under natural epiphytotic conditions. High level of resistance in M2 generation against powdery mildew could not be achieved. Plant progenies in the M3 generation were also evaluated for resistance to Ascochyta pinodes as well as Erysiphe pisi through detached leaf technique. Six mutants of Lincoln and only one of Palam Priya were found resistant to A. pinodes. One mutant of Palam Priya (P15-3) showed resistance to both the pathogens. Increased phenylalanine ammonia lyase activity was observed in all the resistant mutants. New isoforms of peroxidase could be detected in the mutant P15-3 (Palam Priya) and also in L0.2-1 (Lincoln). However, not much variation for esterase could be observed [it
Liyanage, Kapila K; Khan, Sehroon; Brooks, Siraprapa; Mortimer, Peter E; Karunarathna, Samantha C; Xu, Jianchu; Hyde, Kevin D
Powdery mildew disease of rubber affects immature green leaves, buds, inflorescences, and other immature tissues of rubber trees, resulting in up to 45% losses in rubber latex yield worldwide. The disease is often controlled by dusting the diseased plants with powdered sulfur, which can have long-term negative effects on the environment. Therefore, it is necessary to search for alternative and environmentally friendly control methods for this disease. This study aimed to identify mycoparasites associated with rubber powdery mildew species, and characterize them on the basis of morpho-molecular characteristics and phylogenetic analyses of ITS rDNA regions. We observed that the Ampelomyces fungus parasitizes rubber powdery mildew, and eventually destroys it. Furthermore, on the basis of phylogenetic analyses and morphological characteristics we confirmed that the Ampelomyces mycoparasite isolated from rubber powdery mildew is closely related to other mycohost taxa in the Erysiphe genus. A total of 73 (71 retrieved from GenBank and two obtained from fresh collections of rubber powdery mildew fungi) Ampelomyces spp. were analyzed using ITS rDNA sequences and 153 polymorphic sites were identified through haplotypic analyses. A total of 28 haplotypes (H1-H28) were identified to have a complex network of mutation events. The results from phylogenetic tree constructed on the basis of maximum likelihood analyses, and the haplotype network tree revealed similar relationships of clustering pattern. This work presents the first report on morpho-molecular characterization of Ampelomyces species that are mycoparasites of powdery mildew of Hevea brasiliensis .
Full Text Available Unidentified powdery mildew was found on leaves of a medicinal plant, Plantago major in Indonesia. The present studies were aimed to identify the causal fungal species of powdery mildew of P. major and study the effect of acidity, temperature and light on the causal fungus. Identification was conducted by observing morphological characteristics of the fungus scraped from diseased leaves under light microscope. The infection process was observed by staining the inoculated leaves followed observation under light microscope. Conidia were suspended in various pH solutions to examine effect of pH on conidial germination and hyphal length. For testing effects of temperature on conidial germination and hyphal length, conidial suspensions were dropped onto glass slides then incubated in temperature ranges from 20–35 °C, the germinating conidia and length of the existing hypha were counted and measured 24 hours later. With the same method as above the glass slides were incubated in 25 °C either in the dark or exposed under illuminated white light tube (400 Lux for study effect of light on conidial germination. The causal fungus was identified as Golovinomyces sordidus (syn. Erysiphe sordida with its anamorph state as Oidium. The germinating conidia penetrate directly into leaf tissue within 24 hours. The optimal conditions for the conidia to germinate are pH between 4 and 7, temperature between 25 °C and 30 °C, and dark condition.
Amer, M.; Fahim, M.M.; Moustafa, N.A.
This program aims to improve barley (Hordeum vulgar L.) resistance to powdery mildew (Erysiphe graminis f. sp. hordi) using mutation induction technique via physical and chemical mutagens. Grains of two local cultivars were treated with gamma rays (150, 250 GY) at a dose rate of 9.02 Rad/ Sec alone or with the concentrations of chemical mutagens, i.e.,EMS (4 and 8 mM), MH (10 and 20 mM) for two hours. After mass selection for the resistance in M2, the two cultivars were varied in their responses to the fifteen treatments. In M3 generation, the frequencies of plant resistance were increased at 20 mM of MH, 8 mM of EMS or 250 GY with either of them for the cultivar G124. However, the same trend was also found at 10 mM of MH, 250GY alone and with 4 or 8 mM EMS for cultivar G125. Moreover, eight mutants were selected from the progenies of M4 plants and evaluated in M5 generation. These mutants are characterized by highly disease resistance and high yield components, one of them has been characterized by non crytics and awnless .The desirable mutants should go to further evaluation for grain yield and grain quality in subsequent generations. (author)
Mutation induction was used to analyse the host/pathogen interaction of barley and Erysiphe graminis. By irradiation or chemical mutagens, a number of similar mutations were induced in the ml-o gene (locus) of barley. The mutants had non-specific and durable resistance, which is rather uncommon. Studies revealed, that in spite of their similarity (the same mutated locus, monogenic recessive inheritance), the mutants were not identical and represent unique sources of disease resistant germ plasm. To study more fundamentally the interference of induced mutations in host/pathogen interactions, barley carrying the dominant resistance gene M1-a 12 was irradiated to mutate this gene. Instead of the expected ''monogenic recessive susceptibility'', several different mutational events inside and outside the locus were found to modify the resistance towards a more or less susceptible reaction. A third interesting approach was to induce mutations in the pathogen and thus create new virulence genes. The result, that no true mutation towards virulence was obtained in extremely large populations, deserves attention and further study to be sure about its implication. 13 refs
Full Text Available Abstract. The study was conducted to examine the variation in the agronomic and morphological traits in spring barley. For this purpose, 22 lines from the ICARDA High Input Barley Program for favorable environment and 3 check varieties (Rihane-03, VMorales and Veslets were tested in an alpha-lattice design with two replications at the Institute of Agriculture – Karnobat, Bulgaria in 2014 and 2015 growing season. The traits days to heading, plant height, number of tillers per plant, flag leaf length, flag leaf width, spike length, awn length, peduncle length, spikelet number per spike, grain number per spike, grain weight per spike, 1000 grains weight, grain yield, powdery mildew (Erysiphe graminis f. sp. hordei, net blotch (Pyrenophora teres f. teres and stripe rust (Puccinia striiformis f. sp. hordei infection were studied. Significant differences between lines for all studied traits were found. The number of fertile tillers per plant was significantly positively correlated with grain yield. Lines expressed higher grain yields, shorter stem, better tolerance to net blotch and stripe rust than Bulgarian check variety Veslets were identified. These genotypes can, therefore, be used as parents for the improvement of spring barley.
Fabiano José Perina
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.
Using, DNA markers and genome organization, several important disease resistance genes have been analyzed in mungbean (Vigna radiata), cowpea (Vigna unguiculata), common bean (Phaseolus vulgaris), and soybean (Glycine max). In the process, medium-density linkage maps consisting of restriction fragment length polymorphism (RFLP) markers were constructed for both mungbean and cowpea. Comparisons between these maps, as well as the maps of soybean and common bean, indicate that there is significant conservation of DNA marker order, though the conserved blocks in soybean are much shorter than in the others. DNA mapping results also indicate that a gene for seed weight may be conserved between mungbean and cowpea. Using the linkage maps, genes that control bruchid (genus Callosobruchus) and powdery mildew (Erysiphe polygoni) resistance in mungbean, aphid resistance in cowpea (Aphis craccivora), and cyst nematode (Heterodera glycines) resistance in soybean have all been mapped and characterized. For some of these traits resistance was found to be oligogenic and DNA mapping uncovered multiple genes involved in the phenotype. (author)
Giese, Nanna Henriette; Jensen, Hans Peter; Jørgensen, Jørgen Helms
Seven barley lines or varieties, each with a different gene at the Ml-a locus for resistance to Erysiphe graminis were intercrossed. Progeny testing of the F2s using two different fungal isolates per cross provided evidence that there are two or more loci in the Ml-a region. Apparent recombinants...... were also screened for recombination between the Hor1 and Hor2 loci which are situated either side of the Ml-a locus. The cross between Ricardo and Iso42R (Rupee) yielded one possible recombinant, with Ml-a3 and Ml-a(Rul) in the coupling phase; other recombinants had wild-type genes in the coupling...... phase. Iso20R, derived from Hordeum spontaneum 'H204', carrying Ml-a6, had an additional gene, in close coupling with Ml-a6, tentatively named Ml-aSp2 or Reglv, causing an intermediate infection type with isolate EmA30. It is suggested that Ml-a(Ar) in Emir and Ml-a(Rul), shown to differ from other Ml...
Yan, Xiaoxiao; Qiao, Hengbo; Zhang, Xiuming; Guo, Chunlei; Wang, Mengnan; Wang, Yuejin; Wang, Xiping
Thaumatin-like protein (TLP) is present as a large family in plants, and individual members play different roles in various responses to biotic and abiotic stresses. Here we studied the role of 33 putative grape (Vitis vinifera L.) TLP genes (VvTLP) in grape disease resistance. Heat maps analysis compared the expression profiles of 33 genes in disease resistant and susceptible grape species infected with anthracnose (Elsinoe ampelina), powdery mildew (Erysiphe necator) or Botrytis cinerea. Among these 33 genes, the expression level of TLP29 increased following the three pathogens inoculations, and its homolog from the disease resistant Chinese wild grape V. quinquangularis cv. 'Shang-24', was focused for functional studies. Over-expression of TLP29 from grape 'Shang-24' (VqTLP29) in Arabidopsis thaliana enhanced its resistance to powdery mildew and the bacterium Pseudomonas syringae pv. tomato DC3000, but decreased resistance to B. cinerea. Moreover, the stomatal closure immunity response to pathogen associated molecular patterns was strengthened in the transgenic lines. A comparison of the expression profiles of various resistance-related genes after infection with different pathogens indicated that VqTLP29 may be involved in the salicylic acid and jasmonic acid/ethylene signaling pathways.
Waakeh, W.; Aldahmani, J.H.; Deadman, M.L.; Saadi, A.A.
A preliminary survey on pesticide uses in 40 vegetable-growing farms representing different agricultural areas in Oman and the UAE, twenty farms from each country, revealed that all the vegetable farms used pesticides for crop protection. Among the major insect-pests, white flies (Bemisia tabaci), leafminers (Liriomyza trifolii), melon fruit flies (Bactrocera ciliatus), aphids (Aphis spp.) and tobacco leafworm (Spodoptera litteralis) were recorded in Omani farms. In the UAE, white flies, leafminers, cutworms (Agrotis ypsilan), tomato fruitworms (Helicoverpa armigera) and eggplant fruitworms (Leucinodes orbonalis) were the 5 top insect-pests. Among the plant diseases, powdery mildew (Erysiphe spp.), blight (Alternaria spp.), damping off (Pythium spp.), leafspot (Alternaria spp.) and mosaic (CMV) Were major cause of vegetable diseases in Omani farms; whereas, damping off (Pythium aphanidermatum), downy mildew (Pseudoperonspora cubensis), early blight (Alternaria solani), septoria leaf spot (Septoria lycopersici) and anthracnose rip rot (colletotrichum spp.) were the most predominant diseases encountered in most UAE farms. Among the most commonly used pesticides, 29 insecticides, 16 fungicides and 3 herbicides were used by the vegetable farmers. Around 55% of Omani farms used routine application of pesticides, irrespective of the pest presence. Whereas, in the UAE, most farmers started to spray pesticides at 6-20% pest (insect, disease and weeds) infection. Over 65 of the farms, in both the countries, received chemical pest management information from the sales representatives. (author)
L. T. Timina
Full Text Available As a result of monitoring of causative agents of diseases of vegetable crops and studying of its species specification, the genus and species of fungi and bacteria, were found. Previously unknown in the Central region of Russia pathogens of carrot were identified: Sclerotinia nevales, Gleocladium roseum, Verticillium spp, Trichotecium roseum, Streptomyces scabies, F. nivale, F. chlamidosporum, F. equiseti, F. proliferatum, Chaetomium spp., Erysiphe umbelliferum, Erwinia carotovora. Main causative agents of diseases of carrot during storage were also described: Alternaria infectoria, A. alternatа, A. arborescens, A. radicina, A. cheiranthi, A. corotiincultae, A. cinerariae, Embellisia spp., Nimbia spp., Cladosporium spp. It was found new pathogen for onion (Aspergillus niger, garlic (Fusarium semitectum, F. subglutinans, F. proliferatum, F.avenacium, red beet (Typhula ishikariensis, and radish (Drechslera Bondartseva.
Moral, Juan; Montilla-Bascón, Gracia; Canales, Francisco J; Rubiales, Diego; Prats, Elena
In this work, we investigated the involvement of the long-term dynamics of cytoskeletal reorganization on the induced inaccessibility phenomenon by which cells that successfully defend against a previous fungal attack become highly resistant to subsequent attacks. This was performed on pea through double inoculation experiments using inappropriate (Blumeria graminis f. sp. avenae, Bga) and appropriate (Erysiphe pisi, Ep) powdery mildew fungi. Pea leaves previously inoculated with Bga showed a significant reduction of later Ep infection relative to leaves inoculated only with Ep, indicating that cells had developed induced inaccessibility. This reduction in Ep infection was higher when the time interval between Bga and Ep inoculation ranged between 18 and 24 h, although increased penetration resistance in co-infected cells was observed even with time intervals of 24 days between inoculations. Interestingly, this increase in resistance to Ep following successful defence to the inappropriate Bga was associated with an increase in actin microfilament density that reached a maximum at 18-24 h after Bga inoculation and very slowly decreased afterwards. The putative role of cytoskeleton reorganization/disorganization leading to inaccessibility is supported by the suppression of the induced resistance mediated by specific actin (cytochalasin D, latrunculin B) or general protein (cycloheximide) inhibitors. © 2016 BSPP AND JOHN WILEY & SONS LTD.
Badere, R.S.; Koche, D.K.; Choudhary, A.D.; Pawar, S.E.
The Vigna radiata (L.) Wilczek (Green gram), a major pulse crop is prone to damaging diseases caused by Erysiphe polygoni, Cercospora canescens and Rhizoctonia sp. Therefore, the development of multiple resistance is a major breeding objective in green gram. Resistance to powdery mildew has already been developed, however, there are no reports on the development of resistance to Cercospora in green gram. Owing to limitation of conventional screening methods, the improvement for multiple disease resistance is inadequate, in this crop. It needs an efficient and quick selection method, for screening the plant population at an early stage. It is well established that the resistant interaction, in plants, involves accumulation of antibiotic compound phytoalexin (Genestein in Vigna radiata) and induction of enzymes such as β-1,3 gulcanase and Chitinases. These compounds are not only induced by pathogens but also pathogen-derived elicitors. These biochemical compounds can be used as resistance indicative biochemical markers for screening the natural or mutagen induced genetic diversity in populations of Vigna radiata in non-destructive manner. It, however, needs a systematic study of plant defense response. This paper deals with the response of resistant and susceptible cultivars of vigna radiata to Cercospora elicitor and development of non-destructive selection method for disease resistance. (author)
Karavaev, V A; Solntsev, M K; Iurina, T P; Iurina, E V; Poliakova, I B; Kuznetsov, A M
We found that extracts from the leaves of medicinal comfrey and cowparsnip strongly inhibit the germination of Erysiphe graminis conidia and uredospores of Puccinia graminis. Spraying wheat seedlings with these extracts, in contrast to the irrigation of soil, markedly diminished infection in plants with powdery mildew. Antifungal activity in vitro and protective activity (when plants were sprayed) correlated with the level of phenolic compounds in these extracts. Experiments with healthy plants have demonstrated that the photosynthetic apparatus of wheat plants is stimulated by extracts. Spraying seedlings with the extracts resulted in an increased rate of O2 evolution calculated per unit of chlorophyll, an increase in the ratio (FM-FT)/FT in the experiments that recorded slow fluorescence induction, an increase in the relative light intensity of band A, and a decrease of relative intensity of band C in experiments with thermoluminescence of wheat leaves. These results provide evidence that the protective activity of comfrey and cowparsnip extracts is associated with their action on the pathogenic fungus and with the activation of natural defense reactions of the host plant.
Full Text Available Gerbera (Gerbera jamesonii is one of the most popular ornamental plants in the world, used as cut or vase flower. The experiment aimed to evaluate the effect of milk in natura to control powdery mildew (Erysiphe cichoracearum on gerbera. The treatments tested were: two concentrations of cow's milk in natura (8 and 16%, with and without adjuvant (vegetal oil, three fungicides (fenarimol -6 g a.i.100 L-1 H2O, chlorothalonil -150 g a.i.100 L-1 H2O and azoxystrobin + mineral oil - 10 g a.i.100 L-1 H2O and control treatment. The area under the disease progress curve (AUDPC was calculated for each plot based on disease severity. Milk in natura applied with adjuvant controlled the disease and did not allow the infection and development of pathogen. The addition of adjuvant improves the efficiency of milk in natura, but it requires subsequent washing of plants with H2O + detergent. The fungicide fenarimol promoted the best control and also the best gerbera visual aspect. The fungicide azoxystrobin + mineral oil and the chlorothalonil were phytotoxic to gerbera plants, affecting the aspect of leaves and flowers.A gérbera (Gerbera jamesonii é uma das mais populares plantas ornamentais do mundo, tanto como flor de corte como de vaso. O objetivo deste trabalho foi avaliar o leite in natura no controle do oídio (Erysiphe cichoracearum na cultura da gérbera. Foram utilizadas duas concentrações de leite de vaca in natura (8 e 16%, com e sem adição de adjuvante (óleo vegetal, três fungicidas (fenarimol -6 g i.a.100 L-1 H2O, chlorothalonil -150 g i.a.100 L-1 H2O e azoxystrobin + óleo mineral -10 g i.a.100 L-1 H2O e testemunha. Com os dados de severidade foi calculada a área abaixo da curva de progresso da doença (AACPD. O leite in natura aplicado com o adjuvante controlou o oídio, não permitindo a instalação e o desenvolvimento do patógeno. O uso do adjuvante melhorou a eficiência do leite in natura, no entanto requer a lavagem posterior das
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.
Wen, Zhifeng; Gao, Min; Jiao, Chen; Wang, Qian; Xu, Hui; Walter, Monika; Xu, Weirong; Bassett, Carole; Wang, Xiping
Retinoblastoma-related (RBR) genes, a conserved gene family in higher eukaryotes, play important roles in cell differentiation, development, and mammalian cell death; however, little is known of their function in plants. In this study, a RBR gene was isolated from the Chinese wild grape, Vitis pseudoreticulata W. T. Wang clone "Baihe-35-1", and designated as VpRBR . The cDNA sequence of VpRBR was 3,030 bp and contained an open reading frame of 3,024 bp. Conceptual translation of this gene indicated a composition of 1,007 amino acids with a predicted molecular mass of 117.3 kDa. The predicted protein showed a retinoblastoma-associated protein domain A from amino acid residues 416 to 579, and domain B from residues 726 to 855. The result of expression analysis indicated that VpRBR was expressed in tissues, leaves, stem, tendrils, flower, and grape skin at different expression levels. Further quantitative reverse transcription-PCR (qRT-PCR) data indicated that VpRBR levels were higher in Erysiphe necator-treated "Baihe-35-1" and "Baihe-13-1", two resistant clones of Chinese wild V. pseudoreticulata , than in E. necator-treated "Hunan-1", a susceptible clone of V. pseudoreticulata . Furthermore, the expression of VpRBR in response to salicylic acid (SA), methyl jasmonate (MeJA), and ethylene (Eth) in grape leaves was also investigated. Taken together, these data indicate that VpRBR may contribute to some aspect of powdery mildew resistance in grape.
Dai, Ru; Ge, Hui; Howard, Susanne; Qiu, Wenping
Stilbenic compounds are natural phytoalexins that have antimicrobial activities in plant defense against pathogens. Stilbene synthase (STS) is the key enzyme that catalyzes the biosynthesis of stilbenic compounds. Grapevine genome contains a family of preliminarily annotated 35 STS genes, the regulation of each STS gene needs to be studied to define their roles. In this study, we selected eight STS genes, STS8, STS27/31, STS16/22, STS13/17/23, and applied quantitative polymerase chain reaction (qPCR) to characterize their transcriptional expression profiles in leaf tissues upon infection by the powdery mildew fungus (PM), Erysiphe necator (Schw.) Burr. Their transcripts were also compared in young and old leaves as well as in the berry skin at five developmental stages in Vitis vinifera 'Cabernet Sauvignon' and Vitis aestivalis 'Norton'. The results showed that transcripts of selected STS genes increased significantly in Cabernet Sauvignon leaves at 24 and 48 h post inoculation with PM spores and remained unchanged in Norton leaves in response to the PM infection. Transcripts of STS8, STS27/31 and STS13/17/23 were more abundant in the old leaves of Norton than in Cabernet Sauvignon. STS genes showed lower expression levels in young leaves than in old leaves. Transcript levels of the eight STS genes increased drastically in the berry skin of Cabernet Sauvignon and Norton post véraison. In addition, the content of trans-resveratrol in the berry skin rapidly increased post véraison and reached the highest level at harvest. These assays demonstrated that individual STS genes are regulated differentially in response to PM infection and during development in the two grape varieties. The present study yields basic knowledge for further investigation of the regulation and function of each STS gene in grapevine and provides experimental evidences for the functional annotation of the STS gene family in the grapevine genome. Copyright © 2012 Elsevier Ireland Ltd. All
Full Text Available The desiccation tolerant cyanobacterium Lyngbya arboricola, isolated from bark surfaces of Mangifera indica, possessed up to four stable isoforms of catalase in addition to other antioxidative enzymes, for several years under a dry state. Purification of the two most persistent isoforms of catalase (Cat has been undertaken by employing acetone precipitation, ethanol: chloroform treatment, gel filtration and ion exchange chromatography. The two isoforms of catalase remained almost unchanged on varying matric and osmotic hydration levels of mats of the cyanobacterium. The purification procedures resulted in a 1.3 % yield of purified single isoform (0.22 mg mL-1 protein with 709 Units mg-1 specific activity and a purity index of 0.83. Five millimolar of dithiothreitol (DTT was observed to be pertinent in maintaining the optimum redox state of the enzyme. The purification procedures additionally facilitated the simultaneous elimination and procurement of phycoerythrins (PE and mycosporine-like amino acids (MAA. Each purified isoform gave a single band (~45kDa upon SDS-PAGE and denaturing urea isoelectric focusing (IEF depicted the presence of 2 subunits each of CatA and CatB. The monoisotopic mass and pI value of CatA and CatB as revealed by LC-MS analysis and internal amino acid sequencing was 78.96, 5.89 and 80.77, 5.92, respectively, showing resemblance with CatA of Erysiphe graminis subs. hordei and CatB of Ajellomyces capsulata. The heterotetrameric monofunctional catalase (~320 kDa, due to its stability in the form of resistance to ethanol: chloroform, its thermoalkaliphilic nature and the presence of innumerable hydrophobic amino acid residues (~40%, thus exhibited its potential for biotechnological applications.
Quentin, Michaël; Baurès, Isabelle; Hoefle, Caroline; Caillaud, Marie-Cécile; Allasia, Valérie; Panabières, Franck; Abad, Pierre; Hückelhoven, Ralph; Keller, Harald; Favery, Bruno
The oomycete Hyaloperonospora arabidopsidis and the ascomycete Erysiphe cruciferarum are obligate biotrophic pathogens causing downy mildew and powdery mildew, respectively, on Arabidopsis. Upon infection, the filamentous pathogens induce the formation of intracellular bulbous structures called haustoria, which are required for the biotrophic lifestyle. We previously showed that the microtubule-associated protein AtMAP65-3 plays a critical role in organizing cytoskeleton microtubule arrays during mitosis and cytokinesis. This renders the protein essential for the development of giant cells, which are the feeding sites induced by root knot nematodes. Here, we show that AtMAP65-3 expression is also induced in leaves upon infection by the downy mildew oomycete and the powdery mildew fungus. Loss of AtMAP65-3 function in the map65-3 mutant dramatically reduced infection by both pathogens, predominantly at the stages of leaf penetration. Whole-transcriptome analysis showed an over-represented, constitutive activation of genes involved in salicylic acid (SA) biosynthesis, signaling, and defense execution in map65-3, whereas jasmonic acid (JA)-mediated signaling was down-regulated. Preventing SA synthesis and accumulation in map65-3 rescued plant susceptibility to pathogens, but not the developmental phenotype caused by cytoskeleton defaults. AtMAP65-3 thus has a dual role. It positively regulates cytokinesis, thus plant growth and development, and negatively interferes with plant defense against filamentous biotrophs. Our data suggest that downy mildew and powdery mildew stimulate AtMAP65-3 expression to down-regulate SA signaling for infection. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology. All rights reserved. For permissions, please email: email@example.com.
Full Text Available Brassica juncea (Indian mustard is a commercially important oil seed crop, which is highly affected by many biotic stresses. Among them, Alternaria leaf blight and powdery mildew are the most devastating diseases leading to huge yield losses in B. juncea around the world. In this regard, genetic engineering is a promising tool that may possibly allow us to enhance the B. juncea disease resistance against these pathogens. NPR1 (non-expressor of pathogen-related gene 1 is a bonafide receptor of salicylic acid (SA which modulates multiple immune responses in plants especially activation of induced and systemic acquired resistance (SAR. Here, we report the isolation and characterization of new NPR1 homolog (BjNPR1 from B. juncea. The phylogenetic tree constructed based on the deduced sequence of BjNPR1 with homologs from other species revealed that BjNPR1 grouped together with other known NPR1 proteins of Cruciferae family, and was nearest to B. napus. Furthermore, expression analysis showed that BjNPR1 was upregulated after SA treatment and fungal infection but not by jasmonic acid or abscisic acid. To understand the defensive role of this gene, we generated B. juncea transgenic lines overexpressing BjNPR1, and further confirmed by PCR and Southern blotting. The transgenic lines showed no phenotypic abnormalities, and constitutive expression of BjNPR1 activates defense signaling pathways by priming the expression of antifungal PR genes. Moreover, BjNPR1 transgenic lines showed enhanced resistance to Alternaria brassicae and Erysiphe cruciferarum as there was delay in symptoms and reduced disease severity than non-transgenic plants. In addition, the rate of disease spreading to uninfected or distal parts was also delayed in transgenic plants thus suggesting the activation of SAR. Altogether, the present study suggests that BjNPR1 is involved in broad spectrum of disease resistance against fungal pathogens.
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.
Moustafa Hemdan Ahmed MOHARAM
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.
Mohapatra, Chinmayee; Chand, Ramesh; Navathe, Sudhir; Sharma, Sandeep
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. Copyright © 2016 Elsevier Masson SAS. All rights reserved.
Nesler, Andrea; Perazzolli, Michele; Puopolo, Gerardo; Giovannini, Oscar; Elad, Yigal; Pertot, Ilaria
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.
Weber, Marjorie G; Porturas, Laura D; Taylor, Scott A
Mite domatia are small structures on the underside of plant leaves that provide homes for predacious or fungivorous mites. In turn, mites inhabiting domatia defend the plant by consuming leaf herbivores and pathogens, which can result in a domatia-mediated, plant-mite defence mutualism. Several recent studies have suggested that plants receive enhanced benefits when they provide a foliar food source, such as sugars secreted from extrafloral nectaries, to mite mutualists alongside mite domatia. However, the effect of foliar sugar on reducing leaf pathogen load via domatia-inhabiting mites has not been directly investigated. To fill this gap, the links between foliar sugar addition, domatia-inhabiting mite abundance, and pathogen load were experimentally evaluated in wild grape. Furthermore, because the proposed combined benefits of providing food and housing have been hypothesized to select for the evolutionary correlation of extrafloral nectaries and domatia across plant lineages, a literature survey aimed at determining the overlap of mite domatia and extrafloral nectaries across plant groups was also conducted. It was found that leaves with artificial addition of foliar sugar had 58-80 % more mites than leaves without foliar sugar addition, and that higher mite abundances translated to reduced powdery mildew (Erysiphe necator) loads on leaves. It was found that mite domatia and extrafloral nectaries occur non-randomly in the same clades across Eudicots. Genera with both traits are reported to highlight candidate lineages for future studies. Together, the results demonstrate that foliar sugar can indeed enhance the efficacy of domatia-mediated plant-mite mutualisms, and suggest that this synergism has the potential to influence the co-distribution of foliar nectar and mite domatia across plants. © The Author 2016. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: firstname.lastname@example.org.
Full Text Available Khorasan wheat occupies a special place in the group of new-old cereals (Triticum turgidum, ssp. Turanicum McKey. It is an ancient species, native to eastern Persia, that is very close to durum wheat by morphological characteristics. Investigations were carried out in agro ecological conditions of the eastern Srem, with two wheat populations with dark and bright awns as objects of study. The following morphological and productive characteristics were investigated: plant height (PH, spike length (SH, number of spikelets per spike (NSS, absolute weight (AW and grain weight per spike (GW, seed germination (G and grains yield (YG. Field micro-experiments were set on the carbonate chernozem soil type on loess plateau in 2011 and 2012. Hand wheat sowing was conducted in early March with drill row spacing of 12 cm. The experiment was established as complete randomized block system with four replications. Tending crops measures were not applied during the growing season. Plants were grown without usage of NPK mineral nutrients. Chemical crop protection measures were not applied, although powdery mildew (Erysiphe graminis was appeared before plants spike formation in a small extent. The results showed that both populations have a genetic yield potential. In general, both populations manifested a satisfactory tolerance on lodging and there was no seed dispersal. Plants from bright awns population were higher, had longer spikes and larger number of spikelet’s per spike. However, plants from dark awns population had higher absolute weight and grains weight per spike, as well as grain yield per plant. Strong correlation connections were identified among the investigated characteristics. The determination of correlations, as well as direct and indirect affects, enabled easier understanding of the mutual relationships and their balancing in order to improve the yield per unit area. [Projekat Ministarstva nauke Republike Srbije, br. TR 31078 i br. TR 31022
Abdalla Abdelrahim Satti
Full Text Available Powdery mildews caused by several fungi, particularly of the genera Erysiphe, Sphaerotheca and Leveillula, are destructive diseases of various cultivated and wild plants during winter season (December–March in Sudan. Application of synthetic fungicides is the only control measure practiced. Fortuitously, during a field survey, congregations of coccinellid adults and grubs were found associated with powdery mildews on a wild plant, Xanthium brasilicum Vell., locally known as “Ramtouk”, at Shambat area/Khartoum North. Therefore, the insect was subjected to some bionomical studies conducted during winter season 2011/12. Emphasis was devoted to morphometric investigations, supported with life cycle durations and seasonal trend on the foregoing host. Accordingly, the species was recognized as Psyllobora bisoctonotata (Muls., a well known powdery mildew feeder in several countries. This is the first record of a mycophagous insect in Sudan. Hence, the important morphological features of the different stages were presented. The rearing of the insect on powdery mildew infected Ramtouk leaves in the laboratory (27.50 ± 3.75 °C and 15.83 ± 3.82% R.H. revealed that the mean total lifecycle from egg to adult was 25.28 ± 1.57 days. The insect appeared on X. brasilicum in a very small number in December, peaked in February, and then gradually declined thereafter coinciding with an increase in temperature and a decrease in powdery mildew infection. So far, the real distribution of this mycophagous species and its host range are waiting for more investigations. Meticulous bio-ecological studies are important to ascertain the proper habitat for such insect throughout the year, and to evaluate its potential role as a biocontrol agent for the powdery mildews.
Weis, Corina; Hückelhoven, Ralph; Eichmann, Ruth
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.
Karaoglanidis George S.
Full Text Available Powdery mildew, caused by Erysiphe betae is a major foliar disease of sugar beet in areas with dry and relatively warm weather conditions throughout the world. In the present study, four fungicides belonging to the relatively new class of strobilurin fungicides, azoxystrobin, kresoxim-methyl pyraclostrobin and trifloxystrobin were evaluated in three different application doses (100, 150 and 200 mg a.i. ha–1 during 2003-2004 for the control of the disease. Among the four strobilurin fungicides tested trifloxystrobin and kresoxim-methyl were the most effective with control efficiency values higher than 94% compared to the control treatment even when applied at lower application dose of 100 mg a.i. ha–1. Azoxystrobin and pyraclostrobin showed a poor to modest activity against the disease even when applied at the highest application dose of 200 μg a.i. ha–1. Disease severity, in terms of AUDPC values was significantly correlated to decreased root yield, while no significant correlation existed among disease severity and sugar content of the roots or sucrose yield. In addition, the efficiency of tank mixtures of four strobilurin fungicides applied at 100 μg a.i. ha–1 with two sterol demethylation - inhibiting fungicides (DMIs, difenoconazole and cyproconazole applied at 62.5 and 25 mg a.i. ha–1, respectively, was evaluated. The mixtures of azoxystrobin and pyraclostrobin with either difenoconazole or cyproconazole provided a better control efficiency compared to the single application of each mixture partner, while the tank mixtures of trifloxystrobin and kresoxim-methyl with either difenoconazole or cyproconazole provided a better control efficiency compared to single application of difenoconazole or cyproconazole and similar control efficiency compared to the efficiency obtained by single application of the strobilurin fungicides.
Full Text Available The research was conduced in the years 1999-2000. The aim of the research was to determine the health condition of overground parts and seeds of the following spring oilseed crops: crambe (Crambe abbysinica Hoechst. cv. B o r o w s k i, false flax (Camelina sativa L. cv. B o r o w s k a, spring rape (Brassica napus ssp. oleifera L. cv. M a r g o and oleiferous radish (Raphanus sativus var. oleiferus L. cv. P e g l e t t a. In all the years of the research alternaria blight was found on the leaves and siliques of spring rape and oleiferous radish and on the leaves and stems of crambe. False flax proved to be weakly infected by pathogens. On its leaves gray mould (Botrytis cinerea was found in all the years of the research. The disease was found on the siliques only in 1999. In 2000 powdery mildew was found on spring rape and false flax (respectively, Erysiphe crucifearum and E.cichoracearum. The weather conditions affected the intensity of the diseases on the studied spring oilseed crops. Alernaria genus, especially A.alternata was most commonly isolated from the seeds of examined plants. It constituted from 37% (in crambe to 63,3% (in spring rape of all the isolates. Of the remaining pathogenic species, numerous fungi of the Fusarium genus (F.avenaceum, F.culmorum, F.equiseti and F.oxysporum were isolated. They constituted from 1,0% (false flax to 17,3% (crambe of the isolates.
Wolf, P F J; Verreet, A
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
Sun, Suli; Deng, Dong; Wang, Zhongyi; Duan, Canxing; Wu, Xiaofei; Wang, Xiaoming; Zong, Xuxiao; Zhu, Zhendong
A novel er1 allele, er1 -7, conferring pea powdery mildew resistance was characterized by a 10-bp deletion in PsMLO1 cDNA, and its functional marker was developed and validated in pea germplasms. Pea powdery mildew caused by Erysiphe pisi DC is a major disease worldwide. Pea cultivar 'DDR-11' is an elite germplasm resistant to E. pisi. To identify the gene conferring resistance in DDR-11, the susceptible Bawan 6 and resistant DDR-11 cultivars were crossed to produce F1, F2, and F(2:3) populations. The phenotypic segregation patterns in the F2 and F(2:3) populations fit the 3:1 (susceptible:resistant) and 1:2:1 (susceptible homozygotes:heterozygotes:resistant homozygotes) ratios, respectively, indicating that resistance was controlled by a single recessive gene. Analysis of er1-linked markers in the F2 population suggested that the recessive resistance gene in DDR-11 was an er1 allele, which was mapped between markers ScOPE16-1600 and c5DNAmet. To further characterize er1 allele, the cDNA sequences of PsMLO1 from the parents were obtained and a novel er1 allele in DDR-11 was identified and designated as er1-7, which has a 10-bp deletion in position 111-120. The er1-7 allele caused a frame-shift mutation, resulting in a premature termination of translation of PsMLO1 protein. A co-dominant functional marker specific for er1-7 was developed, InDel111-120, which co-segregated with E. pisi resistance in the mapping population. The marker was able to distinguish between pea germplasms with and without the er1-7. Of 161 pea germplasms tested by InDel111-120, seven were detected containing resistance allele er1-7, which was verified by sequencing their PsMLO1 cDNA. Here, a novel er1 allele was characterized and its an ideal functional marker was validated, providing valuable genetic information and a powerful tool for breeding pea resistance to powdery mildew.
Timus Asea M.
Full Text Available Sugar beet is one of the most important agricultural crops in the Republic of Moldova. The North and Central regions have good enough pedoclimatic conditions. The genetic potential of sorts and hybrids can be created through the application of modern technologies in order to grow at least 32-35 tons/ha of sugar beet roots. In the Republic of Moldova, sugar beet vegetates between 160 and 180 days in the first year and needs approximately an amount of 2400-2900°C, average of 15.3-15.4°C. Each phenological phase needs different temperatures: at least 4C° is necessary for planting and springing an amount of 650°C is necessary for foliar apparatus; an amount of 1150- 1800°C is necessary to grow the volume of roots and for sugar depositing the average of 2400 to 2600°C is necessary. The mentioned temperatures ensure a normal development of sugar beet plants. If these temperatures fluctuate, the pathogens and pests are stimulated to develop. The most frequent diseases of sugar beet are: Pythium de baryanum Hesse., Aphanomyces cochlioides Dresch. Peronospora schachtii Fuck., Phoma betae Fr. Cercospora beticola Sacc. Erysiphe communis Grev. f. betae Jacz., virosis - Beta virus 2, 3 si 4 etc. The main pests belong to the following categories: Homoptera: Aphis fabae Scop. (fam. Aphididae, Pemphigus fuscicornis Koch. (fam. Pemphigidae Coleoptera: Agriotes sp. (fam. Elateridae, Chaetocnema concinna M. Ch. breviuscula Fld., Cassida nebulosa L. (fam. Chrysomelidae, Atomaria linearis Step. (fam. Cryptophagidae; Bothynoderes punctiventris Germ., Tanymechus dilaticollis Gyll., T. palliatus F., Psalidium maxillosum F. (Curculionidae; Lepidoptera: Agrotis segetum Den. et Schiff., Authographa gamma L. Mamestra (Barathra brassicae L. (Noctuidae, Loxostege sticticalis L. (Pyralidae, Gnorimoschema ocellatella Boyd.; Diptera Pegomyia betae Curtis. (fam. Anthomyidae. Heterodera schachtii Schmidt (Heteroderidae. The most recommended insecticides for fighting the
Sun, Suli; Fu, Haining; Wang, Zhongyi; Duan, Canxing; Zong, Xuxiao; Zhu, Zhendong
Pea powdery mildew, caused by Erysiphe pisi D.C., is an important disease worldwide. Deployment of resistant varieties is the main way to control this disease. This study aimed to screen Chinese pea (Pisum sativum L.) landraces resistant to E. pisi, and to characterize the resistance gene(s) at the er1 locus in the resistant landraces, and to develop functional marker(s) specific to the novel er1 allele. The 322 landraces showed different resistance levels. Among them, 12 (3.73%), 4 (1.24%) and 17 (5.28%) landraces showed immunity, high resistance and resistance to E. pisi, respectively. The other landraces appeared susceptible or highly susceptible to E. pisi. Most of the immune and highly resistant landraces were collected from Yunnan province. To characterize the resistance gene at the er1 locus, cDNA sequences of PsMLO1 gene were determined in 12 immune and four highly resistant accessions. The cDNAs of PsMLO1 from the immune landrace G0005576 produced three distinct transcripts, characterized by a 129-bp deletion, and 155-bp and 220-bp insertions, which were consistent with those of er1-2 allele. The PsMLO1 cDNAs in the other 15 resistant landraces produced identical transcripts, which had a new point mutation (T→C) at position 1121 of PsMLO1, indicating a novel er1 allele, designated as er1-6. This mutation caused a leucine to proline change in the amino acid sequence. Subsequently, the resistance allele er1-6 in landrace G0001778 was confirmed by resistance inheritance analysis and genetic mapping on the region of the er1 locus using populations derived from G0001778 × Bawan 6. Finally, a functional marker specific to er1-6, SNP1121, was developed using the high-resolution melting technique, which could be used in pea breeding via marker-assisted selection. The results described here provide valuable genetic information for Chinese pea landraces and a powerful tool for pea breeders. PMID:26809053
Full Text Available Programmed cell death (PCD is a genetically determined process in all multicellular organisms. Plant PCD is effected by a unique group of papain-type cysteine endopeptidases (CysEP with a C-terminal KDEL endoplasmic reticulum (ER retention signal (KDEL CysEP. KDEL CysEPs can be stored as pro-enzymes in ER-derived endomembrane compartments and are released as mature CysEPs in the final stages of organelle disintegration. KDEL CysEPs accept a wide variety of amino acids at the active site, including the glycosylated hydroxyprolines of the extensins that form the basic scaffold of the cell wall. In Arabidopsis, three KDEL CysEPs (AtCEP1, AtCEP2, and AtCEP3 are expressed. Cell- and tissue-specific activities of these three genes suggest that KDEL CysEPs participate in the abscission of flower organs and in the collapse of tissues in the final stage of PCD as well as in developmental tissue remodelling.We observed that AtCEP1 is expressed in response to biotic stress stimuli in the leaf. atcep1 knockout mutants showed enhanced susceptibility to powdery mildew caused by the biotrophic ascomycete Erysiphe cruciferarum. A translational fusion protein of AtCEP1 with a three-fold hemaglutinin-tag and the green fluorescent protein under control of the endogenous AtCEP1 promoter (PCEP1::pre-pro-3xHA-EGFP-AtCEP1-KDEL rescued the pathogenesis phenotype demonstrating the function of AtCEP1 in restriction of powdery mildew. The spatiotemporal AtCEP1-reporter expression during fungal infection together with microscopic inspection of the interaction phenotype suggested a function of AtCEP1 in controlling late stages of compatible interaction including late epidermal cell death. Additionally, expression of stress response genes appeared to be deregulated in the interaction of atcep1 mutants and E. cruciferarum. Possible functions of AtCEP1 in restricting parasitic success of the obligate biotrophic powdery mildew fungus are discussed.
Feechan, Angela; Kocsis, Marianna; Riaz, Summaira; Zhang, Wei; Gadoury, David M; Walker, M Andrew; Dry, Ian B; Reisch, Bruce; Cadle-Davidson, Lance
The Toll/interleukin-1 receptor nucleotide-binding site leucine-rich repeat 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 V. vinifera cultivars. However, sporulating powdery mildew colonies and cleistothecia of the heterothallic pathogen have been found on introgression lines containing the RUN1 locus growing in New York (NY). Two E. necator isolates collected from RUN1 vines were designated NY1-131 and NY1-137 and were used in this study to inform a strategy for durable RUN1 deployment. In order to achieve this, fitness parameters of NY1-131 and NY1-137 were quantified relative to powdery mildew isolates collected from V. rotundifolia and V. vinifera on vines containing alleles of the powdery mildew resistance genes RUN1, RUN2, or REN2. The results clearly demonstrate the race specificity of RUN1, RUN2, and REN2 resistance alleles, all of which exhibit programmed cell death (PCD)-mediated resistance. The NY1 isolates investigated were found to have an intermediate virulence on RUN1 vines, although this may be allele specific, while the Musc4 isolate collected from V. rotundifolia was virulent on all RUN1 vines. Another powdery mildew resistance locus, RUN2, was previously mapped in different V. rotundifolia genotypes, and two alleles (RUN2.1 and RUN2.2) were identified. The RUN2.1 allele was found to provide PCD-mediated resistance to both an NY1 isolate and Musc4. Importantly, REN2 vines were resistant to the NY1 isolates and RUN1REN2 vines combining both genes displayed additional resistance. Based on these results, RUN1-mediated resistance in grapevine may be enhanced by pyramiding with RUN2.1 or REN2; however, naturally occurring isolates in North America display some virulence on vines with these resistance genes. The characterization of additional resistance sources is needed to identify
Wang, Bao-Lei; Zhu, Hong-Wei; Li, Zheng-Ming; Wang, Li-Zhong; Zhang, Xiao; Xiong, Li-Xia; Song, Hai-Bin
In recent years, pyridylpyrazole derivatives, such as pyridylpyrazole-containing anthranilic diamide have attracted much attention by virtue of their useful insecticidal properties and unique action mode. Moreover, some pyridylpyrazole-containing compounds have also been found to possess significant fungicidal activities. With the aim of discovering new bioactive agrochemicals for crop protection, a series of poly-heterocyclic compounds containing pyridylpyrazole and aziridine, or β-lactam, or thiazolinone moieties were synthesized. A series of pyridylpyrazole-containing poly-heterocyclic compounds were obtained, and confirmed through IR, 1 H NMR, 13 C NMR, HRMS and elemental analysis. The crystalline structure of 4-(3-bromo-1-(3-chloropyridin-2-yl)-1H-pyrazol-5-yl)-3-chloro-1-mesitylazetidin-2-one (compound 13f) was determined to further illustrate a trans- configuration of the β-lactam motif. In addition, bioassays showed that most of these new compounds exhibited modest insecticidal activity towards Mythimna separate Walker at 200 µg mL -1 . Some of the compounds displayed excellent fungicidal activity towards some plant fungi, including Cercospora arachidicola (13j: EC 50 = 14.5 µg mL -1 ), Physalospora piricola (12d and 13d: EC 50 = 10.5 and 9.70 µg mL -1 ), Alternaria solani Sorauer (13j: EC 50 = 7.29 µg mL -1 ), Puccinia sorghi Schw. (13d: control efficacy 99.0 ± 2.1% at 200 µg mL -1 ) and Erysiphe graminis (14d: control efficacy 95.0 ± 1.4% at 200 µg mL -1 ). Compounds 12b-12e, 13a, 13d, 13f, 13j, 13 k and 14d could be considered potential fungicidal lead compounds to do further structural optimization. The structure-activity relationship analysis in this study brings some new understanding to the biological activities of N-pyridylpyrazole-containing compounds, and provides important information for the research and development of novel agricultural fungicides with poly-heterocyclic structures. © 2017 Society of Chemical Industry. © 2017 Society
Alkooranee, Jawadayn Talib; Yin, Yongtai; Aledan, Tamarah Raad; Jiang, Yingfen; Lu, Guangyuan; Wu, Jiangsheng; Li, Maoteng
Trichoderma harzianum TH12 is a microbial pesticide for certain rapeseed diseases. The mechanism of systemic resistance induced by TH12 or its cell-free culture filtrate (CF) in Brassica napus (AACC) and Raphanus alboglabra (RRCC) to powdery mildew disease caused by ascomycete Erysiphe cruciferarum was investigated. In this study, we conducted the first large-scale global study on the cellular and molecular aspects of B. napus and R. alboglabra infected with E. cruciferarum. The histological study showed the resistance of R. alboglabra to powdery mildew disease. The growth of fungal colonies was not observed on R. alboglabra leaves at 1, 2, 4, 6, 8, and 10 days post-inoculation (dpi), whereas this was clearly observed on B. napus leaves after 6 dpi. In addition, the gene expression of six plant defense-related genes, namely, PR-1, PR-2 (a marker for SA signaling), PR-3, PDF 1.2 (a marker for JA/ET signaling), CHI620, and CHI570, for both genotypes were analyzed in the leaves of B. napus and R. alboglabra after treatment with TH12 or CF and compared with the non-treated ones. The qRT-PCR results showed that the PR-1 and PR-2 expression levels increased in E. cruciferarum-infected leaves, but decreased in the TH12-treated leaves compared with leaves treated with CF. The expression levels of PR-3 and PDF1.2 decreased in plants infected by E. cruciferarum. However, expression levels increased when the leaves were treated with TH12. For the first time, we disclosed the nature of gene expression in B. napus and R. alboglabra to explore the resistance pathways in the leaves of both genotypes infected and non-infected by powdery mildew and inoculated or non-inoculated with elicitor factors. Results suggested that R. alboglabra exhibited resistance to powdery mildew disease, and the application of T. harzianum and its CF are a useful tool to facilitate new protection methods for resist or susceptible plants.
Verreet, J A; Heger, M; Oerke, E; Dehne, H W; Finger, I; Busse, C; Klink, H
Under the primary utilisation of phytosanitary production factors such as selection of variety, crop rotation and N fertilisation according to plant requirements, the IPM Wheat Model comprises the elements diagnosis (qualitative = type of pathogen, quantitative = disease severity), scientifically grounded treatment thresholds which, as critical values in pathogen development, can be applied to define the optimum time of fungicide application, and pathogen-specific effective fungicides and application amounts. This leads to the location and year-specific optimised control of the pathogen and of the associated yield performance. After several years of development in Bavaria (from 1985 on) and Schleswig-Holstein (1993-1999), the model was tested as part of a project involving the Universities of Bonn and Kiel and the plant protection services of the German states of Lower Saxony, North Rhine-Westphalia and Schleswig-Holstein in a three-year study (1999-2001) in interregional locations (usually nine per state) with the winter wheat variety Ritmo (interregional indicator variety) and a further variety of regional importance in different variations (untreated control, three to four times growth stage-oriented variants for the determination of the absolute damage potential, IPM-variant). In exact records (approx. 12 dates per vegetation period), the disease epidemics were recorded weekly. With the genetically uniform indicator variety Ritmo, the results documented substantially differing year- and location-specific disease and yield patterns. Interregionally, a broad wheat pathogen spectrum (Puccinia striiformis, P. recondita, Septoria tritici, Stagonospora (syn. Septoria) nodorum, Blumeria (syn. Erysiphe) graminis, Pseudocercosporella herpotrichoides, Drechslera tritici-repentis) in differing composition, disease severity and damage effect was demonstrated. The heterogeneity of the infection and damage patterns was increased in the case of the second variety, in
Pap, Dániel; Riaz, Summaira; Dry, Ian B; Jermakow, Angelica; Tenscher, Alan C; Cantu, Dario; Oláh, Róbert; Walker, M Andrew
Grapevine powdery mildew Erysiphe necator is a major fungal disease in all grape growing countries worldwide. Breeding for resistance to this disease is crucial to avoid extensive fungicide applications that are costly, labor intensive and may have detrimental effects on the environment. In the past decade, Chinese Vitis species have attracted attention from grape breeders because of their strong resistance to powdery mildew and their lack of negative fruit quality attributes that are often present in resistant North American species. In this study, we investigated powdery mildew resistance in multiple accessions of the Chinese species Vitis piasezkii that were collected during the 1980 Sino-American botanical expedition to the western Hubei province of China. A framework genetic map was developed using simple sequence repeat markers in 277 seedlings of an F1 mapping population arising from a cross of the powdery mildew susceptible Vitis vinifera selection F2-35 and a resistant accession of V. piasezkii DVIT2027. Quantitative trait locus analyses identified two major powdery mildew resistance loci on chromosome 9 (Ren6) and chromosome 19 (Ren7) explaining 74.8 % of the cumulative phenotypic variation. The quantitative trait locus analysis for each locus, in the absence of the other, explained 95.4 % phenotypic variation for Ren6, while Ren7 accounted for 71.9 % of the phenotypic variation. Screening of an additional 259 seedlings of the F1 population and 910 seedlings from four pseudo-backcross populations with SSR markers defined regions of 22 kb and 330 kb for Ren6 and Ren7 in the V. vinifera PN40024 (12X) genome sequence, respectively. Both R loci operate post-penetration through the induction of programmed cell death, but vary significantly in the speed of response and degree of resistance; Ren6 confers complete resistance whereas Ren7 confers partial resistance to the disease with reduced colony size. A comparison of the kinetics of induction of powdery
Fabio Fernando de Araújo
Full Text Available O lodo de esgoto, atendendo as exigências ambientais, apresenta potencial para disposição em solos agrícolas. Sua incorporação altera as propriedades químicas, físicas e biológicas do solo, pois é rico em macro e micronutrientes e matéria orgânica. Estas alterações podem proporcionar benefícios como aumento da disponibilidade de nutrientes às culturas, indução de supressividade a fitopatógenos habitantes do solo e de resistência às doenças da parte aérea. Por outro lado, pode influenciar negativamente o equilíbrio biológico e químico no solo, devido à presença de contaminantes. O objetivo do trabalho foi avaliar os efeitos da incorporação de lodo de esgoto ao solo sobre a severidade de oídio (Erysiphe diffusa e na supressividade a Rhizoctonia solani e a Macrophomina phaseolina da soja (Glycine max. Para tanto, foram utilizados solos que receberam quatro aplicações (1999 a 2001 sucessivas de lodos de esgoto originários das Estações de Tratamento de Esgoto de Barueri e de Franca, SP, nas concentrações de 0, 1, 2, 4 e 8 vezes (0N a 8N a dose de N recomendada para a cultura do milho. Os estudos com oídio foram realizados em casa de vegetação com inoculação natural em dois cultivos sucessivos de soja. Também foi estudado o efeito de substrato produzido com 0%, 2,5%, 5% 10%, 15% e 20% de lodo de Franca sobre a emergência de plântulas e sobre a severidade de oídio da soja em três e dois ciclos, respectivamente. Nos estudos com R. solani e M. phaseolina, os solos foram artificialmente infestados com os patógenos e posteriormente cultivados com soja por dois ciclos, sendo avaliado o tombamento e a severidade das doenças. A aplicação de lodo de esgoto no solo aumentou a atividade eliciadora de fitoalexinas em soja e a severidade do oídio foi inversamente proporcional às concentrações do lodo, tanto no estudo com o solo de campo, como com o substrato obtido com o lodo de Franca. A emergência das pl