Toxigenic Alternaria species from Argentinean blueberries.

Science.gov (United States)

Greco, M; Patriarca, A; Terminiello, L; Fernández Pinto, V; Pose, G

2012-03-15

Blueberries are traditionally consumed in North America, some European countries and Japan. In Argentina, the blueberry crop is profitable because production starts in November, when the northern hemisphere lacks fresh fruit. Fungal contaminants can grow and produce mycotoxins in fresh fruit. The aims of this work were to identify the main genera of the mycobiota of blueberries grown in Argentina and to determine the toxicogenic potential, pathogenicity and host specificity of the species isolated. The genus Alternaria was the main component of the blueberry mycobiota (95%); minor proportions of Phoma spp. (4%) and Penicillium spp. (1%) were also isolated. According to their sporulation patterns, 127 Alternaria isolates belonged to the Alternaria tenuissima species-group, 5 to the Alternaria alternata species-group and 2 to the Alternaria arborescens species-group. The last mentioned species-group was not isolated at 5°C. Of the 134 isolates, 61% were toxicogenic in autoclaved rice; 97% of these produced alternariol (AOH) in a range from 0.14 to 119.18 mg/kg, 95% produced alternariol methylether (AME) in a range from 1.23 to 901.74 mg/kg and 65% produced tenuazonic acid (TA) in a range from 0.13 to 2778 mg/kg. Fifty two isolates co-produced the three mycotoxins. According to the size of the lesion that they caused on blueberries, the isolates were classified as slightly pathogenic, moderately pathogenic and very pathogenic. No significant differences in pathogenicity were found on different blueberry varieties. In this work, high incidence and toxicogenic potential of the Alternaria isolates from blueberries were demonstrated. Thus, more studies should be done to evaluate the health risk posed by the presence of the Alternaria toxins in blueberries and in the manufactured by-products. Copyright © 2012 Elsevier B.V. All rights reserved.

Multiplexed lateral flow microarray assay for detection of citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis pv citri

Energy Technology Data Exchange (ETDEWEB)

Cary,; Bruce, R [Santa Fe, NM; Stubben, Christopher J [Los Alamos, NM

2011-03-22

The invention provides highly sensitive and specific assays for the major citrus pathogens Xylella fastidiosa and Xanthomonas axonopodis, including a field deployable multiplexed assay capable of rapidly assaying for both pathogens simultaneously. The assays are directed at particular gene targets derived from pathogenic strains that specifically cause the major citrus diseases of citrus variegated chlorosis (Xylella fastidiosa 9a5c) and citrus canker (Xanthomonas axonopodis pv citri). The citrus pathogen assays of the invention offer femtomole sensitivity, excellent linear dynamic range, and rapid and specific detection.

Restyling Alternaria

NARCIS (Netherlands)

Woudenberg, J.H.C.

2015-01-01

The omnipresent dematiaceous hyphomycete genus Alternaria is associated with a wide variety of substrates including seeds, plants, agricultural products, humans, soil and even the atmosphere. It includes saprophytic, endophytic and pathogenic species, among which multiple plant

Characterization and Pathogenicity of Alternaria vanuatuensis, a New Record from Allium Plants in Korea and China.

Science.gov (United States)

Li, Mei Jia; Deng, Jian Xin; Paul, Narayan Chandra; Lee, Hyang Burm; Yu, Seung Hun

2014-12-01

Alternaria from different Allium plants was characterized by multilocus sequence analysis. Based on sequences of the β-tubulin (BT2b), the Alternaria allergen a1 (Alt a1), and the RNA polymerase II second largest subunit (RPB2) genes and phylogenetic data analysis, isolates were divided into two groups. The two groups were identical to representative isolates of A. porri (EGS48-147) and A. vanuatuensis (EGS45-018). The conidial characteristics and pathogenicity of A. vanuatuensis also well supported the molecular characteristics. This is the first record of A. vanuatuensis E. G. Simmons & C. F. Hill from Korea and China.

Occurrence of Leaf Blight on Cosmos Caused by Alternaria cosmosa in Korea

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Jian Xin Deng

2015-03-01

Full Text Available In 2011, a leaf blight disease was observed on cosmos (Cosmos bipinnatus leaves in Nonsan, Korea. The causal pathogen was isolated and identified based on morphological and molecular approaches. Morphological characteristics of the pathogen matched well with the Alternaria cosmosa and also easily distinguishable from Alternaria zinniae reported from cosmos seeds by producing branched beak. Phylogenetically, the pathogen could not be distinguished from A. passiflorae based on the sequence analysis of a combined data set of Alt a1 and gpd genes. However, A. passiflorae was distinguished from the present species by having conidiophores with 4 to 5 conidiogenous loci. The results indicate that the present Alternaria species is A. cosmosa. Pathogenicity tests revealed that the isolate was pathogenic to the leaves of Cosmos bipinnatus. This is the first report of Alternaria blight disease caused by A. cosmosa on cosmos in Korea.

Role of mannitol metabolism in the pathogenicity of the necrotrophic fungus Alternaria brassicicola

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Benoit eCalmes

2013-05-01

Full Text Available In this study, the physiological functions of fungal mannitol metabolism in the pathogenicity and protection against environmental stresses were investigated in the necrotrophic fungus Alternaria brassicicola. Mannitol metabolism was examined during infection of Brassica oleracea leaves by sequential HPLC quantification of the major soluble carbohydrates and expression analysis of genes encoding two proteins of mannitol metabolism, i.e. a mannitol dehydrogenase (AbMdh, and a mannitol-1-phosphate dehydrogenase (AbMpd. Knockout mutants deficient for AbMdh or AbMpd and a double mutant lacking both enzyme activities were constructed. Their capacity to cope with various oxidative and drought stresses and their pathogenic behaviour were evaluated. Metabolic and gene expression profiling indicated an increase in mannitol production during plant infection. Depending on the mutants, distinct pathogenic processes, such as leaf and silique colonization, sporulation, survival on seeds, were impaired by comparison to the wild-type. This pathogenic alteration could be partly explained by the differential susceptibilities of mutants to oxidative and drought stresses. These results highlight the importance of mannitol metabolism with respect to the ability of A. brassicicola to efficiently accomplish key steps of its pathogenic life cycle.

Alternaria spp.: from general saprophyte to specific parasite

NARCIS (Netherlands)

Thomma, B.P.H.J.

2003-01-01

Alternaria species are mainly saprophytic fungi. However, some species have acquired pathogenic capacities collectively causing disease over a broad host range. This review summarizes the knowledge on pathogenic strategies employed by the fungus to plunder the host. Furthermore, strategies employed

RESISTÊNCIA DE TOMATEIRO (Lycopersicon esculentum AO PATÓGENO Alternaria solani RESISTANCE OF TOMATO (Lycopersicon esculentum TO Alternaria solani PATHOGEN

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Wilson Ferreira de Oliveira

2007-09-01

resistant were F1 hibrid Hawaii 7998 x Monense and Rotam 4. The genotypes Ohio 4013 and the F1 Hawaii 7998 x Monense hibrid were the ones that more stood out for resistance to these pathogen and could be suitable for future breeding programs.

KEY-WORDS: Tomato; resistance; Alternaria solani.

Alternaria Toxins: Potential Virulence Factors and Genes Related to Pathogenesis

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Mukesh Meena

2017-08-01

Full Text Available Alternaria is an important fungus to study due to their different life style from saprophytes to endophytes and a very successful fungal pathogen that causes diseases to a number of economically important crops. Alternaria species have been well-characterized for the production of different host-specific toxins (HSTs and non-host specific toxins (nHSTs which depend upon their physiological and morphological stages. The pathogenicity of Alternaria species depends on host susceptibility or resistance as well as quantitative production of HSTs and nHSTs. These toxins are chemically low molecular weight secondary metabolites (SMs. The effects of toxins are mainly on different parts of cells like mitochondria, chloroplast, plasma membrane, Golgi complex, nucleus, etc. Alternaria species produce several nHSTs such as brefeldin A, tenuazonic acid, tentoxin, and zinniol. HSTs that act in very low concentrations affect only certain plant varieties or genotype and play a role in determining the host range of specificity of plant pathogens. The commonly known HSTs are AAL-, AK-, AM-, AF-, ACR-, and ACT-toxins which are named by their host specificity and these toxins are classified into different family groups. The HSTs are differentiated on the basis of bio-statistical and other molecular analyses. All these toxins have different mode of action, biochemical reactions and signaling mechanisms to cause diseases. Different species of Alternaria produced toxins which reveal its biochemical and genetic effects on itself as well as on its host cells tissues. The genes responsible for the production of HSTs are found on the conditionally dispensable chromosomes (CDCs which have been well characterized. Different bio-statistical methods like basic local alignment search tool (BLAST data analysis used for the annotation of gene prediction, pathogenicity-related genes may provide surprising knowledge in present and future.

77 FR 59709 - Citrus Greening and Asian Citrus Psyllid; Quarantine and Interstate Movement Regulations

Science.gov (United States)

2012-10-01

... occur. The pathogen can also be transmitted by two insect vectors in the family Psyllidae: Diaphorina... California due to the presence of Asian citrus psyllid (ACP), a vector of the bacterial pathogen that causes... INFORMATION: Background Citrus greening, also known as Huanglongbing disease of citrus, is considered to be...

Genetic diversity of citrus bacterial canker pathogens preserved in herbarium specimens.

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Li, Wenbin; Song, Qijian; Brlansky, Ronald H; Hartung, John S

2007-11-20

Citrus bacterial canker (CBC) caused by Xanthomonas axonopodis pv. citri (Xac) was first documented in India and Java in the mid 19th century. Since that time, the known distribution of the disease has steadily increased. Concurrent with the dispersion of the pathogen, the diversity of described strains continues to increase, with novel strains appearing in Saudi Arabia, Iran, and Florida in the last decade. Herbarium specimens of infected plants provide an historical record documenting both the geographic distribution and genetic diversity of the pathogen in the past. However, no method was available to assess the genetic diversity within these herbarium samples. We have developed a method, insertion event scanning (IES), and applied the method to characterize the diversity present within CBC populations documented as herbarium specimens over the past century. IES is based on the specific amplification of junction fragments that define insertion events. The potential for IES in current forensic applications is demonstrated by finding an exact match of pathogen genotypes preserved in herbarium specimens from Japan and Florida, demonstrating the source of the original outbreak of citrus canker in Florida in 1911. IES is a very sensitive technique for differentiating bacterial strains and can be applied to any of the several hundred bacteria for which full genomic sequence data are available.

Identificação de híbridos de citros resistentes à mancha-marrom-de-alternária por meio de fAFLP e testes de patogenicidade Alternaria brown spot resistant citrus hybrid identification by means of fAFLP and pathogenicity tests

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Edvan Alves Chagas

2007-07-01

Full Text Available O objetivo deste trabalho foi identificar híbridos, oriundos de hibridações controladas entre 'Folha Murcha' x 'Ponkan' e testá-los quanto à resistência a Alternaria alternata f. sp. citri. As plântulas foram obtidas via cultura in vitro de embriões. Utilizou-se o marcador molecular fAFLP para identificação dos híbridos e, em seguida, realizou-se o teste de patogenicidade nos híbridos com isolados de Alternaria alternata f. sp. citri, em condições de laboratório. Os pares de primers EcoRI AAG - MseI CAG e EcoRI ACC - MseI CAA foram os mais eficientes na identificação dos híbridos, os quais identificaram 48,5% de híbridos. Os híbridos F64, F108, F111, F113, F131 e F139 são potencialmente resistentes a Alternaria alternata f. sp. citri.The objective of this work was to identify hybrids obtained from controlled crossings between 'Folha Murcha' x 'Ponkan', and to check their resistance to Alternaria alternata f. sp. citri. The seedlings were obtained by in vitro embryo culture. The fAFLP marker technique was used to identify the hybrids, then laboratory pathogenicity test of the hybrids was accomplished with Alternaria alternata f. sp. citri isolates. The pairs of primers EcoRI AAG - Msel CAG and EcoRI ACC - Msel CAA were the most efficient for hybrids identification, and distinguished 48.5% of hybrids. Hybrids F64, F108, F111, F113, F131 and F139 showed potential resistance to the Alternaria alternata f. sp. citri.

Furfural from Pine Needle Extract Inhibits the Growth of a Plant Pathogenic Fungus, Alternaria mali

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Yoo, Sun Kyun; Moon, Sung-Kwon; Lee, Ung-Soo

2007-01-01

The antifungal effect of pine needle extract prepared by a distinguishable extraction method and the dry distillation method, was examined. The effect of this extract itself was insignificant. The chemical components of pine needle extract were then investigated by gas chromatographic analysis, and four chemical components, acetol, furfural, 5-methyl furfural, and terpine-4-ol, were identified. The antifungal effects of those four chemical components against Alternaria mali (A. mali), an agent of Alternaria blotch of apple, were then examined. It was observed that the minimum inhibitory concentrations (MICs) were 6.25, 0.78, 0.78, and 12.5 (mg/ml) of acetol, furfural, 5-methyl furfural, and terpine-4-ol, respectively. MICs of furfural and 5-methyl furfural had the same order of magnitude as that of an antifungal agrochemical, chlorothalonil. Although furfural itself can not be completely substituted for an antifungal agrochemical, a partial mixture of furfural and antifungal agrochemical may be used as a substitute. The use of agrochemicals for the prevention of plant disease caused by pathogenic fungus such as A. mali could be partially reduced by the application of this mixture. PMID:24015067

78 FR 63369 - Citrus Canker, Citrus Greening, and Asian Citrus Psyllid; Interstate Movement of Regulated...

Science.gov (United States)

2013-10-24

... that seed transmission may occur. The pathogen can also be transmitted by two insect vectors in the... by the Secretary prior to movement. Citrus canker is a plant disease that is caused by a complex of....75-6. Citrus greening, also known as Huanglongbing disease of citrus, is considered to be one of the...

The presence of Alternaria spp. on the seed of Apiaceae plants and their influence on seed emergence

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Bulajić Aleksandra

2009-01-01

Full Text Available Considerable damping-off of the seedlings of several commercial Apiaceae plant species was observed in Serbia. The infection of a total of 48 seed samples of nine vegetable and spice plants with phytopathogenic Alternaria spp. was established using the deep-freeze-blotter method. Identification of Alternaria species was performed using both conventional methods and PCR. Four different plant-pathogenic Alternaria species were detected in Serbia: A. dauci, A. radicina, A. petroselini, and A. alternata, all of which caused reduction of carrot, parsley, parsnip, and celery seed emergence. Alternaria dauci, A. radicina, and A. petroselini were relatively more aggressive compared to A. alternata. Substantial seed infection levels and strong influence of Alternaria spp. on seed emergence indicated that production of Apiaceae seed needs to be improved in order to obtain pathogen-free seed.

A Major Facilitator Superfamily Transporter-Mediated Resistance to Oxidative Stress and Fungicides Requires Yap1, Skn7, and MAP Kinases in the Citrus Fungal Pathogen Alternaria alternata.

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Li-Hung Chen

Full Text Available Major Facilitator Superfamily (MFS transporters play an important role in multidrug resistance in fungi. We report an AaMFS19 gene encoding a MFS transporter required for cellular resistance to oxidative stress and fungicides in the phytopathogenic fungus Alternaria alternata. AaMFS19, containing 12 transmembrane domains, displays activity toward a broad range of substrates. Fungal mutants lacking AaMFS19 display profound hypersensitivities to cumyl hydroperoxide, potassium superoxide, many singlet oxygen-generating compounds (eosin Y, rose Bengal, hematoporphyrin, methylene blue, and cercosporin, and the cell wall biosynthesis inhibitor, Congo red. AaMFS19 mutants also increase sensitivity to copper ions, clotrimazole, fludioxonil, and kocide fungicides, 2-chloro-5-hydroxypyridine (CHP, and 2,3,5-triiodobenzoic acid (TIBA. AaMFS19 mutants induce smaller necrotic lesions on leaves of a susceptible citrus cultivar. All observed phenotypes in the mutant are restored by introducing and expressing a wild-type copy of AaMFS19. The wild-type strain of A. alternata treated with either CHP or TIBA reduces radial growth and formation and germination of conidia, increases hyphal branching, and results in decreased expression of the AaMFS19 gene. The expression of AaMFS19 is regulated by the Yap1 transcription activator, the Hog1 and Fus3 mitogen-activated protein (MAP kinases, the 'two component' histidine kinase, and the Skn7 response regulator. Our results demonstrate that A. alternata confers resistance to different chemicals via a membrane-bound MFS transporter.

Toxin production by Fusarium solani from declining citrus plants and ...

African Journals Online (AJOL)

The highest Fusarium sp. followed by Aspergillus, Phytophthora, Pythium, Penicillium and Alternaria species were remote from the collected samples of roots and soil from the four tehsils of Sargodha district of Pakistan. The maximum Fusarium sp. was isolated from the roots of declining citrus trees from tehsil Bhalwal ...

Infection Density Dynamics of the Citrus Greening Bacterium “Candidatus Liberibacter asiaticus” in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants

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Ukuda-Hosokawa, Rie; Sadoyama, Yasutsune; Kishaba, Misaki; Kuriwada, Takashi; Anbutsu, Hisashi

2015-01-01

Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, “Candidatus Liberibacter asiaticus,” and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of “Ca. Liberibacter asiaticus” in field populations of D. citri with experiments using field-collected insects to address how “Ca. Liberibacter asiaticus” infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from “Ca. Liberibacter asiaticus”-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were “Ca. Liberibacter asiaticus” positive. The infections were systemic across head-thorax and abdomen, ranging from 103 to 107 bacteria per insect. In spring, the infection densities were low in March, at ∼103 bacteria per insect, increasing up to 106 to 107 bacteria per insect in April and May, and decreasing to 105 to 106 bacteria per insect in late May, whereas the infection densities were constantly ∼106 to 107 bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with “Ca. Liberibacter asiaticus” infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected “Ca. Liberibacter asiaticus”-infected insects suggested that (i) “Ca. Liberibacter asiaticus”-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (∼106 bacteria per insect) of “Ca. Liberibacter asiaticus” density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits “Ca. Liberibacter asiaticus” to citrus plants in a stochastic manner. These

Evaluation of a triplex real-time PCR system to detect the plant-pathogenic molds Alternaria spp., Fusarium spp. and C. purpurea.

Science.gov (United States)

Grube, Sabrina; Schönling, Jutta; Prange, Alexander

2015-12-01

This article describes the development of a triplex real-time PCR system for the simultaneous detection of three major plant-pathogenic mold genera (Alternaria spp., Fusarium spp. and the species Claviceps purpurea). The designed genus-specific primer-probe systems were validated for sensitivity, specificity and amplification in the presence of background DNA. Copyright © 2015 Elsevier B.V. All rights reserved.

Infection Density Dynamics of the Citrus Greening Bacterium "Candidatus Liberibacter asiaticus" in Field Populations of the Psyllid Diaphorina citri and Its Relevance to the Efficiency of Pathogen Transmission to Citrus Plants.

Science.gov (United States)

Ukuda-Hosokawa, Rie; Sadoyama, Yasutsune; Kishaba, Misaki; Kuriwada, Takashi; Anbutsu, Hisashi; Fukatsu, Takema

2015-06-01

Huanglongbing, or citrus greening, is a devastating disease of citrus plants recently spreading worldwide, which is caused by an uncultivable bacterial pathogen, "Candidatus Liberibacter asiaticus," and vectored by a phloem-sucking insect, Diaphorina citri. We investigated the infection density dynamics of "Ca. Liberibacter asiaticus" in field populations of D. citri with experiments using field-collected insects to address how "Ca. Liberibacter asiaticus" infection density in the vector insect is relevant to pathogen transmission to citrus plants. Of 500 insects continuously collected from "Ca. Liberibacter asiaticus"-infected citrus trees with pathological symptoms in the spring and autumn of 2009, 497 (99.4%) were "Ca. Liberibacter asiaticus" positive. The infections were systemic across head-thorax and abdomen, ranging from 10(3) to 10(7) bacteria per insect. In spring, the infection densities were low in March, at ∼ 10(3) bacteria per insect, increasing up to 10(6) to 10(7) bacteria per insect in April and May, and decreasing to 10(5) to 10(6) bacteria per insect in late May, whereas the infection densities were constantly ∼ 10(6) to 10(7) bacteria per insect in autumn. Statistical analysis suggested that several factors, such as insect sex, host trees, and collection dates, may be correlated with "Ca. Liberibacter asiaticus" infection densities in field D. citri populations. Inoculation experiments with citrus seedlings using field-collected "Ca. Liberibacter asiaticus"-infected insects suggested that (i) "Ca. Liberibacter asiaticus"-transmitting insects tend to exhibit higher infection densities than do nontransmitting insects, (ii) a threshold level (∼ 10(6) bacteria per insect) of "Ca. Liberibacter asiaticus" density in D. citri is required for successful transmission to citrus plants, and (iii) D. citri attaining the threshold infection level transmits "Ca. Liberibacter asiaticus" to citrus plants in a stochastic manner. These findings provide

Induced resistance in tomato fruit by γ-aminobutyric acid for the control of alternaria rot caused by Alternaria alternata.

Science.gov (United States)

Yang, Jiali; Sun, Cui; Zhang, Yangyang; Fu, Da; Zheng, Xiaodong; Yu, Ting

2017-04-15

The study investigated the effect of γ-aminobutyric acid (GABA) on the control of alternaria rot in tomato fruit and the possible mechanism involved. Our results showed exogenous GABA could stimulate remarkable resistance to the alternaria rot, while it had no direct antifungal activity against Alternaria alternata. Moreover, the activities of antioxidant enzymes, including peroxidase, superoxide dismutase and catalase, along with the expression of these corresponding genes, were significantly induced in the GABA treatment. The obtained data suggested GABA induced resistance against the necrotrophic pathogen A. alternata, at least in part by activating antioxidant enzymes, restricting the levels of cell death caused by reactive oxygen species. Meanwhile, the key enzyme genes of GABA shunt, GABA transaminase and succinic-semialdehyde dehydrogenase, were found up-regulated in the GABA treatment. The activation of the GABA shunt might play a vital role in the resistance mechanism underpinning GABA-induced plant immunity. Copyright © 2016 Elsevier Ltd. All rights reserved.

The potential for citrus cryotherapy

Science.gov (United States)

Citrus collections of pathogen-free plants are needed for breeding, research, and distribution to the user community. The Citrus Research Board funded research project “Development of cryotherapy as an improved method of eliminating graft transmissible pathogens in Citrus” sought to use cryotherapy,...

Bacterial diversity analysis of Huanglongbing pathogen-infected citrus, using PhyloChip and 16S rRNA gene clone library sequencing

Energy Technology Data Exchange (ETDEWEB)

Shankar Sagaram, U.; DeAngelis, K.M.; Trivedi, P.; Andersen, G.L.; Lu, S.-E.; Wang, N.

2009-03-01

The bacterial diversity associated with citrus leaf midribs was characterized 1 from citrus groves that contained the Huanglongbing (HLB) pathogen, which has yet to be cultivated in vitro. We employed a combination of high-density phylogenetic 16S rDNA microarray and 16S rDNA clone library sequencing to determine the microbial community composition of symptomatic and asymptomatic citrus midribs. Our results revealed that citrus leaf midribs can support a diversity of microbes. PhyloChip analysis indicated that 47 orders of bacteria from 15 phyla were present in the citrus leaf midribs while 20 orders from phyla were observed with the cloning and sequencing method. PhyloChip arrays indicated that nine taxa were significantly more abundant in symptomatic midribs compared to asymptomatic midribs. Candidatus Liberibacter asiaticus (Las) was detected at a very low level in asymptomatic plants, but was over 200 times more abundant in symptomatic plants. The PhyloChip analysis was further verified by sequencing 16S rDNA clone libraries, which indicated the dominance of Las in symptomatic leaves. These data implicate Las as the pathogen responsible for HLB disease. Citrus is the most important commercial fruit crop in Florida. In recent years, citrus Huanglongbing (HLB), also called citrus greening, has severely affected Florida's citrus production and hence has drawn an enormous amount of attention. HLB is one of the most devastating diseases of citrus (6,13), characterized by blotchy mottling with green islands on leaves, as well as stunting, fruit decline, and small, lopsided fruits with poor coloration. The disease tends to be associated with a phloem-limited fastidious {alpha}-proteobacterium given a provisional Candidatus status (Candidatus Liberobacter spp. later changed to Candidatus Liberibacter spp.) in nomenclature (18,25,34). Previous studies indicate that HLB infection causes disorder in the phloem and severely impairs the translocation of assimilates in

Diaphorina citri (Hemiptera: Liviidae) Vector Competence for the Citrus Greening Pathogen 'Candidatus Liberibacter Asiaticus'.

Science.gov (United States)

Tabachnick, Walter J

2015-06-01

Characterizing the vector competence of Diaphorina citri Kuwayama for 'Candidatus Liberibacter asiaticus,' the pathogen causing citrus greening, is essential for understanding the epidemiology of this disease that is threatening the U.S. citrus industry. Vector competence studies have been difficult because of the biology of D. citri, the inability to culture the pathogen, and the available diagnostic methods used to detect the bacteria in plant and insect tissues. The methods employed in many studies of D. citri vector competence may have overestimated amounts of live 'Ca. L. asiaticus' in both plant and insect tissues, and it is possible that the amounts of phloem ingested by psyllids may not contain sufficient detectable pathogen using current diagnostic methods. As a result of the difficulty in characterizing D. citri vector competence, the several daunting challenges for providing D. citri that are unable to inoculate 'Ca. L. asiaticus', as a novel method to control greening are discussed. Suggestions to overcome some of these challenges are provided. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Monograph on alternaria diseases of crucifers. Technical bulletin No. 1994-6E

Energy Technology Data Exchange (ETDEWEB)

Verma, P R

1994-12-31

The brassicas include an important group of oilseed crops such as canola and commercial vegetables such as cabbage and broccoli. Infection by species of the fungus Alternaria causes severe yield losses to those crops. This document compiles the most recent information on fundamental and applied knowledge of Alternaria species infecting Brassicaceae crops and weeds. It includes a review of the symptoms, geographical distribution, yield losses, and disease assessment methods of infections from the four most widely distributed species of Alternaria; information on the characteristics of the pathogen, its host range, disease cycle, process of infection, epidemiology, fine structures and electron microscopy, resistance, and phytotoxins; and techniques for disease infection and management. The document concludes with an evaluation of future strategies and priorities in the management of Alternaria diseases.

Regulation of pathogenicity in hop stunt viroid-related group II citrus viroids.

Science.gov (United States)

Reanwarakorn, K; Semancik, J S

1998-12-01

Nucleotide sequences were determined for two hop stunt viroid-related Group II citrus viroids characterized as either a cachexia disease non-pathogenic variant (CVd-IIa) or a pathogenic variant (CVd-IIb). Sequence identity between the two variants of 95.6% indicated a conserved genome with the principal region of nucleotide difference clustered in the variable (V) domain. Full-length viroid RT-PCR cDNA products were cloned into plasmid SP72. Viroid cDNA clones as well as derived RNA transcripts were transmissible to citron (Citrus medica L.) and Luffa aegyptiaca Mill. To determine the locus of cachexia pathogenicity as well as symptom expression in Luffa, chimeric viroid cDNA clones were constructed from segments of either the left terminal, pathogenic and conserved (T1-P-C) domains or the conserved, variable and right terminal (C-V-T2) domains of CVd-IIa or CVd-IIb in reciprocal exchanges. Symptoms induced by the various chimeric constructs on the two bioassay hosts reflected the differential response observed with CVd-IIa and -IIb. Constructs with the C-V-T2 domains region from clone-IIa induced severe symptoms on Luffa typical of CVd-IIa, but were non-symptomatic on mandarin as a bioassay host for the cachexia disease. Constructs with the same region (C-V-T2) from the clone-IIb genome induced only mild symptoms on Luffa, but produced a severe reaction on mandarin, as observed for CVd-IIb. Specific site-directed mutations were introduced into the V domain of the CVd-IIa clone to construct viroid cDNA clones with either partial or complete conversions to the CVd-IIb sequence. With the introduction of six site-specific changes into the V domain of the clone-IIa genome, cachexia pathogenicity was acquired as well as a moderation of severe symptoms on Luffa.

Csn5 Is Required for the Conidiogenesis and Pathogenesis of the Alternaria alternata Tangerine Pathotype

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Mingshuang Wang

2018-03-01

Full Text Available The COP9 signalosome (CSN is a highly conserved protein complex involved in the ubiquitin-proteasome system. Its metalloisopeptidase activity resides in subunit 5 (CSN5. Functions of csn5 in phytopathogenic fungi are poorly understood. Here, we knocked out the csn5 ortholog (Aacsn5 in the tangerine pathotype of Alternaria alternata. The ΔAacsn5 mutant showed a moderately reduced growth rate compared to the wildtype strain and was unable to produce conidia. The growth of ΔAacsn5 mutant was not affected in response to oxidative and osmotic stresses. Virulence assays revealed that ΔAacsn5 induced no or significantly reduced necrotic lesions on detached citrus leaves. The defects in hyphal growth, conidial sporulation, and pathogenicity of ΔAacsn5 were restored by genetic complementation of the mutant with wildtype Aacsn5. To explore the molecular mechanisms of conidiation and pathogenesis underlying Aacsn5 regulation, we systematically examined the transcriptomes of both ΔAacsn5 and the wildtype. Generally, 881 genes were overexpressed and 777 were underexpressed in the ΔAacsn5 mutant during conidiation while 694 overexpressed and 993 underexpressed during infection. During asexual development, genes related to the transport processes and nitrogen metabolism were significantly downregulated; the expression of csn1–4 and csn7 in ΔAacsn5 was significantly elevated; secondary metabolism gene clusters were broadly affected; especially, the transcript level of the whole of cluster 28 and 30 was strongly induced. During infection, the expression of the host-specific ACT toxin gene cluster which controls the biosynthesis of the citrus specific toxin was significantly repressed; many other SM clusters with unknown products were also regulated; 86 out of 373 carbohydrate-active enzymes responsible for breaking down the plant dead tissues showed uniquely decreased expression. Taken together, our results expand our understanding of the roles of csn5

Huanglongbing increases Diplodia Stem End Rot in Citrus sinensis

Science.gov (United States)

Huanglongbing (HLB), one of the most devastating diseases of citrus is caused by the a-Proteobacteria Candidatus Liberibacter. Diplodia natalensis Pole-Evans is a fungal pathogen which has been known to cause a postharvest stem-end rot of citrus, the pathogen infects citrus fruit under the calyx, an...

Potencial de pseudomonas spp. fluorescentes para biocontrole de alternaria ricini em mamoneira Potential of fluorescent pseudomonas spp. For biological control of alternaria ricini on castorbean

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Francisco de A.G. da Silva

1998-06-01

Full Text Available The potential of fluorescent Pseudomonas spp. to control Alternaria leaf spot on castorbean, caused by Alternaria ricini, was studied under greenhouse conditions. Two periods for antagonist applications were tested: 48h before and simultaneously to the pathogen inoculation. Among the antagonists tested JA4 and BJ22 were the most effectives showing disease severity reduction of 20.9% and 17.8% respectively, when applied simultaneously. The effect of Pseudomonas spp. on the micelial growth and sporulation was also studied throughout three different methods (funel, streak and celophane. Inhibition of micelial growth and sporulation was observed. There was no correlation between in vitro and in vivo data. Antibiosis was showed as a mode of action for Pseudomonas spp. in relation to Alternaria ricini. Ultrastructural studies confirmed the inhibition of spore germination by the bacteria.

Overexpression of a modified plant thionin enhances disease resistance to citrus canker and huanglongbing (HLB, citrus greening)

Science.gov (United States)

Huanglongbing (HLB or citrus greening disease) caused by Candidatus Liberibacter asiaticus (Las) is a great threat to the United States citrus industry. Citrus canker is also an economically important disease associated with a bacterial pathogen (Xanthomonas citri). In this study, we characterized e...

Effect of citrus pulp on the viability of Saccharomyces boulardii in the presence of enteric pathogens

Science.gov (United States)

Saccharomyces cerevisiae subtype boulardii is frequently used as a dietary supplement to promote intestinal health and reduce the impact of growth of enteric pathogens in livestock, including cattle and swine. Citrus by-products are also fed as dietary supplements that have the additional benefit o...

Phagostimulants for the Asian citrus psyllid also elicit volatile release from citrus leaves

Science.gov (United States)

Chemical cues that elicit orientation by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), are of great interest because it is the primary vector of the causal pathogen of citrus greening disease. We identified an optimal blend ratio of formic and acetic acids that stimulate...

Role of the pathotype-specific ACRTS1 gene encoding a hydroxylase involved in the biosynthesis of host-selective ACR-toxin in the rough lemon pathotype of Alternaria alternata.

Science.gov (United States)

Izumi, Yuriko; Kamei, Eri; Miyamoto, Yoko; Ohtani, Kouhei; Masunaka, Akira; Fukumoto, Takeshi; Gomi, Kenji; Tada, Yasuomi; Ichimura, Kazuya; Peever, Tobin L; Akimitsu, Kazuya

2012-08-01

The rough lemon pathotype of Alternaria alternata produces host-selective ACR-toxin and causes Alternaria leaf spot disease of the rootstock species rough lemon (Citrus jambhiri) and Rangpur lime (C. limonia). Genes controlling toxin production were localized to a 1.5-Mb chromosome carrying the ACR-toxin biosynthesis gene cluster (ACRT) in the genome of the rough lemon pathotype. A genomic BAC clone containing a portion of the ACRT cluster was sequenced which allowed identification of three open reading frames present only in the genomes of ACR-toxin producing isolates. We studied the functional role of one of these open reading frames, ACRTS1 encoding a putative hydroxylase, in ACR-toxin production by homologous recombination-mediated gene disruption. There are at least three copies of ACRTS1 gene in the genome and disruption of two copies of this gene significantly reduced ACR-toxin production as well as pathogenicity; however, transcription of ACRTS1 and production of ACR-toxin were not completely eliminated due to remaining functional copies of the gene. RNA-silencing was used to knock down the remaining ACRTS1 transcripts to levels undetectable by reverse transcription-polymerase chain reaction. The silenced transformants did not produce detectable ACR-toxin and were not pathogenic. These results indicate that ACRTS1 is an essential gene in ACR-toxin biosynthesis in the rough lemon pathotype of A. alternata and is required for full virulence of this fungus.

Characterization of glutathione transferases involved in the pathogenicity of Alternaria brassicicola.

Science.gov (United States)

Calmes, Benoit; Morel-Rouhier, Mélanie; Bataillé-Simoneau, Nelly; Gelhaye, Eric; Guillemette, Thomas; Simoneau, Philippe

2015-06-18

Glutathione transferases (GSTs) represent an extended family of multifunctional proteins involved in detoxification processes and tolerance to oxidative stress. We thus anticipated that some GSTs could play an essential role in the protection of fungal necrotrophs against plant-derived toxic metabolites and reactive oxygen species that accumulate at the host-pathogen interface during infection. Mining the genome of the necrotrophic Brassica pathogen Alternaria brassicicola for glutathione transferase revealed 23 sequences, 17 of which could be clustered into the main classes previously defined for fungal GSTs and six were 'orphans'. Five isothiocyanate-inducible GSTs from five different classes were more thoroughly investigated. Analysis of their catalytic properties revealed that two GSTs, belonging to the GSTFuA and GTT1 classes, exhibited GSH transferase activity with isothiocyanates (ITC) and peroxidase activity with cumene hydroperoxide, respectively. Mutant deficient for these two GSTs were however neither more susceptible to ITC nor less aggressive than the wild-type parental strain. By contrast mutants deficient for two other GSTs, belonging to the Ure2pB and GSTO classes, were distinguished by their hyper-susceptibility to ITC and low aggressiveness against Brassica oleracea. In particular AbGSTO1 could participate in cell tolerance to ITC due to its glutathione-dependent thioltransferase activity. The fifth ITC-inducible GST belonged to the MAPEG class and although it was not possible to produce the soluble active form of this protein in a bacterial expression system, the corresponding deficient mutant failed to develop normal symptoms on host plant tissues. Among the five ITC-inducible GSTs analyzed in this study, three were found essential for full aggressiveness of A. brassicicola on host plant. This, to our knowledge is the first evidence that GSTs might be essential virulence factors for fungal necrotrophs.

Degradation products of citrus volatile organic compounds (VOCs) acting as phagostimulants that increase probing behavior of Asian citrus psyllid

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Volatile phytochemicals play a role in orientation by phytophagous insects. We studied antennal and behavioral responses of the Asian citrus psyllid, Diaphorina citri Kuwayama, vector of the citrus greening disease pathogen. Little or no response to citrus leaf volatiles was detected by electroanten...

Characterization and Pathogenicity of Alternaria burnsii from Seeds of Cucurbita maxima (Cucurbitaceae) in Bangladesh.

Science.gov (United States)

Paul, Narayan Chandra; Deng, Jian Xin; Lee, Hyang Burm; Yu, Seung-Hun

2015-12-01

In the course of survey of endophytic fungi from Bangladesh pumpkin seeds in 2011~2012, two strains (CNU111042 and CNU111043) with similar colony characteristics were isolated and characterized by their morphology and by molecular phylogenetic analysis of the internal transcribed spacer, glyceraldehydes-3-phosphate dehydrogenase (gpd), and Alternaria allergen a1 (Alt a1) sequences. Phylogenetic analysis of all three sequences and their combined dataset revealed that the fungus formed a subclade within the A. alternata clade, matching A. burnsi and showing differences with its other closely related Alternaria species, such as A. longipes, A. tomato, and A. tomaticola. Long ellipsoid, obclavate or ovoid beakless conidia, shorter and thinner conidial size (16~60 [90] × 6.5~14 [~16] µm) distinguish this fungus from other related species. These isolates showed more transverse septation (2~11) and less longitudinal septation (0~3) than did other related species. Moreover, the isolate did not produce any diffusible pigment on media. Therefore, our results reveal that the newly recorded fungus from a new host, Cucurbita maxima, is Alternaria burnsii Uppal, Patel & Kamat.

Reference genes for accurate transcript normalization in citrus genotypes under different experimental conditions.

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Valéria Mafra

Full Text Available Real-time reverse transcription PCR (RT-qPCR has emerged as an accurate and widely used technique for expression profiling of selected genes. However, obtaining reliable measurements depends on the selection of appropriate reference genes for gene expression normalization. The aim of this work was to assess the expression stability of 15 candidate genes to determine which set of reference genes is best suited for transcript normalization in citrus in different tissues and organs and leaves challenged with five pathogens (Alternaria alternata, Phytophthora parasitica, Xylella fastidiosa and Candidatus Liberibacter asiaticus. We tested traditional genes used for transcript normalization in citrus and orthologs of Arabidopsis thaliana genes described as superior reference genes based on transcriptome data. geNorm and NormFinder algorithms were used to find the best reference genes to normalize all samples and conditions tested. Additionally, each biotic stress was individually analyzed by geNorm. In general, FBOX (encoding a member of the F-box family and GAPC2 (GAPDH was the most stable candidate gene set assessed under the different conditions and subsets tested, while CYP (cyclophilin, TUB (tubulin and CtP (cathepsin were the least stably expressed genes found. Validation of the best suitable reference genes for normalizing the expression level of the WRKY70 transcription factor in leaves infected with Candidatus Liberibacter asiaticus showed that arbitrary use of reference genes without previous testing could lead to misinterpretation of data. Our results revealed FBOX, SAND (a SAND family protein, GAPC2 and UPL7 (ubiquitin protein ligase 7 to be superior reference genes, and we recommend their use in studies of gene expression in citrus species and relatives. This work constitutes the first systematic analysis for the selection of superior reference genes for transcript normalization in different citrus organs and under biotic stress.

New antitumour fungal metabolites from Alternaria porri.

Science.gov (United States)

Phuwapraisirisan, Preecha; Rangsan, Jakaphan; Siripong, Pongpan; Tip-Pyang, Santi

2009-01-01

Chemical investigation of the onion pathogenic fungus Alternaria porri resulted in the isolation of two new phthalides named zinnimide (2) and deprenylzinnimide (8), along with a new bianthraquinone, alterporriol F (10). The structures of the new metabolites were characterised by spectroscopic analysis and chemical degradation. Of the new compounds isolated, alterporriol F was highly cytotoxic towards HeLa and KB cells, with IC(50) values of 6.5 and 7.0 microg mL(-1).

Induction of mutant resistant to alternaria blotch of apple by gamma-ray irradiation

International Nuclear Information System (INIS)

Yoshioka, Toji; Ito, Yuji; Masuda, Tetsuo

2000-01-01

Apple cultivars resistant to Alternaria blotch disease have been produced by cross-breeding, but it is difficult to produce resistance by crossing without changing the properties of cultivar because the gene composition of the cultivar tree is almost heterozygous. This study aimed to investigate the resistant mutation in Alternaria blotch susceptible and semiresistant cultivars. The resistance to Alternaria blotch pathogen or AM toxin is classified into the following three groups: 1) highly sensitive group including Indo, Redgold and Starking delicious, 2) semi-resistant group including Fuji, Orin and Golden delicious and 3) resistant group including Gala and Tsugaru. After gamma ray exposure of 80 Gy (at 5 Gy/hour), AM-toxin insensitive clones were selected in the VM 6 generation. These selected mutants could be rooted and habituated under field conditions. The degree of disease resistance was assessed by AM toxin treatment and Alternaria blotch fungi spore inoculation test. The leaves of these mutants were changed to variegated at high temperature, suggesting that some mutation related to chloroplast might have occurred. Alternaria blotch resistant strains could be produced by exposing to γray and selecting with AM toxin in shoot-tip culture system, but the functional effects of the AM toxin in Alternaria blotch and also the mechanism in the mutant lines were still unclear. (M.N.)

Specific PCR-based detection of Alternaria helianthi

DEFF Research Database (Denmark)

Udayashankar, A.C.; Nayaka, S. Chandra; Archana, B.

2012-01-01

Alternaria helianthi is an important seed-borne pathogenic fungus responsible for blight disease in sunflower. The current detection methods, which are based on culture and morphological identification, are time-consuming, laborious and are not always reliable. A PCR-based diagnostic method...... tested. The detection limit of the PCR method was of 10 pg from template DNA. The primers could also detect the pathogen in infected sunflower seed. This species-specific PCR method provides a quick, simple, powerful and reliable alternative to conventional methods in the detection and identification...

Hyperspectral and thermal imaging of oilseed rape (Brassica napus response to fungal species of the genus Alternaria.

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Piotr Baranowski

Full Text Available In this paper, thermal (8-13 µm and hyperspectral imaging in visible and near infrared (VNIR and short wavelength infrared (SWIR ranges were used to elaborate a method of early detection of biotic stresses caused by fungal species belonging to the genus Alternaria that were host (Alternaria alternata, Alternaria brassicae, and Alternaria brassicicola and non-host (Alternaria dauci pathogens to oilseed rape (Brassica napus L.. The measurements of disease severity for chosen dates after inoculation were compared to temperature distributions on infected leaves and to averaged reflectance characteristics. Statistical analysis revealed that leaf temperature distributions on particular days after inoculation and respective spectral characteristics, especially in the SWIR range (1000-2500 nm, significantly differed for the leaves inoculated with A. dauci from the other species of Alternaria as well as from leaves of non-treated plants. The significant differences in leaf temperature of the studied Alternaria species were observed in various stages of infection development. The classification experiments were performed on the hyperspectral data of the leaf surfaces to distinguish days after inoculation and Alternaria species. The second-derivative transformation of the spectral data together with back-propagation neural networks (BNNs appeared to be the best combination for classification of days after inoculation (prediction accuracy 90.5% and Alternaria species (prediction accuracy 80.5%.

The citrus postharvest pathogen Penicillium digitatum depends on the PdMpkB kinase for developmental and virulence functions.

Science.gov (United States)

Ma, Haijie; Sun, Xuepeng; Wang, Mingshuang; Gai, Yunpeng; Chung, Kuang-Ren; Li, Hongye

2016-11-07

The postharvest pathogen Penicillium digitatum causes green mold decay on citrus fruit, resulting in severe economic losses. To explore possible factors involved in fungal pathogenesis, phenotypic characterization of the budding yeast Fus3/Kiss1 mitogen-activated protein (MAP) kinase homolog was carried out. The P. digitatum MAP kinase B coding gene, designated PdMpkB, was functionally inactivated via homologous recombination. The fungal strain (∆PdMpkB) carrying a PdMpkBdeletion demonstrated altered gene expression profiles, reduced growth and conidiogenesis, elevated resistance to osmotic stress, and failed to induce green mold decay on citrus fruit. ∆PdMpkB was more resistant to CaCl2, NaCl and sorbitol than its progenitor strain, indicating a negative regulatory function of PdMpkB in osmotic stress adaptation. Fungal infection assays on citrus fruit revealed that ∆PdMpkB proliferated poorly within host tissues, induced water-soaking lesions, failed to break through host cuticle layers and thus, failed to produce aerial hyphae and conidia. Introduction of a functional copy of PdMpkB into a null mutant restored all defective phenotypes. Transcriptome analysis revealed that inactivation of PdMpkB impacted expression of the genes associated with cell wall-degrading enzyme activities, carbohydrate and amino acid metabolisms, conidial formation, and numerous metabolic processes. Our results define pivotal roles of the PdMpkB-mediated signaling pathway in developmental and pathological functions in the citrus postharvest pathogen P. digitatum. Copyright © 2016 Elsevier B.V. All rights reserved.

78 FR 8435 - Importation of Fresh Citrus Fruit From Uruguay, Including Citrus Hybrids and Fortunella

Science.gov (United States)

2013-02-06

...] australis, causal agent of sweet orange scab); and a pathogen (Xanthomonas citri subsp. citri, causal agent... oranges (Citrus sinensis (L.) Osbeck), lemons (C. limon (L.) Burm. f.), four species of mandarins (C... of the reading room). The PRA, titled ``Importation of Fresh Citrus Fruit, including Sweet Orange...

Regulation of gene expression for defensins and lipid transfer protein in Scots pine seedlings by necrotrophic pathogen Alternaria alternata (Fr.

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Hrunyk Nataliya

2017-06-01

Full Text Available Damping-off disease in pine seedling, caused by fungi and oomycetes (Fusarium, Alternaria, Botrytis, Phytophthora and other species, is one of the most dangerous diseases in conifer nurseries and greenhouses worldwide. Alternaria alternata is a necrotrophic pathogen, which causes early blight in higher plants and results in massive economic losses in agro-industry as well as in forestry. Pine seedlings that lack strong lignificated and suberized cell walls at early stages of their growth are vulnerable to damping-off disease. So, triggering the synthesis of antimicrobial compounds, such as phytoalexins, anticipins and pathogenesis-related (PR proteins, is the main defense strategy to confine pathogens at early stages of pine ontogenesis. Defensins and lipid transfer proteins are members of two PR-protein families (PR-12 and PR-14 respectively and possess antimicrobial activities in vitro through contact toxicity, and the involvement in defense signalling. In this work, we describe the changes in the expression levels of four defensin genes and lipid transfer protein in Scots pine seedlings infected with A. alternata. The expression levels of PsDef1 and PsDef2 increased at 48 h.p.i. (hours post inoculation. The levels of PsDef4 transcripts have increased after 6 and 24 hours. Notably, at 48 h.p.i., the level of PsDef4 transcripts was decreased by 1.2 times compared to control. The level of PsDef3 transcripts was reduced at all three time points. On the other hand, the level of PsLTP1 transcripts increased at 6 h and 48 h.p.i.; while at 24 h.p.i., it decreased by 20% when compared to the control sample. Our results suggest that defensins and lipid transfer protein are involved in the defense response of young Scots pine to necrotrophic pathogen. Thus, those genes can be used as the molecular markers in forestry selection and development of the ecologically friendly remedies for coniferous seedlings cultivation in greenhouses and nurseries.

Fungal-specific transcription factor AbPf2 activates pathogenicity in Alternaria brassicicola

Energy Technology Data Exchange (ETDEWEB)

Cho, Yangrae; Ohm, Robin A. [US Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA, 94598, USA; Grigoriev, Igor V. [US Department of Energy Joint Genome Institute, 2800 Mitchell Drive, Walnut Creek, CA, 94598, USA; Srivastava, Akhil [Plant and Environmental Protection Sciences, University of Hawaii at Manoa, 3190 Maile Way, St John 317, Honolulu, HI, 96822, USA

2013-05-24

Alternaria brassicicola is a successful saprophyte and necrotrophic plant pathogen. To identify molecular determinants of pathogenicity, we created non-pathogenic mutants of a transcription factor-encoding gene, AbPf2. The frequency and timing of germination and appressorium formation on host plants were similar between the non-pathogenic abpf2 mutants and wild-type A. brassicicola. The mutants were also similar in vitro to wild-type A. brassicicola in terms of vegetative growth, conidium production, and responses to a phytoalexin, reactive oxygen species and osmolites. The hyphae of the mutants grew slowly but did not cause disease symptoms on the surface of host plants. Transcripts of the AbPf2 gene increased exponentially soon after wild-type conidia contacted their host plants . A small amount of AbPf2 protein, as monitored using GFP fusions, was present in young, mature conidia. The protein level decreased during saprophytic growth, but increased and was located primarily in fungal nuclei during pathogenesis. Levels of the proteins and transcripts sharply decreased following colonization of host tissues beyond the initial infection site. When expression of the transcription factor was induced in the wild-type during early pathogenesis, 106 fungal genes were also induced in the wild-type but not in the abpf2 mutants. Notably, 33 of the 106 genes encoded secreted proteins, including eight putative effector proteins. Plants inoculated with abpf2 mutants expressed higher levels of genes associated with photosynthesis, the pentose phosphate pathway and primary metabolism, but lower levels of defense-related genes. Our results suggest that AbPf2 is an important regulator of pathogenesis, but does not affect other cellular processes in A. brassicicola.

Morphological, cultural, pathogenic and molecular variability ...

African Journals Online (AJOL)

Alternaria blight (Alternaria brassicae) causes severe foliar damage to Indian mustard in Uttarakhand. Ten (10) isolates of A. brassicae were collected from different hosts and characterized for cultural, morphological, pathogenic and molecular variations. A. brassicae colonies varied in their cultural behaviour ranging from ...

Characterization of small-spored Alternaria from Argentinean crops through a polyphasic approach

DEFF Research Database (Denmark)

da Cruz Cabral, Lucía; Rodriguero, Marcela; Stenglein, Sebastián

2017-01-01

exporter of agricultural products, so it is essential to thoroughly understand the physiological behaviour of this pathogen in a food safety context. Thus, the objective of this work was to characterize small-spored Alternaria spp. obtained from tomato fruits, pepper fruits, wheat grains and blueberries...

Phyllosticta citriasiana sp. nov., the cause of Citrus tan spot of Citrus maxima in Asia

NARCIS (Netherlands)

Wulandari, N.F.; To-anun, C.; Hyde, K.D.; Duong, L.M.; Gruyter, de J.; Meffert, J.P.; Groenewald, J.Z.; Crous, P.W.

2009-01-01

Guignardia citricarpa, the causal agent of Citrus Black Spot, is subject to phytosanitary legislation in the European Union and the U.S.A. This species is frequently confused with G. mangiferae, which is a non-pathogenic, and is commonly isolated as an endophyte from citrus fruits and a wide range

Phyllosticta citriasiana sp nov., the cause of Citrus tan spot of Citrus maxima in Asia

NARCIS (Netherlands)

Wulandari, N.F.; To-anun, C.; Hyde, K.D.; Duong, L.M.; de Gruyter, J.; Meffert, J.P.; Groenewald, J.Z.; Crous, P.W.

2009-01-01

Guignardia citricarpa, the causal agent of Citrus Black Spot, is subject to phytosanitary legislation in the European Union and the U.S.A. This species is frequently confused with G. mangiferae, which is a non-pathogenic, and is commonly isolated as an endophyte from citrus fruits and a wide range

Cultural, morphological, pathogenic and molecular characterization ...

African Journals Online (AJOL)

Alternaria blotch (Alternaria mali) causes severe foliar damage to apple trees in Kashmir. Twenty one (21) isolates of A. mali were collected from different locations and characterized for cultural, morphological, pathogenic and molecular variations. A. mali colonies varied in their cultural behaviour ranging from velvety to ...

Multilocus phylogeny and MALDI-TOF analysis of the plant pathogenic species Alternaria dauci and relatives

DEFF Research Database (Denmark)

Brun, Sophie; Madrid, Hugo; Gerrits Van Den Ende, Bert

2013-01-01

The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species-complexes of morp......The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species...... trees based on ITS sequences did not differentiate strains of A. solani, A. tomatophila, and A. porri, but these three species formed a clade separate from strains of A. dauci. The resolution improved in trees based on gpd and Alt a 1, which distinguished strains of the four species as separate clades...... of A. solani, and the third included all strains of A. tomatophila, as well as all but one strain of A. solani, and one strain of A. porri. Thus, this study shows the usefulness of MALDI-TOF mass spectrometry as a promising tool for identification of these four species of Alternaria which are closely...

Genome Sequence of the Necrotrophic Plant Pathogen Alternaria brassicicola Abra43

Science.gov (United States)

Belmas, Elodie; Briand, Martial; Kwasiborski, Anthony; Colou, Justine; N’Guyen, Guillaume; Iacomi, Béatrice; Grappin, Philippe; Campion, Claire; Simoneau, Philippe; Barret, Matthieu

2018-01-01

ABSTRACT Alternaria brassicicola causes dark spot (or black spot) disease, which is one of the most common and destructive fungal diseases of Brassicaceae spp. worldwide. Here, we report the draft genome sequence of strain Abra43. The assembly comprises 29 scaffolds, with an N50 value of 2.1 Mb. The assembled genome was 31,036,461 bp in length, with a G+C content of 50.85%. PMID:29439047

Citrus Functional Genomics and Molecular Modeling in Relation to Citrus sinensis (Sweet Orange) Infection with Xylella fastidiosa (Citrus Variegated Chlorosis).

Science.gov (United States)

Dwivedi, Upendra N; Tiwari, Sameeksha; Prasanna, Pragya; Awasthi, Manika; Singh, Swati; Pandey, Veda P

2016-08-01

Citrus are among the economically most important fruit tree crops in the world. Citrus variegated chlorosis (CVC), caused by Xylella fastidiosa infection, is a serious disease limiting citrus production at a global scale. With availability of citrus genomic resources, it is now possible to compare citrus expressed sequence tag (EST) data sets and identify single-nucleotide polymorphisms (SNPs) within and among different citrus cultivars that can be exploited for citrus resistance to infections, citrus breeding, among others. We report here, for the first time, SNPs in the EST data sets of X. fastidiosa-infected Citrus sinensis (sweet orange) and their functional annotation that revealed the involvement of eight C. sinensis candidate genes in CVC pathogenesis. Among these genes were xyloglucan endotransglycosylase, myo-inositol-1-phosphate synthase, and peroxidase were found to be involved in plant cell wall metabolism. These have been further investigated by molecular modeling for their role in CVC infection and defense. Molecular docking analyses of the wild and the mutant (SNP containing) types of the selected three enzymes with their respective substrates revealed a significant decrease in the binding affinity of substrates for the mutant enzymes, thus suggesting a decrease in the catalytic efficiency of these enzymes during infection, thereby facilitating a favorable condition for infection by the pathogen. These findings offer novel agrigenomics insights in developing future molecular targets and strategies for citrus fruit cultivation in ways that are resistant to X. fastidiosa infection, and by extension, with greater harvesting efficiency and economic value.

Metabolic interplay between the Asian citrus psyllid and its Profftella symbiont: An Achilles’ heel of the citrus greening insect vector

Science.gov (United States)

‘Candidatus Liberibacter asiaticus’ (CLas), the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including ‘Candidatus Profftella armatura’, are likely to impact tra...

Fungi of genus Alternaria occurring on tomato

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Joanna Marcinkowska

2013-12-01

Full Text Available Tomato early blight in central Poland was caused by Alternaria solani (A. porri f. sp., solani and A. alernata (A. tenuis. A. alternata was isolated more often than A. solani. All isolates of A. solani in controlled conditions killed tomato seedlings, while pathogenic isolates of A. alternata caused only slight seedling blight. In greenhouse tests A. solani proved to be strongly pathogenic for leaves and stems of tomato but A. alternata was weakly pathogenic. The latter species attacked only injured fruits while, A. solanicould penetrate through undamaged peel of fruits. Both of these species caused the same type of symptoms; the differences consisted only in intensification of disease symptoms. During 1974 and 1975 field tomatoes were moderately attacked by early blight. Thebest development of this disease occurred by the turn of August and September. Determinate variety 'New Yorker' was distinguished by more severe infection of stem parts of tomato whereas the fruits of a stock variety 'Apollo' were more strongly attacked.

Annotation of the Asian citrus psyllid genome reveals a reduced innate immune system

Science.gov (United States)

Citrus production worldwide is currently facing significant losses due to citrus greening disease, also known as huanglongbing. The citrus greening bacteria, Candidatus Liberibacter asiaticus (CLas), is a persistent propagative pathogen transmitted by the Asian citrus psyllid, Diaphorina citri Kuway...

A phagostimulant blend for the Asian citrus psyllid

Science.gov (United States)

Chemical cues that condition orientation by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), are of great interest because it is the primary vector of the causal pathogen of citrus greening disease. Previous work in our lab identified a blend of formic and acetic acids as s...

Ectopic Expression of Xylella fastidiosa rpfF Conferring Production of Diffusible Signal Factor in Transgenic Tobacco and Citrus Alters Pathogen Behavior and Reduces Disease Severity.

Science.gov (United States)

Caserta, R; Souza-Neto, R R; Takita, M A; Lindow, S E; De Souza, A A

2017-11-01

The pathogenicity of Xylella fastidiosa is associated with its ability to colonize the xylem of host plants. Expression of genes contributing to xylem colonization are suppressed, while those necessary for insect vector acquisition are increased with increasing concentrations of diffusible signal factor (DSF), whose production is dependent on RpfF. We previously demonstrated that transgenic citrus plants ectopically expressing rpfF from a citrus strain of X. fastidiosa subsp. pauca exhibited less susceptibility to Xanthomonas citri subsp. citri, another pathogen whose virulence is modulated by DSF accumulation. Here, we demonstrate that ectopic expression of rpfF in both transgenic tobacco and sweet orange also confers a reduction in disease severity incited by X. fastidiosa and reduces its colonization of those plants. Decreased disease severity in the transgenic plants was generally associated with increased expression of genes conferring adhesiveness to the pathogen and decreased expression of genes necessary for active motility, accounting for the reduced population sizes achieved in the plants, apparently by limiting pathogen dispersal through the plant. Plant-derived DSF signal molecules in a host plant can, therefore, be exploited to interfere with more than one pathogen whose virulence is controlled by DSF signaling.

Multilocus phylogeny and MALDI-TOF analysis of the plant-pathogenic species Alternaria dauci and relatives

NARCIS (Netherlands)

Brun, S.; Madrid, H.; Gerrits van den Ende, A.H.G.; Andersen, B.; Marinach-Patrice, C.; Mazier, D.; de Hoog, G.S.

2013-01-01

The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species-complexes of

Multilocus phylogeny and MALDI-TOF analysis of the plant pathogenic species Alternaria dauci and relatives

NARCIS (Netherlands)

Brun, S.; Madrid, H.; Gerritis van den Ende, B.; Andersen, B.; Marinach-Patrice, C.; Mazier, D.; de Hoog, G.S.

2013-01-01

The genus Alternaria includes numerous phytopathogenic species, many of which are economically relevant. Traditionally, identification has been based on morphology, but is often hampered by the tendency of some strains to become sterile in culture and by the existence of species-complexes of

Identification, characterization and mycotoxigenic ability of Alternaria spp. causing core rot of apple fruit in Greece.

Science.gov (United States)

Ntasiou, Panagiota; Myresiotis, Charalampos; Konstantinou, Sotiris; Papadopoulou-Mourkidou, Euphemia; Karaoglanidis, George S

2015-03-16

Alternaria core rot is a major postharvest disease of apple fruit in several countries of the world, including Greece. The study was conducted aiming to identify the disease causal agents at species level, investigate the aggressiveness of Alternaria spp. isolates and the susceptibility of different apple varieties and determine the mycotoxigenic potential of Alternaria spp. isolates from apple fruit. Seventy-five Alternaria spp. isolates obtained from apple fruit showing core rot symptoms were identified as either Alternaria tenuissima or Alternaria arborescens at frequencies of 89.3 and 11.7%, respectively, based on the sequence of endopolygalacturonase (EndoPG) gene. Artificial inoculations of fruit of 4 different varieties (Fuji, Golden Delicious, Granny Smith and Red Delicious) and incubation at two different temperatures (2 and 25°C) showed that fruit of Fuji variety were the most susceptible and fruit of Golden Delicious the most resistant to both pathogens. In addition, the production of 3 mycotoxins, alternariol (AOH), alternariol monomethyl ether (AME) and tentoxin (TEN) was investigated in 30 isolates of both species. Mycotoxin determination was conducted both in vitro, on artificial nutrient medium and in vivo on artificially inoculated apple fruit, using a high performance liquid chromatography with diode array detector (HPLC-DAD). The results showed that most of the isolates of both species were able to produce all the 3 metabolites both in vivo and in vitro. On apple fruit A. tenuissima isolates produced more AOH than A. arborescens isolates, whereas the latter produced more TEN than the former. Such results indicate that Alternaria core rot represents a major threat of apple fruit production not only due to quantitative yield losses but also for qualitative deterioration of apple by-products. Copyright © 2014 Elsevier B.V. All rights reserved.

Bostrycin and 4-deoxybostrycin: two nonspecific phytotoxins produced by Alternaria eichhorniae.

OpenAIRE

Charudattan, R; Rao, K V

1982-01-01

Two crystalline red pigments with phytotoxic activity were isolated from culture filtrates of Alternaria eichhorniae, a pathogen of the water hyacinth Eichhornia crassipes. The pigments were present in the ratio of 4:1 and were identified as bostrycin and 4-deoxybostrycin, respectively. This is the first isolation of 4-deoxybostrycin from a natural source. Bostrycin, 4-deoxybostrycin, and their isopropylidene derivatives induced necrosis on tested plant leaves comparable to the A. eichhorniae...

Improved annotation of the insect vector of citrus greening disease: Biocuration by a diverse genomics community

Science.gov (United States)

The Asian citrus psyllid (Diaphorina citri Kuwayama) is the insect vector of the bacterium Candidatus Liberibacter asiaticus (CLas), the pathogen associated with citrus Huanglongbing (HLB, citrus greening). HLB threatens citrus production worldwide. Suppression or reduction of the insect vector usin...

Protein interaction networks at the host-microbe interface in Diaphorina citri, the insect vector of the citrus greening pathogen.

Science.gov (United States)

Ramsey, J S; Chavez, J D; Johnson, R; Hosseinzadeh, S; Mahoney, J E; Mohr, J P; Robison, F; Zhong, X; Hall, D G; MacCoss, M; Bruce, J; Cilia, M

2017-02-01

The Asian citrus psyllid ( Diaphorina citri) is the insect vector responsible for the worldwide spread of ' Candidatus Liberibacter asiaticus' (CLas), the bacterial pathogen associated with citrus greening disease. Developmental changes in the insect vector impact pathogen transmission, such that D. citri transmission of CLas is more efficient when bacteria are acquired by nymphs when compared with adults. We hypothesize that expression changes in the D. citri immune system and commensal microbiota occur during development and regulate vector competency. In support of this hypothesis, more proteins, with greater fold changes, were differentially expressed in response to CLas in adults when compared with nymphs, including insect proteins involved in bacterial adhesion and immunity. Compared with nymphs, adult insects had a higher titre of CLas and the bacterial endosymbionts Wolbachia, Profftella and Carsonella. All Wolbachia and Profftella proteins differentially expressed between nymphs and adults are upregulated in adults, while most differentially expressed Carsonella proteins are upregulated in nymphs. Discovery of protein interaction networks has broad applicability to the study of host-microbe relationships. Using protein interaction reporter technology, a D. citri haemocyanin protein highly upregulated in response to CLas was found to physically interact with the CLas coenzyme A (CoA) biosynthesis enzyme phosphopantothenoylcysteine synthetase/decarboxylase. CLas pantothenate kinase, which catalyses the rate-limiting step of CoA biosynthesis, was found to interact with a D. citri myosin protein. Two Carsonella enzymes involved in histidine and tryptophan biosynthesis were found to physically interact with D. citri proteins. These co-evolved protein interaction networks at the host-microbe interface are highly specific targets for controlling the insect vector responsible for the spread of citrus greening.

Prophage-mediated dynamics of 'Candidatus Liberibacter asiaticus' populations, the destructive bacterial pathogens of citrus huanglongbing.

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Lijuan Zhou

Full Text Available Prophages are highly dynamic components in the bacterial genome and play an important role in intraspecies variations. There are at least two prophages in the chromosomes of Candidatus Liberibacter asiaticus' (Las Floridian isolates. Las is both unculturable and the most prevalent species of Liberibacter pathogens that cause huanglongbing (HLB, a worldwide destructive disease of citrus. In this study, seven new prophage variants resulting from two hyper-variable regions were identified by screening clone libraries of infected citrus, periwinkle and psyllids. Among them, Types A and B share highly conserved sequences and localize within the two prophages, FP1 and FP2, respectively. Although Types B and C were abundant in all three libraries, Type A was much more abundant in the libraries from the Las-infected psyllids than from the Las-infected plants, and Type D was only identified in libraries from the infected host plants but not from the infected psyllids. Sequence analysis of these variants revealed that the variations may result from recombination and rearrangement events. Conventional PCR results using type-specific molecular markers indicated that A, B, C and D are the four most abundant types in Las-infected citrus and periwinkle. However, only three types, A, B and C are abundant in Las-infected psyllids. Typing results for Las-infected citrus field samples indicated that mixed populations of Las bacteria present in Floridian isolates, but only the Type D population was correlated with the blotchy mottle symptom. Extended cloning and sequencing of the Type D region revealed a third prophage/phage in the Las genome, which may derive from the recombination of FP1 and FP2. Dramatic variations in these prophage regions were also found among the global Las isolates. These results are the first to demonstrate the prophage/phage-mediated dynamics of Las populations in plant and insect hosts, and their correlation with insect transmission and

Prophage-mediated dynamics of 'Candidatus Liberibacter asiaticus' populations, the destructive bacterial pathogens of citrus huanglongbing.

Science.gov (United States)

Zhou, Lijuan; Powell, Charles A; Li, Wenbin; Irey, Mike; Duan, Yongping

2013-01-01

Prophages are highly dynamic components in the bacterial genome and play an important role in intraspecies variations. There are at least two prophages in the chromosomes of Candidatus Liberibacter asiaticus' (Las) Floridian isolates. Las is both unculturable and the most prevalent species of Liberibacter pathogens that cause huanglongbing (HLB), a worldwide destructive disease of citrus. In this study, seven new prophage variants resulting from two hyper-variable regions were identified by screening clone libraries of infected citrus, periwinkle and psyllids. Among them, Types A and B share highly conserved sequences and localize within the two prophages, FP1 and FP2, respectively. Although Types B and C were abundant in all three libraries, Type A was much more abundant in the libraries from the Las-infected psyllids than from the Las-infected plants, and Type D was only identified in libraries from the infected host plants but not from the infected psyllids. Sequence analysis of these variants revealed that the variations may result from recombination and rearrangement events. Conventional PCR results using type-specific molecular markers indicated that A, B, C and D are the four most abundant types in Las-infected citrus and periwinkle. However, only three types, A, B and C are abundant in Las-infected psyllids. Typing results for Las-infected citrus field samples indicated that mixed populations of Las bacteria present in Floridian isolates, but only the Type D population was correlated with the blotchy mottle symptom. Extended cloning and sequencing of the Type D region revealed a third prophage/phage in the Las genome, which may derive from the recombination of FP1 and FP2. Dramatic variations in these prophage regions were also found among the global Las isolates. These results are the first to demonstrate the prophage/phage-mediated dynamics of Las populations in plant and insect hosts, and their correlation with insect transmission and disease development.

Resistance evaluation of Pera (Citrus sinensis) genotypes to citrus canker in greenhouse conditions

Science.gov (United States)

Citrus canker, caused by the bacterium Xanthomonas citri subsp. citri results in serious yield losses and phytoregulation penalties. The use of resistant genotypes is recognized as an important tool to facilitate control of the pathogen. Studies have show that artificial inoculation results in typic...

Metabolic Interplay between the Asian Citrus Psyllid and Its Profftella Symbiont: An Achilles' Heel of the Citrus Greening Insect Vector.

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John S Ramsey

Full Text Available 'Candidatus Liberibacter asiaticus' (CLas, the bacterial pathogen associated with citrus greening disease, is transmitted by Diaphorina citri, the Asian citrus psyllid. Interactions among D. citri and its microbial endosymbionts, including 'Candidatus Profftella armatura', are likely to impact transmission of CLas. We used quantitative mass spectrometry to compare the proteomes of CLas(+ and CLas(- populations of D. citri, and found that proteins involved in polyketide biosynthesis by the endosymbiont Profftella were up-regulated in CLas(+ insects. Mass spectrometry analysis of the Profftella polyketide diaphorin in D. citri metabolite extracts revealed the presence of a novel diaphorin-related polyketide and the ratio of these two polyketides was changed in CLas(+ insects. Insect proteins differentially expressed between CLas(+ and CLas(- D. citri included defense and immunity proteins, proteins involved in energy storage and utilization, and proteins involved in endocytosis, cellular adhesion, and cytoskeletal remodeling which are associated with microbial invasion of host cells. Insight into the metabolic interdependence between the insect vector, its endosymbionts, and the citrus greening pathogen reveals novel opportunities for control of this disease, which is currently having a devastating impact on citrus production worldwide.

Phytophthora parasitica transcriptome, a new concept in the understanding of the citrus gummosis

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Daniel D. Rosa

2007-01-01

Full Text Available Due to the economic importance of gummosis disease for the citriculture, studies on P. parasitica-Citrus interaction comprise a significant part in the Brazilian Citrus genome data bank (CitEST. Among them, two cDNA libraries constructed from two different growth conditions of the P. parasitica pathogen are included which has generated the PP/CitEST database (CitEST - Center APTA Citros Sylvio Moreira/IAC- Millennium Institute. Through this genomic approach and clustering analyses the following has been observed: out of a total of 13,285 available in the Phytophthora parasitica database, a group of 4,567 clusters was formed, comprising 2,649 singlets and 1,918 contigs. Out of a total of 4,567 possible genes, only 2,651 clusters were categorized; among them, only 4.3% shared sequence similarities with pathogenicity factors and defense. Some of these possible genes (103 corresponding to 421 ESTs, were characterized by phylogenetic analysis and discussed. A comparison made with the COGEME database has shown homology which may be part of an evolutionary pathogenicity pathway present in Phytophthora and also in other fungi. Many of the genes which were identified here, which may encode proteins associated to mechanisms of citrus gummosis pathogenicity, represent only one facet of the pathogen-host Phytophthora - Citrus interaction.

Signaling pathways in a Citrus EST database

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Angela Mehta

2007-01-01

Full Text Available Citrus spp. are economically important crops, which in Brazil are grown mainly in the State of São Paulo. Citrus cultures are attacked by several pathogens, causing severe yield losses. In order to better understand this culture, the Millenium Project (IAC Cordeirópolis was launched in order to sequence Citrus ESTs (expressed sequence tags from different tissues, including leaf, bark, fruit, root and flower. Plants were submitted to biotic and abiotic stresses and investigated under different development stages (adult vs. juvenile. Several cDNA libraries were constructed and the sequences obtained formed the Citrus ESTs database with almost 200,000 sequences. Searches were performed in the Citrus database to investigate the presence of different signaling pathway components. Several of the genes involved in the signaling of sugar, calcium, cytokinin, plant hormones, inositol phosphate, MAPKinase and COP9 were found in the citrus genome and are discussed in this paper. The results obtained may indicate that similar mechanisms described in other plants, such as Arabidopsis, occur in citrus. Further experimental studies must be conducted in order to understand the different signaling pathways present.

Phylogeny of Alternaria fungi known to produce host-specific toxins on the basis of variation in internal transcribed spacers of ribosomal DNA.

Science.gov (United States)

Kusaba, M; Tsuge, T

1995-10-01

The internal transcribed spacer regions (ITS1 and ITS2) of ribosomal DNA from Alternaria species, including seven fungi known to produce host-specific toxins, were analyzed by polymerase chain reaction-amplification and direct sequencing. Phylogenetic analysis of the sequence data by the Neighbor-joining method showed that the seven toxin-producing fungi belong to a monophyletic group together with A. alternata. In contract, A. dianthi, A. panax, A. dauci, A. bataticola, A. porri, A. sesami and A. solani, species that can be morphologically distinguished from A. alternata, could be clearly separated from A. alternata by phylogenetic of the ITS variation. These results suggest that Alternaria pathogens which produce host-specific toxins are pathogenic variants within a single variable species, A. alternata.

Ex Vivo Application of Secreted Metabolites Produced by Soil-Inhabiting Bacillus spp. Efficiently Controls Foliar Diseases Caused by Alternaria spp.

Science.gov (United States)

Ali, Gul Shad; El-Sayed, Ashraf S A; Patel, Jaimin S; Green, Kari B; Ali, Mohammad; Brennan, Mary; Norman, David

2016-01-15

Bacterial biological control agents (BCAs) are largely used as live products to control plant pathogens. However, due to variable environmental and ecological factors, live BCAs usually fail to produce desirable results against foliar pathogens. In this study, we investigated the potential of cell-free culture filtrates of 12 different bacterial BCAs isolated from flower beds for controlling foliar diseases caused by Alternaria spp. In vitro studies showed that culture filtrates from two isolates belonging to Bacillus subtilis and Bacillus amyloliquefaciens displayed strong efficacy and potencies against Alternaria spp. The antimicrobial activity of the culture filtrate of these two biological control agents was effective over a wider range of pH (3.0 to 9.0) and was not affected by autoclaving or proteolysis. Comparative liquid chromatography-mass spectrometry (LC-MS) analyses showed that a complex mixture of cyclic lipopeptides, primarily of the fengycin A and fengycin B families, was significantly higher in these two BCAs than inactive Bacillus spp. Interaction studies with mixtures of culture filtrates of these two species revealed additive activity, suggesting that they produce similar products, which was confirmed by LC-tandem MS analyses. In in planta pre- and postinoculation trials, foliar application of culture filtrates of B. subtilis reduced lesion sizes and lesion frequencies caused by Alternaria alternata by 68 to 81%. Taken together, our studies suggest that instead of live bacteria, culture filtrates of B. subtilis and B. amyloliquefaciens can be applied either individually or in combination for controlling foliar diseases caused by Alternaria species. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Swainsonine biosynthesis genes in diverse symbiotic and pathogenic fungi

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Swainsonine, a cytotoxic fungal alkaloid and a potential cancer therapy drug, is produced by the insect pathogen and plant symbiont, Metarhizium robertsii, the clover pathogen Slafractonia leguminicola, locoweed symbionts belonging to Alternaria sect. Undifilum, and a recently discovered morning glo...

Antifungal activity of aloe vera gel against plant pathogenic fungi

International Nuclear Information System (INIS)

Sitara, U.; Hassan, N.; Naseem, J.

2011-01-01

Aloe vera gel extracted from the Aloe vera leaves was evaluated for their antifungal activity at the rate of 0.15%, 0.25% and 0.35% concentration against five plants pathogenic fungi viz., Aspergillus niger, Aspergillus flavus, Alternaria alternata, Drechslera hawaiensis and Penicillum digitatum 0.35% concentration Aloe vera gel completely inhibited the growth of Drechslera hawaiensis and Alternaria alternata. (author)

Pathogenic mycoflora on carrot seeds

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Bogdan Nowicki

2013-12-01

Full Text Available Altogether 300 seed samples were collected during 9 years in 8 regions of Poland and the fungi Were isolated and their pathogenicity to carrot seedlings was examined. Alternaria rudicina provcd to be the most important pathogen although. A. alternata was more common. The other important pathogens were Fusarium spp., Phoma spp. and Botrytis cinerea. The infection of carrot seeds by A. radicina should be used as an important criterium in seed quality evaluation.

Some new and noteworthy diseases of poplars in India. [Botryodiplodia sett-rot; Alternaria tip blight; Cladosporium leaf spot; Fusarium pink incrustation

Energy Technology Data Exchange (ETDEWEB)

Singh, S.

1983-09-01

Four new diseases of poplars namely Botryodiplodia sett-rott, Alternaria tip blight, Cladosporium leaf spot and Fusarium pink incrustation are described in this paper. Botryodiplodia palmarum causes sett-rott of poplars both at pre-sprouting and post-sprouting stage. The pathogen also causes mortality of poplar plants in the field within 4-6 weeks after planting. Alternaria stage of Pleuspora infectoria has been found as the cause of blackening and dying of growing tips and young leaves of a Populus sp. and P. deltoides in nurseries. Cladosporium humile has been recorded as the cause of brown spot followed by crumpling and premature shedding of leaves in P. ciliata, P. nigra and P. alba. The cause of Fusarium incrustation disease on P. cilata has been identified as Fusarium sp. of Gibbosum group. Pathogenicity of Botryodiplodia palmarum and Alternaria stage of Pleospora infectoria was confirmed by artificial inoculations. Brief descriptions of Alternaria, Cladosporium and Fusarium are also given. The paper also gives a short account of some noteworthy diseases recorded on poplars namely Ganoderma root rot, foliage ruts and stem cankers. Ganoderma root-rot is found to reach alarming proportions in closely spaced poplar plantations. Melampsora ciliata, an indigenous rust, is found to attack mainly clones of P. deltoides, P. yunnanensis, P. trichocarpa, P. alba and some cultivars of P. x euramericana in nurseries. A brief account of three types of stem cankers i.e. cankers due to pink disease fungus, Corticium salmonicolor, sun-scaled cankers and cankers associated with slime flux on various clones of P. deltoides is also given.

Insecticidal suppression of Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae vector of huanglongbing pathogens.

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Jawwad A Qureshi

Full Text Available Diaphorina citri vectors pathogens that cause 'huanglongbing' or citrus greening disease which poses a serious threat to citrus production worldwide. Vector suppression is critical to reduce disease spread. Efficacy is a main concern when choosing an insecticide. Insecticidal treatments of 49 products or 44 active ingredients (a.i labeled or experimental were field tested between 2005-2013 as foliar sprays (250 treatments, 39 a.i or soil applications (47 treatments, 9 a.i to control D. citri in citrus. A combined effect of nymphal and adult suppression in response to sprays of 23 insecticides representing 9 modes of action (MoA groups and 3 unknown MoA provided more than 90% reduction of adult D. citri over 24-68 days. Observable effects on nymphs were generally of shorter duration due to rapid maturation of flush. However, reduction of 76-100% nymphs or adults over 99-296 days was seen on young trees receiving drenches of the neonicotinoids imidacloprid, thiamethoxam or clothianidin (MoA 4A and a novel anthranilic diamide, cyantraniliprole (MoA 28. Effective products identified for foliar sprays to control D. citri provide sufficient MoA groups for rotation to delay evolution of insecticide resistance by D. citri and other pests. However, cyantraniliprole is now the only available alternative for rotation with neonicotinoids in soil application to young trees. Sprays of up to eight of the most effective insecticides could be rotated over a year without repetition of any MoA and little or no recourse to neonicotinoids or cyantraniliprole, so important for protection of young trees. Other considerations effecting decisions of what and when to spray include prevalence of huanglongbing, pest pressure, pre-harvest intervals, overall budget, equipment availability, and conservation of beneficial arthropods. Examples of spray programs utilizing broad-spectrum and relatively selective insecticides are provided to improve vector management and may vary

Insecticidal suppression of Asian citrus psyllid Diaphorina citri (Hemiptera: Liviidae) vector of huanglongbing pathogens.

Science.gov (United States)

Qureshi, Jawwad A; Kostyk, Barry C; Stansly, Philip A

2014-01-01

Diaphorina citri vectors pathogens that cause 'huanglongbing' or citrus greening disease which poses a serious threat to citrus production worldwide. Vector suppression is critical to reduce disease spread. Efficacy is a main concern when choosing an insecticide. Insecticidal treatments of 49 products or 44 active ingredients (a.i) labeled or experimental were field tested between 2005-2013 as foliar sprays (250 treatments, 39 a.i) or soil applications (47 treatments, 9 a.i) to control D. citri in citrus. A combined effect of nymphal and adult suppression in response to sprays of 23 insecticides representing 9 modes of action (MoA) groups and 3 unknown MoA provided more than 90% reduction of adult D. citri over 24-68 days. Observable effects on nymphs were generally of shorter duration due to rapid maturation of flush. However, reduction of 76-100% nymphs or adults over 99-296 days was seen on young trees receiving drenches of the neonicotinoids imidacloprid, thiamethoxam or clothianidin (MoA 4A) and a novel anthranilic diamide, cyantraniliprole (MoA 28). Effective products identified for foliar sprays to control D. citri provide sufficient MoA groups for rotation to delay evolution of insecticide resistance by D. citri and other pests. However, cyantraniliprole is now the only available alternative for rotation with neonicotinoids in soil application to young trees. Sprays of up to eight of the most effective insecticides could be rotated over a year without repetition of any MoA and little or no recourse to neonicotinoids or cyantraniliprole, so important for protection of young trees. Other considerations effecting decisions of what and when to spray include prevalence of huanglongbing, pest pressure, pre-harvest intervals, overall budget, equipment availability, and conservation of beneficial arthropods. Examples of spray programs utilizing broad-spectrum and relatively selective insecticides are provided to improve vector management and may vary depending on

The quest for a non-vector psyllid: Natural variation in acquisition and transmission of the huanglongbing pathogen 'Candidatus Liberibacter asiaticus' by Asian citrus psyllid isofemale lines

Science.gov (United States)

Genetic variability in insect vectors is valuable to study vector competence determinants and to select non-vector populations that may help reduce the spread of vector-borne pathogens. We collected and tested vector competency of 15 isofemale lines of Asian citrus psyllid (ACP) Diaphorina citri, v...

Quantitative distribution of 'Candidatus Liberibacter asiaticus' in citrus plants with citrus huanglongbing.

Science.gov (United States)

Li, Wenbin; Levy, Laurene; Hartung, John S

2009-02-01

Citrus huanglongbing (HLB), or greening disease, is strongly associated with any of three nonculturable gram-negative bacteria belonging to 'Candidatus Liberibacter spp.' 'Ca. Liberibacter spp.' are transmitted by citrus psyllids to all commercial cultivars of citrus. The diseases can be lethal to citrus and have recently become widespread in both São Paulo, Brazil, and Florida, United States, the locations of the largest citrus industries in the world. Asiatic HLB, the form of the disease found in Florida, is associated with 'Ca. Liberibacter asiaticus' and is the subject of this report. The nonculturable nature of the pathogen has hampered research and little is known about the distribution of 'Ca. L. asiaticus' in infected trees. In this study, we have used a quantitative polymerase chain reaction assay to systematically quantify the distribution of 'Ca. L. asiaticus' genomes in tissues of six species of citrus either identified in the field during survey efforts in Florida or propagated in a greenhouse in Beltsville, MD. The populations of 'Ca. L. asiaticus' inferred from the distribution of 16S rDNA sequences specific for 'Ca. L. asiaticus' in leaf midribs, leaf blades, and bark samples varied by a factor of 1,000 among samples prepared from the six citrus species tested and by a factor of 100 between two sweet orange trees tested. In naturally infected trees, above-ground portions of the tree averaged 10(10) 'Ca. L. asiaticus' genomes per gram of tissue. Similar levels of 'Ca. L. asiaticus' genomes were observed in some but not all root samples from the same plants. In samples taken from greenhouse-inoculated trees, levels of 'Ca. L. asiaticus' genomes varied systematically from 10(4) genomes/g at the graft inoculation site to 10(10) genomes/g in some leaf petioles. Root samples from these trees also contained 'Ca. L. asiaticus' at 10(7) genomes/g. In symptomatic fruit tissues, 'Ca. L. asiaticus' genomes were also readily detected and quantified. The highest

Inhibitory effects of crude extracts from several plants on postharvest pathogens of citrus

Science.gov (United States)

Gong, Mingfu; Guan, Qinlan; Xu, Shanshan

2018-04-01

China is one of the most important origin of citrus. Enormous economic losses was caused by fungal diseases in citrus harvest storage every year. The effective antimicrobial substances of garlic, ginger, celery and pepper were extracted by ethanol extraction and water extraction respectively. The inhibitory effects of the crude extract on Penicillium sp. caused fungal diseases in citrus harvest storage were also determined. The results showed that the extracts of garlic, ginger and celery had inhibitory effect on P. sp., but the extracts of pepper had no inhibitory effect on P. sp.. The garlic ethanol extracts had the best inhibitory effect on P. citrinum.

Characterization of Pseudomonas syringae pv. syringae, Causal Agent of Citrus Blast of Mandarin in Montenegro

OpenAIRE

Ivanovi?, ?arko; Perovi?, Tatjana; Popovi?, Tatjana; Blagojevi?, Jovana; Trkulja, Nenad; Hrn?i?, Snje?ana

2017-01-01

Citrus blast caused by bacterium Pseudomonas syringae is a very important disease of citrus occuring in many areas of the world, but with few data about genetic structure of the pathogen involved. Considering the above fact, this study reports genetic characterization of 43 P. syringae isolates obtained from plant tissue displaying citrus blast symptoms on mandarin (Citrus reticulata) in Montenegro, using multilocus sequence analysis of gyrB, rpoD, and gap1 gene sequences. Gene sequences from...

Delivery of gene biotechnologies to plants: Pathogen and pest control

Science.gov (United States)

Treatment of oligonucleotides to plants for host delivered suppression of microbes and insect pests of citrus was successful. FANA_ASO, (2'-deoxy-2'-fluoro-D- arabinonucleic acid)_( antisense oligonucleotides- AUM LifeTech) designed to: Asian citrus psyllid; Citrus plant bacterial pathogen of citru...

Ecobiophysical Aspects on Nanosilver Biogenerated from Citrus reticulata Peels, as Potential Biopesticide for Controlling Pathogens and Wetland Plants in Aquatic Media

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Marcela Elisabeta Barbinta-Patrascu

2017-01-01

Full Text Available In recent years, a considerable interest was paid to ecological strategies in management of plant diseases and plant growth. Metallic nanoparticles (MNPs gained considerable interest as alternative to pesticides due to their interesting properties. Green synthesis of MNPs using plant extracts is very advantageous taking into account the fact that plants are easily available and eco-friendly and possess many phytocompounds that help in bioreduction of metal ions. In this research work, we phytosynthesized AgNPs from aqueous extract of Citrus reticulata peels, with high antioxidant, antibacterial, and antifungal potential. These “green” AgNPs were characterized by modern biophysical methods (absorption and FTIR spectroscopy, AFM, and zeta potential measurements. The nanobioimpact of Citrus-based AgNPs on four invasive wetland plants, Cattail (Typha latifolia, Flowering-rush (Butomus umbellatus, Duckweed (Lemna minor, and Water-pepper (Polygonum hydropiper, was studied by absorption spectroscopy, by monitoring the spectral signature of chlorophyll. The invasive plants exhibited different behavior under AgNP stress. Deep insights were obtained from experiments conducted on biomimetic membranes marked with chlorophyll a. Our results pointed out the potential use of Citrus-based AgNPs as alternative in controlling pathogens in aqueous media and in management of aquatic weeds growth.

Maculosin, a host-specific phytotoxin for spotted knapweed from Alternaria alternata

Science.gov (United States)

Stierle, Andrea C.; Cardellina, John H.; Strobel, Gary A.

1988-01-01

Several diketopiperazines have been isolated from liquid cultures of Alternaria alternata, the causal agent of black leaf blight of spotted knapweed, Centaurea maculosa Lam. One of these compounds, maculosin [the diketopiperazine cyclo(-L-Pro-L-Tyr-)], was active in the nicked-leaf bioassay at 10-5 M; synthetic maculosin possessed chemical and biological activities identical to those of the natural product. Other diketopiperazines isolated from the fungus possessed either less activity or none at all. In tests against 19 plant species, maculosin was phytotoxic only to spotted knapweed. Thus maculosin is a host-specific phytotoxin from a weed pathogen. PMID:16593989

Development of loop-mediated isothermal amplification and SYBR green real-time PCR methods for the detection of Citrus yellow mosaic badnavirus in citrus species.

Science.gov (United States)

Anthony Johnson, A M; Dasgupta, I; Sai Gopal, D V R

2014-07-01

Citrus yellow mosaic badnavirus (CMBV) is an important pathogen in southern India spread by infected citrus propagules. One of the measures to arrest the spread of CMBV is to develop methods to screen and certify citrus propagules as CMBV-free. The methods loop-mediated isothermal amplification (LAMP) and SYBR green real-time PCR (SGRTPCR) have been developed for the efficient detection of CMBV in citrus propagules. This paper compares the sensitivities of LAMP and SGRTPCR with polymerase chain reaction (PCR) for the detection of CMBV. Whereas PCR and LAMP were able to detect CMBV from a minimum of 10 ng of total DNA of infected leaf samples, SGRTPCR could detect the same from 1 ng of total DNA. Using SGRTPCR, the viral titres were estimated to be the highest in rough lemon and lowest in Nagpur Mandarin of the five naturally infected citrus species tested. The results will help in designing suitable strategies for the sensitive detection of CMBV from citrus propagules. Copyright © 2014 Elsevier B.V. All rights reserved.

Characterization of a Proposed Dichorhavirus Associated with the Citrus Leprosis Disease and Analysis of the Host Response

Science.gov (United States)

Cruz-Jaramillo, José Luis; Ruiz-Medrano, Roberto; Rojas-Morales, Lourdes; López-Buenfil, José Abel; Morales-Galván, Oscar; Chavarín-Palacio, Claudio; Ramírez-Pool, José Abrahán; Xoconostle-Cázares, Beatriz

2014-01-01

The causal agents of Citrus leprosis are viruses; however, extant diagnostic methods to identify them have failed to detect known viruses in orange, mandarin, lime and bitter orange trees with severe leprosis symptoms in Mexico, an important citrus producer. Using high throughput sequencing, a virus associated with citrus leprosis was identified, belonging to the proposed Dichorhavirus genus. The virus was termed Citrus Necrotic Spot Virus (CNSV) and contains two negative-strand RNA components; virions accumulate in the cytoplasm and are associated with plasmodesmata—channels interconnecting neighboring cells—suggesting a mode of spread within the plant. The present study provides insights into the nature of this pathogen and the corresponding plant response, which is likely similar to other pathogens that do not spread systemically in plants. PMID:25004279

A plant natriuretic peptide-like molecule of the pathogen Xanthomonas axonopodis pv. citri causes rapid changes in the proteome of its citrus host

Directory of Open Access Journals (Sweden)

Ottado Jorgelina

2010-03-01

Full Text Available Abstract Background Plant natriuretic peptides (PNPs belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. The citrus pathogen Xanthomonas axonopodis pv. citri possesses a PNP-like peptide (XacPNP uniquely present in this bacteria. Previously we observed that the expression of XacPNP is induced upon infection and that lesions produced in leaves infected with a XacPNP deletion mutant were more necrotic and lead to earlier bacterial cell death, suggesting that the plant-like bacterial PNP enables the plant pathogen to modify host responses in order to create conditions favorable to its own survival. Results Here we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrate that the peptide improves the physiological conditions of the tissue. Importantly, the proteomic analysis revealed that these responses are mirrored by rapid changes in the host proteome that include the up-regulation of Rubisco activase, ATP synthase CF1 α subunit, maturase K, and α- and β-tubulin. Conclusions We demonstrate that XacPNP induces changes in host photosynthesis at the level of protein expression and in photosynthetic efficiency in particular. Our findings suggest that the biotrophic pathogen can use the plant-like hormone to modulate the host cellular environment and in particular host metabolism and that such modulations weaken host defence.

Secondary metabolite profiling of Alternaria dauci, A. porri, A. solani, and A. tomatophila

DEFF Research Database (Denmark)

Andersen, Birgitte; Dongo, Anita; Pryor, Barry M.

2008-01-01

Chemotaxonomy (secondary metabolite profiling) has been shown to be of great value in the classification and differentiation in Ascomycota. However, few studies have investigated the use of metabolite production for classification and identification purposes of plant pathogenic Alternaria species....... The purpose of the present study was to describe the methodology behind metabolite profiling in chemotaxonomy using A. dauci, A. porri, A. solani, and A. tomatophila strains as examples of the group. The results confirmed that A. dauci, A. solani, and A. tomatophila are three distinct species each...

Citrus plant nutritional profile in relation to huanglongbing prevalence in Pakistan

International Nuclear Information System (INIS)

Razi, M.F.U.D.; Khan, I.A.; Jaskani, M.J.

2011-01-01

Citrus is an important fruit crop in Pakistan that requires proper crop nutrition and disease management strategies as it is a tree crop and withstands harsh seasonal conditions for decades. Huanglongbing (HLB) is a century old, devastating disease of citrus caused by phloem limiting bacteria of the alpha-proteobacteria subdivision. As disease has no known cure, so, effective prevention methods are useful in crop management. Improper crop nutrition impairs plant genetic resistance to invasive pathogens, decreases yield and reduces productive life of the plant. In this study we selected 116 citrus trees from 43 orchard of Punjab for a nutritional assessment. All the trees were showing HLB symptoms and were subjected to NPK and Zn analysis as well as molecular detection of Candidatus L. asiaticus, the pathogen associated with HLB. Nitrogen and Zn were significantly higher (P=0.05) in HLB infected trees. Out of 48 diseased trees, 19, 43 and 27 were deficient in nitrogen, phosphorous and potash, respectively. Our study concludes that there is no relationship between nutritional deficiency status and HLB incidence in citrus; however, nutritional treatments may help in stress relief to infected plants. (author)

Endophytic and pathogenic Phyllosticta species, with reference to those associated with Citrus Black Spot

NARCIS (Netherlands)

Glienke, C.; Pereira, O.L.; Stringari, D.; Fabris, J.; Kava-Cordeiro, V.; Galli-Terasawa, L.; Cunnington, J.; Shivas, R.G.; Groenewald, J.Z.; Crous, P.W.

2011-01-01

We investigated the identity and genetic diversity of more than 100 isolates belonging to Phyllosticta (teleomorph Guignardia), with particular emphasis on Phyllosticta citricarpa and Guignardia mangiferae s.l. occurring on Citrus. Phyllosticta citricarpa is the causal agent of Citrus Black Spot and

Characterization of Pseudomonas syringae pv. syringae, Causal Agent of Citrus Blast of Mandarin in Montenegro.

Science.gov (United States)

Ivanović, Žarko; Perović, Tatjana; Popović, Tatjana; Blagojević, Jovana; Trkulja, Nenad; Hrnčić, Snježana

2017-02-01

Citrus blast caused by bacterium Pseudomonas syringae is a very important disease of citrus occuring in many areas of the world, but with few data about genetic structure of the pathogen involved. Considering the above fact, this study reports genetic characterization of 43 P. syringae isolates obtained from plant tissue displaying citrus blast symptoms on mandarin ( Citrus reticulata ) in Montenegro, using multilocus sequence analysis of gyrB , rpoD , and gap1 gene sequences. Gene sequences from a collection of 54 reference pathotype strains of P. syringae from the Plant Associated and Environmental Microbes Database (PAMDB) was used to establish a genetic relationship with our isolates obtained from mandarin. Phylogenetic analyses of gyrB , rpoD , and gap1 gene sequences showed that P. syringae pv. syringae causes citrus blast in mandarin in Montenegro, and belongs to genomospecies 1. Genetic homogeneity of isolates suggested that the Montenegrian population might be clonal which indicates a possible common source of infection. These findings may assist in further epidemiological studies of this pathogen and for determining mandarin breeding strategies for P. syringae control.

Characterization of Pseudomonas syringae pv. syringae, Causal Agent of Citrus Blast of Mandarin in Montenegro

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Žarko Ivanović

2017-02-01

Full Text Available Citrus blast caused by bacterium Pseudomonas syringae is a very important disease of citrus occuring in many areas of the world, but with few data about genetic structure of the pathogen involved. Considering the above fact, this study reports genetic characterization of 43 P. syringae isolates obtained from plant tissue displaying citrus blast symptoms on mandarin (Citrus reticulata in Montenegro, using multilocus sequence analysis of gyrB, rpoD, and gap1 gene sequences. Gene sequences from a collection of 54 reference pathotype strains of P. syringae from the Plant Associated and Environmental Microbes Database (PAMDB was used to establish a genetic relationship with our isolates obtained from mandarin. Phylogenetic analyses of gyrB, rpoD, and gap1 gene sequences showed that P. syringae pv. syringae causes citrus blast in mandarin in Montenegro, and belongs to genomospecies 1. Genetic homogeneity of isolates suggested that the Montenegrian population might be clonal which indicates a possible common source of infection. These findings may assist in further epidemiological studies of this pathogen and for determining mandarin breeding strategies for P. syringae control.

Dancy mandarin: a new alternative for citrus growing in the piedmont plains of Colombia

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Diana Mateus Cagua

2015-01-01

Full Text Available The major citrus production of the world are located between 20-40 degrees north and south latitude. In these conditions the mandarins get the best internal and external qualities. ‘Arrayana’ is the main mandarin cultivated in Colombia tropical lowlands (around 04° N. This variety is characterized by a high concentration of the harvest in december and january because it has only one principal bloom in the year (two weeks after onset of rainy season; and an average external quality that prevents it from being highly competitive. Both conditions reduce the profitability of citrus growers in the region. In order to identify and develop mandarin genotypes who obtain outstanding qualities in tropical lowlands, was evaluated at Corpoica La Libertad Research Center (Villavicencio, Meta the Dancy variety since 2000 (Citrus reticulata Blanco var. Dancy for vegetative growth, fruit yield, quality and consumer acceptance through a hedonic test. This information was compared with that obtained in experimental field of Arrayana tangerine; both were grafted on ‘Cleopatra’ mandarin rootstock (Citrus reshni hort. ex Tanaka. The outstanding fruit quality of Dancy (TSS: 10,8; TSS/TA ratio: 18,1; fruit weight: 145,85 g and high cumulative production confirms the adaptation of the variety to the conditions of the Foothills of Meta department; while good consumer acceptance, suggests its recommendation to be established as complementary to the Arrayana’s production. The evaluated clone is susceptible to Alternaria which may limit its cultivation in tropical medium lands conditions where the rainfall regime is bimodal and relative humidity can be high.

Characterization of a Proposed Dichorhavirus Associated with the Citrus Leprosis Disease and Analysis of the Host Response

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José Luis Cruz-Jaramillo

2014-07-01

Full Text Available The causal agents of Citrus leprosis are viruses; however, extant diagnostic methods to identify them have failed to detect known viruses in orange, mandarin, lime and bitter orange trees with severe leprosis symptoms in Mexico, an important citrus producer. Using high throughput sequencing, a virus associated with citrus leprosis was identified, belonging to the proposed Dichorhavirus genus. The virus was termed Citrus Necrotic Spot Virus (CNSV and contains two negative-strand RNA components; virions accumulate in the cytoplasm and are associated with plasmodesmata—channels interconnecting neighboring cells—suggesting a mode of spread within the plant. The present study provides insights into the nature of this pathogen and the corresponding plant response, which is likely similar to other pathogens that do not spread systemically in plants.

Molecular Detection of Spiroplasma Citri Associated with Stubborn Disease in Citrus Orchards in Syria

Science.gov (United States)

Spiroplasma citri, a phloem-limited pathogen, causes citrus stubborn disease (CSD) and can be transmitted from plant to plant by several species of phloem-feeding leafhoppers. CSD is an important disorder in certain warm and arid citrus-growing areas, and its agent has been recorded from several Med...

Temporal occurrence and niche preferences of Phytophthora species causing brown rot of citrus in the Central Valley of California

Science.gov (United States)

Brown rot of citrus fruits is caused by several species of Phytophthora and is currently of serious concern for the California citrus industry. Two species, P. syringae and P. hibernalis, are quarantine pathogens in China, a major export market for California citrus. To maintain trade and estimate t...

[Expression of plant antimicrobial peptide pro-SmAMP2 gene increases resistance of transgenic potato plants to Alternaria and Fusarium pathogens].

Science.gov (United States)

Vetchinkina, E M; Komakhina, V V; Vysotskii, D A; Zaitsev, D V; Smirnov, A N; Babakov, A V; Komakhin, R A

2016-09-01

The chickweed (Stellaria media L.) pro-SmAMP2 gene encodes the hevein-like peptides that have in vitro antimicrobial activity against certain harmful microorganisms. These peptides play an important role in protecting the chickweed plants from infection, and the pro-SmAMP2 gene was previously used to protect transgenic tobacco and Arabidopsis plants from phytopathogens. In this study, the pro-SmAMP2 gene under control of viral CaMV35S promoter or under control of its own pro-SmAMP2 promoter was transformed into cultivated potato plants of two cultivars, differing in the resistance to Alternaria: Yubiley Zhukova (resistant) and Skoroplodny (susceptible). With the help of quantitative real-time PCR, it was demonstrated that transgenic potato plants expressed the pro-SmAMP2 gene under control of both promoters at the level comparable to or exceeding the level of the potato actin gene. Assessment of the immune status of the transformants demonstrated that expression of antimicrobial peptide pro-SmAMP2 gene was able to increase the resistance to a complex of Alternaria sp. and Fusarium sp. phytopathogens only in potato plants of the Yubiley Zhukova cultivar. The possible role of the pro-SmAMP2 products in protecting potatoes from Alternaria sp. and Fusarium sp. is discussed.

A plant natriuretic peptide-like molecule of the pathogen Xanthomonas axonopodis pv. citri causes rapid changes in the proteome of its citrus host

KAUST Repository

Garavaglia, Betiana S; Thomas, Ludivine; Zimaro, Tamara; Gottig, Natalia; Daurelio, Lucas D; Ndimba, Bongani; Orellano, Elena G; Ottado, Jorgelina; Gehring, Christoph A

2010-01-01

Background: Plant natriuretic peptides (PNPs) belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. The citrus pathogen Xanthomonas axonopodis pv. citri possesses a PNP-like peptide (XacPNP) uniquely present in this bacteria. Previously we observed that the expression of XacPNP is induced upon infection and that lesions produced in leaves infected with a XacPNP deletion mutant were more necrotic and lead to earlier bacterial cell death, suggesting that the plant-like bacterial PNP enables the plant pathogen to modify host responses in order to create conditions favorable to its own survival.Results: Here we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrate that the peptide improves the physiological conditions of the tissue. Importantly, the proteomic analysis revealed that these responses are mirrored by rapid changes in the host proteome that include the up-regulation of Rubisco activase, ATP synthase CF1 ? subunit, maturase K, and ?- and ?-tubulin.Conclusions: We demonstrate that XacPNP induces changes in host photosynthesis at the level of protein expression and in photosynthetic efficiency in particular. Our findings suggest that the biotrophic pathogen can use the plant-like hormone to modulate the host cellular environment and in particular host metabolism and that such modulations weaken host defence. 2010 Garavaglia et al; licensee BioMed Central Ltd.

A plant natriuretic peptide-like molecule of the pathogen Xanthomonas axonopodis pv. citri causes rapid changes in the proteome of its citrus host

KAUST Repository

Garavaglia, Betiana S

2010-03-21

Background: Plant natriuretic peptides (PNPs) belong to a novel class of peptidic signaling molecules that share some structural similarity to the N-terminal domain of expansins and affect physiological processes such as water and ion homeostasis at nano-molar concentrations. The citrus pathogen Xanthomonas axonopodis pv. citri possesses a PNP-like peptide (XacPNP) uniquely present in this bacteria. Previously we observed that the expression of XacPNP is induced upon infection and that lesions produced in leaves infected with a XacPNP deletion mutant were more necrotic and lead to earlier bacterial cell death, suggesting that the plant-like bacterial PNP enables the plant pathogen to modify host responses in order to create conditions favorable to its own survival.Results: Here we measured chlorophyll fluorescence parameters and water potential of citrus leaves infiltrated with recombinant purified XacPNP and demonstrate that the peptide improves the physiological conditions of the tissue. Importantly, the proteomic analysis revealed that these responses are mirrored by rapid changes in the host proteome that include the up-regulation of Rubisco activase, ATP synthase CF1 ? subunit, maturase K, and ?- and ?-tubulin.Conclusions: We demonstrate that XacPNP induces changes in host photosynthesis at the level of protein expression and in photosynthetic efficiency in particular. Our findings suggest that the biotrophic pathogen can use the plant-like hormone to modulate the host cellular environment and in particular host metabolism and that such modulations weaken host defence. 2010 Garavaglia et al; licensee BioMed Central Ltd.

Studies on the cost-effective management of Alternaria blight of rapeseed-mustard (Brassica spp.

Directory of Open Access Journals (Sweden)

M.M. Khan

2007-08-01

Full Text Available Three systemic fungicides: Topsin-M (Thiophanate methyl, 70%WP, Ridomil MZ (Mancozeb, 64% + Metalaxyl, 8%WP, and Bavistin (Carbendazim, 50%WP alone and in combination with four non-systemic fungicides Captaf (Captan, 50%WP, Indofil M-45 (Mancozeb, 75%WP, Indofil Z-78 (Zineb, 75%WP, and Thiram (Thiram, 75%WP were evaluated both in vitro and in vivo for their effectiveness to manage Alternaria blight of rapeseedmustard caused by Alternaria brassicae. A pure culture of the pathogenic fungus was applied in the field at 2 g colonized sorghum seeds kg-1 soil. All the fungicides were evaluated for their efficacy at various concentrations, 50, 100, 150, 200 and 500 ppm, and were sprayed in the field at 0.2% a.i. l-1. All fungicides significantly reduced the severity of the disease but Ridomil MZ was most effective. Topsin-M at a concentration of 500 ppm was the most effective in reducing radial growth of the pathogenic fungi (74.2%. Ridomil MZ reduced disease severity by 32% and was followed in effectiveness by the combination Bavistin+Captaf (26.5%. Maximum yield was obtained in plots sprayed with Bavistin+Captaf (1198 kg ha-1 followed by Bavistin+Indofil Z-78 (1172 kg ha-1. It was worth noting that the highest net profit as well as the highest cost-benefit ratio was obtained with Bavistin+Indofil Z-78 (1:3.2, followed by Bavistin+Captaf (1:1.3.

Ultrastructure of the salivary glands, alimentary canal and bacteria-like organisms in the Asian citrus psyllid, vector of citrus huanglongbing-disease bacteria

Science.gov (United States)

Several psyllids (Hemiptera: Psylloidea) are known as vectors of some economically important viral and bacterial plant pathogens. The Asian citrus psyllid (ACP, Diaphorina citri, Hemiptera, Liviidae) is the principal vector of ‘Candidatus Liberibacter asiaticus’ (Las), the putative bacterial causal ...

The Distribution of Coumarins and Furanocoumarins in Citrus Species Closely Matches Citrus Phylogeny and Reflects the Organization of Biosynthetic Pathways.

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Audray Dugrand-Judek

Full Text Available Citrus plants are able to produce defense compounds such as coumarins and furanocoumarins to cope with herbivorous insects and pathogens. In humans, these chemical compounds are strong photosensitizers and can interact with medications, leading to the "grapefruit juice effect". Removing coumarins and furanocoumarins from food and cosmetics imply additional costs and might alter product quality. Thus, the selection of Citrus cultivars displaying low coumarin and furanocoumarin contents constitutes a valuable alternative. In this study, we performed ultra-performance liquid chromatography coupled with mass spectrometry analyses to determine the contents of these compounds within the peel and the pulp of 61 Citrus species representative of the genetic diversity all Citrus. Generally, Citrus peel contains larger diversity and higher concentrations of coumarin/furanocoumarin than the pulp of the same fruits. According to the chemotypes found in the peel, Citrus species can be separated into 4 groups that correspond to the 4 ancestral taxa (pummelos, mandarins, citrons and papedas and extended with their respective secondary species descendants. Three of the 4 ancestral taxa (pummelos, citrons and papedas synthesize high amounts of these compounds, whereas mandarins appear practically devoid of them. Additionally, all ancestral taxa and their hybrids are logically organized according to the coumarin and furanocoumarin pathways described in the literature. This organization allows hypotheses to be drawn regarding the biosynthetic origin of compounds for which the biogenesis remains unresolved. Determining coumarin and furanocoumarin contents is also helpful for hypothesizing the origin of Citrus species for which the phylogeny is presently not firmly established. Finally, this work also notes favorable hybridization schemes that will lead to low coumarin and furanocoumarin contents, and we propose to select mandarins and Ichang papeda as Citrus

Shedding light on the role of photosynthesis in pathogen colonization and host defense

KAUST Repository

Garavaglia, Betiana S.; Thomas, Ludivine; Gottig, Natalia; Zimaro, Tamara; Garofalo, Cecilia G.; Gehring, Christoph A; Ottado, Jorgelina

2010-01-01

The role of photosynthesis in plant defense is a fundamental question awaiting further molecular and physiological elucidation. To this end we investigated host responses to infection with the bacterial pathogen Xanthomonas axonopodis pv. citri, the pathogen responsible for citrus canker. This pathogen encodes a plant-like natriuretic peptide (XacPNP) that is expressed specifically during the infection process and prevents deterioration of the physiological condition of the infected tissue. Proteomic assays of citrus leaves infected with a XacPNP deletion mutant (DeltaXacPNP) resulted in a major reduction in photosynthetic proteins such as Rubisco, Rubisco activase and ATP synthase as a compared with infection with wild type bacteria. In contrast, infiltration of citrus leaves with recombinant XacPNP caused an increase in these host proteins and a concomitant increase in photosynthetic efficiency as measured by chlorophyll fluorescence assays. Reversion of the reduction in photosynthetic efficiency in citrus leaves infected with DeltaXacPNP was achieved by the application of XacPNP or Citrus sinensis PNP lending support to a case of molecular mimicry. Finally, given that DeltaXacPNP infection is less successful than infection with the wild type, it appears that reducing photosynthesis is an effective plant defense mechanism against biotrophic pathogens.

Shedding light on the role of photosynthesis in pathogen colonization and host defense

KAUST Repository

Garavaglia, Betiana S.

2010-09-01

The role of photosynthesis in plant defense is a fundamental question awaiting further molecular and physiological elucidation. To this end we investigated host responses to infection with the bacterial pathogen Xanthomonas axonopodis pv. citri, the pathogen responsible for citrus canker. This pathogen encodes a plant-like natriuretic peptide (XacPNP) that is expressed specifically during the infection process and prevents deterioration of the physiological condition of the infected tissue. Proteomic assays of citrus leaves infected with a XacPNP deletion mutant (DeltaXacPNP) resulted in a major reduction in photosynthetic proteins such as Rubisco, Rubisco activase and ATP synthase as a compared with infection with wild type bacteria. In contrast, infiltration of citrus leaves with recombinant XacPNP caused an increase in these host proteins and a concomitant increase in photosynthetic efficiency as measured by chlorophyll fluorescence assays. Reversion of the reduction in photosynthetic efficiency in citrus leaves infected with DeltaXacPNP was achieved by the application of XacPNP or Citrus sinensis PNP lending support to a case of molecular mimicry. Finally, given that DeltaXacPNP infection is less successful than infection with the wild type, it appears that reducing photosynthesis is an effective plant defense mechanism against biotrophic pathogens.

Bostrycin and 4-deoxybostrycin: two nonspecific phytotoxins produced by Alternaria eichhorniae.

Science.gov (United States)

Charudattan, R; Rao, K V

1982-04-01

Two crystalline red pigments with phytotoxic activity were isolated from culture filtrates of Alternaria eichhorniae, a pathogen of the water hyacinth Eichhornia crassipes. The pigments were present in the ratio of 4:1 and were identified as bostrycin and 4-deoxybostrycin, respectively. This is the first isolation of 4-deoxybostrycin from a natural source. Bostrycin, 4-deoxybostrycin, and their isopropylidene derivatives induced necrosis on tested plant leaves comparable to the A. eichhorniae-induced necrosis on water hyacinth. The lowest phytotoxic concentrations of crystalline bostrycin and 4-deoxybostrycin on water hyacinth leaves were about 7 and 30 microgram/ml, respectively. Both substances were inhibitory to Bacillus subtilis but were inactive against the fungus Geotrichum candidum.

Oligo-DNA custom macroarray for monitoring major pathogenic and non-pathogenic fungi and bacteria in the phyllosphere of apple trees.

Science.gov (United States)

He, Ying-Hong; Isono, Sayaka; Shibuya, Makoto; Tsuji, Masaharu; Adkar Purushothama, Charith-Raj; Tanaka, Kazuaki; Sano, Teruo

2012-01-01

To monitor the richness in microbial inhabitants in the phyllosphere of apple trees cultivated under various cultural and environmental conditions, we developed an oligo-DNA macroarray for major pathogenic and non-pathogenic fungi and bacteria inhabiting the phyllosphere of apple trees. First, we isolated culturable fungi and bacteria from apple orchards by an agar-plate culture method, and detected 32 fungal and 34 bacterial species. Alternaria, Aureobasidium, Cladosporium, Rhodotorula, Cystofilobasidium, and Epicoccum genera were predominant among the fungi, and Bacillus, Pseudomonas, Sphingomonas, Methylobacterium, and Pantoea genera were predominant among the bacteria. Based on the data, we selected 29 major non-pathogenic and 12 phytopathogenic fungi and bacteria as the targets of macroarray. Forty-one species-specific 40-base pair long oligo-DNA sequences were selected from the nucleotide sequences of rDNA-internal transcribed spacer region for fungi and 16S rDNA for bacteria. The oligo-DNAs were fixed on nylon membrane and hybridized with digoxigenin-labeled cRNA probes prepared for each species. All arrays except those for Alternaria, Bacillus, and their related species, were specifically hybridized. The array was sensitive enough to detect 10(3) CFU for Aureobasidium pullulans and Bacillus cereus. Nucleotide sequencing of 100 each of independent fungal rDNA-ITS and bacterial 16S-rDNA sequences from apple tree was in agreement with the macroarray data obtained using the same sample. Finally, we analyzed the richness in the microbial inhabitants in the samples collected from apple trees in four orchards. Major apple pathogens that cause scab, Alternaria blotch, and Marssonina blotch were detected along with several non-phytopathogenic fungal and bacterial inhabitants. The macroarray technique presented here is a strong tool to monitor the major microbial species and the community structures in the phyllosphere of apple trees and identify key species

Oligo-DNA custom macroarray for monitoring major pathogenic and non-pathogenic fungi and bacteria in the phyllosphere of apple trees.

Directory of Open Access Journals (Sweden)

Ying-Hong He

Full Text Available BACKGROUND: To monitor the richness in microbial inhabitants in the phyllosphere of apple trees cultivated under various cultural and environmental conditions, we developed an oligo-DNA macroarray for major pathogenic and non-pathogenic fungi and bacteria inhabiting the phyllosphere of apple trees. METHODS AND FINDINGS: First, we isolated culturable fungi and bacteria from apple orchards by an agar-plate culture method, and detected 32 fungal and 34 bacterial species. Alternaria, Aureobasidium, Cladosporium, Rhodotorula, Cystofilobasidium, and Epicoccum genera were predominant among the fungi, and Bacillus, Pseudomonas, Sphingomonas, Methylobacterium, and Pantoea genera were predominant among the bacteria. Based on the data, we selected 29 major non-pathogenic and 12 phytopathogenic fungi and bacteria as the targets of macroarray. Forty-one species-specific 40-base pair long oligo-DNA sequences were selected from the nucleotide sequences of rDNA-internal transcribed spacer region for fungi and 16S rDNA for bacteria. The oligo-DNAs were fixed on nylon membrane and hybridized with digoxigenin-labeled cRNA probes prepared for each species. All arrays except those for Alternaria, Bacillus, and their related species, were specifically hybridized. The array was sensitive enough to detect 10(3 CFU for Aureobasidium pullulans and Bacillus cereus. Nucleotide sequencing of 100 each of independent fungal rDNA-ITS and bacterial 16S-rDNA sequences from apple tree was in agreement with the macroarray data obtained using the same sample. Finally, we analyzed the richness in the microbial inhabitants in the samples collected from apple trees in four orchards. Major apple pathogens that cause scab, Alternaria blotch, and Marssonina blotch were detected along with several non-phytopathogenic fungal and bacterial inhabitants. CONCLUSIONS: The macroarray technique presented here is a strong tool to monitor the major microbial species and the community structures in

Partial resistance of carrot to Alternaria dauci correlates with in vitro cultured carrot cell resistance to fungal exudates.

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Mickaël Lecomte

Full Text Available Although different mechanisms have been proposed in the recent years, plant pathogen partial resistance is still poorly understood. Components of the chemical warfare, including the production of plant defense compounds and plant resistance to pathogen-produced toxins, are likely to play a role. Toxins are indeed recognized as important determinants of pathogenicity in necrotrophic fungi. Partial resistance based on quantitative resistance loci and linked to a pathogen-produced toxin has never been fully described. We tested this hypothesis using the Alternaria dauci-carrot pathosystem. Alternaria dauci, causing carrot leaf blight, is a necrotrophic fungus known to produce zinniol, a compound described as a non-host selective toxin. Embryogenic cellular cultures from carrot genotypes varying in resistance against A. dauci were confronted with zinniol at different concentrations or to fungal exudates (raw, organic or aqueous extracts. The plant response was analyzed through the measurement of cytoplasmic esterase activity, as a marker of cell viability, and the differentiation of somatic embryos in cellular cultures. A differential response to toxicity was demonstrated between susceptible and partially resistant genotypes, with a good correlation noted between the resistance to the fungus at the whole plant level and resistance at the cellular level to fungal exudates from raw and organic extracts. No toxic reaction of embryogenic cultures was observed after treatment with the aqueous extract or zinniol used at physiological concentration. Moreover, we did not detect zinniol in toxic fungal extracts by UHPLC analysis. These results suggest that strong phytotoxic compounds are present in the organic extract and remain to be characterized. Our results clearly show that carrot tolerance to A. dauci toxins is one component of its partial resistance.

Deciphering the bacterial microbiome of citrus plants in response to ‘Candidatus Liberibacter asiaticus’-infection and antibiotic treatment

Science.gov (United States)

Huanglongbing (HLB), the most devastating citrus disease worldwide, is vectored by phloem-feeding insects, and the pathogen in the USA is Candidatus Liberibacter asiaticus (Las). The bacterial microbiome of citrus after Las-infection and treatments with ampicillin (Amp) and gentamicin (Gm) was chara...

LRR-RLK family from two Citrus species: genome-wide identification and evolutionary aspects.

Science.gov (United States)

Magalhães, Diogo M; Scholte, Larissa L S; Silva, Nicholas V; Oliveira, Guilherme C; Zipfel, Cyril; Takita, Marco A; De Souza, Alessandra A

2016-08-12

Leucine-rich repeat receptor-like kinases (LRR-RLKs) represent the largest subfamily of plant RLKs. The functions of most LRR-RLKs have remained undiscovered, and a few that have been experimentally characterized have been shown to have important roles in growth and development as well as in defense responses. Although RLK subfamilies have been previously studied in many plants, no comprehensive study has been performed on this gene family in Citrus species, which have high economic importance and are frequent targets for emerging pathogens. In this study, we performed in silico analysis to identify and classify LRR-RLK homologues in the predicted proteomes of Citrus clementina (clementine) and Citrus sinensis (sweet orange). In addition, we used large-scale phylogenetic approaches to elucidate the evolutionary relationships of the LRR-RLKs and further narrowed the analysis to the LRR-XII group, which contains several previously described cell surface immune receptors. We built integrative protein signature databases for Citrus clementina and Citrus sinensis using all predicted protein sequences obtained from whole genomes. A total of 300 and 297 proteins were identified as LRR-RLKs in C. clementina and C. sinensis, respectively. Maximum-likelihood phylogenetic trees were estimated using Arabidopsis LRR-RLK as a template and they allowed us to classify Citrus LRR-RLKs into 16 groups. The LRR-XII group showed a remarkable expansion, containing approximately 150 paralogs encoded in each Citrus genome. Phylogenetic analysis also demonstrated the existence of two distinct LRR-XII clades, each one constituted mainly by RD and non-RD kinases. We identified 68 orthologous pairs from the C. clementina and C. sinensis LRR-XII genes. In addition, among the paralogs, we identified a subset of 78 and 62 clustered genes probably derived from tandem duplication events in the genomes of C. clementina and C. sinensis, respectively. This work provided the first comprehensive

Characterization of Alternaria strains from Argentinean blueberry, tomato, walnut and wheat

DEFF Research Database (Denmark)

Andersen, Birgitte; Nielsen, Kristian Fog; Fernández Pinto, Virginia

2015-01-01

of the chemical potential. Four strains belonged to the Alternaria infectoria sp.-grp., 6 to the Alternaria arborescens sp.-grp., 6 showed a sporulation pattern similar to that of “M” according to Simmons, 1 to that of Alternaria vaccinii, and the remaining 70 constituted a diverse group belonging...... sporulation pattern “M” were only isolated from tomatoes. Otherwise, no clear association between substrate and identity could be found. The analyses in the study show that at least 75% of the Argentinean strains are able to produce potential mycotoxins....

High incidence of preharvest colonization of huanglongbing-symptomatic Citrus sinensis fruit by Lasiodiplodia theobromae (Diplodia natalensis) and exacerbation of postharvest fruit decay by that fungus

Science.gov (United States)

Huanglongbing (HLB), presumably caused by bacterium Candidatus Liberibacter asiaticus (CLas), is a devastating citrus disease associated with excessive pre-harvest fruit drop. Lasiodiplodia theobromae (Diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit ...

Amplification of DNA of Xanthomonas axonopodis pv. citri from historic citrus canker herbarium specimens.

Science.gov (United States)

Li, Wenbin; Brlansky, Ronald H; Hartung, John S

2006-05-01

Herbaria are important resources for the study of the origins and dispersal of plant pathogens, particularly bacterial plant pathogens that incite local lesions in which large numbers of pathogen genomes are concentrated. Xanthomonas axonopodis pv. citri (Xac), the causal agent of citrus bacterial canker disease, is a notable example of such a pathogen. The appearance of novel strains of the pathogen in Florida and elsewhere make it increasingly important to understand the relationships among strains of this pathogen. USDA-ARS at Beltsville, Maryland maintains approximately 700 herbarium specimens with citrus canker disease lesions up to 90 years old, originally collected from all over the world, and so is an important resource for phytogeographic studies of this bacterium. Unfortunately, DNA in herbarium specimens is degraded and may contain high levels of inhibitors of PCR. In this study, we compared a total of 23 DNA isolation techniques in combination with 31 novel primer pairs in order to develop an efficient protocol for the analysis of Xac DNA in herbarium specimens. We identified the most reliable extraction method, identified in terms of successful amplification by our panel of 31 primer pairs. We also identified the most robust primer pairs, identified as successful in the largest number of extracts prepared by different methods. We amplified Xac genomic sequences up to 542 bp long from herbarium samples up to 89 years old. Primers varied in effectiveness, with some primer pairs amplifying Xac DNA from a 1/10,000 dilution of extract from a single lesion from a citrus canker herbarium specimen. Our methodology will be useful to identify pathogens and perform molecular analyses of bacterial and possibly fungal genomes from herbarium specimens.

[Determination of the profiles of secondary metabolites characteristic of Alternaria strains isolated from tomato].

Science.gov (United States)

Benavidez Rozo, Martha Elizabeth; Patriarca, Andrea; Cabrera, Gabriela; Fernández Pinto, Virginia E

2014-01-01

Many Alternaria species have been studied for their ability to produce bioactive secondary metabolites, such as tentoxin (TEN), some of which have toxic properties. The main food contaminant toxins are tenuazonic acid, alternariol (AOH), alternariol monomethyl ether (AME), altenuene, and altertoxins i, ii and iii. To determine the profiles of secondary metabolites characteristic of Alternaria strains isolated from tomato for their chemotaxonomic classification. The profiles of secondary metabolites were determined by HPLC MS. The Alternaria isolates obtained from spoiled tomatoes belong, according to their morphological characteristics, to the species groups Alternaria alternata, Alternaria tenuissima and Alternaria arborescens, with A. tenuissima being the most frequent. The most frequent profiles of secondary metabolites belonging to the species groups A. alternata (AOH, AME, TEN), A. tenuissima (AOH, AME, TEN, tenuazonic acid) and A. arborescens (AOH, AME, TEN, tenuazonic acid) were determined, with some isolates of the latter being able to synthesize AAL toxins. Secondary metabolite profiles are a useful tool for the differentiation of small spored Alternaria isolates not easily identifiable by their morphological characteristics. Copyright © 2013 Revista Iberoamericana de Micología. Published by Elsevier Espana. All rights reserved.

Green Synthesis and Biological Activities of Gold Nanoparticles Functionalized with Citrus reticulata, Citrus aurantium, Citrus sinensis and Citrus grandis

International Nuclear Information System (INIS)

Islam, N. U.; Shahid, M.; Ahsan, F.; Khan, I.; Shah, M. R.; Khan, M. A.

2015-01-01

In the present study, gold nanoparticles (GNPs) were prepared at boiling temperature (90-95 degree C) by treating gold ions with Citrus fruit extracts. The effect of mixing ratios of the reactants and concentration of gold hydrochloride was studied. In the standardization process, 10/sup -3/ M solution of HAuCl/sub 4/.3H/sub 2/O was reacted with fruit extracts for half an hour at 90-95 degree C in different ratios. GNPs were characterized by UV-Vis spectroscopy (UV-Vis) and atomic force microscopy (AFM). Their stability was evaluated against varying pH solutions and volumes of sodium chloride along with metals and antibiotics sensing ability. The gold nanoparticles were tested for antibacterial and antifungal activities against various pathogenic strains. The UV-Vis spectra of gold nanoparticles gave surface plasmon resonance at about 540 nm while the AFM images revealed the particle size within the range of 70-100 nm. GNPs showed remarkable stability in varying pH solutions and salt volumes as well as high detection ability towards cobalt, copper, ceftriaxone and penicillin. Moreover, the GNPs possessed moderate antibacterial and good antifungal activity. These results concluded that the Citrus fruit extracts can be utilized for large scale synthesis of cost-effective nanoparticles which may have compatibility for biomedical and pharmaceutical applications. (author)

Differentiation of Alternaria infectoria and Alternaria alternata based on morphology, metabolite profiles, and cultural characteristics

DEFF Research Database (Denmark)

Andersen, Birgitte; Thrane, Ulf

1996-01-01

Some small-spored species belonging to the genus Alternaria Nees have been studied according to their chemical, morphological, and cultural characteristics. A data matrix was constructed based on a combination of characters. Cluster analysis of the combined data set showed good resolution of two...

Fungitoxic potential of tagetes erectus for the management of alternaria alternata strains of tomato

International Nuclear Information System (INIS)

Mehmood, T.; Shafique, S.; Shafique, S.; Zaheer, Z.

2014-01-01

Tomato (Lycopersicum esculentum Mill.) is economically the most vital vegetable crops of this world but diseases reduce tomato production to a greater extent worldwide. Plants exudates contribute a lot in fight against pathogens. The current study indicates the pathogenic potential of Alternaria alternata FCBP-573 against tomato. RAPD analysis confirmed that A. alternata FCBP-573 had variability in its genetic constitution with other two isolates; this disparity in genetic constitution might be a cause to stir up more pathogenicity in this isolate. Therefore, it was selected as the most pathogenic isolate and subjected to biological control through Tagetes erectus L. In antifungal bioassays different plant parts of T. erectus with 1-4% concentrations of aqueous, and organic extracts of each part were evaluated against A. alternata FCBP- 573. Results revealed that the growth of A. alternata FCBP-573 was greatly inhibited at 4% concentration of methanol extract followed by aqueous and n-hexane extract. Among different plant parts tested, root extract exhibited more promising results by causing 81-92% reduction in biomass. The research concludes that aqueous and organic extracts of ornamentals have potential to obstruct dreadful effect of pathogenic fungi by suppressing their growth. T. erectus conferred vital and surprisingly stable compounds having inhibitory potential against A. alternata FCBP-573. (author)

The Arabidopsis thaliana-Alternaria brassicicola pathosystem: A model interaction for investigating seed transmission of necrotrophic fungi

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Pochon Stephanie

2012-05-01

Full Text Available Abstract Background Seed transmission constitutes a major component of the parasitic cycle for several fungal pathogens. However, very little is known concerning fungal or plant genetic factors that impact seed transmission and mechanisms underlying this key biological trait have yet to be clarified. Such lack of available data could be probably explained by the absence of suitable model pathosystem to study plant-fungus interactions during the plant reproductive phase. Results Here we report on setting up a new pathosystem that could facilitate the study of fungal seed transmission. Reproductive organs of Arabidopsis thaliana were inoculated with Alternaria brassicicola conidia. Parameters (floral vs fruit route, seed collection date, plant and silique developmental stages that could influence the seed transmission efficiency were tested to define optimal seed infection conditions. Microscopic observations revealed that the fungus penetrates siliques through cellular junctions, replum and stomata, and into seed coats either directly or through cracks. The ability of the osmosensitive fungal mutant nik1Δ3 to transmit to A. thaliana seeds was analyzed. A significant decrease in seed transmission rate was observed compared to the wild-type parental strain, confirming that a functional osmoregulation pathway is required for efficient seed transmission of the fungus. Similarly, to test the role of flavonoids in seed coat protection against pathogens, a transparent testa Arabidopsis mutant (tt4-1 not producing any flavonoid was used as host plant. Unexpectedly, tt4-1 seeds were infected to a significantly lower extent than wild-type seeds, possibly due to over-accumulation of other antimicrobial metabolites. Conclusions The Arabidopsis thaliana-Alternaria brassicicola pathosystem, that have been widely used to study plant-pathogen interactions during the vegetative phase, also proved to constitute a suitable model pathosystem for detailed analysis

Determination of mycotoxin profiles characteristic of Alternaria strains isolated from Malbec grapes

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Vargas Trinidad Andrea

2015-01-01

Full Text Available The world grape production has increased, reaching 751 million quintals (Mql in 2013. Many Alternaria species have been studied for their ability to produce secondary metabolites in foods, some of which have toxic properties with tenu- azonic acid (TA, alternariol (AOH, alternariol methyl ether (AME being the most important ones. The aim was to determine the characteristic mycotoxin production profiles of Alternaria strains isolated from Malbec grapes in the Patagonian region of Argentina. Fifty Alternaria isolates (5 A. alternata, 5 A. arborescens and 40 A. tenuissima were analyzed for the produc- tion of mycotoxins (TA, AOH and AME in autoclaved rice media by High Performance Liquid Chromatography (HPLC. All isolates were found to be producers of mycotoxins; the 100% was producer of TA (0.016–21.031 mg/kg, 98% produced AOH (0.003–0.057 mg/kg and 36% produced AME (0.001–0.133 mg/kg. Thirty-three isolates co-produced the three mycotoxins. In this study, it was demonstrated a high toxigenic potential of Alternaria isolates. Although Alternaria growth on grapes has been amply demonstrated, there are few studies about the incidence their more characteristic mycotoxin sand their toxicogenic capac- ity determination in grapes, wines and derivatives. In addition, mycotoxins studied in this work are not regulated in oenology. Therefore, further studies should be conducted to assess the health risk due to the presence of Alternaria toxins in grapes, wine, grape juice and raisins.

The quest for a non-vector psyllid: Natural variation in acquisition and transmission of the huanglongbing pathogen ‘Candidatus Liberibacter asiaticus’ by Asian citrus psyllid isofemale lines

Science.gov (United States)

Ammar, El-Desouky; Hall, David G.; Hosseinzadeh, Saeed

2018-01-01

Genetic variability in insect vectors is valuable to study vector competence determinants and to select non-vector populations that may help reduce the spread of vector-borne pathogens. We collected and tested vector competency of 15 isofemale lines of Asian citrus psyllid, Diaphorina citri, vector of ‘Candidatus Liberibacter asiaticus’ (CLas). CLas is associated with huanglongbing (citrus greening), the most serious citrus disease worldwide. D. citri adults were collected from orange jasmine (Murraya paniculata) hedges in Florida, and individual pairs (females and males) were caged on healthy Murraya plants for egg laying. The progeny from each pair that tested CLas-negative by qPCR were maintained on Murraya plants and considered an isofemale line. Six acquisition tests on D. citri adults that were reared as nymphs on CLas-infected citrus, from various generations of each line, were conducted to assess their acquisition rates (percentage of qPCR-positive adults). Three lines with mean acquisition rates of 28 to 32%, were classified as ‘good’ acquirers and three other lines were classified as ‘poor’ acquirers, with only 5 to 8% acquisition rates. All lines were further tested for their ability to inoculate CLas by confining CLas-exposed psyllids for one week onto healthy citrus leaves (6–10 adults/leaf/week), and testing the leaves for CLas by qPCR. Mean inoculation rates were 19 to 28% for the three good acquirer lines and 0 to 3% for the three poor acquirer lines. Statistical analyses indicated positive correlations between CLas acquisition and inoculation rates, as well as between CLas titer in the psyllids and CLas acquisition or inoculation rates. Phenotypic and molecular characterization of one of the good and one of the poor acquirer lines revealed differences between them in color morphs and hemocyanin expression, but not the composition of bacterial endosymbionts. Understanding the genetic architecture of CLas transmission will enable the

Development and systematic validation of qPCR assays for rapid and reliable differentiation of Xylella fastidiosa strains causing citrus variegated chlorosis.

Science.gov (United States)

Li, Wenbin; Teixeira, Diva C; Hartung, John S; Huang, Qi; Duan, Yongping; Zhou, Lijuan; Chen, Jianchi; Lin, Hong; Lopes, Silvio; Ayres, A Juliano; Levy, Laurene

2013-01-01

The xylem-limited, Gram-negative, fastidious plant bacterium Xylella fastidiosa is the causal agent of citrus variegated chlorosis (CVC), a destructive disease affecting approximately half of the citrus plantations in the State of São Paulo, Brazil. The disease was recently found in Central America and is threatening the multi-billion U.S. citrus industry. Many strains of X. fastidiosa are pathogens or endophytes in various plants growing in the U.S., and some strains cross infect several host plants. In this study, a TaqMan-based assay targeting the 16S rDNA signature region was developed for the identification of X. fastidiosa at the species level. Another TaqMan-based assay was developed for the specific identification of the CVC strains. Both new assays have been systematically validated in comparison with the primer/probe sets from four previously published assays on one platform and under similar PCR conditions, and shown to be superior. The species specific assay detected all X. fastidiosa strains and did not amplify any other citrus pathogen or endophyte tested. The CVC-specific assay detected all CVC strains but did not amplify any non-CVC X. fastidiosa nor any other citrus pathogen or endophyte evaluated. Both sets were multiplexed with a reliable internal control assay targeting host plant DNA, and their diagnostic specificity and sensitivity remained unchanged. This internal control provides quality assurance for DNA extraction, performance of PCR reagents, platforms and operators. The limit of detection for both assays was equivalent to 2 to 10 cells of X. fastidiosa per reaction for field citrus samples. Petioles and midribs of symptomatic leaves of sweet orange harbored the highest populations of X. fastidiosa, providing the best materials for detection of the pathogen. These new species specific assay will be invaluable for molecular identification of X. fastidiosa at the species level, and the CVC specific assay will be very powerful for the

Description of a novel mild strain of Citrus tristeza virus in California that reacts with monoclonal antibody MCA13

Science.gov (United States)

Quick decline caused by Citrus tristeza virus (CTV) destroyed citrus on sour orange rootstock in southern California in the 1930’s -40’s. However, use of resistant/tolerant CTV rootstocks, certified pathogen-free budwood, and quarantines have limited further economic damage from CTV. Multi-locus mar...

76 FR 23449 - Citrus Canker, Citrus Greening, and Asian Citrus Psyllid; Interstate Movement of Regulated...

Science.gov (United States)

2011-04-27

... for all germplasm and budwood destined for propagation in nurseries within the State, construction and... movement of citrus nursery stock is considered to be a high-risk pathway for citrus canker and citrus..., we did not initiate rulemaking at that time to establish such a systems approach. Rather, we decided...

Antifungal Activities of Extracts from Selected Lebanese Wild Plants against Plant Pathogenic Fungi

Directory of Open Access Journals (Sweden)

Y. Abou-Jawdah

2004-12-01

Full Text Available Extracts of nine plant species growing wild in Lebanon were tested for their efficacy against seven plant pathogenic fungi: Botrytis cinerea, Alternaria solani, Penicillium sp., Cladosporium sp., Fusarium oxysporum f. sp. melonis, Rhizoctonia solani and Sphaerotheca cucurbitae. Extracts of three of the plants, Origanum syriacum, Micromeria nervosa and Plumbago maritima, showed the highest levels of in vitro activity against spore germination and mycelial growth of the fungi tested. Inula viscosa showed high activity against spore germination but only moderate activity against mycelial growth. The other five plant species tested Calamintha origanifolia, Micromeria juliana, Ruta sp., Sideritis pullulans and Urginea maritima showed only moderate to low activity against these fungi. Preventive sprays with extracts of O. syriacum, M. nervosa, P. maritima and I. viscosa, applied at concentrations ranging between 4 and 8% to squash and cucumber seedlings, gave efficient protection against gray mold caused by B. cinerea and powdery mildew caused by S. cucurbitae. However, these extracts did not control green mold of citrus fruits caused by Penicillium sp. Thin layer chromatography revealed three inhibitory bands in extracts of O. syriacum, two in I. viscosa and only one in each of the other plants tested: M. nervosa, P. maritima, C. origanifolia and Ruta sp.

Visual, instrumental, mycological and mycotoxicological characterization of wheat inoculated with and protected against Alternaria spp.

Directory of Open Access Journals (Sweden)

Janić-Hajnal Elizabet P.

2016-01-01

Full Text Available The aim of this work was to characterize visual properties, instrumentally measured colour properties, field fungi presence and Alternaria toxins levels in wheat samples grown under conditions aimed at inhibition and stimulation of wheat infection with fungi from the Alternaria genus. Experiment was carried out on the wheat treated by fungicide and wheat inoculated by Alternaria spp., while non treated wheat was used as a control. Statistically significant difference was observed between all three treatments using visual scale. Protected wheat samples were significantly different from other samples in terms of all measured colour parameters while inoculated and control wheat samples were significantly different in terms of lightness and dominant wavelength. Identification of field fungi in the all examined wheat samples showed that the dominant mycotoxigenic fungus was Alternaria spp., followed by Fusarium spp. The content of Alternaria toxins in samples of wheat hulls and dehulled kernels point out at higher concentrations of Alternaria toxins in hulls than in dehulled kernels. [Projekat Ministarstvo nauke Republike Srbije, br. III 46001 i br. III 46005

Localization and dynamics of Wolbachia infection in Asian citrus psyllid Diaphorina citri, the insect vector of the causal pathogens of Huanglongbing.

Science.gov (United States)

Ren, Su-Li; Li, Yi-Han; Ou, Da; Guo, Yan-Jun; Qureshi, Jawwad A; Stansly, Philip A; Qiu, Bao-Li

2018-03-23

Wolbachia is a group of intracellular bacteria that infect a wide range of arthropods including the Asian citrus psyllid (ACP), Diaphorina citri Kuwayama. This insect is the vector of Candidatus Liberibacter asiaticus (CLas), the causal pathogen of Huanglongbing or citrus greening disease. Here, we investigated the localization pattern and infection dynamics of Wolbachia in different developmental stages of ACP. Results revealed that all developmental stages of ACP including egg, 1st-5th instar nymphs, and adults of both gender were infected with Wolbachia. FISH visualization of an ACP egg showed that Wolbachia moved from the egg stalk of newly laid eggs to a randomly distributed pattern throughout the egg prior to hatching. The infection rate varied between nymphal instars. The titers of Wolbachia in fourth and fifth instar nymphs were significantly higher than those in the first and second instar nymphs. Wolbachia were scattered in all nymphal stages, but with highest intensity in the U-shaped bacteriome located in the abdomen of the nymph. Wolbachia was confined to two symmetrical organizations in the abdomen of newly emerged female and male adults. The potential mechanisms of Wolbachia infection dynamics are discussed. © 2018 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

The Evolutionary History and Spatiotemporal Dynamics of the NC Lineage of Citrus Tristeza Virus

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María José Benítez-Galeano

2017-10-01

Full Text Available Citrus tristeza virus (CTV is a major pathogen affecting citrus trees worldwide. However, few studies have focused on CTV’s evolutionary history and geographic behavior. CTV is locally dispersed by an aphid vector and long distance dispersion due to transportation of contaminated material. With the aim to delve deeper into the CTV-NC (New Clade genotype evolution, we estimated an evolution rate of 1.19 × 10−3 subs/site/year and the most common recent ancestor in 1977. Furthermore, the place of origin of the genotype was in the United States, and a great expansion of the population was observed in Uruguay. This expansion phase could be a consequence of the increment in the number of naïve citrus trees in Uruguayan orchards encompassing citrus industry growth in the past years.

Agrobacterium-mediated transformation of grapefruit with the wild-type and mutant RNA-dependent RNA polymerase genes of Citrus tristeza virus

Science.gov (United States)

Citrus paradisi Macf. cv. Duncan was transformed with constructs coding for the wild-type and mutant RNA-dependent RNA polymerase (RdRp) of Citrus tristeza virus (CTV) for exploring replicase-mediated pathogen-derived resistance (RM-PDR). The RdRp gene was amplified from CTV genome and used to gener...

Inhibitory activity of plant extracts on the early blight pathogen ...

African Journals Online (AJOL)

This study evaluated the effect of two plant extracts, Ricinus communis and Chromolaena odorata on the control of the early blight pathogen, Alternaria solani (Ell. and Mart.). The study was conducted in the Laboratory of the Crop Production and Horticulture Department, Federal University of Technology, Yola, Adamawa ...

Sclerenchymatous ring as a barrier to phloem feeding by Asian citrus psyllid: Evidence from electrical penetration graph and visualization of stylet pathways

Science.gov (United States)

Asian citrus psyllid (ACP) feeding behaviors play a significant role in the transmission of the phloem-limited Candidatus Liberibacter asiaticus (CLas) bacteria that cause citrus greening disease. Sustained phloem ingestion by ACP on CLas infected plants is very important in pathogen acquisition and...

First report of Phyllosticta citricarpa and description of two new species, P. paracapitalensis and P. paracitricarpa, from citrus in Europe

NARCIS (Netherlands)

Guarnaccia, V.; Groenewald, J.Z.; Li, H.; Glienke, C.; Carstens, E.; Hattingh, V.; Fourie, P.H.; Crous, P.W.

2017-01-01

Abstract The genus Phyllosticta occurs worldwide, and contains numerous plant pathogenic, endophytic and saprobic species. Phyllosticta citricarpa is the causal agent of Citrus Black Spot disease (CBS), affecting fruits and leaves of several citrus hosts (Rutaceae), and can also be isolated from

Citrus tissue culture employing vegetative explants.

Science.gov (United States)

Chaturvedi, H C; Singh, S K; Sharma, A K; Agnihotri, S

2001-11-01

culture of shoots of C grandis without loss of regeneration capacity during 31 years, observed so far, are some other significant results. Plants of C. aurantifolia and C. sinensis raised from shoot meristem and micrografting were grown in a nethouse and those from nodal stem segments in the field along with the in vitro-raised plants of rootstocks, namely, C. jambhiri, C. karna and C. limonia. All the plants showed normal healthy growth. Significantly enough, the meristem regenerated plants of C. aurantifolia attained the reproductive phase just in 1 year of transplantation to soil similar to those raised from nodal stem segments of mature trees, which also produced normal fruits in the subsequent year while growing under field conditions. Thus, a significant fundamental concept of a maturity factor, carried over through as small a shoot meristem as 200 microm in length to cloned plants has been demonstrated. The concept is of far-reaching significance in citrus industry besides production of pathogen-free orchards.

Sequencing the Major Mycosphaerella Pathogens of Wheat and Banana

NARCIS (Netherlands)

Kema, G.H.J.

2009-01-01

Mycosphaerella is one of the largest genera of plant-pathogenic fungi with more than 1,000 named species, many of which are important pathogens causing leaf spotting diseases in a wide variety of crops including cereals, citrus, banana, eucalypts, soft fruits and horticultural crops. A few species

Sequencing the Major Mycosphaerella Pathogens of Wheat and Banana

NARCIS (Netherlands)

Kema, G.H.; Dunkle, L.D.; Churchill, A.C.; Carlier, J.; James, A.; Souza, M.T.; Crous, P.W.; Roux, N.; Lee, T.A. van der; Wiitenberg, A.; Lindquist, E.; Grigoriev, I.; Bristow, J.; Goodwin, S.B.

2007-01-01

Mycosphaerella is one of the largest genera of plant pathogenic fungi with more than 1,000 named species, many of which are important pathogens causing leaf spotting diseases in a wide variety of crops including cereals, citrus, banana, eucalypts, soft fruits, and horticultural crops. A few species

An Evaluation of the Genetic Diversity of Xylella fastidiosa Isolated from Diseased Citrus and Coffee in São Paulo, Brazil.

Science.gov (United States)

Qin, X; Miranda, V S; Machado, M A; Lemos, E G; Hartung, J S

2001-06-01

ABSTRACT Strains of Xylella fastidiosa, isolated from sweet orange trees (Citrus sinensis) and coffee trees (Coffea arabica) with symptoms of citrus variegated chlorosis and Requeima do Café, respectively, were indistinguishable based on repetitive extragenic palindromic polymerase chain reaction (PCR) and enterobacterial repetitive intergenic consensus PCR assays. These strains were also indistinguishable with a previously described PCR assay that distinguished the citrus strains from all other strains of Xylella fastidiosa. Because we were not able to document any genomic diversity in our collection of Xylella fastidiosa strains isolated from diseased citrus, the observed gradient of increasing disease severity from southern to northern regions of São Paulo State is unlikely due to the presence of significantly different strains of the pathogen in the different regions. When comparisons were made to reference strains of Xylella fastidiosa isolated from other hosts using these methods, four groups were consistently identified consistent with the hosts and regions from which the strains originated: citrus and coffee, grapevine and almond, mulberry, and elm, plum, and oak. Independent results from random amplified polymorphic DNA (RAPD) PCR assays were also consistent with these results; however, two of the primers tested in RAPD-PCR were able to distinguish the coffee and citrus strains. Sequence comparisons of a PCR product amplified from all strains of Xylella fastidiosa confirmed the presence of a CfoI polymorphism that can be used to distinguish the citrus strains from all others. The ability to distinguish Xylella fastidiosa strains from citrus and coffee with a PCR-based assay will be useful in epidemiological and etiological studies of this pathogen.

Visual, instrumental, mycological and mycotoxicological characterization of wheat inoculated with and protected against Alternaria spp.

OpenAIRE

Janić-Hajnal Elizabet P.; Belović Miona M.; Plavšić Dragana V.; Mastilović Jasna S.; Bagi Ferenc F.; Budakov Dragana B.; Kos Jovana J.

2016-01-01

The aim of this work was to characterize visual properties, instrumentally measured colour properties, field fungi presence and Alternaria toxins levels in wheat samples grown under conditions aimed at inhibition and stimulation of wheat infection with fungi from the Alternaria genus. Experiment was carried out on the wheat treated by fungicide and wheat inoculated by Alternaria spp., while non treated wheat was used as a control. Statistically significant ...

Alternaria Mycotoxins in Food and Feed: An Overview

Directory of Open Access Journals (Sweden)

Laura Escrivá

2017-01-01

Full Text Available Alternaria is one of the major mycotoxigenic fungal genera with more than 70 reported metabolites. Alternaria mycotoxins showed notably toxicity, such as mutagenicity, carcinogenicity, induction of DNA strand break, sphingolipid metabolism disruption, or inhibition of enzymes activity and photophosphorylation. This review reports on the toxicity, stability, metabolism, current analytical methods, and prevalence of Alternaria mycotoxins in food and feed through the most recent published research. Half of the publications were focused on fruits, vegetables, and derived products—mainly tomato and apples—while cereals and cereal by-products represented 38%. The most studied compounds were alternariol, alternariol methyl ether, tentoxin, and tenuazonic acid, but altenuene, altertoxins (I, II, and III, and macrosporin have been gaining importance in recent years. Solid-liquid extraction (50% with acetonitrile or ethyl acetate was the most common extraction methodology, followed by QuEChERS and dilution-direct injection (both 14%. High- and ultraperformance liquid chromatography coupled with tandem mass spectrometry was the predominant determination technique (80%. The highest levels of alternariol and alternariol methyl ether were found in lentils, oilseeds, tomatoes, carrots, juices, wines, and cereals. Tenuazonic acid highest levels were detected in cereals followed by beer, while alternariol, alternariol methyl ether, tenuazonic acid, and tentoxin were found in legumes, nuts, and oilseeds.

Variety of plant pathogens of ornamental shrubs of the genus Rosa L.

Directory of Open Access Journals (Sweden)

Marchenko Alla Borisovna

2015-12-01

In the Ukraine’s forest-steppe environment, over the years of research, the most common disease among different representatives of the genus Rosa L. is Diplocarpon rosae FA Wolf, about 52.7%. Diseases caused by Sphaerotheca pannosa var. rosae Woron account for 28.3%: Coniothyrium wernsdorffiae Laubert―19.2%; Botrytis cinerea Pers.―16.9%; Phragmidium mucronatum (Pers. Schltdl., Phragmidium tuberculatum Müll. Hal., Nectria cinnabarina (Tode Fr.―from 7.2 to 6.7%. Pathogens Alternaria alternata (Fr. Keissl., Alternaria tenuissima (Kunze Wiltshire, Fusarium oxysporum Schltdl., Fusarium solani (Mart. Sacc., Phytophthora cactorum J. Schröt., Verticillium dahliae Kleb., Verticillium albo-atrum Reinke Berthold are less common―5%.

Epidemiology of dark leaf spot caused by Alternaria brassicicola and Alternaria brassicae in organic seed production of cauliflower

NARCIS (Netherlands)

Köhl, J.; Tongeren, van C.A.M.; Groenenboom-de Haas, B.H.; Hoof, van R.A.; Driessen, R.; Heijden, van der L.

2010-01-01

In organic seed production of Brassica vegetables, infections by Alternaria brassicicola and A. brassicae can cause severe losses of yield and seed quality. Four field experiments with or without artificial inoculation with A. brassicicola were conducted in organically managed seed-production crops

Use of micro-CT to elucidate details of the anatomy and feeding of the Asian citrus psyllid Diaphorina citri Kuwayama, 1908 (Insecta: Hemiptera, Liviidae)

Science.gov (United States)

Huanglongbing (HLB), also known as citrus greening disease, is caused by plant-infecting bacteria. The most prominent pathogen within the Americas: United States of America, Mexico, and Brazil, is Candidatus Liberibacter asiaticus, which affects plants of the Family: Rutaceae, in particularly citrus...

Temporal progression of 'Candidatus Liberibacter asiaticus' infection in citrus and acquisition efficiency by Diaphorina citri.

Science.gov (United States)

Coletta-Filho, Helvecio D; Daugherty, Matthew P; Ferreira, Cléderson; Lopes, João R S

2014-04-01

Over the last decade, the plant disease huanglongbing (HLB) has emerged as a primary threat to citrus production worldwide. HLB is associated with infection by phloem-limited bacteria ('Candidatus Liberibacter' spp.) that are transmitted by the Asian citrus psyllid, Diaphorina citri. Transmission efficiency varies with vector-related aspects (e.g., developmental stage and feeding periods) but there is no information on the effects of host-pathogen interactions. Here, acquisition efficiency of 'Candidatus Liberibacter asiaticus' by D. citri was evaluated in relation to temporal progression of infection and pathogen titer in citrus. We graft inoculated sweet orange trees with 'Ca. L. asiaticus'; then, at different times after inoculation, we inspected plants for HLB symptoms, measured bacterial infection levels (i.e., titer or concentration) in plants, and measured acquisition by psyllid adults that were confined on the trees. Plant infection levels increased rapidly over time, saturating at uniformly high levels (≈10(8) copy number of 16S ribosomal DNA/g of plant tissue) near 200 days after inoculation-the same time at which all infected trees first showed disease symptoms. Pathogen acquisition by vectors was positively associated with plant infection level and time since inoculation, with acquisition occurring as early as the first measurement, at 60 days after inoculation. These results suggest that there is ample potential for psyllids to acquire the pathogen from trees during the asymptomatic phase of infection. If so, this could limit the effectiveness of tree rouging as a disease management tool and would likely explain the rapid spread observed for this disease in the field.

Fungi pathogenic on wild radish (Raphanus raphanistrum L. in northern Tunisia

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N. Djebali

2009-09-01

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.

Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis) Ciferri

OpenAIRE

Satyabrata Nanda; Subodh Kumar Chand; Purander Mandal; Pradyumna Tripathy; Raj Kumar Joshi

2016-01-01

Purple blotch, caused by Alternaria porri (Ellis) Cifferi, is a serious disease incurring heavy yield losses in the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification of effective resistance sources for use in host resistance breeding. A total of 43 Allium genotypes were screened for purple blotch resistance under field conditions. Allium cepa accession ?CBT-Ac77? and cultivar ?Arka Kalyan? were observed to be highly resistant. In vitro inoculation...

Effect of eosinophils activated with Alternaria on the production of extracellular matrix from nasal fibroblasts.

Science.gov (United States)

Shin, Seung-Heon; Ye, Mi-Kyung; Choi, Sung-Yong; Kim, Yee-Hyuk

2016-06-01

Eosinophils and fibroblasts are known to play major roles in the pathogenesis of nasal polyps. Fungi are commonly found in nasal secretion and are associated with airway inflammation. To investigate whether activated eosinophils by airborne fungi can influence the production of extracellular matrix (ECM) from nasal fibroblasts. Inferior turbinate and nasal polyp fibroblasts were stimulated with Alternaria or Aspergillus, respectively, for 24 hours and ECM messenger RNA (mRNA) and protein expressions were measured. Eosinophils isolated from healthy volunteers were stimulated with Alternaria or Aspergillus for 4 hours then superoxide, eosinophil peroxidase, and transforming growth factor β1 were measured. Then activated eosinophils were cocultured with nasal fibroblasts for 24 hours, and ECM mRNA expressions were measured. Alternaria strongly enhanced ECM mRNA expression and protein production from nasal fibroblasts. Alternaria also induced the production of superoxide, eosinophil peroxidase, and transforming growth factor β1 from eosinophils, and activated eosinophils enhanced ECM mRNA expression when they were cocultured without the Transwell insert system. Eosinophils activated with Alternaria enhanced ECM mRNA expression from nasal polyp fibroblasts. Alternaria plays an important role in tissue fibrosis in the pathogenesis of nasal polyps by directly or indirectly influencing the production of ECM from nasal fibroblasts. Copyright © 2016 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

Citrus leprosis transmission by Brevipalpus yothersi mites through non citrus hosts

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Guillermo León M.

2017-05-01

Full Text Available Citrus leprosis virus (C i LV was detected in Colombia at the eastern plains in 2004; it is a threat the disease spreads to other regions of the country. The main vector is Brevipalpus yothersi Baker (formerly identified as Brevipalpus phoenicis. This research determined the viability of B. yothersi to transmit C i LV to citrus plants, after been hosted in non-citrus plants. To virus acquisition, mites spent three days on symptomatic orange (Citrus x sinensis leaves positives to C i LV-C2; then mites were placed on six non-citrus plants (Dieffenbachia sp., Hibiscus rosa-sinensis,Codiaeum variegatum, Swinglea glutinosa, Sida acutaand Stachytarpheta cayennensis. A randomized design with 6 treatments and 4 replicates was carried out. After scheduled time in non-citrus plants, mites were three days relocated on C. x sinensis healthy plants. Leaves of receptor plants, were evaluated to the occurrence or absence of symptoms and collected for RT-PCR tests. B. yothersi mites were able to transmit the C i LV virus over 85 % of Valencia orange plants (Citrus x sinensis L., after feeding from 2-20 days on non-citrus host plants. The first leprosis symptoms on C. x sinensis leaves was confirmed from 14 to 51 days after transmission. The present research work further established that C i LV-C2 is a persistently transmitted virus. The implement quarantine diagnostic measures to prevent spread of CiLV to disease-free zones is suggested.

Toxigenic profile and AFLP variability of Alternaria alternata and Alternaria infectoria occurring on wheat

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María Silvina Oviedo

2013-01-01

Full Text Available The objectives of this study were to evaluate the ability to produce alternariol (AOH, alternariol monomethyl ether (AME and tenuazonic acid (TA by A. alternata and A. infectoria strains recovered from wheat kernels obtained from one of the main production area in Argentina; to confirm using AFLPs molecular markers the identify of the isolates up to species level, and to evaluate the intra and inter-specific genetic diversity of these two Alternaria species. Among all the Alternaria strains tested (254, 84% of them were able to produce mycotoxins. The most frequent profile of toxin production found was the co-production of AOH and AME in both species tested. TA was only produced by strains of A. alternata. Amplified fragment polymorphism (AFLPs analysis was applied to a set of 89 isolates of Alternaria spp (40 were A. infectoria and 49 were A. alternata in order to confirm the morphological identification. The results showed that AFLPs are powerful diagnostic tool for differentiating between A. alternata and A. infectoria. Indeed, in the current study the outgroup strains, A. tenuissima was consistently classified. Characteristic polymorphic bands separated these two species regardless of the primer combination used. Related to intraspecific variability, A. alternata and A. infectoria isolates evaluated seemed to form and homogeneous group with a high degree of similarity among the isolates within each species. However, there was more scoreable polymorphism within A. alternata than within A. infectoria isolates. There was a concordance between morphological identification and separation up to species level using molecular markers. Clear polymorphism both within and between species showed that AFLP can be used to asses genetic variation in A. alternata and A. infectoria. The most important finding of the present study was the report on AOH and AME production by A. infectoria strains isolated from wheat kernels in Argentina on a semisynthetic

Characterisation of Alternaria species-groups associated with core rot of apples in South Africa

DEFF Research Database (Denmark)

Serdani, M.; Kang, J.C.; Andersen, Birgitte

2002-01-01

Alternaria core rot of red apple cultivars is a serious post-harvest disease in South Africa. Thirty isolates of Alternaria spp. previously isolated from apple, together with reference isolates of A. alternata and A. infectoria, were characterised and grouped according to their sporulation patter...

Combining 'omics and microscopy to visualize interactions between the Asian citrus psyllid vector and the Huanglongbing pathogen Candidatus Liberibacter asiaticus in the insect gut.

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Angela Kruse

Full Text Available Huanglongbing, or citrus greening disease, is an economically devastating bacterial disease of citrus. It is associated with infection by the gram-negative bacterium Candidatus Liberibacter asiaticus (CLas. CLas is transmitted by Diaphorina citri, the Asian citrus psyllid (ACP. For insect transmission to occur, CLas must be ingested during feeding on infected phloem sap and cross the gut barrier to gain entry into the insect vector. To investigate the effects of CLas exposure at the gut-pathogen interface, we performed RNAseq and mass spectrometry-based proteomics to analyze the transcriptome and proteome, respectively, of ACP gut tissue. CLas exposure resulted in changes in pathways involving the TCA cycle, iron metabolism, insecticide resistance and the insect's immune system. We identified 83 long non-coding RNAs that are responsive to CLas, two of which appear to be specific to the ACP. Proteomics analysis also enabled us to determine that Wolbachia, a symbiont of the ACP, undergoes proteome regulation when CLas is present. Fluorescent in situ hybridization (FISH confirmed that Wolbachia and CLas inhabit the same ACP gut cells, but do not co-localize within those cells. Wolbachia cells are prevalent throughout the gut epithelial cell cytoplasm, and Wolbachia titer is more variable in the guts of CLas exposed insects. CLas is detected on the luminal membrane, in puncta within the gut epithelial cell cytoplasm, along actin filaments in the gut visceral muscles, and rarely, in association with gut cell nuclei. Our study provides a snapshot of how the psyllid gut copes with CLas exposure and provides information on pathways and proteins for targeted disruption of CLas-vector interactions at the gut interface.

The study of Bacteriocin of Pseudomonas fluorescens and Citrus limon effects against Propionibacterium acnes and Staphylococcus epidermidis in acne patients

Science.gov (United States)

Ahmed, Mais E.

2018-05-01

Research was carried out on the antibacterial effect of (Citrus limon) juice on Acnevulgaris. Samples were obtained from individuals with pimples by swabbing their faces. Natural substances that derive from plants are promising to treat disease cause Acnevulgaris, the study in vitro biological activity of the juice, as well as bacterocin cultivated and fruits was investigated on two strains of bacteria (Propionibacterium acnes, Staphylococcus epidermidis). The new antimicrobial (bacteriocin and Citrus juice) is an ongoing search. This study used juice at different concentrations at (20%, 30%, 40%, 60%, 80% and 100%). The bacteriocin produced from local P. fluorescens isolates from wound infection and majority of isolates were found to produce crude bacteriocin were (P1 and P2) in Pseudomonas agar at 37°C for 24 hrs. Crude bacteriocin and Citrus limon juice against some pathogenic skin bacteria was find to be effective juice Citrus limon aganist S. epidermidis at 100% Concentrations with a range of inhibition zone (18) mm. The isolates of P. fluorescens (P2) was positive as producer of bacteriocin with a wide inhibition growth against gram positive pathogenic bacteria with a range between (10-12) mm.

Infectopyrone, a potential mycotoxin from Alternaria infectoria

DEFF Research Database (Denmark)

Larsen, Thomas Ostenfeld; Perry, N.B.; Andersen, Birgitte

2003-01-01

A new metabolite, infectopyrone (1), has been isolated from the filamentous fungus Alternaria infectoria. The structure of 1 was elucidated by analysis of 2D NMR spectroscopic data. Compound 1 is an alpha-pyrone resembling known toxins, and is a useful phenotaxonomic marker for the A. infectoria ...

Alternaria and Fusarium in Norwegian grains of reduced quality - a matched pair sample study

DEFF Research Database (Denmark)

Kosiak, B.; Torp, M.; Skjerve, E.

2004-01-01

The occurrence and geographic distribution of species belonging to the genera Alternaria and Fusarium in grains of reduced and of acceptable quality were studied post-harvest in 1997 and 1998. A total of 260 grain samples of wheat, barley and oats was analysed. The distribution of Alternaria and ...

Survey and prevalence of species causing Alternaria leaf spots on brassica species in Pernambuco Levantamento e prevalência de espécies causadoras da alternariose em brássicas em Pernambuco

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Sami J Michereff

2012-06-01

Full Text Available Brassicaceae family comprises plant species that are very important as vegetable crops, such as the species complex Brassica oleracea and Brassica rapa. Alternaria brassicicola and A. brassicae are among the most important pathogens of Brassicaceae causing Alternaria leaf spot disease. The occurrence and prevalence of Alternaria species causing leaf spots in brassica crops in Pernambuco was acessed, as well as the existence of a possible preference by vegetable host for these pathogens. Twenty-eight fields were surveyed in the Agreste region of Pernambuco state, in the 2005 and 2006 growing seasons. In each year, 10 Chinese cabbage, six cabbage, six cauliflower and six broccoli fields were visited. In each field, 50 leaves showing at least five lesions were randomly collected. Species identification was performed taking into account morphology of the conidia that was compared with literature data. Among the two Alternaria species found, A. brassicae was found in all Chinese cabbage fields while A. brassicicola was found in all fields of cabbage, cauliflower and broccoli. Overall, A. brassicicola was more prevalent than A. brassicae. In Chinese cabbage there was predominance of A. brassicae, with mean prevalence of 91.0% and 96.5% in 2005 and 2006. On the other hand, in broccoli and cabbage there was high predominance of A. brassicicola, with mean prevalence between 95.1% and 99.8%. In cauliflower, although the prevalence has been of A. brassicicola, high frequency of A. brassicae was noted. The frequency of co-occurrence of both Alternaria species was very low. The results of this study reinforce the hypothesis of existence of host preference within species of Alternaria that cause leaf spots in brassica crops, especially when Chinese cabbage, broccoli and cabbage are considered. This information is critical to developing strategies for managing Alternaria leaf spots in Brassicaceae species.A família Brassicaceae possui espécies importantes

Emerging Fusarium and Alternaria Mycotoxins: Occurrence, Toxicity and Toxicokinetics

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Sophie Fraeyman

2017-07-01

Full Text Available Emerging Fusarium and Alternaria mycotoxins gain more and more interest due to their frequent contamination of food and feed, although in vivo toxicity and toxicokinetic data are limited. Whereas the Fusarium mycotoxins beauvericin, moniliformin and enniatins particularly contaminate grain and grain-based products, Alternaria mycotoxins are also detected in fruits, vegetables and wines. Although contamination levels are usually low (µg/kg range, higher contamination levels of enniatins and tenuazonic acid may occasionally occur. In vitro studies suggest genotoxic effects of enniatins A, A1 and B1, beauvericin, moniliformin, alternariol, alternariol monomethyl ether, altertoxins and stemphyltoxin-III. Furthermore, in vitro studies suggest immunomodulating effects of most emerging toxins and a reproductive health hazard of alternariol, beauvericin and enniatin B. More in vivo toxicity data on the individual and combined effects of these contaminants on reproductive and immune system in both humans and animals is needed to update the risk evaluation by the European Food Safety Authority. Taking into account new occurrence data for tenuazonic acid, the complete oral bioavailability, the low total body clearance in pigs and broiler chickens and the limited toxicity data, a health risk cannot be completely excluded. Besides, some less known Alternaria toxins, especially the genotoxic altertoxins and stemphyltoxin III, should be incorporated in risk evaluation as well.

Discovering novel Alternaria solani succinate dehydrogenase inhibitors by in silico modeling and virtual screening strategies to combat early blight

NARCIS (Netherlands)

Iftikhar, Sehrish; Shahid, Ahmad A.; Halim, Sobia A.; Wolters, Pieter J.; Vleeshouwers, Vivianne G.A.A.; Khan, Ajmal; Al-Harrasi, Ahmed; Ahmad, Shahbaz

2017-01-01

Alternaria blight is an important foliage disease caused by Alternaria solani. The enzyme Succinate dehydrogenase (SDH) is a potential drug target because of its role in tricarboxylic acid cycle. Hence targeting Alternaria solani SDH enzyme could be efficient tool to design novel fungicides against

Collection and chemical composition of phloem sap from Citrus sinensis L. Osbeck (sweet orange).

Science.gov (United States)

Hijaz, Faraj; Killiny, Nabil

2014-01-01

Through utilizing the nutrient-rich phloem sap, sap feeding insects such as psyllids, leafhoppers, and aphids can transmit many phloem-restricted pathogens. On the other hand, multiplication of phloem-limited, uncultivated bacteria such as Candidatus Liberibacter asiaticus (CLas) inside the phloem of citrus indicates that the sap contains all the essential nutrients needed for the pathogen growth. The phloem sap composition of many plants has been studied; however, to our knowledge, there is no available data about citrus phloem sap. In this study, we identified and quantified the chemical components of phloem sap from pineapple sweet orange. Two approaches (EDTA enhanced exudation and centrifugation) were used to collect phloem sap. The collected sap was derivatized with methyl chloroformate (MCF), N-methyl-N- [tert-butyl dimethylsilyl]-trifluroacetamide (MTBSTFA), or trimethylsilyl (TMS) and analyzed with GC-MS revealing 20 amino acids and 8 sugars. Proline, the most abundant amino acid, composed more than 60% of the total amino acids. Tryptophan, tyrosine, leucine, isoleucine, and valine, which are considered essential for phloem sap-sucking insects, were also detected. Sucrose, glucose, fructose, and inositol were the most predominant sugars. In addition, seven organic acids including succinic, fumaric, malic, maleic, threonic, citric, and quinic were detected. All compounds detected in the EDTA-enhanced exudate were also detected in the pure phloem sap using centrifugation. The centrifugation technique allowed estimating the concentration of metabolites. This information expands our knowledge about the nutrition requirement for citrus phloem-limited bacterial pathogen and their vectors, and can help define suitable artificial media to culture them.

The WRKY Transcription Factor Family in Citrus: Valuable and Useful Candidate Genes for Citrus Breeding.

Science.gov (United States)

Ayadi, M; Hanana, M; Kharrat, N; Merchaoui, H; Marzoug, R Ben; Lauvergeat, V; Rebaï, A; Mzid, R

2016-10-01

WRKY transcription factors belong to a large family of plant transcriptional regulators whose members have been reported to be involved in a wide range of biological roles including plant development, adaptation to environmental constraints and response to several diseases. However, little or poor information is available about WRKY's in Citrus. The recent release of completely assembled genomes sequences of Citrus sinensis and Citrus clementina and the availability of ESTs sequences from other citrus species allowed us to perform a genome survey for Citrus WRKY proteins. In the present study, we identified 100 WRKY members from C. sinensis (51), C. clementina (48) and Citrus unshiu (1), and analyzed their chromosomal distribution, gene structure, gene duplication, syntenic relation and phylogenetic analysis. A phylogenetic tree of 100 Citrus WRKY sequences with their orthologs from Arabidopsis has distinguished seven groups. The CsWRKY genes were distributed across all ten sweet orange chromosomes. A comprehensive approach and an integrative analysis of Citrus WRKY gene expression revealed variable profiles of expression within tissues and stress conditions indicating functional diversification. Thus, candidate Citrus WRKY genes have been proposed as potentially involved in fruit acidification, essential oil biosynthesis and abiotic/biotic stress tolerance. Our results provided essential prerequisites for further WRKY genes cloning and functional analysis with an aim of citrus crop improvement.

Inhibitory activity of Indian spice plant Cinnamomum zeylanicum extracts against Alternaria solani and Curvularia lunata, the pathogenic dematiaceous moulds

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Sharma Bechan

2009-03-01

Full Text Available Abstract Background Dematiaceous moulds are pathogenic microorganisms and act as etiological agents of mycoses with different degrees of severity in humans and animals. These moulds also cause loss of food crops and storage food products. The information regarding antimicrobial efficacy of the plant preparations on these moulds is scanty. The present study reveals phytochemical characterization and the effect of bark and leaf extracts of Indian spice plant, Cinnamomum zeylanicum (Cz, against the growth of two species of dematiaceous moulds, Alternaria solani and Curvularia lunata. Methods Cz bark and leaf samples were sequentially extracted in different solvents using Soxhlet apparatus. Phytochemical analyses of extracts were done as per standard protocols. The antifungal bioassay of extracts was done by hanging drop technique. The inhibition of fungal spore germination was monitored under influence of three different concentrations of extracts. Results The lowest test concentration (50 μg/ml of extracts of Cz bark prepared into acetone and that of Cz leaf into petroleum ether and ethanol exhibited complete inhibition (100% of spore germination in both the moulds. At 100 μg/ml concentration all the extracts showed about 50 to 100% inhibition. However, the treatment of the spores of the two fungal species with highest concentration (500 μg/ml of bark and leaf extracts in all the solvents showed 100% fungicidal activity as it completely arrested the germination of spores. Relatively lower activity of aqueous extracts at 50 and 100 μg/ml concentrations suggests that the antifungal ingredients present in Cz bark and leaf are more soluble in organic solvents than water. Conclusion The results demonstrated that the Cz bark and leaves contain certain fungicidal constituents exhibiting potential antimould activity against A. solani and C. lunata.

Alternaria Leaf Spot on Mealycup Sage (Salvia farinacea Benth.) Caused by Alternaria alternata (Fr.) Keissler

OpenAIRE

Hiromitsu, NEGISHI; Kazuo, SUYAMA; Faculty of Agriculture,Tokyo University of Agriculture; Faculty of Agriculture,Tokyo University of Agriculture

2002-01-01

In June 1995, a disease causing round to irregular-shaped, water-soaked, brown to blackish brown spots on mealycup sage (Salvia farinacea Benth.) was found in Atsugi-shi, Kanagawa Prefecture, Japan. The symptoms were seen only on leaves, not on neither flower petals or stems. The disease was also found in Setagaya-ku, Tokyo, Memambetsu-cho, Hokkaido and Shimoda-shi and Matsuzaki-cho, Shizuoka. An Alternaria sp. was frequently isolated from these diseased plants. The isolates were severely pat...

Secondary metabolite profiling of Alternaria dauci, A. porri, A. solani, and A. tomatophila.

Science.gov (United States)

Andersen, Birgitte; Dongo, Anita; Pryor, Barry M

2008-02-01

Chemotaxonomy (secondary metabolite profiling) has been shown to be of great value in the classification and differentiation in Ascomycota. However, few studies have investigated the use of metabolite production for classification and identification purposes of plant pathogenic Alternaria species. The purpose of the present study was to describe the methodology behind metabolite profiling in chemotaxonomy using A. dauci, A. porri, A. solani, and A. tomatophila strains as examples of the group. The results confirmed that A. dauci, A. solani, and A. tomatophila are three distinct species each with their own specific metabolite profiles, and that A. solani and A. tomatophila both produce altersolanol A, altertoxin I, and macrosporin. By using automated chemical image analysis and other multivariate statistic analyses, three sets of species-specific metabolites could be selected, one each for A. dauci, A. solani, and A. tomatophila.

Transformation of sweet orange [Citrus sinensis (L.) Osbeck] with pthA-nls for acquiring resistance to citrus canker disease.

Science.gov (United States)

Yang, Li; Hu, Chunhua; Li, Na; Zhang, Jiayin; Yan, Jiawen; Deng, Ziniu

2011-01-01

The COOH terminal of pthA encoding three nuclear localizing signals (NLS) was amplified by polymerase chain reaction (PCR) from the plasmid of Xanthomonas axonopodis pv. citri, the pathogen of citrus canker disease. Then the sense and antisense strands of the nls were cloned into pBI121 vector. pthA-nls driven by the CaMV35 s promoter was transferred into sweet orange via Agrobacterium -mediated transformation. Successful integration was confirmed by PCR and Southern blotting, and 12 sense-nls (nls (+)) and 9 antisense-nls (nls (-)) transgenic clones were obtained. The expression of nls fragment was analyzed by RT-PCR, Real time q-PCR and Western blotting, in which the specific NLS protein was detected only in nls (+) transgenic clones. In an in vitro assay, when pin-puncture inoculation was performed with 2.5 × 10(7) cfu/ml of bacterial solution, the nls (+) transgenic clones showed no typical lesion development, while typical symptoms were observed in the wild types and the nls (-) transgenic clones. In vivo assay results indicated that the nls (+) transgenic clones showed less disease incidence, in comparison with the wild types and the nls (-) transgenic clones, when pin-puncture inoculation was performed with 10(4)-10(5) cfu/ml. The minimum disease incidence was 23.3% for 'Sucarri' sweet orange and 33.3% for 'Bingtang' sweet orange. When 10(4)-10(7) cfu/ml of pathogen was spray inoculated, the nls (+) transgenic clones did not show any symptom, and even the concentration raised to 10(9) cfu/ml, the disease incidence was 20-80%, while the wild types and the nls (-) transgenic clones had 100% disease development with whatever concentration of inoculum. Two transgenic clones were confirmed to be resistant to citrus canker disease in the repeated inoculation. The results suggested that the transformation of nls sense strands may offer an effective way to acquire resistance to citrus canker disease.

Natural occurrence of mycotoxins and toxigenic capacity of Alternaria strains from mouldy peppers

DEFF Research Database (Denmark)

da Cruz Cabral, Lucía; Terminiello, Laura; Fernández Pinto, Virginia

2016-01-01

Sweet pepper (Capsicum annuum) is an important crop cultivated worldwide, with Argentina being one of the major producers in South America. The fruit is susceptible to several fungal diseases, leading to severe economic losses for producers. In this study, Alternaria was found as the prevalent...... genus in mouldy peppers (50% fruits infected). Morphological identification revealed that all 64 Alternaria isolates belonged to small-spored species, most of them corresponding to A. tenuissima, A. arborescens and A. alternata species-groups. Their secondary metabolite profile was evaluated in vitro......; alternariols were synthesized by most of the isolates (91% for alternariol and 92% for alternariol monomethyl ether). A high number of Alternaria spp. also produced tenuazonic acid (64%), altenuene (84%) and tentoxin (72%). In addition, damaged pepper fruits were analysed for the presence of tenuazonic acid...

Alternaria infectoria phaeohyphomycosis in a renal transplant patient.

NARCIS (Netherlands)

Nulens, E.; Laere, E. De; Vandevelde, H.; Hilbrands, L.B.; Rijs, A.J.M.M.; Melchers, W.J.G.; Verweij, P.E.

2006-01-01

A male renal transplant patient developed a tumor on the dorsum of his right hand. After excision, histological examination of the tumor showed hyphal structures, but growth developed very slowly. Therapy consisted of surgery alone. A definitive identification of Alternaria infectoria was only

Combining 'omics and microscopy to visualize interactions between the Asian citrus psyllid vector and the Huanglongbing pathogen Candidatus Liberibacter asiaticus in the insect gut

Science.gov (United States)

Huanglongbing, or citrus greening disease, is an economically devastating bacterial disease of citrus. It is associated with infection by the gram-negative bacterium Candidatus Liberibacter asiaticus (CLas). CLas is transmitted by Diaphorina citri, the Asian citrus psyllid (ACP). For insect transmis...

Effect of irradiation as quarantine treatment on citrus fruit quality

International Nuclear Information System (INIS)

Betancurt, Pablo; Montalban, Antonio; Arcia, Patricia; Borthagaray, Maria D.; Curutchet, Ana; Pica, Leticia; Soria, Alejandra; Abreu, Anibal V.; Ares, M. Ines

2009-01-01

Gamma radiations have been used to improve sanitation treatments without significant effects on fresh fruit quality. The objective of this work was to evaluate the fruit quality characteristics of citrus variety Valencia (Valencia Late), main variety produced and exported in Uruguay. All samples were stored at 3-5 deg C, 80% RH, for 20 and 40 days. Irradiation doses used were 0,35 kGy min. and 0,80 kGy max. (doses that also eliminate the fruit fly). Irradiation experiments were conducted using irradiation equipment from Atomic Center (CAE), year 1968, Co60 source, 800.000 Ci. The effects of irradiation on sensory qualities and physical characteristics were studied. The attributes evaluated were visual appearance (1- 4 hedonic scale, expert), overall acceptance (1-9 hedonic scale, consumers), texture (TAB Stevens, speed: 2m/s, distance: 2mm), yield of juice and colour (Hunter values). In general, no significant changes in these parameters were observed after irradiation. Quality was not significantly affected by doses usually applied to decrease the viability of pathogen that cause citrus Scab. This is an important contribution for the protocols that would allow citrus fruit exportation. (author)

Phenylethanol promotes adhesion and biofilm formation of the antagonistic yeast Kloeckera apiculata for the control of blue mold on citrus.

Science.gov (United States)

Pu, Liu; Jingfan, Fang; Kai, Chen; Chao-an, Long; Yunjiang, Cheng

2014-06-01

The yeast Kloeckera apiculata strain 34-9 is an antagonist with biological control activity against postharvest diseases of citrus fruit. In a previous study it was demonstrated that K. apiculata produced the aromatic alcohol phenylethanol. In the present study, we found that K. apiculata was able to form biofilm on citrus fruit and embed in an extracellular matrix, which created a mechanical barrier interposed between the wound surface and pathogen. As a quorum-sensing molecule, phenylethanol can promote the formation of filaments by K. apiculata in potato dextrose agar medium, whereas on the citrus fruit, the antagonist remains as yeast after being treated with the same concentration of phenylethanol. It only induced K. apiculata to adhere and form biofilm. Following genome-wide computational and experimental identification of the possible genes associated with K. apiculata adhesion, we identified nine genes possibly involved in triggering yeast adhesion. Six of these genes were significantly induced after phenylethanol stress treatment. This study provides a new model system of the biology of the antagonist-pathogen interactions that occur in the antagonistic yeast K. apiculata for the control of blue mold on citrus caused by Penicillium italicum. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

PENDIDIKAN DAN PELATIHAN PEMBIBITAN JERUK BEBAS PENYAKIT CVPD (Citrus Vein Phloem Degeneration DI DESA KATUNG KINTAMANI

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Adiartayasa W

2012-10-01

Full Text Available The community service in the form of training about free orange seed of disease CVPD (Citrus Vein Phloem Degenaration was conducted in Katung village, district of Kintamani, Bangli regency on 10 August 2007. The training activity aimed to improve knowledge of farmers about CVPD disease, symptom, transmission, insect vector, and integrated pest management. The topics covered were disease symptoms, and pathogen bacteria, Diaphorina citri are as insect vector infection mechanism, election of free orange mains crops CVPD, disease distribution and integrated management of CVPD. The training was attended by 25 participants from local groups of Katung village. The methods used in this activity were lectures, demonstration and practical work in the citrus field. All participants enthusiastically took part and hoped to have the next intensive training of citrus culture.

Agrobacterium-mediated transformation of Citrus sinensis and Citrus limonia epicotyl segments

OpenAIRE

Almeida,Weliton Antonio Bastos de; Mourão Filho,Francisco de Assis Alves; Mendes,Beatriz Madalena Januzzi; Pavan,Alexandra; Rodriguez,Adriana Pinheiro Martinelli

2003-01-01

Genetic transformation allows the release of improved cultivars with desirable characteristics in a shorter period of time and therefore may be useful in citrus breeding programs. The objective of this research was to establish a protocol for genetic transformation of Valencia and Natal sweet oranges (Citrus sinensis L. Osbeck) and Rangpur lime (Citrus limonia L. Osbeck). Epicotyl segments of germinated in vitro plantlets (three weeks in darkness and two weeks in a 16-h photoperiod) were used...

Nutritional deficiency in citrus with symptoms of citrus variegated chlorosis disease

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ME. Silva-Stenico

Full Text Available It is well known that citrus plants that have been infected by Xylella fastidiosa display nutritional deficiencies, probably caused by production of extracellular polymers by the bacteria that block normal nutrient flow through the xylem. The aim of this work was to study the mineral composition of specific foliar areas in different stages of infection in citrus. Thus, the concentrations of macro and micronutrients in leaves of citrus infected by X. fastidiosa were measured. Samples from four infected citrus orchards in the State of São Paulo, Brazil, were respectively collected from Santa Rita do Passa Quatro, Neves Paulista, Gavião Peixoto and Paraíso counties. The presence of X. fastidiosa in leaves was confirmed by polymerase chain reaction (PCR using specific PCR primers. To understand the variation in leaf-nutrient content in citrus plants, we used foliar nutrient values from control (non-symptomatic plants as a reference. Chemometric analysis showed that the deficiency of P and K in symptomatic trees for all orchards and high concentrations of Fe, Mn and Zn were observed in chlorotic areas, although other studies revealed deficiency of zinc in leaves. This is the first report showing that a correlation between chlorotic citrus leaf and higher concentrations of Fe, Mn and Zn are observed when infected and healthy plants were compared.

Citrus and Prunuscopia-like retrotransposons.

Science.gov (United States)

Asíns, M J; Monforte, A J; Mestre, P F; Carbonell, E A

1999-08-01

Many of the world's most important citrus cultivars ("Washington Navel", satsumas, clementines) have arisen through somatic mutation. This phenomenon occurs fairly often in the various species and varieties of the genus.The presence of copia-like retrotransposons has been investigated in fruit trees, especially citrus, by using a PCR assay designed to detect copia-like reverse transcriptase (RT) sequences. Amplification products from a genotype of each the following species Citrus sinensis, Citrus grandis, Citrus clementina, Prunus armeniaca and Prunus amygdalus, were cloned and some of them sequenced. Southern-blot hybridization using RT clones as probes showed that multiple copies are integrated throughout the citrus genome, while only 1-3 copies are detected in the P. armeniaca genome, which is in accordance with the Citrus and Prunus genome sizes. Sequence analysis of RT clones allowed a search for homologous sequences within three gene banks. The most similar ones correspond to RT domains of copia-like retrotransposons from unrelated plant species. Cluster analysis of these sequences has shown a great heterogeneity among RT domains cloned from the same genotype. This finding supports the hypothesis that horizontal transmission of retrotransposons has occurred in the past. The species presenting a RT sequence most similar to citrus RT clones is Gnetum montanum, a gymnosperm whose distribution area coincides with two of the main centers of origin of Citrus spp. A new C-methylated restriction DNA fragment containing a RT sequence is present in navel sweet oranges, but not in Valencia oranges from which the former originated suggesting, that retrotransposon activity might be, at least in part, involved in the genetic variability among sweet orange cultivars. Given that retrotransposons are quite abundant throughout the citrus genome, their activity should be investigated thoroughly before commercializing any transgenic citrus plant where the transgene(s) is part

Evaluation of the Tolerance of Some Citrus Rootstocks to Citrus Nematode in Greenhouse (Tylenchulus semipenetrans

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Y. Mohammad Alian

2018-02-01

Full Text Available Introduction: Citrus nematode is one of the most important damaging nematodes of citrus trees, spreading widely in most areas under citrus planting causing dieback, the gradual decline of trees and crop decrease in citrus orchards. Eighty citrus cultivars and species are sensitive to this nematode. From other nematode hosts, we can refer to olive, fig, medlar, persimmon, pear and grapevine. Surveys Full filled in Mazandaran province is indicative of the widespread of this nematode in citrus horticulture and the level of infection in some samples is so high, thus it is necessary to use different ways of controlling this parasite. Materials and Methods: This research was carried out for 2 successive years and the reaction of sin citrus rootstocks including Citromelo, Poncirus, Sour Orange, Bakraee, Rough lemon and Off-type to citrus nematode under controlled conditions in the greenhouse was evaluated. Three months years old plants of this rootstock Were planted in completely random design with 5 replications in pots containing the population of 40 larvae per cubic centimeter of soil and after six months, the level of infection of roots was investigated and then the most tolerable rootstock for nematode was introduced on the basis of the least population of young females and adult females injected in one gram of root volume. Results and Discussion: Experiment results on the basis of LSD test in two successive years indicated that there is a meaningful statistical difference between Citrumelo and poncirus Poncirus with the least population of nematode of adult female on the root and other treatments the results show that sour orange and off-type rootstocks are the most sensitive to citrus nematode, poncirus Poncirus and Citrumelo are the most tolerable to nematode Bakraee and Rough lemon are in the biotype group with average tolerance (relatively sensitive to citrus nematode. Purpose of this research is to assess the sensitivity level of six citrus

Genome editing of the disease susceptibility gene CsLOB1 in citrus confers resistance to citrus canker.

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Jia, Hongge; Zhang, Yunzeng; Orbović, Vladimir; Xu, Jin; White, Frank F; Jones, Jeffrey B; Wang, Nian

2017-07-01

Citrus is a highly valued tree crop worldwide, while, at the same time, citrus production faces many biotic challenges, including bacterial canker and Huanglongbing (HLB). Breeding for disease-resistant varieties is the most efficient and sustainable approach to control plant diseases. Traditional breeding of citrus varieties is challenging due to multiple limitations, including polyploidy, polyembryony, extended juvenility and long crossing cycles. Targeted genome editing technology has the potential to shorten varietal development for some traits, including disease resistance. Here, we used CRISPR/Cas9/sgRNA technology to modify the canker susceptibility gene CsLOB1 in Duncan grapefruit. Six independent lines, D LOB 2, D LOB 3, D LOB 9, D LOB 10, D LOB 11 and D LOB 12, were generated. Targeted next-generation sequencing of the six lines showed the mutation rate was 31.58%, 23.80%, 89.36%, 88.79%, 46.91% and 51.12% for D LOB 2, D LOB 3, D LOB 9, D LOB 10, D LOB 11 and D LOB 12, respectively, of the cells in each line. D LOB 2 and D LOB 3 showed canker symptoms similar to wild-type grapefruit, when inoculated with the pathogen Xanthomonas citri subsp. citri (Xcc). No canker symptoms were observed on D LOB 9, D LOB 10, D LOB 11 and D LOB 12 at 4 days postinoculation (DPI) with Xcc. Pustules caused by Xcc were observed on D LOB 9, D LOB 10, D LOB 11 and D LOB 12 in later stages, which were much reduced compared to that on wild-type grapefruit. The pustules on D LOB 9 and D LOB 10 did not develop into typical canker symptoms. No side effects and off-target mutations were detected in the mutated plants. This study indicates that genome editing using CRISPR technology will provide a promising pathway to generate disease-resistant citrus varieties. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

One Target, Two Mechanisms: The Impact of 'Candidatus Liberibacter asiaticus' and Its Vector, Diaphorina citri, on Citrus Leaf Pigments.

Science.gov (United States)

Killiny, Nabil; Nehela, Yasser

2017-07-01

Huanglongbing (HLB) is currently the largest threat to global citrus production. We examined the effect of HLB pathogen 'Candidatus Liberibacter asiaticus' infection or infestation by its vector, Diaphorina citri, on 'Valencia' sweet orange leaf pigments using high-performance liquid chromatography, followed by gene expression analysis for 46 involved genes in carotenoid and chlorophyll biosynthesis pathways. Both 'Ca. L. asiaticus' and D. citri alter the total citrus leaf pigment balance with a greater impact by 'Ca. L. asiaticus'. Although zeaxanthin was accumulated in 'Ca. L. asiaticus'-infected leaves, chlorophyllide a was increased in D. citri-infested plants. Our findings support the idea that both 'Ca. L. asiaticus' and D. citri affect the citrus pigments and promote symptom development but using two different mechanisms. 'Ca. L. asiaticus' promotes chlorophyll degradation but accelerates the biosynthesis of carotenoid pigments, resulting in accumulation of abscisic acid and its precursor, zeaxanthin. Zeaxanthin also has a photoprotective role. By contrast, D. citri induced the degradation of most carotenoids and accelerated chlorophyll biosynthesis, leading to chlorophyllide a accumulation. Chlorophyllide a might have an antiherbivory role. Accordingly, we suggest that citrus plants try to defend themselves against 'Ca. L. asiaticus' or D. citri using multifaceted defense systems, based on the stressor type. These findings will help in better understanding the tritrophic interactions among plant, pathogen, and vector.

Two previously unknown Phytophthora species associated with brown rot of Pomelo (Citrus grandis fruits in Vietnam.

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Ivana Puglisi

Full Text Available Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis, a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana rootstocks grafted with 'King' mandarin (Citrus nobilis and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch's postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi, sweet orange (Citrus x sinensis and bergamot (Citrus x bergamia as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on 'Carrizo' citrange (C. sinensis 'Washington Navel' x Poncirus trifoliata. This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity.

Two previously unknown Phytophthora species associated with brown rot of Pomelo (Citrus grandis) fruits in Vietnam.

Science.gov (United States)

Puglisi, Ivana; De Patrizio, Alessandro; Schena, Leonardo; Jung, Thomas; Evoli, Maria; Pane, Antonella; Van Hoa, Nguyen; Van Tri, Mai; Wright, Sandra; Ramstedt, Mauritz; Olsson, Christer; Faedda, Roberto; Magnano di San Lio, Gaetano; Cacciola, Santa Olga

2017-01-01

Two distinct Phytophthora taxa were found to be associated with brown rot of pomelo (Citrus grandis), a new disease of this ancestral Citrus species, in the Vinh Long province, Mekong River Delta area, southern Vietnam. On the basis of morphological characters and using the ITS1-5.8S-ITS2 region of the rDNA and the cytochrome oxidase subunit 1 (COI) as barcode genes, one of the two taxa was provisionally named as Phytophthora sp. prodigiosa, being closely related to but distinct from P. insolita, a species in Phytophthora Clade 9, while the other one, was closely related to but distinct from the Clade 2 species P. meadii and was informally designated as Phytophthora sp. mekongensis. Isolates of P. sp. prodigiosa and P. sp. mekongensis were also obtained from necrotic fibrous roots of Volkamer lemon (C. volkameriana) rootstocks grafted with 'King' mandarin (Citrus nobilis) and from trees of pomelo, respectively, in other provinces of the Mekong River Delta, indicating a widespread occurrence of both Phytophthora species in this citrus-growing area. Koch's postulates were fulfilled via pathogenicity tests on fruits of various Citrus species, including pomelo, grapefruit (Citrus x paradisi), sweet orange (Citrus x sinensis) and bergamot (Citrus x bergamia) as well as on the rootstock of 2-year-old trees of pomelo and sweet orange on 'Carrizo' citrange (C. sinensis 'Washington Navel' x Poncirus trifoliata). This is the first report of a Phytophthora species from Clade 2 other than P. citricola and P. citrophthora as causal agent of fruit brown rot of Citrus worldwide and the first report of P. insolita complex in Vietnam. Results indicate that likely Vietnam is still an unexplored reservoir of Phytophthora diversity.

Marginal scorch caused by Alternaria alternata on Purple-Caitai ...

African Journals Online (AJOL)

Marginal scorch caused by Alternaria alternata on Purple-Caitai (Brassia campestris L. ssp. chinensis L.var. utilis Tsen et Lee) in China. Qijun Nie, Zhongjiu Jiao, Fengjuan Zhu, Zhenbiao Jiao, Xiaohui Deng, Zhengming Qiu, Jinping Wu ...

Inducible expression of Bs2 R gene from Capsicum chacoense in sweet orange (Citrus sinensis L. Osbeck) confers enhanced resistance to citrus canker disease.

Science.gov (United States)

Sendín, Lorena Noelia; Orce, Ingrid Georgina; Gómez, Rocío Liliana; Enrique, Ramón; Grellet Bournonville, Carlos Froilán; Noguera, Aldo Sergio; Vojnov, Adrián Alberto; Marano, María Rosa; Castagnaro, Atilio Pedro; Filippone, María Paula

2017-04-01

Transgenic expression of the pepper Bs2 gene confers resistance to Xanthomonas campestris pv. vesicatoria (Xcv) pathogenic strains which contain the avrBs2 avirulence gene in susceptible pepper and tomato varieties. The avrBs2 gene is highly conserved among members of the Xanthomonas genus, and the avrBs2 of Xcv shares 96% homology with the avrBs2 of Xanthomonas citri subsp. citri (Xcc), the causal agent of citrus canker disease. A previous study showed that the transient expression of pepper Bs2 in lemon leaves reduced canker formation and induced plant defence mechanisms. In this work, the effect of the stable expression of Bs2 gene on citrus canker resistance was evaluated in transgenic plants of Citrus sinensis cv. Pineapple. Interestingly, Agrobacterium-mediated transformation of epicotyls was unsuccessful when a constitutive promoter (2× CaMV 35S) was used in the plasmid construction, but seven transgenic lines were obtained with a genetic construction harbouring Bs2 under the control of a pathogen-inducible promoter, from glutathione S-transferase gene from potato. A reduction of disease symptoms of up to 70% was observed in transgenic lines expressing Bs2 with respect to non-transformed control plants. This reduction was directly dependent on the Xcc avrBs2 gene since no effect was observed when a mutant strain of Xcc with a disruption in avrBs2 gene was used for inoculations. Additionally, a canker symptom reduction was correlated with levels of the Bs2 expression in transgenic plants, as assessed by real-time qPCR, and accompanied by the production of reactive oxygen species. These results indicate that the pepper Bs2 resistance gene is also functional in a family other than the Solanaceae, and could be considered for canker control.

Disruption of Vector Host Preference with Plant Volatiles May Reduce Spread of Insect-Transmitted Plant Pathogens.

Science.gov (United States)

Martini, Xavier; Willett, Denis S; Kuhns, Emily H; Stelinski, Lukasz L

2016-05-01

Plant pathogens can manipulate the odor of their host; the odor of an infected plant is often attractive to the plant pathogen vector. It has been suggested that this odor-mediated manipulation attracts vectors and may contribute to spread of disease; however, this requires further broad demonstration among vector-pathogen systems. In addition, disruption of this indirect chemical communication between the pathogen and the vector has not been attempted. We present a model that demonstrates how a phytophathogen (Candidatus Liberibacter asiaticus) can increase its spread by indirectly manipulating the behavior of its vector (Asian citrus psyllid, Diaphorina citri Kuwayama). The model indicates that when vectors are attracted to pathogen-infected hosts, the proportion of infected vectors increases, as well as, the proportion of infected hosts. Additionally, the peak of infected host populations occurs earlier as compared with controls. These changes in disease dynamics were more important during scenarios with higher vector mortality. Subsequently, we conducted a series of experiments to disrupt the behavior of the Asian citrus psyllid. To do so, we exposed the vector to methyl salicylate, the major compound released following host infection with the pathogen. We observed that during exposure or after pre-exposure to methyl salicylate, the host preference can be altered; indeed, the Asian citrus psyllids were unable to select infected hosts over uninfected counterparts. We suggest mechanisms to explain these interactions and potential applications of disrupting herbivore host preference with plant volatiles for sustainable management of insect vectors.

Aislamiento, identificación y pruebas in vitro de cepas autóctonas de Bacillus subtilis como agente de biocontrol de Alternaria spp en Brassica oleracea var.italica.

OpenAIRE

Ñacato Suntaxi, Carolina Aracely; Valencia Gordón, María Fernanda

2016-01-01

There is an increasing consumer demand for quality food, a concept which mainly involves the availability of disease-free products and harmful to human health chemical waste, which is why the need for new options for sustainable management arises broccoli crop against the causative pathogen damage in inflorescence. The disease caused by the phytopathogenic fungus Alternaria spp is a major cause of damage to broccoli cultivars. Field sampling and laboratory investigations w...

The diversity of citrus endophytic bacteria and their interactions with Xylella fastidiosa and host plants

Science.gov (United States)

Azevedo, João Lúcio; Araújo, Welington Luiz; Lacava, Paulo Teixeira

2016-01-01

Abstract The bacterium Xylella fastidiosa is the causal agent of citrus variegated chlorosis (CVC) and has been associated with important losses in commercial orchards of all sweet orange [Citrus sinensis (L.)] cultivars. The development of this disease depends on the environmental conditions, including the endophytic microbial community associated with the host plant. Previous studies have shown that X. fastidiosa interacts with the endophytic community in xylem vessels as well as in the insect vector, resulting in a lower bacterial population and reduced CVC symptoms. The citrus endophytic bacterium Methylobacterium mesophilicum can trigger X. fastidiosa response in vitro, which results in reduced growth and induction of genes associated with energy production, stress, transport, and motility, indicating that X. fastidiosa has an adaptive response to M. mesophilicum. Although this response may result in reduced CVC symptoms, the colonization rate of the endophytic bacteria should be considered in studies that intend to use this endophyte to suppress CVC disease. Symbiotic control is a new strategy that uses symbiotic endophytes as biological control agents to antagonize or displace pathogens. Candidate endophytes for symbiotic control of CVC must occupy the xylem of host plants and attach to the precibarium of sharpshooter insects to access the pathogen. In the present review, we focus on interactions between endophytic bacteria from sweet orange plants and X. fastidiosa, especially those that may be candidates for control of CVC. PMID:27727362

Molecular mechanisms behind the accumulation of adenosine triphosphate (ATP) and H2O2 in citrus plants in response to ‘Candidatus Liberibacter asiaticus’ infection

Science.gov (United States)

Candidatus Liberibacter asiaticus (Las) is a fastidious, phloem-restricted pathogen with a significantly reduced genome, and attacks all citrus species with no immune cultivars documented to date. Like other plant bacterial pathogens, Las deploys effector proteins into the organelles of plant cells,...

Effect of Nigerian citrus ( Citrus sinensis Osbeck) honey on ethanol ...

African Journals Online (AJOL)

The effect of Nigerian citrus (Citrus sinensis Osbeck) honey on ethanol metabolism was tested using 45 consenting individuals in apparent good health and between the ages of 25 and 35 years. The subjects were moderate social drinkers matched in terms of body weight and build. The results obtained showed that on ...

An Ecoinformatics Approach to Field-Scale Evaluation of Insecticide Effects in California Citrus: Are Citrus Thrips and Citrus Red Mite Induced Pests?

Science.gov (United States)

Livingston, George; Hack, Lindsey; Steinmann, Kimberly P; Grafton-Cardwell, Elizabeth E; Rosenheim, Jay A

2018-05-28

Experimental approaches to studying the consequences of pesticide use, including impacts on beneficial insects, are vital; however, they can be limited in scale and realism. We show that an ecoinformatics approach that leverages existing data on pesticides, pests, and beneficials across multiple fields can provide complementary insights. We do this using a multi-year dataset (2002-2013) on pesticide applications and density estimates of two pests, citrus thrips (Scirtothrips citri (Moulton [Thysanoptera: Thripidae])) and citrus red mites (Panonychus citri McGregor [Acari: Tetranychidae]), and a natural enemy (Euseius spp. predatory mites) collected from citrus groves in the San Joaquin Valley of California. Using correlative analyses, we investigated the long-term consequences of pesticide use on S. citri and P. citri population densities to evaluate the hypothesis that the pest status of these species is largely due to the disruption of natural biological control-i.e., these are induced pests. We also evaluated short-term pesticide efficacy (suppression of citrus thrips and citrus red mite populations immediately post-application) and asked if it was correlated with the suppression of Euseius predator populations. Although the short-term efficacy of different pesticides varied significantly, our dataset does not suggest that the use of citrus pesticides suppressed Euseius densities or worsened pest problems. We also find that there is no general trade-off between pesticide efficacy and pesticide risk to Eusieus, such that highly effective and minimally disruptive compounds were available to citrus growers during the studied time period.

Evaluation of resistance to asiatic citrus canker among selections of pera sweet orange (Citrus sinensis)

Science.gov (United States)

Asiatic citrus canker (ACC, caused by the bacterium Xanthomonas citri subsp. citri) is a destructive disease of citrus in Brazil and in several other citrus-producing countries. ACC management is problematic, and bactericides such as copper can be reasonably efficacious but do not completely control...

Eficiência e custo do controle químico da mancha de alternaria em tangor murcote Efficiency and cost of chemical control of alternaria brown spot

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Adimara Bentivoglio Colturato

2009-09-01

Full Text Available A mancha de alternaria, causada por Alternaria alternata f. sp. citri, afeta tangelos Minneola, tangerinas Dancy, tangores Murcote e, menos freqüentemente, tangelos Orlando, tangerinas Novas, Lees e Sunburst. Esta doença causa desfolha grave, queda de frutos e manchas nas frutas. O objetivo deste trabalho foi estabelecer o melhor fungicida e a melhor dose para o controle da mancha marrom de alternaria. O delineamento experimental foi de parcelas subdivididas em blocos, com 10 tratamentos principais e 3 doses (subparcelas, com 5 repetições. Foram feitas 5 aplicações, com intervalo de 15 dias. Os tratamentos foram: azoxystrobin, pyraclostrobin, trifloxystrobin, trifloxystrobin + tebuconazole (2 aplicações seguido de 3 aplicações de mancozeb, difenoconazole, trifloxystrobin + propiconazole, iprodione, trifloxystrobin + propineb (2 aplicações seguido de 3 aplicações de oxicloreto de cobre, oxicloreto de cobre + óleo e testemunha. Simultaneamente foram feitas avaliações de incidência e número de lesões por folha. Ao surgimento dos frutos foram avaliadas a incidência em frutos e a produtividade em Kg/ha. Todos os tratamentos foram superiores à testemunha quanto a produtividade. Entre os produtos utilizados o tratamento com trifloxystrobin + propiconazole foi rentável comparando-se custo e produtividade.Alternaria brown spot, caused by Alternaria alternata sp. citri, attacks with more intensity the Tangelos Minneola, tangerine Dancy, and Murcotts, and with less intensity the tangelos Orlando and the tangerinas Novas, Lees and Sunburst. This disease causes severe defoliation and drop or necrotic spots in the fruits. The aim of this work was to evaluated the chemical control of brown spot, and to define the most appropriate dosage of fungicide to control it. The experimental design was split-spot, with ten treatments and 3 doses of fungicides, with five replicates, the fungicides were: azoxystrobin, pyraclostrobin, trifloxystrobin

Accumulation of the sesquiterpenes nootkatone and valencene by callus cultures of Citrus paradisi, Citrus limonia and Citrus aurantium.

Science.gov (United States)

Del Río, J A; Ortuño, A; Puig, D G; Iborra, J L; Sabater, F

1991-10-01

The production of the sesquiterpenes nootkatone and valencene by callus cultures of Citrus species is described. The levels of these compounds were examined by gas chromatography-mass spectrometry and their yields were compared with the amounts found in mature fruits. A simultaneous increase and decrease in the levels of nootkatone and valencene, respectively, were observed with the aging of callus cultures of Citrus paradisi. These results suggest that valencene might be a possible precursor of nootkatone in this species. The high level of nootkatone detected in 9-month-old callus cultures of Citrus paradisi might be associated with the corresponding cell morphological changes observed.

Antifungal Edible Coatings for Fresh Citrus Fruit: A Review

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Lluís Palou

2015-12-01

Full Text Available According to their origin, major postharvest losses of citrus fruit are caused by weight loss, fungal diseases, physiological disorders, and quarantine pests. Cold storage and postharvest treatments with conventional chemical fungicides, synthetic waxes, or combinations of them are commonly used to minimize postharvest losses. However, the repeated application of these treatments has led to important problems such as health and environmental issues associated with fungicide residues or waxes containing ammoniacal compounds, or the proliferation of resistant pathogenic fungal strains. There is, therefore, an increasing need to find non-polluting alternatives to be used as part of integrated disease management (IDM programs for preservation of fresh citrus fruit. Among them, the development of novel natural edible films and coatings with antimicrobial properties is a technological challenge for the industry and a very active research field worldwide. Chitosan and other edible coatings formulated by adding antifungal agents to composite emulsions based on polysaccharides or proteins and lipids are reviewed in this article. The most important antifungal ingredients are selected for their ability to control major citrus postharvest diseases like green and blue molds, caused by Penicillium digitatum and Penicillium italicum, respectively, and include low-toxicity or natural chemicals such as food additives, generally recognized as safe (GRAS compounds, plant extracts, or essential oils, and biological control agents such as some antagonistic strains of yeasts or bacteria.

Repellent Activity of Botanical Oils against Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae).

Science.gov (United States)

Kuhns, Emily H; Martini, Xavier; Hoyte, Angel; Stelinski, Lukasz L

2016-07-14

The Asian citrus psyllid, Diaphorina citri Kuwayama, is the insect vector of the pathogen causing huanglongbing. We selected three botanical oils to evaluate behavioral activity against D. citri. In laboratory olfactometer assays, fir oil was repellent to D. citri females, while litsea and citronella oils elicited no response from D. citri females. In choice settling experiments, D. citri settled almost completely on control plants rather than on plants treated with fir oil at a 9.5 mg/day release rate. Therefore, we conducted field trials to determine if fir oil reduced D. citri densities in citrus groves. We found no repellency of D. citri from sweet orange resets that were treated with fir oil dispensers releasing 10.4 g/day/tree as compared with control plots. However, we found a two-week decrease in populations of D. citri as compared with controls when the deployment rate of these dispensers was doubled. Our results suggest that treatment of citrus with fir oil may have limited activity as a stand-alone management tool for D. citri and would require integration with other management practices.

Symptomatic Citrus trees reveal a new pathogenic lineage in Fusarium and two new Neocosmospora species

NARCIS (Netherlands)

Sandoval-Denis, M.; Guarnaccia, V.; Polizzi, G.; Crous, P.W.

2018-01-01

The diversity of fusaria in symptomatic Citrus trees in Greece, Italy and Spain was evaluated using morphological and molecular multi-locus analyses based on fragments of the calmodulin (CAM), intergenic spacer region of the rDNA (IGS), internal transcribed spacer region of the rDNA (ITS), large

Deep-sequencing revealed Citrus bark cracking viroid (CBCVd) as a highly aggressive pathogen on hop

Czech Academy of Sciences Publication Activity Database

Jakše, J.; Radišek, S.; Pokorn, T.; Matoušek, Jaroslav; Javornik, B.

2015-01-01

Roč. 64, č. 4 (2015), s. 831-842 ISSN 0032-0862 R&D Projects: GA MŠk(CZ) LH14255 Institutional support: RVO:60077344 Keywords : Bioinformatic * Citrus bark cracking viroid * Hop * Next-generation sequencing Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.383, year: 2015

IDENTIFICATION AND QUANTIFICATION OF DIFFERENTIALLY EXPRESSED GENES ASSOCIATED WITH CITRUS BLIGHT (Citrus spp.

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José Renato de Abreu

2015-02-01

Full Text Available Brazil is the largest citrus producer in the world, being responsible for more than 20% of its production, which is, however still low due to phytosanitary issues such as citrus blight. Citrus blight is an anomaly whose causes still have not yet been determined, therefore there are no efficient control measures to minimize the production losses with the use of resistant varieties being considered the most appropriate method. However, little is known about the genes involved in the defense response of the plants to this anomaly. Considering that many physiological alterations associated with plant stress responses are controlled at a transcriptional level, in this study we sought the identification and characterization of the gene expression products differentially expressed in the response to the citrus blight. Through the suppressive subtractive hybridization technique, expressed cDNA libraries were built using mRNAs isolated from "Cravo" lemon tree roots (Citrus limonia L. Osbeck under "Pera" orange (Citrus sinensis L. Osbeck of healthy and sick plants. 129 clones were obtained by subtraction and their sequences were compared in databases. 34 of them linked to proteins associated to stress processes, while the others were similar to sequences of unknown functions or did not present similarity with sequences deposited in the databases. 3 genes were selected and their expressions were studied by RT - qPCR in real-time. Plants with citrus blight presented an increase of the expression level in two of those genes, suggesting that these can be directly involved with this anomaly.

Citrus Waste Biomass Program

Energy Technology Data Exchange (ETDEWEB)

Karel Grohman; Scott Stevenson

2007-01-30

Renewable Spirits is developing an innovative pilot plant bio-refinery to establish the commercial viability of ehtanol production utilizing a processing waste from citrus juice production. A novel process based on enzymatic hydrolysis of citrus processing waste and fermentation of resulting sugars to ethanol by yeasts was successfully developed in collaboration with a CRADA partner, USDA/ARS Citrus and Subtropical Products Laboratory. The process was also successfully scaled up from laboratory scale to 10,000 gal fermentor level.

Spatial Genetic Structure of Coffee-Associated Xylella fastidiosa Populations Indicates that Cross Infection Does Not Occur with Sympatric Citrus Orchards.

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Francisco, Carolina S; Ceresini, Paulo C; Almeida, Rodrigo P P; Coletta-Filho, Helvécio D

2017-04-01

Xylella fastidiosa, an economically important plant-pathogenic bacterium, infects both coffee and citrus trees in Brazil. Although X. fastidiosa in citrus is well studied, knowledge about the population structure of this bacterium infecting coffee remains unknown. Here, we studied the population structure of X. fastidiosa infecting coffee trees in São Paulo State, Brazil, in four regions where citrus is also widely cultivated. Genotyping of over 500 isolates from coffee plants using 14 genomic microsatellite markers indicated that populations were largely geographically isolated, as previously found with populations of X. fastidiosa infecting citrus. These results were supported by a clustering analysis, which indicated three major genetic groups among the four sampled regions. Overall, approximately 38% of isolates showed significant membership coefficients not related to their original geographical populations (i.e., migrants), characterizing a significant degree of genotype flow among populations. To determine whether admixture occurred between isolates infecting citrus and coffee plants, one site with citrus and coffee orchards adjacent to each other was selected; over 100 isolates were typed from each host plant. No signal of natural admixture between citrus- and coffee-infecting isolates was found; artificial cross-infection assays with representative isolates also yielded no successful cross infection. A comparison determined that X. fastidiosa populations from coffee have higher genetic diversity and allelic richness compared with citrus. The results showed that coffee and citrus X. fastidiosa populations are effectively isolated from each other and, although coffee populations are spatially structured, migration has an important role in shaping diversity.

Structural and physiological analyses of the alkanesulphonate-binding protein (SsuA of the citrus pathogen Xanthomonas citri.

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Fabiano Tófoli de Araújo

Full Text Available BACKGROUND: The uptake of sulphur-containing compounds plays a pivotal role in the physiology of bacteria that live in aerobic soils where organosulfur compounds such as sulphonates and sulphate esters represent more than 95% of the available sulphur. Until now, no information has been available on the uptake of sulphonates by bacterial plant pathogens, particularly those of the Xanthomonas genus, which encompasses several pathogenic species. In the present study, we characterised the alkanesulphonate uptake system (Ssu of Xanthomonas axonopodis pv. citri 306 strain (X. citri, the etiological agent of citrus canker. METHODOLOGY/PRINCIPAL FINDINGS: A single operon-like gene cluster (ssuEDACB that encodes both the sulphur uptake system and enzymes involved in desulphurisation was detected in the genomes of X. citri and of the closely related species. We characterised X. citri SsuA protein, a periplasmic alkanesulphonate-binding protein that, together with SsuC and SsuB, defines the alkanesulphonate uptake system. The crystal structure of SsuA bound to MOPS, MES and HEPES, which is herein described for the first time, provides evidence for the importance of a conserved dipole in sulphate group coordination, identifies specific amino acids interacting with the sulphate group and shows the presence of a rather large binding pocket that explains the rather wide range of molecules recognised by the protein. Isolation of an isogenic ssuA-knockout derivative of the X. citri 306 strain showed that disruption of alkanesulphonate uptake affects both xanthan gum production and generation of canker lesions in sweet orange leaves. CONCLUSIONS/SIGNIFICANCE: The present study unravels unique structural and functional features of the X. citri SsuA protein and provides the first experimental evidence that an ABC uptake system affects the virulence of this phytopathogen.

Induced resistance against the Asian citrus psyllid, Diaphorina citri, by β-aminobutyric acid in citrus.

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Tiwari, Siddharth; Meyer, Wendy L; Stelinski, Lukasz L

2013-10-01

β-Aminobutyric acid (BABA) is known to induce resistance to microbial pathogens, nematodes and insects in several host plant/pest systems. The present study was undertaken to determine whether a similar effect of BABA occurred against the Asian citrus psyllid, Diaphorina citri Kuwayama, in citrus. A 25 mM drench application of BABA significantly reduced the number of eggs/plant as compared with a water control, whereas 200 and 100 mM applications of BABA reduced the numbers of nymphs/plant and adults/plants, respectively. A 5 mM foliar application of BABA significantly reduced the number of adults but not eggs or nymphs when compared with a water control treatment. In addition, leaf-dip bioassays using various concentrations (25–500 mM) of BABA indicated no direct toxic effect on 2nd and 5th instar nymphs or adult D. citri. BABA-treated plants were characterized by significantly lower levels of iron, magnesium, phosphorus, sodium, sulfur and zinc as compared with control plants. The expression level of the PR-2 gene (β-1,3-glucanase) in BABA-treated plants that were also damaged by D. citri adult feeding was significantly higher than in plants exposed to BABA, D. citri feeding alone or control plants. Our results indicate the potential for using BABA as a systemic acquired resistance management tool for D. citri.

Microjets of citrus fruit

Science.gov (United States)

Smith, Nicholas; Dickerson, Andrew

2017-11-01

The rupture of oil glands in the citrus exocarp is a common experience to the discerning citrus consumer. When peeled, oil cavities housed with the citrus exocarp often rupture outwardly in response to externally applied bending stresses. Bending of the peel compresses the soft material surrounding the glands, the albedo, increasing fluid pressure. Ultimately, the fluid pressure exceeds the failure strength of the outermost membrane, the flavedo. The ensuing high-velocity discharge of oil and exhaustive emptying of oil glands creates a novel method for jetting small quantities of the aromatic and volatile oil. We compare the jetting behavior across five citrus hybrids through high-speed videography and material testing of exocarps. The jetting oil undergoes an initial acceleration surpassing 5,000 gravities, reaching velocities in excess of 10 m/s. Film of citrus jets and mimicking jets in the lab reveal their high level of instability is caused by irregular and non-circular orifice geometry. Through material characterization and bending simulations, we rationalize the combination of material properties necessary to generate the internal gland pressures required for explosive dispersal.

THE USE OF AZADIRACHTA INDICA EXTRACT TO DECREASE OF ALTERNARIA PORRI DISEASE ON ONION

OpenAIRE

Loso Winarto; Novia Chairuman

2013-01-01

Purple spot caused by Alternaria porri a major disease in the onion crop in the world. The disease is also widespread in the onion crop in Indonesia. This research aim was to know the effect of mimba leaf (Azadirachta indica) extract concentration to decrease of Alternaria porri on onion (Allium ascalonicum L).This research conducted at Research Garden of the Center of Agricultural Technology Assessment of North Sumatra Province, from October 2010 until January 2011.The researc...

Estimation of Fluoride Concentration of Various Citrus and Non-Citrus Fruits Commonly Consumed and Commercially Available in Mathura City

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Navin Anand Ingle

2013-01-01

Full Text Available Background: Since fluoride is available from various sources, the total ingestion of fluoride by a person should be estimated taking into consideration the fluoride consumed from all the sources including fruits. There are very few epidemiological studies carried out associated with fluoride estimation in fruit samplesand especially in the Indian scenario Objective: To estimate and compare the fluoride concentration of different commercially available citrus and non-citrus fruits in Mathura city. Materials & Method: Fifteen different types of fruits commercially available and consumed by people ofMathura City were collected. Out of the 15 fruit samples 5 were citrus fruits and 10 were non-citrus fruits. The fluoride estimation of fruit samples was done at Central Laboratory,Lucknow. Juices of all 15 fruit samples were prepared, from each sample 10 ml of juice was measured and fluoride testing of each sample was carried out by using Orion 4 star -ion electrode analyzer. The collected data was analyzed using the statistical software program SPSS, version 17. Results: The fluoride concentration in citrus fruits ranged from 0.04ppm (Orange to 0.08 ppm (Tomato while in non-citrus fruits it ranged from 0.04ppm (chikoo to 0.18 ppm (Guava. No significant difference was observed between the mean fluoride concentration of citrus and non citrus fruits. Conclusions: Both citrus and non citrus fruits have fluorides. Guava was found to have the maximumamount of fluoridecontent (0.18 ppm among both the citrus and non citrus fruits.

THE INFLUENCE OF NATURAL ESSENTIAL OILS ON THE GROWTH OF PHYTOPHTHORA SPP. ISOLATED FROM PELARGONIUM CUTTINGS

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Marcelina Machura

2017-10-01

Full Text Available Ornamental plants play an important role in human life. Plants positively influence the psyche and improve the well-being of people around them. They produce oxygen, provide a barrier to dust and noise, lower the temperature and increase air humidity, thereby positively impacting the microclimate. The unmatched appeal of pelargonium, ease of cultivation and care, abundance of flowering from spring to late autumn and its decorative qualities make it a universal application. The aim of the study was to isolate the microorganisms that inhabit the cuttings of pelargonium, identify fungal isolates, investigate the pathogenicity of selected isolates and evaluate the influence of certain essential oils (Carum carvi L. essential oils, Citrus limon L. essential oils, Citrus reticulatae aetheroleum essential oils, essential oil of tea tree in in vitro circumstances on the linear growth of the mycelium: Phytophthora cryptogea, Phytophthora nicotianae var. nicotianae. Previcur Energy 840 SL was used as a standard chemical protection. The most numerous isolated fungi were: Phytophthora, Botrytis, Cylindrocladium, Alternaria and Cylindrocarpon. The highest efficiency in relation to Phytophthora cryptogea characterized the Citrus limon L. essential oils (concentration 0.1% and 1% and Carum carvi L. essential oil (concentration 1%.

Field Evaluation of Plant Defense Inducers for the Control of Citrus Huanglongbing.

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Li, Jinyun; Trivedi, Pankaj; Wang, Nian

2016-01-01

Huanglongbing (HLB) is currently the most economically devastating disease of citrus worldwide and no established cure is available. Defense inducing compounds are able to induce plant resistance effective against various pathogens. In this study the effects of various chemical inducers on HLB diseased citrus were evaluated in four groves (three with sweet orange and one with mandarin) in Florida (United States) for two to four consecutive growing seasons. Results have demonstrated that plant defense inducers including β-aminobutyric acid (BABA), 2,1,3-benzothiadiazole (BTH), and 2,6-dichloroisonicotinic acid (INA), individually or in combination, were effective in suppressing progress of HLB disease. Ascorbic acid (AA) and the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DDG) also exhibited positive control effects on HLB. After three or four applications for each season, the treatments AA (60 to 600 µM), BABA (0.2 to 1.0 mM), BTH (1.0 mM), INA (0.1 mM), 2-DDG (100 µM), BABA (1.0 mM) plus BTH (1.0 mM), BTH (1.0 mM) plus AA (600 µM), and BTH (1.0 mM) plus 2-DDG (100 µM) slowed down the population growth in planta of 'Candidatus Liberibacter asiaticus', the putative pathogen of HLB and reduced HLB disease severity by approximately 15 to 30% compared with the nontreated control, depending on the age and initial HLB severity of infected trees. These treatments also conferred positive effect on fruit yield and quality. Altogether, these findings indicate that plant defense inducers may be a useful strategy for the management of citrus HLB.

Colonization of citrus seed coats by 'Candidatus Liberibacter asiaticus': implications for seed transmission of the bacterium.

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Hilf, Mark E

2011-10-01

Huanglongbing is an economically damaging disease of citrus associated with infection by 'Candidatus Liberibacter asiaticus'. Transmission of the organism via infection of seeds has not been demonstrated but is a concern since some citrus varieties, particularly those used as rootstocks in commercial plantings are propagated from seed. We compared the incidence of detection of 'Ca. Liberibacter asiaticus' DNA in individual fruit peduncles, seed coats, seeds, and in germinated seedlings from 'Sanguenelli' sweet orange and 'Conners' grapefruit fruits sampled from infected trees. Using real-time quantitative PCR (qPCR) we detected pathogen DNA in nucleic acid extracts of 36 and 100% of peduncles from 'Sanguenelli' and from 'Conners' fruits, respectively. We also detected pathogen DNA in extracts of 37 and 98% of seed coats and in 1.6 and 4% of extracts from the corresponding seeds of 'Sanguenelli' and 'Conners', respectively. Small amounts of pathogen DNA were detected in 10% of 'Sanguenelli' seedlings grown in the greenhouse, but in none of 204 extracts from 'Conners' seedlings. Pathogen DNA was detected in 4.9% and in 89% of seed coats peeled from seeds of 'Sanguenelli' and 'Conners' which were germinated on agar, and in 5% of 'Sanguenelli' but in none of 164 'Conners' seedlings which grew from these seeds on agar. No pathogen DNA was detected in 'Ridge Pineapple' tissue at 3 months post-grafting onto 'Sanguenelli' seedlings, even when pathogen DNA had been detected initially in the 'Sanguenelli' seedling. Though the apparent colonization of 'Conners' seeds was more extensive and nearly uniform compared with 'Sanguenelli' seeds, no pathogen DNA was detected in 'Conners' seedlings grown from these seeds. For either variety, no association was established between the presence of pathogen DNA in fruit peduncles and seed coats and in seedlings.

Bacillus subtilis based-formulation for the control of postbloom fruit drop of citrus.

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Klein, Mariana Nadjara; da Silva, Aline Caroline; Kupper, Katia Cristina

2016-12-01

Postbloom fruit drop (PFD) caused by Colletotrichum acutatum affects flowers and causes early fruit drop in all commercial varieties of citrus. Biological control with the isolate ACB-69 of Bacillus subtilis has been considered as a potential method for controlling this disease. This study aimed to develop and optimize a B. subtilis based-formulation with a potential for large-scale applications and evaluate its effect on C. acutatum in vitro and in vivo. Bacillus subtilis based-formulations were developed using different carrier materials, and their ability to control PFD was evaluated. The results of the assays led to the selection of the B. subtilis based-formulation with talc + urea (0.02 %) and talc + ammonium molybdate (1 mM), which inhibited mycelial growth and germination of C. acutatum. Studies with detached citrus flowers showed that the formulations were effective in controlling the pathogen. In field conditions, talc + urea (0.02 %) provided 73 % asymptomatic citrus flowers and 56 % of the average number of effective fruit (ANEF), equating with fungicide treatment. On the contrary, non-treated trees had 8.8 % of asymptomatic citrus flowers and 0.83 % ANEF. The results suggest that B. subtilis based-formulations with talc as the carrier supplemented with a nitrogen source had a high potential for PFD control.

Microbes Associated with Freshly Prepared Juices of Citrus and Carrots

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Kamal Rai Aneja

2014-01-01

Full Text Available Fruit juices are popular drinks as they contain antioxidants, vitamins, and minerals that are essential for human being and play important role in the prevention of heart diseases, cancer, and diabetes. They contain essential nutrients which support the growth of acid tolerant bacteria, yeasts, and moulds. In the present study, we have conducted a microbiological examination of freshly prepared juices (sweet lime, orange, and carrot by serial dilution agar plate technique. A total of 30 juice samples were examined for their microbiological quality. Twenty-five microbial species including 9 bacterial isolates, 5 yeast isolates, and 11 mould isolates were isolated from juices. Yeasts and moulds were the main cause of spoilage of juices. Aspergillus flavus and Rhodotorula mucilaginosa were observed in the maximum number of juice samples. Among bacteria Bacillus cereus and Serratia were dominant. Escherichia coli and Staphylococcus aureus were detected in few samples. Candida sp., Curvularia, Colletotrichum, and Acetobacter were observed only in citrus juice samples. Alternaria, Aspergillus terreus, A. niger, Cladosporium, and Fusarium were also observed in tested juice samples. Some of the microorganisms detected in these juice samples can cause disease in human beings, so there is need for some guidelines that can improve the quality of fruit juices.

A Climatic Classification for Citrus Winter Survival in China.

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Shou, Bo Huang

1991-05-01

The citrus tree is susceptible to frost damage. Winter injury to citrus from freezing weather is the major meteorological problem in the northern pail of citrus growing regions in China. Based on meteorological data collected at 120 stations in southern China and on the extent of citrus freezing injury, five climatic regions for citrus winter survival in China were developed. They were: 1) no citrus tree injury. 2) light injury to mandarins (citrus reticulate) or moderate injury to oranges (citrus sinensis), 3) moderate injury to mandarins or heavy injury to oranges, 4) heavy injury to mandarins, and 5) impossible citrus tree growth. This citrus climatic classification was an attempt to provide guidelines for regulation of citrus production, to effectively utilize land and climatic resources, to chose suitable citrus varieties, and to develop methods to prevent injury by freezing.

The diversity of citrus endophytic bacteria and their interactions with Xylella fastidiosa and host plants

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João Lúcio Azevedo

Full Text Available Abstract The bacterium Xylella fastidiosa is the causal agent of citrus variegated chlorosis (CVC and has been associated with important losses in commercial orchards of all sweet orange [Citrus sinensis (L.] cultivars. The development of this disease depends on the environmental conditions, including the endophytic microbial community associated with the host plant. Previous studies have shown that X. fastidiosa interacts with the endophytic community in xylem vessels as well as in the insect vector, resulting in a lower bacterial population and reduced CVC symptoms. The citrus endophytic bacterium Methylobacterium mesophilicum can trigger X. fastidiosa response in vitro, which results in reduced growth and induction of genes associated with energy production, stress, transport, and motility, indicating that X. fastidiosa has an adaptive response to M. mesophilicum. Although this response may result in reduced CVC symptoms, the colonization rate of the endophytic bacteria should be considered in studies that intend to use this endophyte to suppress CVC disease. Symbiotic control is a new strategy that uses symbiotic endophytes as biological control agents to antagonize or displace pathogens. Candidate endophytes for symbiotic control of CVC must occupy the xylem of host plants and attach to the precibarium of sharpshooter insects to access the pathogen. In the present review, we focus on interactions between endophytic bacteria from sweet orange plants and X. fastidiosa, especially those that may be candidates for control of CVC.

Occurrence of root parsley pathogens inhabiting seeds

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Bogdan Nowicki

2013-12-01

Full Text Available The studies on root parsley pathogens inhabiting seeds were conducted during 1981-1988 and in 1993. Filter paper method with prefreezing and keeping under light was used. Each test sample comprised 500 seeds. Pathogenicity of collected fungal isolates was tested following two laboratory methods. 238 seed samples were studied. 18 fungal species were found but only 7 proved to be important pathogens of root parsley. The most common inhabitants of root parsley seeds were Alternaria spp. A.allernata occurred on 74,8% of seeds but only a few isolates showed to be slightly pathogenic while A.petroselini and A.radicina were higly pathogenic and inhabited 11,4 and 4,2% of seeds, respectively. The second group of important pathogens were species of Fusarium found on 3,9% of seeds. F.avenaceum dominated as it comprised 48% of Fusarium isolates, the next were as follow: F.culmorum - 20%, F.equiseti - 15%, F.solani - 8%, F.oxysporum - 7% and F.dimerum -2%. Some fungi like Botrytis cinerea, Septoria petroselini and Phoma spp. inhabited low number of seeds, respectively O,4; 0,5 and 0,8%, but they were highly pathogenic to root parsley. The fungi: Bipolaris sorokiniana, Drechslera biseptata, Stemphylium botryosum and Ulocludium consortiale showed slight pathogenicity. They were isolated from 3,8% of seeds.

Chemical constituents of marine mangrove-derived endophytic fungus Alternaria tenuissima EN-192

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Sun, Hong; Gao, Shushan; Li, Xiaoming; Li, Chunshun; Wang, Bingui

2013-03-01

A chemical investigation of the ethyl acetate extract of the fermentation broth of Alternaria tenuissima EN-192, an endophytic fungus obtained from the stems of the marine mangrove plant Rhizophora stylosa, resulted in the isolation of nine known secondary metabolites, including four indole-diterpenoids: penijanthine A ( 1), paspaline ( 2), paspalinine ( 3), and penitrem A ( 4); three tricycloalternarene derivatives: tricycloalternarene 3a ( 5), tricycloalternarene 1b ( 6), and tricycloalternarene 2b ( 7); and two alternariol congeners: djalonensone ( 8) and alternariol ( 9). The chemical structures of these metabolites were characterized through a combination of detailed spectroscopic analyses and their comparison with reports from the literature. The inhibitory activities of each isolated compound against four bacteria were evaluated and compounds 5 and 8 displayed moderate activity against the aquaculture pathogenic bacterium Vibrio anguillarum, with inhibition zone diameters of 8 and 9 mm, respectively, at 100 μg/disk. To the best of our knowledge, this is the first report on the secondary metabolites of mangrove-derived A lternaria tenuissima and also the first report of the isolation of indole-diterpenoids from fungal genus A lternaria.

Effect of postharvest practices including degreening on citrus carpoplane microbial biomes.

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Gomba, A; Chidamba, L; Korsten, L

2017-04-01

To investigate the effect of commercial citrus packhouse processing steps on the fruit surface microbiome of Clementines and Palmer navel oranges. Viable bacteria, yeast and fungi counts, and the pyrosequencing analysis of the 16S rRNA and ITS were used to evaluate the community structure and population dynamics of phylloepiphytic bacteria and fungi associated with commercial postharvest processing. Drenching significantly reduced microbial counts in all cases except for yeasts on navels, while the extent of degreening effects varied between the citrus varieties. Pyrosequencing analysis showed a total of 4409 bacteria and 5792 fungi nonchimeric unique sequences with an average of 1102 bacteria and 1448 fungi reads per sample. Dominant phyla on the citrus carpoplane were Proteobacteria (53·5%), Actinobacteria (19·9%), Bacteroidetes (5·6%) and Deinococcus-Thermus (5·4%) for bacteria and Ascomycota (80·5%) and Basidiomycota (9·8%) for fungi. Beginning with freshly harvested fruit fungal diversity declined significantly after drenching, but had little effect on bacteria and populations recovered during degreening treatments, including those for Penicillium sp. Packhouse processing greatly influences microbial communities on the citrus carpoplane. A broad orange biome was described with pyrosequencing and gave insight into the likely survival and persistence of pathogens, especially as they may affect the quality and safety of the packed product. A close examination of the microbiota of fruit and the impact of intervention strategies on the ecological balance may provide a more durable approach to reduce losses and spoilage. © 2017 The Society for Applied Microbiology.

In vitro control of Alternaria citri using antifungal potentials of ...

African Journals Online (AJOL)

In vitro control of Alternaria citri using antifungal potentials of Trichoderma species. Asma Murtaza, Shazia Shafique, Tehmina Anjum, Sobiya Shafique. Abstract. The antifungal potential of five species of Trichoderma viz., Trichoderma viride, Trichoderma aureoviride, Trichoderma reesei, Trichoderma koningii and ...

PENDIDIKAN DAN PELATIHAN PENGENDALIAN TERPADU PENYAKIT CVPD (CITRUS VEIN PHLOEM DEGENERATION PADA PERTANAMAN JERUK DI DESA PELAGA, KECAMATAN PETANG, KABUPATEN BADUNG

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WAYAN ADIARTAYASA

2012-09-01

Full Text Available ABSTRACT Education and training on integrated pest management (IPM of CVPD (Citrus Vein Phloem Degeneration was held at Pelaga village, Badung regency on 22 September 2005. The activities aimed to improve knowledge of the farmers about CVPD and factors influencing the intensity, insect vector and integrated pest management of CVPD. The topics convered were disease symptons, and pathogen bacteria, Diaphorina citri are as vector insect infection mechanism, disease distribubution and integrated management of CVPD. The training was attended by 26 participants from local groups of Pelaga village. The method used in activities were lectures, demonstration and practical work in the citrus field. All participants enthusiastically took part and hoped to have the next intensive traning of citrus culture.

Alternaria leaf spot in Michigan and fungicide sensitivity issues

Science.gov (United States)

Since 2010 there has been an increase in identification of Alternaria leaf spot on sugar beet in Michigan and other growing regions in the US and Canada. In 2016, the disease was severe enough to cause economic losses in the Michigan growing region. Michigan isolates from sugar beet were examined ...

Ethyl p-coumarate exerts antifungal activity in vitro and in vivo against fruit Alternaria alternata via membrane-targeted mechanism.

Science.gov (United States)

Li, Wusun; Yuan, Shuzhi; Sun, Jing; Li, Qianqian; Jiang, Weibo; Cao, Jiankang

2018-08-02

The fungus Alternaria alternata can cause food contamination by black spot rot and food safety issues due to the production of mycotoxins. In particular, A. alternata can infect many fresh fruits and vegetables and lead to considerable postharvest decay during storage and processing. The use of plant-derived products in postharvest disease management may be an acceptable alternative to traditional chemical fungicides. The aim of this study was to assess the antifungal activity of ethyl p-coumarate (EpCA) against Alternaria alternata in vitro and in vivo, and to determine the underlying mechanism. Results indicated that EpCA exhibited pronounced antifungal activity against in vitro mycelial growth of A. alternata, with half-inhibition concentration of 176.8 μg/mL. Spore germination of the pathogen was inhibited by EpCA in a dose-dependent manner. Moreover, in vivo test confirmed that both 100 and 800 μg/mL EpCA significantly reduced disease development of black spot rot in jujube fruit caused by A. alternata. The EpCA treatments increased plasma membrane permeability as great leakage of intercellular electrolytes, soluble proteins and sugars of A. alternata occurred during incubation. The EpCA treatments also caused increase of the influx of propidium iodide, a fluorescence dye binding nucleus DNA, into the affected spores, indicating the disrupted plasma membrane integrity. Observations of ultrastructure further evidenced the damage to plasma membrane and morphology of A. alternata caused by EpCA, which resulted in distortion, sunken and shrivelled of spores and mycelia of the pathogen. In addition, fluorometric assay by confocal laser scanning microscopy confirmed that the EpCA treatments induced endogenous reactive oxygen species (ROS) formation in the spores of A. alternata, with stronger and more stable accumulation of ROS at higher concentration of EpCA. Therefore, heavy oxidative damage to cellular membranes and organelles might happen as demonstrated

Diaphorina citri Induces Huanglongbing-Infected Citrus Plant Volatiles to Repel and Reduce the Performance of Propylaea japonica.

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Lin, Yongwen; Lin, Sheng; Akutse, Komivi S; Hussain, Mubasher; Wang, Liande

2016-01-01

Transmission of plant pathogens through insect vectors is a complex biological process involving interactions between the host plants, insects, and pathogens. Simultaneous impact of the insect damage and pathogenic bacteria in infected host plants induce volatiles that modify not only the behavior of its insect vector but also of their natural enemies, such as parasitoid wasps. Therefore, it is essential to understand how insects such as the predator ladybird beetle responds to volatiles emitted from a host plant and how the disease transmission alters the interactions between predators, vector, pathogens, and plants. In this study, we investigated the response of Propylaea japonica to volatiles from citrus plants damaged by Diaphorina citri and Candidatus Liberibacter asiaticus through olfactometer bioassays. Synthetic chemical blends were also used to determine the active compounds in the plant volatile. The results showed that volatiles emitted by healthy plants attracted more P. japonica than other treatments, due to the presence of high quantities of D-limonene and beta-ocimene, and the lack of methyl salicylate. When using synthetic chemicals in the olfactory tests, we found that D-limonene attracted P. japonica while methyl salicylate repelled the predator. However, beta-ocimene attracted the insects at lower concentrations but repelled them at higher concentrations. These results indicate that P. japonica could not efficiently search for its host by using volatile cues emitted from psyllids- and Las bacteria-infected citrus plants.

Deciphering the Bacterial Microbiome in Huanglongbing-Affected Citrus Treated with Thermotherapy and Sulfonamide Antibiotics.

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Chuanyu Yang

Full Text Available Huanglongbing (HLB is a serious citrus disease that threatens the citrus industry. In previous studies, sulfonamide antibiotics and heat treatment suppressed 'Candidatus Liberibacter asiaticus' (Las, but did not completely eliminate the Las. Furthermore, there are few reports studying the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics. In this study, combinations of heat (45°C or 40°C and sulfonamide treatment (sulfathiazole sodium-STZ, or sulfadimethoxine sodium-SDX were applied to HLB-affected citrus. The bacterial microbiome of HLB-affected citrus following thermotherapy and/or chemotherapy was characterized by PhyloChipTMG3-based metagenomics. Our results showed that the combination of thermotherapy at 45°C and chemotherapy with STZ and SDX was more effective against HLB than thermotherapy alone, chemotherapy alone, or a combination of thermotherapy at 40°C and chemotherapy. The PhyloChipTMG3-based results indicated that 311 empirical Operational Taxonomic Units (eOTUs were detected in 26 phyla. Cyanobacteria (18.01% were dominant after thermo-chemotherapy. Thermotherapy at 45°C decreased eOTUs (64.43% in leaf samples, compared with thermotherapy at 40°C (73.96% or without thermotherapy (90.68% and it also reduced bacterial family biodiversity. The eOTU in phylum Proteobacteria was reduced significantly and eOTU_28, representing "Candidatus Liberibacter," was not detected following thermotherapy at 45°C. Following antibiotic treatment with SDX and STZ, there was enhanced abundance of specific eOTUs belonging to the families Streptomycetaceae, Desulfobacteraceae, Chitinophagaceae, and Xanthomonadaceae, which may be implicated in increased resistance to plant pathogens. Our study further develops an integrated strategy for combating HLB, and also provides new insight into the bacterial microbiome of HLB-affected citrus treated by heat and sulfonamide antibiotics.

Citrus leprosis virus N: A New Dichorhavirus Causing Citrus Leprosis Disease.

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Ramos-González, Pedro Luis; Chabi-Jesus, Camila; Guerra-Peraza, Orlene; Tassi, Aline Daniele; Kitajima, Elliot Watanabe; Harakava, Ricardo; Salaroli, Renato Barbosa; Freitas-Astúa, Juliana

2017-08-01

Citrus leprosis (CL) is a viral disease endemic to the Western Hemisphere that produces local necrotic and chlorotic lesions on leaves, branches, and fruit and causes serious yield reduction in citrus orchards. Samples of sweet orange (Citrus × sinensis) trees showing CL symptoms were collected during a survey in noncommercial citrus areas in the southeast region of Brazil in 2013 to 2016. Transmission electron microscopy analyses of foliar lesions confirmed the presence of rod-like viral particles commonly associated with CL in the nucleus and cytoplasm of infected cells. However, every attempt to identify these particles by reverse-transcription polymerase chain reaction tests failed, even though all described primers for the detection of known CL-causing cileviruses and dichorhaviruses were used. Next-generation sequencing of total RNA extracts from three symptomatic samples revealed the genome of distinct, although highly related (>92% nucleotide sequence identity), viruses whose genetic organization is similar to that of dichorhaviruses. The genome sequence of these viruses showed trees and those used for the transmission of one of the characterized isolates to Arabidopsis plants were anatomically recognized as Brevipalpus phoenicis sensu stricto. Molecular and biological features indicate that the identified viruses belong to a new species of CL-associated dichorhavirus, which we propose to call Citrus leprosis N dichorhavirus. Our results, while emphasizing the increasing diversity of viruses causing CL disease, lead to a reevaluation of the nomenclature of those viruses assigned to the genus Dichorhavirus. In this regard, a comprehensive discussion is presented.

Weeping dragon, a unique ornamenal citrus

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‘Weeping Dragon’ is a new ornamental citrus cultivar developed by intercrossing of two unusual and unique citrus types, Poncirus trifoliata cultivated variety (cv.) Flying Dragon, and Citrus sinensis cv. ‘Cipo’. This new hybrid cultivar combines strongly contorted and weeping growth traits in a smal...

Isolation and identification of citrus psorosis virus Egyptian isolate (CPsV-EG).

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Ghazal, S A; El-Dougdoug, Kh A; Mousa, A A; Fahmy, H; Sofy, A R

2008-01-01

Citrus psorosis ophiovirus (CPsV), is considered to be of the most serious and deter mental virus pathogen's citrus species trees in Egypt. CPsV-EG was isolated from infected citrus grapefruit (C. paradisi Macf.) at Agric. Res. Centre (ARC). The grapefruit which used for CPsV-EG isolate was found to be free from CTV, CEVd and Spiroplasma citri where as gave -ve results with DTBIA, tissue print hybridization and Diene's stain respectively. CPsV-EG was detected on the basis of biological indexing by graft inoculation which gave oak leaf pattern (OLP) on Dweet tangor and serological assay by DAS-ELISA using Mab specific CPsV. CPsV-EG was reacted with variable responses on 16 host plants belonging to 6 families. Only 8 host plants are susceptible and showed visible external symptoms which appeared as local, systemic and local followed by systemic infections. CPsV-EG isolate was transmitted from infected citrus to citrus by syringe and grafting and herbaceous plants by forefinger inoculation and syringe. The woody indicators and rootstocks were differed in response to CPsV-EG isolate which appeared as no-response, response, sensitivity and hypersensitivity. The serological characters represented as the antigenic determinants of CPsV-EG isolate related to monoclonal antibodies specific CPsV strain where as appeared precipitation reaction by DAS-ELISA and DTBIA. The partial fragment of RNA3 (coat protein gene) of CPsV-EG (-1140bp and -571bp) was amplified by reverse transcription-polymerase chain reaction (RT-PCR) from grapefruit tissues using two sets primers specific CPsV (CPV3 and CPV4) and (PS66 and PS65) respectively. The virus under study was identified as CPsV-EG isolate according to biological, serological and molecular characters.

Effects of Alternaria alternata f.sp. lycopersici toxins on pollen

NARCIS (Netherlands)

Bino, R.J.; Franken, J.; Witsenboer, H.M.A.; Hille, J.; Dons, J.J.M.

1988-01-01

Effects of the phytotoxic compounds (AAL-toxins) isolated from cell-free culture filtrates of Alternaria alternata f.sp. lycopersici on in vitro pollen development were studied. AAL-toxins inhibited both germination and tube growth of pollen from several Lycopersicon genotypes. Pollen from

78 FR 41259 - Importation of Fresh Citrus Fruit From Uruguay, Including Citrus

Science.gov (United States)

2013-07-10

... therefore opposed importation of fresh citrus fruit from Uruguay until its effectiveness could be validated...'' imports. The commenter stated that this argument is invalid due to the year-round marketing of citrus... metric tons, which is less than 3 percent of U.S. production. Uruguay's total fresh orange and lemon...

Repellent Activity of Botanical Oils against Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae

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Emily H. Kuhns

2016-07-01

Full Text Available The Asian citrus psyllid, Diaphorina citri Kuwayama, is the insect vector of the pathogen causing huanglongbing. We selected three botanical oils to evaluate behavioral activity against D. citri. In laboratory olfactometer assays, fir oil was repellent to D. citri females, while litsea and citronella oils elicited no response from D. citri females. In choice settling experiments, D. citri settled almost completely on control plants rather than on plants treated with fir oil at a 9.5 mg/day release rate. Therefore, we conducted field trials to determine if fir oil reduced D. citri densities in citrus groves. We found no repellency of D. citri from sweet orange resets that were treated with fir oil dispensers releasing 10.4 g/day/tree as compared with control plots. However, we found a two-week decrease in populations of D. citri as compared with controls when the deployment rate of these dispensers was doubled. Our results suggest that treatment of citrus with fir oil may have limited activity as a stand-alone management tool for D. citri and would require integration with other management practices.

Small RNA profiling reveals phosphorus deficiency as a contributing factor in symptom expression for citrus huanglongbing disease.

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Zhao, Hongwei; Sun, Ruobai; Albrecht, Ute; Padmanabhan, Chellappan; Wang, Airong; Coffey, Michael D; Girke, Thomas; Wang, Zonghua; Close, Timothy J; Roose, Mikeal; Yokomi, Raymond K; Folimonova, Svetlana; Vidalakis, Georgios; Rouse, Robert; Bowman, Kim D; Jin, Hailing

2013-03-01

Huanglongbing (HLB) is a devastating citrus disease that is associated with bacteria of the genus 'Candidatus Liberibacter' (Ca. L.). Powerful diagnostic tools and management strategies are desired to control HLB. Host small RNAs (sRNA) play a vital role in regulating host responses to pathogen infection and are used as early diagnostic markers for many human diseases, including cancers. To determine whether citrus sRNAs regulate host responses to HLB, sRNAs were profiled from Citrus sinensis 10 and 14 weeks post grafting with Ca. L. asiaticus (Las)-positive or healthy tissue. Ten new microRNAs (miRNAs), 76 conserved miRNAs, and many small interfering RNAs (siRNAs) were discovered. Several miRNAs and siRNAs were highly induced by Las infection, and can be potentially developed into early diagnosis markers of HLB. miR399, which is induced by phosphorus starvation in other plant species, was induced specifically by infection of Las but not Spiroplasma citri that causes citrus stubborn-a disease with symptoms similar to HLB. We found a 35% reduction of phosphorus in Las-positive citrus trees compared to healthy trees. Applying phosphorus oxyanion solutions to HLB-positive sweet orange trees reduced HLB symptom severity and significantly improved fruit production during a 3-year field trial in south-west Florida. Our molecular, physiological, and field data suggest that phosphorus deficiency is linked to HLB disease symptomology.

Green synthesis of gold nanoparticles using Citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) aqueous extract and its characterization

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Sujitha, Mohanan V.; Kannan, Soundarapandian

2013-02-01

This study reports the biological synthesis of gold nanoparticles by the reduction of HAuCl4 by using citrus fruits (Citrus limon, Citrus reticulata and Citrus sinensis) juice extract as the reducing and stabilizing agent. A various shape and size of gold nanoparticles were formed when the ratio of the reactants were altered with respect to 1.0 mM chloroauric acid solution. The gold nanoparticles obtained were characterized by UV-visible spectra, transmission electron microscopy (TEM) and X-ray diffraction (XRD). TEM studies showed the particles to be of various shapes and sizes and particle size ranges from 15 to 80 nm. Selected-area electron diffraction (SAED) pattern confirmed fcc phase and crystallinity of the particles. The X-ray diffraction analysis revealed the distinctive facets (1 1 1, 2 0 0, 2 2 0 and 2 2 2 planes) of gold nanoparticles. Dynamic light scattering (DLS) studies revealed that the average size for colloid gp3 of C. limon, C. reticulata and C. sinensis are 32.2 nm, 43.4 nm and 56.7 nm respectively. The DLS graph showed that the particles size was larger and more polydispersed compared to the one observed by TEM due to the fact that the measured size also includes the bio-organic compounds enveloping the core of the Au NPs. Zeta potential value for gold nanoparticles obtained from colloid gp3 of C. limon, C. reticulata and C. sinensis are -45.9, -37.9 and -31.4 respectively indicating the stability of the synthesized nanoparticles. Herein we propose a novel, previously unexploited method for the biological syntheses of polymorphic gold nanoparticles with potent biological applications.

The LOV protein of Xanthomonas citri subsp. citri plays a significant role in the counteraction of plant immune responses during citrus canker.

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Ivana Kraiselburd

Full Text Available Pathogens interaction with a host plant starts a set of immune responses that result in complex changes in gene expression and plant physiology. Light is an important modulator of plant defense response and recent studies have evidenced the novel influence of this environmental stimulus in the virulence of several bacterial pathogens. Xanthomonas citri subsp. citri is the bacterium responsible for citrus canker disease, which affects most citrus cultivars. The ability of this bacterium to colonize host plants is influenced by bacterial blue-light sensing through a LOV-domain protein and disease symptoms are considerably altered upon deletion of this protein. In this work we aimed to unravel the role of this photoreceptor during the bacterial counteraction of plant immune responses leading to citrus canker development. We performed a transcriptomic analysis in Citrus sinensis leaves inoculated with the wild type X. citri subsp. citri and with a mutant strain lacking the LOV protein by a cDNA microarray and evaluated the differentially regulated genes corresponding to specific biological processes. A down-regulation of photosynthesis-related genes (together with a corresponding decrease in photosynthesis rates was observed upon bacterial infection, this effect being more pronounced in plants infected with the lov-mutant bacterial strain. Infection with this strain was also accompanied with the up-regulation of several secondary metabolism- and defense response-related genes. Moreover, we found that relevant plant physiological alterations triggered by pathogen attack such as cell wall fortification and tissue disruption were amplified during the lov-mutant strain infection. These results suggest the participation of the LOV-domain protein from X. citri subsp. citri in the bacterial counteraction of host plant defense response, contributing in this way to disease development.

The LOV Protein of Xanthomonas citri subsp. citri Plays a Significant Role in the Counteraction of Plant Immune Responses during Citrus Canker

Science.gov (United States)

Kraiselburd, Ivana; Daurelio, Lucas D.; Tondo, María Laura; Merelo, Paz; Cortadi, Adriana A.; Talón, Manuel; Tadeo, Francisco R.; Orellano, Elena G.

2013-01-01

Pathogens interaction with a host plant starts a set of immune responses that result in complex changes in gene expression and plant physiology. Light is an important modulator of plant defense response and recent studies have evidenced the novel influence of this environmental stimulus in the virulence of several bacterial pathogens. Xanthomonas citri subsp. citri is the bacterium responsible for citrus canker disease, which affects most citrus cultivars. The ability of this bacterium to colonize host plants is influenced by bacterial blue-light sensing through a LOV-domain protein and disease symptoms are considerably altered upon deletion of this protein. In this work we aimed to unravel the role of this photoreceptor during the bacterial counteraction of plant immune responses leading to citrus canker development. We performed a transcriptomic analysis in Citrus sinensis leaves inoculated with the wild type X. citri subsp. citri and with a mutant strain lacking the LOV protein by a cDNA microarray and evaluated the differentially regulated genes corresponding to specific biological processes. A down-regulation of photosynthesis-related genes (together with a corresponding decrease in photosynthesis rates) was observed upon bacterial infection, this effect being more pronounced in plants infected with the lov-mutant bacterial strain. Infection with this strain was also accompanied with the up-regulation of several secondary metabolism- and defense response-related genes. Moreover, we found that relevant plant physiological alterations triggered by pathogen attack such as cell wall fortification and tissue disruption were amplified during the lov-mutant strain infection. These results suggest the participation of the LOV-domain protein from X. citri subsp. citri in the bacterial counteraction of host plant defense response, contributing in this way to disease development. PMID:24260514

Citrus allergy from pollen to clinical symptoms.

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Rosa Anna Iorio

Full Text Available Allergy to citrus fruits is often associated with pollinosis and sensitization to other plants due to a phenomenon of cross-reactivity. The aims of the present study were to highlight the cross-reactivity among citrus and the major allergenic pollens/fruits, throughout clinical and molecular investigations, and to evaluate the sensitization frequency to citrus fruits in a population of children and adults with pollinosis. We found a relevant percentage of sensitisation (39% to citrus fruits in the patients recruited and in all of them the IgE-mediated mechanism has been confirmed by the positive response to the prick-to-prick test. RT-PCR experiments showed the expression of Cit s 1, Cit s 3 and a profilin isoform, already described in apple, also in Citrus clementine pollen. Data of multiple sequence alignments demonstrated that Citrus allergens shared high percentage identity values with other clinically relevant species (i.e. Triticum aestivum, Malus domestica, confirming the possible cross-allergenicity citrus/grasses and citrus/apple. Finally, a novelty of the present work has been the expression of two phospholipaseA2 isoforms (PLA2 α and β in Citrus as well as in Triticum pollens; being PLA2 able to generate pro-inflammatory factors, this enzyme could participate in the activation of the allergenic inflammatory cascade.

A compatible interaction of Alternaria brassicicola with Arabidopsis thaliana ecotype DiG: evidence for a specific transcriptional signature

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Gepstein Shimon

2009-03-01

Full Text Available Abstract Background The interaction of Arabidopsis with Alternaria brassicicola provides a model for disease caused by necrotrophs, but a drawback has been the lack of a compatible pathosystem. Infection of most ecotypes, including the widely-studied line Col-0, with this pathogen generally leads to a lesion that does not expand beyond the inoculated area. This study examines an ecotype, Dijon G (DiG, which is considered sensitive to A. brassicicola. Results We show that the interaction has the characteristics of a compatible one, with expanding rather than limited lesions. To ask whether DiG is merely more sensitive to the pathogen or, rather, interacts in distinct manner, we identified genes whose regulation differs between Col-0 and DiG challenged with A. brassicicola. Suppression subtractive hybridization was used to identify differentially expressed genes, and their expression was verified using semi-quantitative PCR. We also tested a set of known defense-related genes for differential regulation in the two plant-pathogen interactions. Several known pathogenesis-related (PR genes are up-regulated in both interactions. PR1, and a monooxygenase gene identified in this study, MO1, are preferentially up-regulated in the compatible interaction. In contrast, GLIP1, which encodes a secreted lipase, and DIOX1, a pathogen-response related dioxygenase, are preferentially up-regulated in the incompatible interaction. Conclusion The results show that DiG is not only more susceptible, but demonstrate that its interaction with A. brassicicola has a specific transcriptional signature.

[Climatic suitability of citrus in subtropical China].

Science.gov (United States)

Duan, Hai-Lai; Qian, Huai-Sui; Li, Ming-Xia; Du, Yao-Dong

2010-08-01

By applying the theories of ecological suitability and the methods of fuzzy mathematics, this paper established a climatic suitability model for citrus, calculated and evaluated the climatic suitability and its spatiotemporal differences for citrus production in subtropical China, and analyzed the climatic suitability of citrus at its different growth stages and the mean climatic suitability of citrus in different regions of subtropical China. The results showed that the citrus in subtropical China had a lower climatic suitability and a higher risk at its flower bud differentiation stage, budding stage, and fruit maturity stage, but a higher climatic suitability and a lower risk at other growth stages. Cold damage and summer drought were the key issues affecting the citrus production in subtropical China. The citrus temperature suitability represented a latitudinal zonal pattern, i. e., decreased with increasing latitude; its precipitation suitability was high in the line of "Sheyang-Napo", medium in the southeast of the line, low in the northwest of the line, and non in high mountainous area; while the sunlight suitability was in line with the actual duration of sunshine, namely, higher in high-latitude areas than in low-latitude areas, and higher in high-altitude areas than in plain areas. Limited by temperature factor, the climatic suitability was in accordance with temperature suitability, i. e., south parts had a higher suitability than north parts, basically representing latitudinal zonal pattern. From the analysis of the inter-annual changes of citrus climatic suitability, it could be seen that the citrus climatic suitability in subtropical China was decreasing, and had obvious regional differences, suggesting that climate change could bring about the changes in the regions suitable for citrus production and in the key stages of citrus growth.

SCREENING FITOKIMIA, AKTIVITAS ANTIOKSIDAN DAN ANTIMIKROBA PADA BUAH JERUK LEMON(Citrus limon DAN JERUK NIPIS (Citrus aurantiifolia

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Anindya Nirmala Permata

2018-03-01

Full Text Available The desire to live healthy by eating natural foods and drinks into the lifestyle of the community. Orange becomes one of the fruits that become functional food to maintain and maintain health. The purpose of this research is to know the difference of antioxidant and antimicrobial activity on Citrus limon and Citrus aurantiifolia. The research method is laboratory experimental research with descriptive analysis. This research was conducted in February-April 2017 at the Laboratory of Plant Biological Microbiology and Plant Chemistry Department of Biology State University of Malang. Phytochemical screening by color reaction method, total phenol with Folin Ciocalteu method, antioxidant activity with DPPH method and antimicrobial activity with disc method. Screening results show the presence of saponins and alkaloids but there are no flavonoids, terpenoids and tannins. Total phenol test showed total phenol content in Lemon (Citrus limon of 110,25 mg GAE / 100ml while in Lime (Citrus aurantiifolia 116,5 mg GAE / 100ml. The antioxidant activity of Lemon Citrus (Citrus limon 49.593 g / ml and Lime (Citrus aurantiifolia 49.589g / ml. Antimicrobial activity test obtained the highest zone of resistance at 100% concentration of each citrus fruit. The conclusion of this study is that there is a difference of antioxidant and antimicrobial activity in both oranges, where the lemon fruits (C.limon antioxidant activity is higher than and Lime (C. aurantiifolia, while the antimicrobial activity of lemon (C. aurantiifolia is higher Rather than lemon (C.limon.

Viability of and Escherichia coli O157:H7 and Listeria monocytogenes in a delicatessen appetizer (yogurt-based) salad as affected by citrus extract (Citrox©) and storage temperature.

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Tsiraki, Maria I; Yehia, Hany M; Elobeid, Tahra; Osaili, Tareq; Sakkas, Hercules; Savvaidis, Ioannis N

2018-02-01

The antimicrobial effect of citrus extract (at 1 mL/kg [C1] and 2 mL/kg [C2]) on naturally occurring microbiota and inoculated pathogens (E. coli O157:H7 and L. monocytogenes at ca. 6 log cfu/g) in the traditional Greek yogurt-based salad Tzatziki stored at 4, 10, or 21 °C, was examined. Lactic acid bacteria (LAB) were high (8.0-8.5 log cfu/g) and varied only minimally for both the control (untreated) and the citrus extract-treated salad samples, whereas the higher citrus extract concentration yielded the lowest yeast populations, irrespective of temperature, during the entire storage period. Populations of inoculated E. coli (6 log cfu/g) declined in both untreated and citrus extract-treated samples from day 0-70, 35, and 15 at 4, 10, and 21 °C, respectively. Citrus extract had a significant effect on the survival of the inoculated E. coli O157:H7, with reductions of 2.8-4.8 log cfu/g in the citrus extract-treated samples at the end of the storage period. Our data show that L. monocytogenes survived in both untreated and citrus extract-treated samples during the entire storage period, irrespective of the storage temperature. The higher concentration of citrus extract had a significant effect on the survival of L. monocytogenes in the treated samples, and reductions of 1.5-3.0 logs were noted on final day 70, 35 and 15 at 4, 10 and 21 °C, respectively. The results of our study demonstrated the potential of citrus extract as a natural compound that can control the growth of food-borne pathogenic bacteria, such as E. coli O157:H7 and L. monocytogenes in Tzatziki, a yogurt-based salad. Copyright © 2017 Elsevier Ltd. All rights reserved.

CONTROL OF Alternaria porri (E11 CIF. AND TOXIC EFFECT OF CAPTAFOL SPRAYING IN GARLIC (Allium sativum L. CONTROLE DE Alternaria porri (E11 Cif. E EFEITO FITOTÓXICO DE CAPTAFOL EM PULVERIZAÇÃO NA CULTURA DO ALHO (Allium sativum L.

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Iraídes Fernandes Carneiro

2007-09-01

Full Text Available

The objective of the present work was to verify the effect of the different concentrations of the captafol fungicide (0, 50, 100, 200 and 400 g.i.a./100 l of water, in the control of Alternaria porri (E11 Cif. and their toxic effects on plants, in two cultivars of garlic (Lavinia and Centenário. The results show that, for the cultivars tested, the fungicide, in the concentrations utilized, didn’t control the pathogen, and it didn’t show fitotoxicity.

Com o objetivo de verificar o efeito do Captafol no controle de Alternaria porri (E11 Cif. na cultura do alho, e seus efeitos fitotóxicos nesta A1iácea, foi instalado um experimento nas dependências da Escola de Agronomia da Universidade Federal de Goiás, em Goiânia. O delineamento experimental foi de blocos ao acaso com parcelas subdivididas utilizando-se as cultivares Lavinia e Centenário, submetidas a pulverizações com o fungicida nas seguintes concentrações: 0, 50, 100, 200 e 400 gramas do princípio ativo por 100 litros de água. Os resultados indicam que, para as duas cultivares utilizadas, o Captafol não controlou o patógeno, nem se mostrou fitotóxico.

Innate immune system capabilities of the Asian citrus psyllid, Diaphorina citri.

Science.gov (United States)

Arp, Alex P; Martini, Xavier; Pelz-Stelinski, Kirsten S

2017-09-01

Citrus production worldwide is currently threatened by Huanglongbing, or citrus greening disease. The associated pathogen, Candidatus Liberibacter asiaticus (CLas), is transmitted by the Asian citrus psyllid, Diaphorina citri. Annotation of the D. citri genome revealed a reduced innate immune system lacking a number of antimicrobial peptides and the Imd pathway associated with defense against Gram-negative bacteria. We characterized this apparent immune reduction in survival assays in which D. citri were exposed to Gram-negative or Gram-positive bacteria. D. citri experienced significant mortality when exposed to Serratia marcescens (Gram-negative) through oral ingestion or by septic injury. Escherichia coli (Gram-negative) also caused significant D. citri mortality, but only when inoculated at high concentrations through oral ingestion or by septic injury. Neither Micrococcus luteus (Gram-positive) or Bacillus subtilis (Gram-positive) caused significant mortality as compared to controls in any experiment. E. coli titers increased rapidly following exposure, while M. luteus titer remained stable for 72 h. We demonstrate that D. citri is capable of defending against E. coli, a Gram-negative bacterium, despite lacking the Imd defense pathway. The tolerance of D. citri to M. luteus infection, yet inability to effectively clear infections, presents questions to efficacy of D. citri immune response to effectively clear Gram-positive infections. Copyright © 2017. Published by Elsevier Inc.

Chemical composition, antioxidant and antimicrobial activities of citrus jambhiri lush and citrus reticulata blanco essential oils

International Nuclear Information System (INIS)

Sadaf, S.; Shahid, M.; Iqbal, Z.

2009-01-01

The aim of this study was to investigate the time interval in which we can get maximum concentration of essential oil from the peels of Citrus jambhiri Lush and Citrus reticulata Blanco, to determine the composition of peel oils and to evaluate the antioxidant and antimicrobial activity of extracted oils. It was observed that in case of Citrus jambhiri Lush maximum oil yield (I %) was obtained when fruits were immature (during October). As the fruit samples got matured, the oil yield decreased. In December the oil yield decreased to 0.2 %. In case of Citrus reticulata Blanco maximum oil yield (0.189 %) was obtained during the last week of January. Chemical analysis of essential oils showed that limonene was the most abundant compound (86 %-93 %) followed by alpha terpinene (2 %-4.5 %), beta-pinene(1 0/0-2 %) and nerol (0.5 %-1.5 %). The radical scavenging and antioxidant activities of essential oils were determined by DPPH and linoleic acid test. The essential oil of Citrus jambhiri Lush inhibited the oxidation of linoleic acid by 54.98 % and that of Citrus reticulata Blanco inhibited by 49.98 %. Moreover, the essential oils also showed antimicrobial activities against the tested microorganisms. (author)

Detection and molecular characterization of Candidatus liberibacter spp. causing huanglongbing (HLB) in indigenous citrus cultivars in Pakistan

International Nuclear Information System (INIS)

Zafarullah, A.; Saleem, F.

2016-01-01

Citrus greening or huanglongbing (HLB) is one of major devastating citrus diseases all over the world. This disease is caused by fastidious ?-proteobacterium, Candidatus liberibacter spp. and is transmitted by grafting as well as psyllids Diaphorina citri or Trioza erytreae. The objective of this study was to identify and characterize the huanglongbing (HLB) infectious pathogen in commercial (Kinnow and sweet oranges) varieties by using molecular markers such as 16S rRNA, 16S/23S rRNA and outer membrane protein fragments from symptomatic leaves of assorted citrus varieties. DNA extracted from forty different citrus (including mandarin and sweet oranges) varieties having HLB-symptomatic plants from different orchards of Pakistan. Gene-specific primers for 16SrDNA, 16S/23SrDNA and outer membrane protein (OMP) gene regions were used for identification of Ca. liberibacter spp. An amplified fragment of 1174 bp from 16SrDNA, 900 bp of 16S/23S rRNA and 600 bp was observed for OMP gene fragments of Asian isolates. The resulted fragments were TA cloned and sequenced from both strands. The infectious bacterium was identified as Candidatus liberibacter asiaticus and was found in 17 samples (42%). The seasonal variation on prevalence of Candidatus liberibacter asiaticus in citrus varieties was well observed. It declined during spring season due to unfavourable temperature and humidity for Candidatus liberibacter asiaticus because disease symptoms showed mostly at low humidity and warm temperature (up to 35 degree C). (author)

A rare case of allergic bronchopulmonary mycosis caused by Alternaria alternata.

NARCIS (Netherlands)

Chowdhary, A.; Agarwal, K.; Randhawa, H.S.; Kathuria, S.; Gaur, S.N.; Najafzadeh, M.J.; Roy, P.; Arora, N.; Khanna, G.; Meis, J.F.G.M.

2012-01-01

A rare case of allergic bronchopulmonary mycosis (ABPM), caused by Alternaria alternata, is reported in an immunocompetent resident of Delhi. Her complaints included a generalized, urticarial skin rash and occasional pain in the right lower chest. Her differential count showed eosinophils, 22%;

Selection of pathogen-resistant mutants in rapeseed

International Nuclear Information System (INIS)

Spanier, A.; Roebbelen, G.

1990-01-01

Full text: Significant yield reductions are due to Phoma lingam and Alternaria brassicae. Toxin containing culture filtrates of the pathogens as well as concentrated toxins of Phoma (Sirodesmins) are used for resistance selections in in-vitro cultures of haploid rapeseed materials. A few days after transfer of the in-vitro materials to the selective media the inhibitory effect of both the culture filtrates as well as the Sirodesmins was apparent. Clones were obtained, surviving several transfers onto toxin containing media. Further experiments shall clarify whether the toxin tolerance, selected in vitro at the cell level, is expressed in the differentiated plant in the greenhouse and finally in the field. (author)

Immunogenesity of spesific protein molecular weight 16 KDa (PS16 leaf of siam citrus infected by citrus vein phloem degeneration (CVPD disease

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Made Sritamin

2012-02-01

Full Text Available Citrus Vein Phloem degeneration (CVPD is an important citrus disese, which damaged citrus plantation and causing decrease of citrus production. In Indonesia, the CVPD disease caused by Liberobacter asiaticum bactery and the disease spread out by vectir insect Diaphorina citri and using infected bud in wood grafting. In infected citrus plant, two specific protein molecules with molecular weigt 16 kDa and 66 kDa are found. These protein molecules are not found in healthy citrus plant. The immunogenicity of PS16 accumulated on leaf of citrus plant infected by CVPD is known yet. The research material were leaves of citrus plant infected CVPD, leaves of healthy citrus plant and reagent used these research are for isolation of the total protein leaf of citrus plant, SDS-PAGE electroforesis, electroelution of PS16, ELISA Methods, Dot-Blot Method, anti-PS16 as aprimery antibody and secondary antibody is anti-Rabbit IgG Conjugated AP. The result of the research showed that of PS16 accumulated on leaf of citrus plant infected CVPD has immunogenic character. It is indicated by increase of the titer anti-PS16 after first immunization ang 2nd booster by indirect ELISA method and can be used to induce antibody (anti-PS16 and so showed that positive reaction between PS16 with anti-PS16. It is indicated by purples dark blue on cellulose membrane by Dot Blot method.

The aconitate hydratase family from Citrus

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Cercos Manuel

2010-10-01

Full Text Available Abstract Background Research on citrus fruit ripening has received considerable attention because of the importance of citrus fruits for the human diet. Organic acids are among the main determinants of taste and organoleptic quality of fruits and hence the control of fruit acidity loss has a strong economical relevance. In citrus, organic acids accumulate in the juice sac cells of developing fruits and are catabolized thereafter during ripening. Aconitase, that transforms citrate to isocitrate, is the first step of citric acid catabolism and a major component of the citrate utilization machinery. In this work, the citrus aconitase gene family was first characterized and a phylogenetic analysis was then carried out in order to understand the evolutionary history of this family in plants. Gene expression analyses of the citrus aconitase family were subsequently performed in several acidic and acidless genotypes to elucidate their involvement in acid homeostasis. Results Analysis of 460,000 citrus ESTs, followed by sequencing of complete cDNA clones, identified in citrus 3 transcription units coding for putatively active aconitate hydratase proteins, named as CcAco1, CcAco2 and CcAco3. A phylogenetic study carried on the Aco family in 14 plant species, shows the presence of 5 Aco subfamilies, and that the ancestor of monocot and dicot species shared at least one Aco gene. Real-time RT-PCR expression analyses of the three aconitase citrus genes were performed in pulp tissues along fruit development in acidic and acidless citrus varieties such as mandarins, oranges and lemons. While CcAco3 expression was always low, CcAco1 and CcAco2 genes were generally induced during the rapid phase of fruit growth along with the maximum in acidity and the beginning of the acid reduction. Two exceptions to this general pattern were found: 1 Clemenules mandarin failed inducing CcAco2 although acid levels were rapidly reduced; and 2 the acidless "Sucreña" orange

Antibacterial activity of different honeys against pathogenic bacteria.

Science.gov (United States)

Voidarou, C; Alexopoulos, A; Plessas, S; Karapanou, A; Mantzourani, I; Stavropoulou, E; Fotou, K; Tzora, A; Skoufos, I; Bezirtzoglou, E

2011-12-01

To study the antimicrobial activity of honey, 60 samples of various botanical origin were evaluated for their antimicrobial activities against 16 clinical pathogens and their respective reference strains. The microbiological quality of honeys and the antibiotic susceptibility of the various isolates were also examined. The bioassay applied for determining the antimicrobial effect employs the well-agar diffusion method and the estimation of minimum active dilution which produces a 1mm diameter inhibition zone. All honey samples, despite their origin (coniferous, citrus, thyme or polyfloral), showed antibacterial activity against the pathogenic and their respective reference strains at variable levels. Coniferous and thyme honeys showed the highest activity with an average minimum dilution of 17.4 and 19.2% (w/v) followed by citrus and polyfloral honeys with 20.8 and 23.8% respectively. Clinical isolates of Staphylococcus aureus subsp. aureus, Escherichia coli, Salmonella enterica subsp. Enterica, Streptococcus pyogenes, Bacillus cereus and Bacillus subtilis were proven to be up to 60% more resistant than their equal reference strains thus emphasizing the variability in the antibacterial effect of honey and the need for further research. Copyright © 2011 Elsevier Ltd. All rights reserved.

Transcriptional analysis of sweet orange trees co-infected with 'Candidatus Liberibacter asiaticus' and mild or severe strains of Citrus tristeza virus.

Science.gov (United States)

Fu, Shimin; Shao, Jonathan; Paul, Cristina; Zhou, Changyong; Hartung, John S

2017-10-31

Citrus worldwide is threatened by huanglongbing (HLB) and tristeza diseases caused by 'Candidatus Liberibacter asiaticus' (CaLas) and Citrus tristeza virus (CTV). Although the pathogens are members of the α-proteobacteria and Closteroviridae, respectively, both are restricted to phloem cells in infected citrus and are transmitted by insect vectors. The response of sweet orange to single infection by either of these two pathogens has been characterized previously by global gene expression analysis. But because of the ubiquity of these pathogens where the diseases occur, co-infection by both pathogens is very common and could lead to increased disease severity based on synergism. We therefore co-inoculated sweet orange trees with CaLas and either a mild or a severe strain of CTV, and measured changes of gene expression in host plants. In plants infected with CaLas-B232, the overall alteration in gene expression was much greater in plants co-inoculated with the severe strain of CTV, B6, than when co-infected with the mild strain of CTV, B2. Plants co-infected with CaLas-B232 and either strain of CTV died but trees co-infected with CTV-B2 survived much longer than those co-infected with CTV-B6. Many important pathways were perturbed by both CTV-B2/CaLas-B232 and/or CTV-B6/CaLas-B232, but always more severely by CTV-B6/CaLas-B232. Genes related to cell wall modification and metal transport responded differently to infection by the pathogens in combination than by the same pathogens singly. The expressions of genes encoding phloem proteins and sucrose loading proteins were also differentially altered in response to CTV-B2 or CTV-B6 in combination with CaLas-B232, leading to different phloem environments in plants co-infected by CaLas and mild or severe CTV. Many host genes were expressed differently in response to dual infection as compared to single infections with the same pathogens. Interactions of the pathogens within the host may lead to a better or worse result

Effects of Molasses on the Fermentation Quality of Wheat Straw and Poultry Litter Ensiled with Citrus Pulp

International Nuclear Information System (INIS)

Migwi, P.K; Gallanga, J.R; Barneveld, R.J

1999-01-01

Studies were conducted to find out whether inclusion of molasses had any effect on the fermentation quality and potential nutritive value of silage when wheat straw and poultry litter were ensiled with citrus pulp. A 4 x 2 factorial experiment in a randomized complete block design with four treatments (T) containing wheat straw, poultry litter and citrus pulp respectively on DM basis with 0 and 5% molasses, were prepared as follows-: T1 (75:25:0); T2 (60:25:15); T3 (45:25:30) and T4 (30:25:45). For each treatment in triplicate between 5-10 kg of thoroughly mixed material were ensiled for for a period of 60 days in 20-l hard plastic container laboratory silos, lined with a double layer of polythene bags. Inclusion of 5% molasses when ensiling wheat straw and poultry litter with 0, 15, 30 and 45% citrus pulp had no significant effect on pH, neutral detergent fibre (NDF), acid detergent fibre (ADF), acid detergent lignin (ADL) and in vitro OM digestibility. However, molasses resulted in a significant decrease in volatile fatty acids including N-butyric acid. There was a complete elimination of coliforms in all treatments, except in the silage that had neither molasses nor citrus pulp. There was a significant difference in titratable acidity levels between silage with 0 and 5% molasses, but this was only in silage with 30% citrus pulp. As the proportion of citrus pulp in silage increased from 0 to 45%, there was significant increase in silage acidity and also an increase in pH. However, there was no significant difference in pH between silage with 30 and 45% citrus pulp. There was a significant (P < 0.001) increase in in vitro OM digestibility from 0.33 to about 0.56 for silage with 0 and 45% citrus pulp respectively. It is concluded that when wheat straw and poultry litter are ensiled with citrus pulp, use of molasses offers no significant benefit inspite of the cost associated with its use. However, when no citrus pulp is included in the pre-mix, addition of some

Genomic Analysis of Terpene Synthase Family and Functional Characterization of Seven Sesquiterpene Synthases from Citrus sinensis

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Berta Alquézar

2017-08-01

Full Text Available Citrus aroma and flavor, chief traits of fruit quality, are derived from their high content in essential oils of most plant tissues, including leaves, stems, flowers, and fruits. Accumulated in secretory cavities, most components of these oils are volatile terpenes. They contribute to defense against herbivores and pathogens, and perhaps also protect tissues against abiotic stress. In spite of their importance, our understanding of the physiological, biochemical, and genetic regulation of citrus terpene volatiles is still limited. The availability of the sweet orange (Citrus sinensis L. Osbeck genome sequence allowed us to characterize for the first time the terpene synthase (TPS family in a citrus type. CsTPS is one of the largest angiosperm TPS families characterized so far, formed by 95 loci from which just 55 encode for putative functional TPSs. All TPS angiosperm families, TPS-a, TPS-b, TPS-c, TPS-e/f, and TPS-g were represented in the sweet orange genome, with 28, 18, 2, 2, and 5 putative full length genes each. Additionally, sweet orange β-farnesene synthase, (Z-β-cubebene/α-copaene synthase, two β-caryophyllene synthases, and three multiproduct enzymes yielding β-cadinene/α-copaene, β-elemene, and β-cadinene/ledene/allo-aromandendrene as major products were identified, and functionally characterized via in vivo recombinant Escherichia coli assays.

Genome wide selection in Citrus breeding.

Science.gov (United States)

Gois, I B; Borém, A; Cristofani-Yaly, M; de Resende, M D V; Azevedo, C F; Bastianel, M; Novelli, V M; Machado, M A

2016-10-17

Genome wide selection (GWS) is essential for the genetic improvement of perennial species such as Citrus because of its ability to increase gain per unit time and to enable the efficient selection of characteristics with low heritability. This study assessed GWS efficiency in a population of Citrus and compared it with selection based on phenotypic data. A total of 180 individual trees from a cross between Pera sweet orange (Citrus sinensis Osbeck) and Murcott tangor (Citrus sinensis Osbeck x Citrus reticulata Blanco) were evaluated for 10 characteristics related to fruit quality. The hybrids were genotyped using 5287 DArT_seq TM (diversity arrays technology) molecular markers and their effects on phenotypes were predicted using the random regression - best linear unbiased predictor (rr-BLUP) method. The predictive ability, prediction bias, and accuracy of GWS were estimated to verify its effectiveness for phenotype prediction. The proportion of genetic variance explained by the markers was also computed. The heritability of the traits, as determined by markers, was 16-28%. The predictive ability of these markers ranged from 0.53 to 0.64, and the regression coefficients between predicted and observed phenotypes were close to unity. Over 35% of the genetic variance was accounted for by the markers. Accuracy estimates with GWS were lower than those obtained by phenotypic analysis; however, GWS was superior in terms of genetic gain per unit time. Thus, GWS may be useful for Citrus breeding as it can predict phenotypes early and accurately, and reduce the length of the selection cycle. This study demonstrates the feasibility of genomic selection in Citrus.

Inhibition of spore germination of Alternaria tenuis by sulfur dioxide

Energy Technology Data Exchange (ETDEWEB)

Couey, H.M.

1962-08-01

As a part of a continuing study of SO/sub 2/ fumigation of table grapes, the effect of SO/sub 2/ on spores of an isolate of A. tenuis Auct. causing decay of table grapes was determined. The amount of SO/sub 2/ required to inhibit completely spore germination depended on availability of moisture and the temperature. At 20/sup 0/C, wet spores required 20-min exposure to 100 ppm SO/sub 2/ to prevent germination, but spores equilibrated at 90% relative humidity (RH) required 10-min exposure to 1000 ppm SO/sub 2/. Dry spores at 60% RH were unaffected by a 20-min exposure to 4000 ppm SO/sub 2/. Increasing the temperature in the range 5-20/sup 0/C increased effectiveness of the SO/sub 2/ treatment. A comparison of Alternaria with Botrytis cinerea Fr. (studied earlier) showed that wet spores of these organisms were about equally sensitive to SO/sub 2/, but that dry Alternaria spores were more resistant to SO/sub 2/ than dry Botrytis spores under comparable conditions.

Phenology of Asian citrus psyllid (Hemiptera: Liviidae) and associated parasitoids on two species of Citrus, kinnow mandarin and sweet orange, in Punjab Pakistan.

Science.gov (United States)

Khan, Shouket Zaman; Arif, Muhammad Jalal; Hoddle, Christina D; Hoddle, Mark S

2014-10-01

The population phenology of Asian citrus psyllid, Diaphorina citri Kuwayama, was monitored weekly for 110 wk on two species of Citrus, kinnow mandarin and sweet orange, at two different research sites in Faisalabad, Punjab Pakistan. Citrus flush growth patterns were monitored and natural enemy surveys were conducted weekly. Flush patterns were similar for kinnow and sweet orange. However, flush on sweet orange was consistently more heavily infested with Asian citrus psyllid than kinnow flush; densities of Asian citrus psyllid eggs, nymphs, and adults were higher on sweet orange when compared with kinnow. When measured in terms of mean cumulative insect or Asian citrus psyllid days, eggs, nymphs, and adults were significantly higher on sweet orange than kinnow. Two parasitoids were recorded attacking Asian citrus psyllid nymphs, Tamarixia radiata (Waterston) and Diaphorencyrtus aligarhensis (Shafee, Alam and Agarwal). The dominant parasitoid species attacking Asian citrus psyllid nymphs on kinnow and sweet orange was T. radiata, with parasitism averaging 26%. D. aligarhensis parasitism averaged 17%. Generalist predators such as coccinellids and chrysopids were collected infrequently and were likely not important natural enemies at these study sites. Immature spiders, in particular, salticids and yellow sac spiders, were common and may be important predators of all Asian citrus psyllid life stages. Low year round Asian citrus psyllid densities on kinnow and possibly high summer temperatures, may, in part, contribute to the success of this cultivar in Punjab where Candidatus Liberibacter asiaticus, the putative causative agent of huanglongbing, a debilitating citrus disease, is widespread and vectored by Asian citrus psyllid.

Induction of gentisic acid 5-O-beta-D-xylopyranoside in tomato and cucumber plants infected by different pathogens.

Science.gov (United States)

Fayos, Joaquín; Bellés, José María; López-Gresa, M Pilar; Primo, Jaime; Conejero, Vicente

2006-01-01

Tomato plants infected with the citrus exocortis viroid exhibited strongly elevated levels of a compound identified as 2,5-dihydroxybenzoic acid (gentisic acid, GA) 5-O-beta-D-xylopyranoside. The compound accumulated early in leaves expressing mild symptoms from both citrus exocortis viroid-infected tomato, and prunus necrotic ringspot virus-infected cucumber plants, and progressively accumulated concomitant with symptom development. The work presented here demonstrates that GA, mainly associated with systemic infections in compatible plant-pathogen interactions [Bellés, J.M., Garro, R., Fayos, J., Navarro, P., Primo, J., Conejero, V., 1999. Gentisic acid as a pathogen-inducible signal, additional to salicylic acid for activation of plant defenses in tomato. Mol. Plant-Microbe Interact. 12, 227-235], is conjugated to xylose. Notably, this result contrasts with those previously found in other plant-pathogen interactions in which phenolics analogues of GA as benzoic or salicylic acids, are conjugated to glucose.

Research Regarding the Simultaneous Control of the Pathogens on Tomatoes Crops under High Plastic Tunnels

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Gabriela ŞOVĂREL

2017-05-01

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/l    0.2% +  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.

H NMR analyses of Citrus macrophylla subjected to Asian citrus psyllid (Diaphorina citri Kuwayama) feeding

Science.gov (United States)

The Asian citrus psyllid (ACP) is a phloem feeding insect that can host and transmit the bacterium Candidatus Liberibacter asiaticus (CLas), which is the putative causative agent of the economically important citrus disease, Huanglongbing (HLB). ACP are widespread in Florida, and are spreading in Ca...

Comparative study of airborne Alternaria conidia levels in two cities in Castilla-La Mancha (central Spain), and correlations with weather-related variables.

Science.gov (United States)

Sabariego, Silvia; Bouso, Veronica; Pérez-Badia, Rosa

2012-01-01

Alternaria conidia are among the airborne biological particles known to trigger allergic respiratory diseases. The presented paper reports on a study of seasonal variations in airborne Alternaria conidia concentrations in 2 cities in the central Spanish region of Castilla-La Mancha, Albacete and Toledo. The influence of weather-related variables on airborne conidia levels and distribution was also analysed. Sampling was carried out from 2008-2010 using a Hirst sampler, following the methodology established by the Spanish Aerobiology Network. Annual airborne Alternaria conidia counts were higher in Toledo (annual mean 3,936 conidia) than in Albacete (annual mean 2,268 conidia). Conidia were detected in the air throughout the year, but levels peaked between May-September. Considerable year-on-year variations were recorded both in total annual counts and in seasonal distribution. A significant positive correlation was generally found between mean daily Alternaria counts and both temperature and hours of sunlight, while a significant negative correlation was recorded for relative humidity, daily and cumulative rainfall, and wind speed. Regression models indicated that between 31%-52% of the variation in airborne Alternaria conidia concentrations could be explained by weather-related variables.

Salicylic acid treatment reduces the rot of postharvest citrus fruit by inducing the accumulation of H2O2, primary metabolites and lipophilic polymethoxylated flavones.

Science.gov (United States)

Zhu, Feng; Chen, Jiajing; Xiao, Xue; Zhang, Mingfei; Yun, Ze; Zeng, Yunliu; Xu, Juan; Cheng, Yunjiang; Deng, Xiuxin

2016-09-15

To comprehensively analyze the effects of salicylic acid (SA) on the storability of Satsuma mandarin (Citrus unshiu), fruits were treated with 2mM SA. The disease incidence of control/SA-treated fruit at 50d and 120d after treatment was 23.3%/10% and 67.3%/23.3%, respectively, suggesting that SA treatment can significantly reduce the rot rate of postharvest citrus fruit. Fruit quality assays revealed that the treatment can maintain fruit firmness without affecting the inner quality. Furthermore, the contents of H2O2 and some defense-related metabolites, such as ornithine and threonine, in citrus pericarp, were significantly increased by SA treatment. Moreover, it was lipophilic polymethoxylated flavones, rather than flavanone glycosides, that accumulated in SA-treated fruits and these can directly inhibit pathogen development. These results suggest that the effects of SA on postharvest citrus fruit may be attributed to the accumulation of H2O2 and defense-related metabolites. Copyright © 2016. Published by Elsevier Ltd.

Detection of a new variant of Citrus tristeza virus in Greek citrus crops

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Elisavet K. CHATZIVASSILIOU

2014-05-01

Full Text Available Citrus tristeza virus (CTV, the most destructive virus of citrus, is a quarantine pathogen in Greece. Since 2000, several accidental imports of infected propagation material have been detected in the country, and while eradication measures were applied, a few disease foci still remain. CTV isolates were collected from Chania (Crete and the “lemonwood” of Poros (Peloponnese, and their genetic variability was studied using single-strand conformation polymorphism (SSCP. One previously characterized isolate from Argolida grafted on a Mexican lime (GR3 and two Italian isolates from Calamondin were also included in the study. ELISA and RT-PCR tests confirmed CTV presence, and SSCP analysis of the virus amplified coat protein (CP gene was used to separate either distinct virus isolates for cloning the CP gene or variants (haplotypes for sequencing. Analyses showed that selected variants of four representative isolates clustered into three of the seven defined phylogenetic groups: groups 3b and 5 (severe isolates and group M (mild isolates. The prevalent haplotypes detected in the CTV from lemonwood of Poros (GR9 were in group 3b, confirming previous results. However, one sequence variant was identified as a recombinant between haplotypes from groups 3b and 5. Variants of these two groups were also detected in the Italian Calamondin isolate. In the grafted Mexican lime isolate (GR3 from Argolida, only one haplotype was found which belonged to group M, while in the field isolate from Chania (GR6 the only haplotype detected was in group 5. This is the first report of variants of group 5 in Greece, suggesting an unknown virus introduction. The prevalence of severe isolates in the area is of particular concern, and implications for the future of the CTV epidemics are discussed.

Whitefly Pest Species (Homoptera: Aleyrodidae) on Citrus Trees

OpenAIRE

Katja Žanić; Sonja Kačić; Miro Katalinić

2000-01-01

Today, the Citrus whitefly, Dialeurodes citri (Ashmead), is a very important pest on all Citrus species throughout the citrus growing areas in Croatia. It causes direct damage by sucking the plant juice from the leaves. Furthermore, immatures excrete honeydew that stimulates sooy mold. The presence of sooty mold on contaminated leaves interferes with the photosynthesis of plants. Citrus fruits coated by sooty mold lose its market value. Because Dialeurodes citri is poorly known in Croatia, th...

Enhanced Acquisition Rates of 'Candidatus Liberibacter asiaticus' by the Asian Citrus Psyllid (Hemiptera: Liviidae) in the Presence of Vegetative Flush Growth in Citrus.

Science.gov (United States)

Sétamou, Mamoudou; Alabi, Olufemi J; Kunta, Madhurababu; Jifon, John L; da Graça, John V

2016-10-01

The Asian citrus psyllid preferentially feeds and exclusively reproduces on young, newly emerged flush shoots of citrus. Asian citrus psyllid nymphs feed and complete their life stages on these flush shoots. Recent studies conducted under greenhouse conditions have shown that the transmission rates of 'Candidatus Liberibacter asiaticus' (CLas), the putative causal agent of huanglongbing disease of citrus, are enhanced when flush shoots are present. However, it is unclear if CLas acquisition by migrant adult Asian citrus psyllids is similarly enhanced. To address this knowledge gap, cohorts of Asian citrus psyllid adults were allowed 1-wk acquisition access period (AAP) on flushing and nonflushing shoots of qPCR-tested symptomatic (CLas+) and asymptomatic (CLas-) 10-yr-old sweet orange trees under field conditions. After the AAP, they were tested for CLas by qPCR. Progeny Asian citrus psyllid adults that emerged 4 wk post-AAP were similarly retrieved and tested. Eighty percent of flushing and 30% of nonflushing CLas+ trees produced infective Asian citrus psyllid adults, indicating that flush shoots have greater potential to be inoculum sources for CLas acquisition. Concomitantly, 21.1% and 6.0% infective adults were retrieved, respectively, from flushing and nonflushing CLas+ trees, indicating that Asian citrus psyllid adults acquire CLas more efficiently from flush shoots relative to mature shoots. In addition, 12.1% of infective Asian citrus psyllid adult progeny were obtained from 70% of flushing CLas+ trees. Significantly lower mean Ct values were also obtained from infective adults retrieved from flushing relative to nonflushing trees. The results underscore the role of flush shoots in CLas acquisition and the need to protect citrus trees from Asian citrus psyllid infestations during flush cycles. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email

Salicylic acid-mediated establishment of the compatibility between Alternaria brassicicola and Brassica juncea is mitigated by abscisic acid in Sinapis alba.

Science.gov (United States)

Mazumder, Mrinmoy; Das, Srirupa; Saha, Upala; Chatterjee, Madhuvanti; Bannerjee, Kaushik; Basu, Debabrata

2013-09-01

This work addresses the changes in the phytohormonal signature in the recognition of the necrotrophic fungal pathogen Alternaria brassicicola by susceptible Brassica juncea and resistant Sinapis alba. Although B. juncea, S. alba and Arabidopsis all belong to the same family, Brassicaceae, the phytohormonal response of susceptible B. juncea towards this pathogen is unique because the latter two species express non-host resistance. The differential expression of the PR1 gene and the increased level of salicylic acid (SA) indicated that an SA-mediated biotrophic mode of defence response was triggered in B. juncea upon challenge with the pathogen. Compared to B. juncea, resistant S. alba initiated enhanced abscisic acid (ABA) and jasmonic acid (JA) responses following challenge with this pathogen, as revealed by monitoring the expression of ABA-related genes along with the concentration of ABA and JA. Furthermore, these results were verified by the exogenous application of ABA on B. juncea leaves prior to challenge with A. brassicicola, which resulted in a delayed disease progression, followed by the inhibition of the pathogen-mediated increase in SA response and enhanced JA levels. Therefore, it seems that A. brassicicola is steering the defence response towards a biotrophic mode by mounting an SA response in susceptible B. juncea, whereas the enhanced ABA response of S. alba not only counteracts the SA response but also restores the necrotrophic mode of resistance by enhancing JA biosynthesis. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

Alternaria cerasidanica sp nov., isolated in Denmark from drupes of Prunus avium

DEFF Research Database (Denmark)

Roberts, R. G.; Reymond, S. T.; Andersen, Birgitte

2010-01-01

The ex-type strain of Alternaria cerasidanica was isolated in 2001 from an immature, asymptomatic drupe of Prunus avium collected at a commercial cherry orchard near Skaelskor, Denmark. Cultural morphology, sporulation pattern and cluster analyses of combined RAPD, RAMS (microsatellite), and AFLP...

Expressed sequence enrichment for candidate gene analysis of citrus tristeza virus resistance.

Science.gov (United States)

Bernet, G P; Bretó, M P; Asins, M J

2004-02-01

Several studies have reported markers linked to a putative resistance gene from Poncirus trifoliata ( Ctv-R) located at linkage group 4 that confers resistance against one of the most important citrus pathogens, citrus tristeza virus (CTV). To be successful in both marker-assisted selection and transformation experiments, its accurate mapping is needed. Several factors may affect its localization, among them two are considered here: the definition of resistance and the genetic background of progeny. Two progenies derived from P. trifoliata, by self-pollination and by crossing with sour orange ( Citrus aurantium), a citrus rootstock well-adapted to arid and semi-arid areas, were used for linkage group-4 marker enrichment. Two new methodologies were used to enrich this region with expressed sequences. The enrichment of group 4 resulted in the fusion of several C. aurantium linkage groups. The new one A(7+3+4) is now saturated with 48 markers including expressed sequences. Surprisingly, sour orange was as resistant to the CTV isolate tested as was P. trifoliata, and three hybrids that carry Ctv-R, as deduced from its flanking markers, are susceptible to CTV. The new linkage maps were used to map Ctv-R under the hypothesis of monogenic inheritance. Its position on linkage group 4 of P. trifoliata differs from the location previously reported in other progenies. The genetic analysis of virus-plant interaction in the family derived from C. aurantium after a CTV chronic infection showed the segregation of five types of interaction, which is not compatible with the hypothesis of a single gene controlling resistance. Two major issues are discussed: another type of genetic analysis of CTV resistance is needed to avoid the assumption of monogenic inheritance, and transferring Ctv-R from P. trifoliata to sour orange might not avoid the CTV decline of sweet orange trees.

Isolation of Xylella fastidiosa from Citrus sinensis (L) Osb. And Vitis vinifera and study of genetic diversity in Costa Rica

International Nuclear Information System (INIS)

Aguilar Alvarez, Estela Yamileth

2007-01-01

Xylella fastidiosa is a plant pathogenic bacterium that causes diseases in different crops. Symptoms similar to those caused by citrus variegated chlorosis (CVC) were observed in sweet orange trees which served as shade and fences in coffee plantations in Costa Rica, in 2002. A total of 35 citrus trees and 24 vines from eight different districts and 3 respectively were evaluated by 'double antibody sandwich enzyme-linked immunosorbent assay' (DASELISA), resulting in 21 citrus and 19 positive vid. From four citrus trees and six of vines, were obtained six isolates and seven isolates respectively in solid medium, whose morphological and biochemical characteristics coincided with those reported in the literature as characteristic of X. fastidiosa. The identity of the isolates is confirmed by the chain polymerase reaction (PCR) using primers 272-1/272-2int and RST31/RST33. Three isolates from Grecia (Alajuela Province) amplified a band of 500pb using specific primers 272-2int/CVC-1 for strains of X. fastidiosa that cause CVC. The genetic variability of isolates from each other in comparison with isolates of coffee in Costa Rica, U.S. grapes and citrus in Brazil have been studied using techniques of random amplification polymorphism DNA (RAPD) and length polymorphisms of restriction fragments (RFLPs) of the products obtained with primers int/272-2int JB-1/JB-2 and 272-1. The results showed a clear separation between citrus isolates of Costa Rica; and, an association of three of them with the strains of citrus in Brasil. Also, an association between strains of coffee of Costa Rica with grape vines in the U.S. An association of molecular analysis confirmed the data variance. (author) [es

Citrus tristeza virus-based RNAi in citrus plants induces gene silencing in Diaphorina citri, a phloem-sap sucking insect vector of citrus greening disease (Huanglongbing).

Science.gov (United States)

Hajeri, Subhas; Killiny, Nabil; El-Mohtar, Choaa; Dawson, William O; Gowda, Siddarame

2014-04-20

A transient expression vector based on Citrus tristeza virus (CTV) is unusually stable. Because of its stability it is being considered for use in the field to control Huanglongbing (HLB), which is caused by Candidatus Liberibacter asiaticus (CLas) and vectored by Asian citrus psyllid, Diaphorina citri. In the absence of effective control strategies for CLas, emphasis has been on control of D. citri. Coincident cohabitation in phloem tissue by CLas, D. citri and CTV was exploited to develop a novel method to mitigate HLB through RNA interference (RNAi). Since CTV has three RNA silencing suppressors, it was not known if CTV-based vector could induce RNAi in citrus. Yet, expression of sequences targeting citrus phytoene desaturase gene by CTV-RNAi resulted in photo-bleaching phenotype. CTV-RNAi vector, engineered with truncated abnormal wing disc (Awd) gene of D. citri, induced altered Awd expression when silencing triggers ingested by feeding D. citri nymphs. Decreased Awd in nymphs resulted in malformed-wing phenotype in adults and increased adult mortality. This impaired ability of D. citri to fly would potentially limit the successful vectoring of CLas bacteria between citrus trees in the grove. CTV-RNAi vector would be relevant for fast-track screening of candidate sequences for RNAi-mediated pest control. Copyright © 2014. Published by Elsevier B.V.

GC-MS analysis and antimicrobial activity determination of Citrus medica L. var proper leaf essential oil from South Sulawesi against skin pathogen microorganism

Science.gov (United States)

Aliyah; Himawan, A.; Rante, H.; Mufidah; Ningsih, D. R.

2017-11-01

A research about Citrus medica L. var sarcodactylis had been conducted and it showed a significant antimicrobial activity, thus drive our curiosity to investigate the other variety from the same species, Citrus medica L. var proper. This research focuses in chemical compound study and antimicrobial activity screening against Staphylococcus aureus, Propionibacterium acne, and Candida albicans of Citrus medica L. var Proper leaves’ essential oil. The essential oil is distillated from fresh leaves by hydrodestillation. The chemical compound was analysed using GC-MS instrument while the antimicrobial activity was tested using disk diffusion method. The results showed that the major component of the essential oil was Z-citral, citral and limonene compounds. The antimicrobial activity test results against the test microorganism are 9.15±0.15 mm, 11.15±1.3 mm and 8.02±0.48 mm, consecutively, for Staphylococcus aureus, Propionibacterium acne and Candida albicans.

Physical Changes in Satsuma Mandarin Leaf after Infection of Elsinoë fawcettii Causing Citrus Scab Disease

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Dilli Prasad Paudyal

2015-12-01

Full Text Available Citrus scab disease is one of the destructive diseases that reduce the value of fruit for the fresh market. We analyzed the process of symptom development after infection with scab pathogen Elsinoë fawcettii in the susceptible satsuma mandarin leaves to observe the structural modification against pathogen. The cuticle and epidermal cells along with 3–5 layers of mesophyll tissue were degraded 1–2 days post inoculation. Surrounding peripheral cells of degraded tissues grew rapidly and then enveloped the necrotic area along with the growing conidia. Cross sections through the lesion revealed hyphal colonization in epidermis and mesophyll tissues. In response to the pathogen colonization, host cell walls were lignified, inner cells were rapidly compartmentalized and a semi-circular boundary was formed that separated the infected region from the non-infected region, and finally prevented the intercellular pathogen spread.

A polyphasic approach to the taxonomy of the Alternaria infectoria species-group

DEFF Research Database (Denmark)

Andersen, Birgitte; Sørensen, Jens Laurids; Nielsen, Kristian Fog

2009-01-01

Different taxa in the species-group of Alternaria infectoria (teleomorph Lewia spp.) are often isolated from various cereals including barley, maize and wheat grain, ornamental plants and skin lesions from animals and humans. In the present study we made a polyphasic characterization of 39 strains...

Cryopreservation and Cryotherapy of Citrus Cultivars

Science.gov (United States)

Long-term conservation of Citrus clones can be accomplished by cryopreservation. Shoot tips will survive liquid nitrogen exposure and storage when appropriately desiccated and treated with cryoprotectant solutions. In our research, vegetative Citrus budwood is shipped from Riverside to Fort Collin...

Field validation of a system for autodissemination of an entomopathogenic fungus, Isaria fumosorosea, to control the Asian citrus psyllid on residential citrus

Science.gov (United States)

The citrus industries of California and Texas share a pressing problem with the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae) and huanglongbing (HLB) spreading in residential citrus near commercial groves. Insecticidal treatment of residential trees for the psyllid is problem...

In Silico Identification of Mimicking Molecules as Defense Inducers Triggering Jasmonic Acid Mediated Immunity against Alternaria Blight Disease in Brassica Species

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Dinesh Pandey

2017-04-01

Full Text Available Alternaria brassicae and Alternaria brassicicola are two major phytopathogenic fungi which cause Alternaria blight, a recalcitrant disease on Brassica crops throughout the world, which is highly destructive and responsible for significant yield losses. Since no resistant source is available against Alternaria blight, therefore, efforts have been made in the present study to identify defense inducer molecules which can induce jasmonic acid (JA mediated defense against the disease. It is believed that JA triggered defense response will prevent necrotrophic mode of colonization of Alternaria brassicae fungus. The JA receptor, COI1 is one of the potential targets for triggering JA mediated immunity through interaction with JA signal. In the present study, few mimicking compounds more efficient than naturally occurring JA in terms of interaction with COI1 were identified through virtual screening and molecular dynamics simulation studies. A high quality structural model of COI1 was developed using the protein sequence of Brassica rapa. This was followed by virtual screening of 767 analogs of JA from ZINC database for interaction with COI1. Two analogs viz. ZINC27640214 and ZINC43772052 showed more binding affinity with COI1 as compared to naturally occurring JA. Molecular dynamics simulation of COI1 and COI1-JA complex, as well as best screened interacting structural analogs of JA with COI1 was done for 50 ns to validate the stability of system. It was found that ZINC27640214 possesses efficient, stable, and good cell permeability properties. Based on the obtained results and its physicochemical properties, it is capable of mimicking JA signaling and may be used as defense inducers for triggering JA mediated resistance against Alternaria blight, only after further validation through field trials.

Citrus water use in South Africa

CSIR Research Space (South Africa)

Vahrmeijer, JT

2012-09-01

Full Text Available scheduling is needed to justify the quantity of water needed for the production of citrus. Models, which are formidable tools to predict water use and crop performance, are therefore vital to provide accurate estimates of citrus water use across different...

Antibacterial effect of citrus press-cakes dried by high speed and far-infrared radiation drying methods

Science.gov (United States)

Samarakoon, Kalpa; Senevirathne, Mahinda; Lee, Won-Woo; Kim, Young-Tae; Kim, Jae-Il; Oh, Myung-Cheol

2012-01-01

In this study, the antibacterial effect was evaluated to determine the benefits of high speed drying (HSD) and far-infrared radiation drying (FIR) compared to the freeze drying (FD) method. Citrus press-cakes (CPCs) are released as a by-product in the citrus processing industry. Previous studies have shown that the HSD and FIR drying methods are much more economical for drying time and mass drying than those of FD, even though FD is the most qualified drying method. The disk diffusion assay was conducted, and the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined with methanol extracts of the dried CPCs against 11 fish and five food-related pathogenic bacteria. The disk diffusion results indicated that the CPCs dried by HSD, FIR, and FD prevented growth of all tested bacteria almost identically. The MIC and MBC results showed a range from 0.5-8.0 mg/mL and 1.0-16.0 mg/mL respectively. Scanning electron microscopy indicated that the extracts changed the morphology of the bacteria cell wall, leading to destruction. These results suggest that CPCs dried by HSD and FIR showed strong antibacterial activity against pathogenic bacteria and are more useful drying methods than that of the classic FD method in CPCs utilization. PMID:22808341

Imidacloprid soil movement under micro-sprinkler irrigation and soil-drench applications to control Asian citrus psyllid (ACP) and citrus leafminer (CLM).

Science.gov (United States)

Fletcher, Evelyn; Morgan, Kelly T; Qureshi, Jawwad A; Leiva, Jorge A; Nkedi-Kizza, Peter

2018-01-01

Imidacloprid (IM) is used to control the Asian Citrus Psyllid (ACP) and citrus leafminer (CLM), which are related to the spread of huanglongbing (HLB or citrus greening) and citrus canker diseases, respectively. In Florida citrus, imidacloprid is mainly soil-drenched around the trees for proper root uptake and translocation into plant canopy to impact ACP and CLM. The objective of this study was to determine the effect of imidacloprid rate, and irrigate amount on concentration of imidacloprid in the soil following drench application to citrus trees in three age classes. The plots were established at the Southwest Florida Research and Education Center, Immokalee, using a randomized complete-block design for three age classes of trees: one-year-old trees (B1), three to five-year-old trees (B2), and eight-year-old trees (B3). The treatments were a combination of two rates each of imidacloprid (1D, 2D) and micro-sprinkling irrigation (1I, 2I). Imidacloprid and bromide (Br-) used as tracer were applied simultaneously. Soil moisture and concentrations of imidacloprid and Br were monitored using soil cores from hand held augers. Soil moisture content (θV) did not differ under two irrigation rates at any given observation day or depth, except following heavy rainfall events. Br- was lost from the observation depths (0-45 cm) about two weeks after soil-drench. Contrarily, imidacloprid persisted for a much longer time (4-8 weeks) at all soil depths, regardless of treatment combinations. The higher retardation of imidacloprid was related to the predominantly unsaturated conditions of the soil (which in turn reduced soil hydraulic conductivities by orders of magnitude), the imidacloprid sorption on soil organic matter, and the citrus root uptake. Findings of this study are important for citrus growers coping with the citrus greening and citrus canker diseases because they suggest that imidacloprid soil drenches can still be an effective control measure of ACP and CLM, and the

Citrus Flavonoids as Regulators of Lipoprotein Metabolism and Atherosclerosis.

Science.gov (United States)

Mulvihill, Erin E; Burke, Amy C; Huff, Murray W

2016-07-17

Citrus flavonoids are polyphenolic compounds with significant biological properties. This review summarizes recent advances in understanding the ability of citrus flavonoids to modulate lipid metabolism, other metabolic parameters related to the metabolic syndrome, and atherosclerosis. Citrus flavonoids, including naringenin, hesperitin, nobiletin, and tangeretin, have emerged as potential therapeutics for the treatment of metabolic dysregulation. Epidemiological studies reveal an association between the intake of citrus flavonoid-containing foods and a decreased incidence of cardiovascular disease. Studies in cell culture and animal models, as well as a limited number of clinical studies, reveal the lipid-lowering, insulin-sensitizing, antihypertensive, and anti-inflammatory properties of citrus flavonoids. In animal models, supplementation of rodent diets with citrus flavonoids prevents hepatic steatosis, dyslipidemia, and insulin resistance primarily through inhibition of hepatic fatty acid synthesis and increased fatty acid oxidation. Citrus flavonoids blunt the inflammatory response in metabolically important tissues including liver, adipose, kidney, and the aorta. The mechanisms underlying flavonoid-induced metabolic regulation have not been completely established, although several potential targets have been identified. In mouse models, citrus flavonoids show marked suppression of atherogenesis through improved metabolic parameters as well as through direct impact on the vessel wall. Recent studies support a role for citrus flavonoids in the treatment of dyslipidemia, insulin resistance, hepatic steatosis, obesity, and atherosclerosis. Larger human studies examining dose, bioavailability, efficacy, and safety are required to promote the development of these promising therapeutic agents.

Effect of genotype and environment on citrus juice carotenoid content.

Science.gov (United States)

Dhuique-Mayer, Claudie; Fanciullino, Anne-Laure; Dubois, Cecile; Ollitrault, Patrick

2009-10-14

A selection of orange and mandarin varieties belonging to the same Citrus accession and cultivated in Mediterranean (Corsica), subtropical (New Caledonia), and tropical areas (principally Tahiti) were studied to assess the effect of genotype and environmental conditions on citrus juice carotenoid content. Juices from three sweet orange cultivars, that is, Pera, Sanguinelli, and Valencia ( Citrus sinensis (L.) Osbeck), and two mandarin species ( Citrus deliciosa Ten and Citrus clementina Hort. ex Tan), were analyzed by HPLC using a C(30) column. Annual carotenoid content variations in Corsican fruits were evaluated. They were found to be very limited compared to variations due to varietal influences. The statistical analysis (PCA, dissimilarity tree) results based on the different carotenoid compounds showed that citrus juice from Corsica had a higher carotenoid content than citrus juices from tropical origins. The tropical citrus juices were clearly differentiated from citrus juices from Corsica, and close correlations were obtained between beta-cryptoxanthin and phytoene (r = 0.931) and beta-carotene and phytoene (r = 0.918). More broadly, Mediterranean conditions amplified interspecific differentiation, especially by increasing the beta-cryptoxanthin and cis-violaxanthin content in oranges and beta-carotene and phytoene-phytofluene content in mandarins. Thus, at a quantitative level, environmental conditions also had a major role in determining the levels of carotenoids of nutritional interest, such as the main provitamin A carotenoids in citrus juice (beta-cryptoxanthin and beta-carotene).

Compatibility of Isaria fumosorosea (Hypocreales: Cordycipitaceae Blastospores with Agricultural Chemicals Used for Management of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae

Directory of Open Access Journals (Sweden)

Pasco B. Avery

2013-11-01

Full Text Available Biorational insecticides are being increasingly emphasized for inclusion in integrated pest management programs for invasive insects. The entomopathogenic fungus, Isaria fumosorosea, can be used to help manage the Asian citrus psyllid with minimal impact on beneficial arthropods, but its effectiveness may be compromised by agrochemicals used to control concurrent arthropod pests and diseases. We evaluated the compatibility of I. fumosorosea blastospores with a range of spray oils and copper-based fungicides registered for use in citrus groves. Results of laboratory and greenhouse tests showed a range of responses of the fungus to the different materials, including compatibility and incompatibility. Overall, I. fumosorosea growth in vitro was reduced least by petroleum-based materials and most by botanical oils and borax, and some of the copper-based fungicides, suggesting that tank mixing of I. fumosorosea with these latter products should be avoided. However, equivalent negative effects of test materials on fungal pathogenicity were not always observed in tests with adult psyllids. We hypothesize that some oils enhanced adherence of blastospores to the insect cuticle, overcoming negative impacts on germination. Our data show that care should be taken in selecting appropriate agrochemicals for tank-mixing with commercial formulations of entomopathogenic fungi for management of citrus pests. The prospects of using I. fumosorosea for managing the invasive Asian citrus psyllid and other citrus pests are discussed.

Production of the Allergenic Protein Alt a 1 by Alternaria Isolates from Working Environments

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Justyna Skóra

2015-02-01

Full Text Available The aim of the study was to evaluate the ability of Alternaria isolates from workplaces to produce Alt a 1 allergenic protein, and to analyze whether technical materials (cellulose, compost, leather present within the working environment stimulate or inhibit Alt a 1 production (ELISA test. Studies included identification of the isolated molds by nucleotide sequences analyzing of the ITS1/ITS2 regions, actin, calmodulin and Alt a 1 genes. It has been shown that Alternaria molds are significant part of microbiocenosis in the archive, museum, library, composting plant and tannery (14%–16% frequency in the air. The presence of the gene encoding the Alt a 1 protein has been detected for the strains: Alternaria alternata, A. lini, A. limoniasperae A. nobilis and A. tenuissima. Environmental strains produced Alt a 1 at higher concentrations (1.103–6.528 ng/mL than a ATCC strain (0.551–0.975 ng/mL. It has been shown that the homogenization of the mycelium and the use of ultrafiltration allow a considerable increase of Alt a 1 concentration. Variations in the production of Alt a 1 protein, depend on the strain and extraction methods. These studies revealed no impact of the technical material from the workplaces on the production of Alt a 1 protein.

Temperature studies with the Asian citrus psyllid, Diaphorina citri: cold hardiness and temperature thresholds for oviposition.

Science.gov (United States)

Hall, David G; Wenninger, Erik J; Hentz, Matthew G

2011-01-01

This study was conducted to obtain information on the cold hardiness of the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), in Florida and to assess upper and lower temperature thresholds for oviposition. The psyllid is an important pest in citrus because it transmits the bacterial pathogens responsible for citrus greening disease, Huanglongbing, considered the most serious citrus disease worldwide. D. citri was first found in Florida during 1998, and the disease was discovered during 2005. Little was known regarding cold hardiness of D. citri, but Florida citrus is occasionally subjected to notable freeze events. Temperature and duration were each significant sources of variation in percent mortality of D. citri subjected to freeze events. Relatively large percentages of adults and nymphs survived after being exposed for several hours to temperatures as low as -5 to -6 °C. Relatively large percentages of eggs hatched after being exposed for several hours to temperatures as low as -8 °C. Research results indicated that adult D. citri become cold acclimated during the winter through exposure to cooler winter temperatures. There was no evidence that eggs became cold acclimated during winter. Cold acclimation in nymphs was not investigated. Research with adult D. citri from laboratory and greenhouse colonies revealed that mild to moderate freeze events were usually nonlethal to the D. citri irrespective of whether they were cold acclimated or not. Upper and lower temperature thresholds for oviposition were investigated because such information may be valuable in explaining the geographic distribution and potential spread of the pest from Florida as well as how cooler winter temperatures might limit population growth. The estimated lower and upper thresholds for oviposition were 16.0 and 41.6 °C, respectively; the estimated temperature of peak oviposition over a 48 h period was 29.6 °C.

A polyphasic approach for the characterization of endophytic Alternaria strains isolated from grapevines

DEFF Research Database (Denmark)

Polizzotto, Rachele; Andersen, Birgitte; Martini, Marta

2012-01-01

A polyphasic approach was set up and applied to characterize 20 fungal endophytes belonging to the genus Alternaria, recovered from grapevine in different Italian regions.Morphological, microscopical, molecular and chemical investigations were performed and the obtained results were combined in a...

Laser diagnostic technology for early detection of pathogen infestation in orange fruits

International Nuclear Information System (INIS)

Giubileo, Gianfranco; Lai, Antonella; Piccinelli, Delinda; Puiu, Adriana

2010-01-01

Due to an increased expectation of food products that respect high quality and safety standards, there is a need for the growth of accurate, fast, objective and non-destructive technologies for quality determination of food and agricultural products. For this purpose, a diagnostic system based on laser photoacoustic spectroscopy (LPAS) was developed at ENEA Frascati Molecular Spectroscopy Laboratory (Italy). In the design of the photoacoustic detector, particular emphasis was placed in attaining a high sensitivity in detecting ethylene (ET) down to sub-parts per billion level (minimum detectable concentration 0.2 ppb). This was required due to the necessity to monitor and follow up ET production at a single fruit scale. ET is normally synthesised in very low amounts by healthy citrus fruits; however stress conditions such as pathogen attack may induce a substantial increase in the synthesised ET. In the present paper, the comparison between the ET emitted by healthy oranges (Citrus sinensis L. Osbeck) cv Navel and by Phytophthora citrophthora infested Navel orange fruits are reported. The obtained results show a well evident increase in ET emission from the infested fruit with respect to the healthy one, even 24 h after the inoculation with the pathogen; at that time the tissue necrosis was not yet visible, and the fruit was also not yet damaged. The possibility to perform a real time non-destructive detection of ET traces makes the LPAS a powerful tool for monitoring the healthy state of the citrus fruits.

Laser diagnostic technology for early detection of pathogen infestation in orange fruits

Science.gov (United States)

Giubileo, Gianfranco; Lai, Antonella; Piccinelli, Delinda; Puiu, Adriana

2010-11-01

Due to an increased expectation of food products that respect high quality and safety standards, there is a need for the growth of accurate, fast, objective and non-destructive technologies for quality determination of food and agricultural products. For this purpose, a diagnostic system based on laser photoacoustic spectroscopy (LPAS) was developed at ENEA Frascati Molecular Spectroscopy Laboratory (Italy). In the design of the photoacoustic detector, particular emphasis was placed in attaining a high sensitivity in detecting ethylene (ET) down to sub-parts per billion level (minimum detectable concentration 0.2 ppb). This was required due to the necessity to monitor and follow up ET production at a single fruit scale. ET is normally synthesised in very low amounts by healthy citrus fruits; however stress conditions such as pathogen attack may induce a substantial increase in the synthesised ET. In the present paper, the comparison between the ET emitted by healthy oranges ( Citrus sinensis L. Osbeck) cv Navel and by Phytophthora citrophthora infested Navel orange fruits are reported. The obtained results show a well evident increase in ET emission from the infested fruit with respect to the healthy one, even 24 h after the inoculation with the pathogen; at that time the tissue necrosis was not yet visible, and the fruit was also not yet damaged. The possibility to perform a real time non-destructive detection of ET traces makes the LPAS a powerful tool for monitoring the healthy state of the citrus fruits.

Laser diagnostic technology for early detection of pathogen infestation in orange fruits

Energy Technology Data Exchange (ETDEWEB)

Giubileo, Gianfranco, E-mail: gianfranco.giubileo@frascati.enea.i [ENEA Frascati, Via E. Fermi 45, 00044 (Italy); Lai, Antonella; Piccinelli, Delinda [ENEA Frascati, Via E. Fermi 45, 00044 (Italy); Puiu, Adriana [Tor Vergata University of Rome, Faculty of Engineering, Via del Politecnico 1, 00133 Rome (Italy)

2010-11-11

Due to an increased expectation of food products that respect high quality and safety standards, there is a need for the growth of accurate, fast, objective and non-destructive technologies for quality determination of food and agricultural products. For this purpose, a diagnostic system based on laser photoacoustic spectroscopy (LPAS) was developed at ENEA Frascati Molecular Spectroscopy Laboratory (Italy). In the design of the photoacoustic detector, particular emphasis was placed in attaining a high sensitivity in detecting ethylene (ET) down to sub-parts per billion level (minimum detectable concentration 0.2 ppb). This was required due to the necessity to monitor and follow up ET production at a single fruit scale. ET is normally synthesised in very low amounts by healthy citrus fruits; however stress conditions such as pathogen attack may induce a substantial increase in the synthesised ET. In the present paper, the comparison between the ET emitted by healthy oranges (Citrus sinensis L. Osbeck) cv Navel and by Phytophthora citrophthora infested Navel orange fruits are reported. The obtained results show a well evident increase in ET emission from the infested fruit with respect to the healthy one, even 24 h after the inoculation with the pathogen; at that time the tissue necrosis was not yet visible, and the fruit was also not yet damaged. The possibility to perform a real time non-destructive detection of ET traces makes the LPAS a powerful tool for monitoring the healthy state of the citrus fruits.

Homologues of CsLOB1 in citrus function as disease susceptibility genes in citrus canker.

Science.gov (United States)

Zhang, Junli; Huguet-Tapia, Jose Carlos; Hu, Yang; Jones, Jeffrey; Wang, Nian; Liu, Sanzhen; White, Frank F

2017-08-01

The lateral organ boundary domain (LBD) genes encode a group of plant-specific proteins that function as transcription factors in the regulation of plant growth and development. Citrus sinensis lateral organ boundary 1 (CsLOB1) is a member of the LBD family and functions as a disease susceptibility gene in citrus bacterial canker (CBC). Thirty-four LBD members have been identified from the Citrus sinensis genome. We assessed the potential for additional members of LBD genes in citrus to function as surrogates for CsLOB1 in CBC, and compared host gene expression on induction of different LBD genes. Using custom-designed transcription activator-like (TAL) effectors, two members of the same clade as CsLOB1, named CsLOB2 and CsLOB3, were found to be capable of functioning similarly to CsLOB1 in CBC. RNA sequencing and quantitative reverse transcription-polymerase chain reaction analyses revealed a set of cell wall metabolic genes that are associated with CsLOB1, CsLOB2 and CsLOB3 expression and may represent downstream genes involved in CBC. © 2016 BSPP AND JOHN WILEY & SONS LTD.

Evaluation of Chemical Composition and Biological Activities of Citrus pseudolimon and Citrus grandis Peel Essential Oils

International Nuclear Information System (INIS)

Sajid, A.; Hanif, M.A.; Shahid, M.

2016-01-01

Essential oils and their volatile constituents are used extensively to prevent and treat human diseases. In the past decades, worldwide demand for citrus essential oils has greatly increased. Citrus essential oils containing 85-99 percent volatile and 1-15 percent non-volatile components. Essential oils from Citrus pseudolimon and Citrus grandis peels were extracted through steam distillation and characterized by GC-MS. C. pseudolimon has thirty six and C. grandis has thirty three total components; limonene 47.07 percent and 71.48 percent was the major component in both oils respectively. Antioxidant activity was checked by 2, 2-diphenyl-1-picrylhydrazyl radical assay and β-carotene/linoleic acid bleaching test. Both oils have modest activity. The antimicrobial potential was assessed against different bacterial and fungus strains. C. pseudolimon oil possessed strong activity against all tested strains while C. grandis has moderate activity. The antitumor activity was evaluated by potato disc assay, C. pseudolimon showed 81.25 inhibition. Hence the essential oils could have a great potential in pharmaceutical industry. (author)

Drought Tip: Irrigating Citrus with Limited Water

OpenAIRE

Faber, Ben

2015-01-01

As an evergreen in California's Mediterranean climate, with wet winters and dry summers, citrus requires some water all year long. Depending on the cultivar and rootstock, citrus can sustain certain levels of drought stress.

Alternaria sp. MG1, a resveratrol-producing fungus: isolation, identification, and optimal cultivation conditions for resveratrol production.

Science.gov (United States)

Shi, Junling; Zeng, Qin; Liu, Yanlin; Pan, Zhongli

2012-07-01

Due to its potential in preventing or slowing the occurrence of many diseases, resveratrol (3,5,4'-trihydroxystilbene) has attracted great research interest. The objective of this study was to identify microorganisms from selected plants that produce resveratrol and to optimize the conditions for resveratrol production. Endophytes from Merlot wine grapes (Vitis vinifera L. cv. Merlot), wild Vitis (Vitis quinquangularis Rehd.), and Japanese knotweed (Polygonum cuspidatum Siebold & Zucc.) were isolated, and their abilities to produce resveratrol were evaluated. A total of 65 isolates were obtained and 21 produced resveratrol (6-123 μg/L) in liquid culture. The resveratrol-producing isolates belonged to seven genera, Botryosphaeria, Penicillium, Cephalosporium, Aspergillus, Geotrichum, Mucor, and Alternaria. The resveratrol-producing capability decreased or was completely lost in most isolates after three rounds of subculture. It was found that only the strain Alternaria sp. MG1 (isolated from cob of Merlot using GA1 medium) had stable and high resveratrol-producing capability in all subcultures. During liquid cultivation of Alternaria sp. MG1 in potato dextrose medium, the synthesis of resveratrol began on the first day, increased to peak levels on day 7, and then decreased sharply thereafter. Cell growth increased during cultivation and reached a stable and high level of biomass after 5 days. The best fermentation conditions for resveratrol production in liquid cultures of Alternaria sp. MG1 were an inoculum size of 6 %, a medium volume of 125 mL in a 250-mL flask, a rotation speed of 101 rpm, and a temperature of 27 °C.

Discovering Novel Alternaria solani Succinate Dehydrogenase Inhibitors by in Silico Modeling and Virtual Screening Strategies to Combat Early Blight

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Sehrish Iftikhar

2017-11-01

Full Text Available Alternaria blight is an important foliage disease caused by Alternaria solani. The enzyme Succinate dehydrogenase (SDH is a potential drug target because of its role in tricarboxylic acid cycle. Hence targeting Alternaria solani SDH enzyme could be efficient tool to design novel fungicides against A. solani. We employed computational methodologies to design new SDH inhibitors using homology modeling; pharmacophore modeling and structure based virtual screening. The three dimensional SDH model showed good stereo-chemical and structural properties. Based on virtual screening results twelve commercially available compounds were purchased and tested in vitro and in vivo. The compounds were found to inhibit mycelial growth of A. solani. Moreover in vitro trials showed that inhibitory effects were enhanced with increase in concentrations. Similarly increased disease control was observed in pre-treated potato tubers. Hence the applied in silico strategy led us to identify novel fungicides.

Seed isolates of Alternaria and Aspergillus fungi increase germination of Astragalus utahensis

Science.gov (United States)

Sean D. Eldredge; Brad Geary; Scott L. Jensen

2016-01-01

Astragalus utahensis (Torr.) Torr. & A. Gray (Fabaceae) (Utah milkvetch) is native lo the arid Great Basin and has desirable attributes that make it a good candidate for restoration in arid, noncompetitive situations. Seed dormancy is a significant barrier to consistent establishment for this species. Species of Alternaria and Aspergillus fungi have...

Genetic transformation of sweet orange with the coat protein gene of Citrus psorosis virus and evaluation of resistance against the virus.

Science.gov (United States)

Zanek, María Cecilia; Reyes, Carina Andrea; Cervera, Magdalena; Peña, Eduardo José; Velázquez, Karelia; Costa, Norma; Plata, Maria Inés; Grau, Oscar; Peña, Leandro; García, María Laura

2008-01-01

Citrus psorosis is a serious viral disease affecting citrus trees in many countries. Its causal agent is Citrus psorosis virus (CPsV), the type member of genus Ophiovirus. CPsV infects most important citrus varieties, including oranges, mandarins and grapefruits, as well as hybrids and citrus relatives used as rootstocks. Certification programs have not been sufficient to control the disease and no sources of natural resistance have been found. Pathogen-derived resistance (PDR) can provide an efficient alternative to control viral diseases in their hosts. For this purpose, we have produced 21 independent lines of sweet orange expressing the coat protein gene of CPsV and five of them were challenged with the homologous CPV 4 isolate. Two different viral loads were evaluated to challenge the transgenic plants, but so far, no resistance or tolerance has been found in any line after 1 year of observations. In contrast, after inoculation all lines showed characteristic symptoms of psorosis in the greenhouse. The transgenic lines expressed low and variable amounts of the cp gene and no correlation was found between copy number and transgene expression. One line contained three copies of the cp gene, expressed low amounts of the mRNA and no coat protein. The ORF was cytosine methylated suggesting a PTGS mechanism, although the transformant failed to protect against the viral load used. Possible causes for the failed protection against the CPsV are discussed.

Expression and functional analysis of citrus carotene hydroxylases: unravelling the xanthophyll biosynthesis in citrus fruits.

Science.gov (United States)

Ma, Gang; Zhang, Lancui; Yungyuen, Witchulada; Tsukamoto, Issei; Iijima, Natsumi; Oikawa, Michiru; Yamawaki, Kazuki; Yahata, Masaki; Kato, Masaya

2016-06-29

Xanthophylls are oxygenated carotenoids and fulfill critical roles in plant growth and development. In plants, two different types of carotene hydroxylases, non-heme di-iron and heme-containing cytochrome P450, were reported to be involved in the biosynthesis of xanthophyll. Citrus fruits accumulate a high amount of xanthophylls, especially β,β-xanthophylls. To date, however, the roles of carotene hydroxylases in regulating xanthophyll content and composition have not been elucidated. In the present study, the roles of four carotene hydroxylase genes (CitHYb, CitCYP97A, CitCYP97B, and CitCYP97C) in the biosynthesis of xanthophyll in citrus fruits were investigated. Phylogenetic analysis showed that the four citrus carotene hydroxylases presented in four distinct clusters which have been identified in higher plants. CitHYb was a non-heme di-iron carotene hydroxylase, while CitCYP97A, CitCYP97B, and CitCYP97C were heme-containing cytochrome P450-type carotene hydroxylases. Gene expression results showed that the expression of CitHYb increased in the flavedo and juice sacs during the ripening process, which was well consistent with the accumulation of β,β-xanthophyll in citrus fruits. The expression of CitCYP97A and CitCYP97C increased with a peak in November, which might lead to an increase of lutein in the juice sacs during the ripening process. The expression level of CitCYP97B was much lower than that of CitHYb, CitCYP97A, and CitCYP97C in the juice sacs during the ripening process. Functional analysis showed that the CitHYb was able to catalyze the hydroxylation of the β-rings of β-carotene and α-carotene in Escherichia coli BL21 (DE3) cells. Meanwhile, when CitHYb was co-expressed with CitCYP97C, α-carotene was hydroxylated on the β-ring and ε-ring sequentially to produce lutein. CitHYb was a key gene for β,β-xanthophyll biosynthesis in citrus fruits. CitCYP97C functioned as an ε-ring hydroxylase to produce lutein using zeinoxanthin as a substrate

Alternaria alternata peritonitis in a patient undergoing continuous ambulatory peritoneal dialysis

Directory of Open Access Journals (Sweden)

Yosra Guedri

2017-01-01

Full Text Available Fungal peritonitis is a serious complication of peritoneal dialysis (PD leading to loss of ultrafiltration and discontinuation of PD treatment. The most frequently isolated fungi are Candida albicans and, filamentous fungi such Alternaria alternata species are found only rarely. We report the case of a 75-year-old woman who developed peritonitis due to this black fungus.

Evaluating citrus germplasm for huanglongbing (HLB) resistance: USDA-ARS Inoculation Program

Science.gov (United States)

The Asian citrus psyllid (ACP), Diaphorina citri, is an important pest because it vectors bacteria responsible for a serious disease of citrus known as huanglongbing (citrus greening disease). USDA-ARS researchers recently established a program for screening citrus germplasm for resistance to the di...

Mechanical Damage Detection of Indonesia Local Citrus Based on Fluorescence Imaging

Science.gov (United States)

Siregar, T. H.; Ahmad, U.; Sutrisno; Maddu, A.

2018-05-01

Citrus experienced physical damage in peel will produce essential oils that contain polymethoxylated flavone. Polymethoxylated flavone is fluorescence substance; thus can be detected by fluorescence imaging. This study aims to study the fluorescence spectra characteristic and to determine the damage region in citrus peel based on fluorescence image. Pulung citrus from Batu district, East Java, as a famous citrus production area in Indonesia, was used in the experiment. It was observed that the image processing could detect the mechanical damage region. Fluorescence imaging can be used to classify the citrus into two categories, sound and defect citruses.

Pathogens present on vegetative organs and seeds of white mustard (Sinapis alba L. and chinese mustad (Brassica juncea L.

Directory of Open Access Journals (Sweden)

Barbara Majchrzak

2013-12-01

Full Text Available The research was conducted in the years 1999-2001. The aim of the research was to determine the health condition of overground parts and seeds of white niuslard (Sinapis alba L. cv. Metex and chinese mustard (Brassica juncea L. cv. Małopolska. In all the years of the research alternaria blight was found on the leaves of white mustard which injury index ranged from 5,6% in 2001 to 17,6% in 200O. The most dangerous disease of chinese mustard also was alternaria blight and its symptoms were found on leaves and siliques. The strongest infection of leaves was in 2000 (50% and the weakest in 2001 (6,7%. In all the years of the research siliques were rather weak infected (50-8,89%. Besides powdery mildew was found on chinese mustard which injury index ranged from 0,3% in 1999 to 32,3% in 2000. Intensity of diseases was affected generally by the weather conditions. From the seeds of white mustard and chinese mustard were isolated respectively 263 and 137 colonies. Alternaria alternata was the most numerous species which makes respectively 60,9% and 42,3% isolates. Among the fungi pathogenic for white and chinese mustard were also isolated: A. brassicae, Botrytis cinerea and Rhizoctonia solami.

Biological control of Alternaria radicina in seed production of carrots with Ulocladium atrum

NARCIS (Netherlands)

Köhl, J.; Langerak, C.J.; Meekes, E.T.M.; Molhoek, W.M.L.

2004-01-01

Black rot of carrots is caused by seed-borne Alternaria radicina. Biological control of seed infestation by treatments applied to plants in flower during seed production with the fungal antagonist Ulocladium atrum was investigated in laboratory and field experiments resulting in a reduction of seed

Antifungal activity of medicinal plant extracts against phytopathogenic fungus Alternaria spp Actividad antifúngica de extractos de plantas medicinales contra el hongo fitopatógeno Alternaria spp

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Paola Díaz Dellavalle

2011-06-01

Full Text Available The aim of the study was to evaluate the antifungal activity of extracts of 10 plant species used in traditional Uruguayan medicine against the phytopathogenic fungus Alternaria spp. The plants were selected on the basis of their reported ethnobotanical uses. Aqueous, saline buffer and acid extracts of different plant species were screened in vitro for their antifungal activity against Alternaria spp. For the antifungal evaluation we used a microspectrophotometric assay. Minimal inhibitory concentration (MIC and minimum fungicidal concentration (MFC of the extracts were determined. Three solvents were assayed on different tissues of the plants and among the 29 evaluated extracts, 31% of the extracts inhibited growth, similar to the effects of a chemical fungicide. Acid extracts of the plants were more effective than the aqueous or buffer extracts against Alternaria spp. The MIC values of the extracts were determined ranging between 1.25 and 25 µg mL-1. The MFC values of the extracts ranged between 1.25 µg mL-1 (Rosmarinus officinalis L. and 10 µg mL-1 (Cynara scolymus L.. MICs and MFCs values obtained from leaves (Salvia officinalis L. and R. officinalis and seeds extracts (Salvia sclarea L. were quite comparable to values obtained with the conventional fungicide captan (2.5 µg mL-1. The extracts of Salvia sclarea, S. officinalis and R. officinalis could be considered as potential sources of antifungal compounds for treating diseases in plants. These extracts showed maximum activity, even at very low concentrations, and the same fungicide effects as chemical fungicide. We conclude from this that these extracts exhibit amazing fungicidal properties that support their traditional use as antiseptics.El objetivo de este trabajo fue evaluar la actividad antifúngica de extractos vegetales de 10 especies utilizadas en la medicina tradicional uruguaya contra el hongo fitopatógeno Alternaria spp. Las plantas fueron seleccionadas en base a usos

Study of the thermal degradation of citrus seeds

Energy Technology Data Exchange (ETDEWEB)

Hernandez-Montoya, V. [Centro de Quimica, Instituto de Ciencias, Universidad Autonoma de Puebla, Apdo. Postal J-55, Puebla 72570, Pue (Mexico); Instituto Nacional del Carbon, CSIC, Apartado 73, E-33080 Oviedo (Spain); Montes-Moran, M.A. [Instituto Nacional del Carbon, CSIC, Apartado 73, E-33080 Oviedo (Spain); Elizalde-Gonzalez, M.P. [Centro de Quimica, Instituto de Ciencias, Universidad Autonoma de Puebla, Apdo. Postal J-55, Puebla 72570, Pue (Mexico)

2009-09-15

The citrus seeds are one of the principal residues in the juice industry and their utilization can decrease significantly the problems of their final disposal. In this work the thermal degradation of three Mexican citrus seeds: orange (Citrus sinensis), lemon (Citrus Limon) and grapefruit (Citrus paradisi) was studied in nitrogen atmosphere. The two components (embryo and husk) of the seeds were characterized separately. The results showed that the thermal effects are very similar between the three embryos and the three husks. The embryos show higher degradability, superior content of nitrogen and higher heating value than the husks. The thermal degradation of the components of the three seeds is completed at 600 C and it is considered to be a global process derived from the decomposition of their principal components (cellulose, hemicellulose and lignin). The results suggest that mixing the three entire seeds will not lead to a severe deviation from their individual thermal behavior and that the industry could apply them for carbonization purposes. (author)

Quantitation of flavonoid constituents in citrus fruits.

Science.gov (United States)

Kawaii, S; Tomono, Y; Katase, E; Ogawa, K; Yano, M

1999-09-01

Twenty-four flavonoids have been determined in 66 Citrus species and near-citrus relatives, grown in the same field and year, by means of reversed phase high-performance liquid chromatography analysis. Statistical methods have been applied to find relations among the species. The F ratios of 21 flavonoids obtained by applying ANOVA analysis are significant, indicating that a classification of the species using these variables is reasonable to pursue. Principal component analysis revealed that the distributions of Citrus species belonging to different classes were largely in accordance with Tanaka's classification system.

Infection of an Insect Vector with a Bacterial Plant Pathogen Increases Its Propensity for Dispersal

Science.gov (United States)

Coy, Monique R.; Stelinski, Lukasz L.; Pelz-Stelinski, Kirsten S.

2015-01-01

The spread of vector-transmitted pathogens relies on complex interactions between host, vector and pathogen. In sessile plant pathosystems, the spread of a pathogen highly depends on the movement and mobility of the vector. However, questions remain as to whether and how pathogen-induced vector manipulations may affect the spread of a plant pathogen. Here we report for the first time that infection with a bacterial plant pathogen increases the probability of vector dispersal, and that such movement of vectors is likely manipulated by a bacterial plant pathogen. We investigated how Candidatus Liberibacter asiaticus (CLas) affects dispersal behavior, flight capacity, and the sexual attraction of its vector, the Asian citrus psyllid (Diaphorina citri Kuwayama). CLas is the putative causal agent of huanglongbing (HLB), which is a disease that threatens the viability of commercial citrus production worldwide. When D. citri developed on CLas-infected plants, short distance dispersal of male D. citri was greater compared to counterparts reared on uninfected plants. Flight by CLas-infected D. citri was initiated earlier and long flight events were more common than by uninfected psyllids, as measured by a flight mill apparatus. Additionally, CLas titers were higher among psyllids that performed long flights than psyllid that performed short flights. Finally, attractiveness of female D. citri that developed on infected plants to male conspecifics increased proportionally with increasing CLas bacterial titers measured within female psyllids. Our study indicates that the phytopathogen, CLas, may manipulate movement and mate selection behavior of their vectors, which is a possible evolved mechanism to promote their own spread. These results have global implications for both current HLB models of disease spread and control strategies. PMID:26083763

Infection of an Insect Vector with a Bacterial Plant Pathogen Increases Its Propensity for Dispersal.

Directory of Open Access Journals (Sweden)

Xavier Martini

Full Text Available The spread of vector-transmitted pathogens relies on complex interactions between host, vector and pathogen. In sessile plant pathosystems, the spread of a pathogen highly depends on the movement and mobility of the vector. However, questions remain as to whether and how pathogen-induced vector manipulations may affect the spread of a plant pathogen. Here we report for the first time that infection with a bacterial plant pathogen increases the probability of vector dispersal, and that such movement of vectors is likely manipulated by a bacterial plant pathogen. We investigated how Candidatus Liberibacter asiaticus (CLas affects dispersal behavior, flight capacity, and the sexual attraction of its vector, the Asian citrus psyllid (Diaphorina citri Kuwayama. CLas is the putative causal agent of huanglongbing (HLB, which is a disease that threatens the viability of commercial citrus production worldwide. When D. citri developed on CLas-infected plants, short distance dispersal of male D. citri was greater compared to counterparts reared on uninfected plants. Flight by CLas-infected D. citri was initiated earlier and long flight events were more common than by uninfected psyllids, as measured by a flight mill apparatus. Additionally, CLas titers were higher among psyllids that performed long flights than psyllid that performed short flights. Finally, attractiveness of female D. citri that developed on infected plants to male conspecifics increased proportionally with increasing CLas bacterial titers measured within female psyllids. Our study indicates that the phytopathogen, CLas, may manipulate movement and mate selection behavior of their vectors, which is a possible evolved mechanism to promote their own spread. These results have global implications for both current HLB models of disease spread and control strategies.

Occurrence of Cladosporium spp. and Alternaria spp. spores in Western, Northern and Central-Eastern Poland in 2004-2006 and relation to some meteorological factors

Science.gov (United States)

Grinn-Gofroń, Agnieszka; Rapiejko, Piotr

2009-08-01

The concentration of airborne spores of Cladosporium spp. and Alternaria spp. has been investigated at three monitoring stations situated along the west-north and central-east transect in Poland (Szczecin, Olsztyn, Warszawa,) i.e. from a height of 100 m to 149 m above sea level. The aerobiological monitoring of fungal spores was performed by means of three Lanzoni volumetric spore traps. Cladosporium spp. spores were dominant at all the stations. The highest Cladosporium spp. and Alternaria spp. numbers of spores were observed at all the cities in July and August. Statistically significant correlations have been found between the Cladosporium spp. and Alternaria spp. concentration in the air and the mean air temperature, amount of precipitation, air pressure and relative air humidity. The spore count of Cladosporium spp. and Alternaria spp. is determined by the diversity of local flora and weather conditions, especially by the air temperature. The identification of factors, which influence and shape spore concentrations, may significantly improve the current methods of allergy prevention.

Distribution Frequency and Incidence of Seed-borne Pathogens of Some Cereals and Industrial Crops in Serbia

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Jelena Lević

2012-01-01

Full Text Available A total of 41 species of fungi were isolated from seed samples of barley, maize, soybean,and sunflower collected at different locations in Serbia. The majority of detected speciesoccurred on barley (35 of 41 species or 87.8% comparing to soybean (17 of 41 species or41.5%, sunflower (16 of 41 species or 39.0% and maize (15 of 41 species or 36.9%. Speciesbelonging to genera Alternaria, Chaetomium, Epicoccum, Fusarium, Penicillium and Rhizopuswere present on seeds of all four plant species. Alternaria species were dominant on soybean,barley and sunflower seeds (85.7%, 84.7% and 76.9%. F. verticillioides and Penicilliumspp. were mainly isolated from maize seeds (100 and 92.3% respectively, while other specieswere isolated up to 38.5% (Chaetomium spp. and Rhizopus spp.. F. graminearum, F. proliferatum,F. poae and F. sporotrichioides were the most common Fusarium species isolatedfrom barley (51.1-93.3%, while on the soybean seeds F. oxysporum (71.4%, F. semitectum(57.1% and F. sporotrichioides (57.1% were prevalent. Frequency of Fusarium species onsunflower seeds varied from 7% (F. equiseti, F. graminearum, F. proliferatum and F. subglutinansto 15.4% (F. verticillioides. Statistically significant negative correlation (r = –0.678* wasdetermined for the incidence of F. graminearum and Alternaria spp., as well as, Fusarium spp.and Alternaria spp. (r = –0.614*, on barley seeds. The obtained results revealed that seedbornepathogens were present in most seed samples of important cereals and industrialcrops grown under different agroecological conditions in Serbia. Some of the identifiedfungi are potential producers of mycotoxins, thus their presence is important in termsof reduced food safety for humans and animals. Therefore, an early and accurate diagnosisand pathogen surveillance will provide time for the development and the applicationof disease strategies.

Phenotypic and Genotypic Evaluation of Pseudomonas syringae pv. syringae Strains, Causing Citrus Blast in the West of Mazandaran and the East of Guilan

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S. Sameie-Shirkadeh

2017-01-01

Full Text Available Introduction: P. syringae pv. syringae (P.s.s, the causal agent of blast of citrus trees, is one of the most important plant pathogens in the world. P.s.s is unique among most P. syringae pathovars according to its ability to cause disease in over 180 species of plants in several unrelated genera. Traditionally, Strains of P.s.s are identified on the basis of biochemical and nutritional tests and symptom expression in host plants. Genomic fingerprinting methods based on the polymerase chain reaction (PCR have been applied for identification and classification of plant-associated bacteria to the subspecies level. The objectives of this study were the phenotypic and molecular evaluation of P.s. pv. syringae strains causing citrus blast in the West of Mazandaran and the East of Guilan, and study of genetic diversity of P.s.s isolates of citrus by using ERIC and REP-PCR markers. Materials and Methods: During 2011 to 2012, citrus infected tissues were sampled from different orchards in the West of Mazandaran and the East of Guilan. Bacterial phenotypes were studied based on standard physiological and biochemical tests. Gram reaction was determined by potassium hydroxide solubility test (KOH test. Strains were grown on King'B medium (KB and fluorescent pigment production was evaluated. Levan formation, oxidase reaction, potato soft rot, Arginine dihydrolase and induction of the hypersensitive reaction in tobacco leaves (LOPAT tests, were done as described by Schadd et al. The standard strains of P.s. pv. syringae form IVIA were used as reference strains in this study. Pathogenicity Test was done as described by Yessad et al. Citrus seedlings were maintained in a greenhouse at 20°C. In addition, a PCR-based method was used to confirm the genus and species of bacteria by using bacterial specific primer pair’s designed for a specific gene of syringomycin B. Genetic diversity among the strains, was studied by rep-PCR fingerprinting. Genomic

Citrus tristeza virus: An increasing trend in the virus occurrence and ...

African Journals Online (AJOL)

ABC

2015-07-29

Jul 29, 2015 ... Citrus tristeza clostervirus (CTV) is one of the most damaging fruit viruses playing havoc in citrus ... diseases of citrus trees reported in Pakistan are tristeza, .... bark. Vein clearing and stem pitting were also observed on sweet orange trees sour ..... disposal of source of inoculum by removing old citrus trees ...

Physicochemical Characteristics of Citrus Seed Oils from Kerman, Iran

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Mohammad Reazai

2014-01-01

Full Text Available Recently, there has been a great deal of attention on usage, byproducts, and wastes of the food industry. There have been many studies on the properties of citrus seeds and extracted oil from citrus grown in Kerman, Iran. The rate of oil content of citrus seeds varies between 33.4% and 41.9%. Linoleic acid (33.2% to 36.3% is the key fatty acid found in citrus seeds oil and oleic (24.8% to 29.3% and palmitic acids (23.5% to 29.4% are the next main fatty acids, respectively. There are also other acids found at trivial rates such as stearic, palmitoleic, and linolenic. With variation between 0.54 meg/kg and 0.77 mgq/kg in peroxide values of citrus seed oils, acidity value of the oil varies between 0.44% and 0.72%. The results of the study showed that citrus seeds under study (orange and sour lemon grown in Kerman province and the extracted oil have the potential of being used as the source of edible oil.

Expression patterns of flowering genes in leaves of 'Pineapple' sweet orange [Citrus sinensis (L.) Osbeck] and pummelo (Citrus grandis Osbeck).

Science.gov (United States)

Pajon, Melanie; Febres, Vicente J; Moore, Gloria A

2017-08-30

In citrus the transition from juvenility to mature phase is marked by the capability of a tree to flower and fruit consistently. The long period of juvenility in citrus severely impedes the use of genetic based strategies to improve fruit quality, disease resistance, and responses to abiotic environmental factors. One of the genes whose expression signals flower development in many plant species is FLOWERING LOCUS T (FT). In this study, gene expression levels of flowering genes CiFT1, CiFT2 and CiFT3 were determined using reverse-transcription quantitative real-time PCR in citrus trees over a 1 year period in Florida. Distinct genotypes of citrus trees of different ages were used. In mature trees of pummelo (Citrus grandis Osbeck) and 'Pineapple' sweet orange (Citrus sinensis (L.) Osbeck) the expression of all three CiFT genes was coordinated and significantly higher in April, after flowering was over, regardless of whether they were in the greenhouse or in the field. Interestingly, immature 'Pineapple' seedlings showed significantly high levels of CiFT3 expression in April and June, while CiFT1 and CiFT2 were highest in June, and hence their expression induction was not simultaneous as in mature plants. In mature citrus trees the induction of CiFTs expression in leaves occurs at the end of spring and after flowering has taken place suggesting it is not associated with dormancy interruption and further flower bud development but is probably involved with shoot apex differentiation and flower bud determination. CiFTs were also seasonally induced in immature seedlings, indicating that additional factors must be suppressing flowering induction and their expression has other functions.

Biocontrol Potential of Streptomyces hydrogenans strain DH16 Towards Alternaria brassicicola to Control Damping Off and Black Leaf Spot of Raphanus sativus

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Rajesh Kumari Manhas

2016-12-01

Full Text Available Biocontrol agents and their bioactive metabolites provide one of the best alternatives to decrease the use of chemical pesticides. In light of this, the present investigation reports the biocontrol potential of Streptomyces hydrogenans DH16 and its metabolites towards Alternaria brassicicola, causal agent of black leaf spot and damping off of seedlings of crucifers. In vitro antibiosis of strain against pathogen revealed complete suppression of mycelial growth of pathogen, grown in potato dextrose broth supplemented with culture supernatant (20% v/v of Streptomyces hydrogenans DH16. Microscopic examination of the fungal growth showed severe morphological abnormalities in the mycelium caused by antifungal metabolites. In vivo studies showed the efficacy of streptomycete cells and culture supernatant as seed dressings to control damping off of Raphanus sativus seedlings. Treatment of pathogen infested seeds with culture supernatant (10% and streptomycete cells significantly improved seed germination (75-80% and vigour index (1167-1538. Furthermore, potential of cells and culture supernatant as foliar treatment to control black leaf spot was also evaluated. Clearly visible symptoms of disease were observed in the control plants with 66.81% disease incidence and retarded growth of root system. However, disease incidence reduced to 6.78 and 1.47% in plants treated with antagonist and its metabolites, respectively. Additionally, treatment of seeds and plants with streptomycete stimulated various growth traits of plants over uninoculated control plants in the absence of pathogen challenge. These results indicate that S. hydrogenans and its culture metabolites can be developed as biofungicides as seed dressings to control seed borne pathogens, and as sprays to control black leaf spot of crucifers.

Understanding the dynamics of citrus water use

CSIR Research Space (South Africa)

Taylor, NJ

2012-12-01

Full Text Available The quantification of water use of citrus orchards is important in order to prevent stress developing in the orchard and to avoid wasting precious water resources. Measurement of citrus orchard water use is not possible under all environ-mental...

Alt a 1 allergen homologs from Alternaria and related taxa: analysis of phylogenetic content and secondary structure.

Science.gov (United States)

Hong, Soon Gyu; Cramer, Robert A; Lawrence, Christopher B; Pryor, Barry M

2005-02-01

A gene for the Alternaria major allergen, Alt a 1, was amplified from 52 species of Alternaria and related genera, and sequence information was used for phylogenetic study. Alt a 1 gene sequences evolved 3.8 times faster and contained 3.5 times more parsimony-informative sites than glyceraldehyde-3-phosphate dehydrogenase (gpd) sequences. Analyses of Alt a 1 gene and gpd exon sequences strongly supported grouping of Alternaria spp. and related taxa into several species-groups described in previous studies, especially the infectoria, alternata, porri, brassicicola, and radicina species-groups and the Embellisia group. The sonchi species-group was newly suggested in this study. Monophyly of the Nimbya group was moderately supported, and monophyly of the Ulocladium group was weakly supported. Relationships among species-groups and among closely related species of the same species-group were not fully resolved. However, higher resolution could be obtained using Alt a 1 sequences or a combined dataset than using gpd sequences alone. Despite high levels of variation in amino acid sequences, results of in silico prediction of protein secondary structure for Alt a 1 demonstrated a high degree of structural similarity for most of the species suggesting a conservation of function.

(HLB) infected citrus

African Journals Online (AJOL)

ONOS

2010-09-06

Sep 6, 2010 ... 1Departments of Crop Science, Faculty of Agriculture, University Putra Malaysia, 43400 Serdang, Selangor Darul ... Huanglongbing (HLB) disease, also known as citrus ..... Huanglongbing: A destructive, newly-emerging,.

Dehydrin-like proteins in the necrotrophic fungus Alternaria brassicicola have a role in plant pathogenesis and stress response.

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Stéphanie Pochon

Full Text Available In this study, the roles of fungal dehydrin-like proteins in pathogenicity and protection against environmental stresses were investigated in the necrotrophic seed-borne fungus Alternaria brassicicola. Three proteins (called AbDhn1, AbDhn2 and AbDhn3, harbouring the asparagine-proline-arginine (DPR signature pattern and sharing the characteristic features of fungal dehydrin-like proteins, were identified in the A. brassicicola genome. The expression of these genes was induced in response to various stresses and found to be regulated by the AbHog1 mitogen-activated protein kinase (MAPK pathway. A knock-out approach showed that dehydrin-like proteins have an impact mainly on oxidative stress tolerance and on conidial survival upon exposure to high and freezing temperatures. The subcellular localization revealed that AbDhn1 and AbDhn2 were associated with peroxisomes, which is consistent with a possible perturbation of protective mechanisms to counteract oxidative stress and maintain the redox balance in AbDhn mutants. Finally, we show that the double deletion mutant ΔΔabdhn1-abdhn2 was highly compromised in its pathogenicity. By comparison to the wild-type, this mutant exhibited lower aggressiveness on B. oleracea leaves and a reduced capacity to be transmitted to Arabidopsis seeds via siliques. The double mutant was also affected with respect to conidiation, another crucial step in the epidemiology of the disease.

Transcriptome analysis of sweet orange trees infected with 'Candidatus Liberibacter asiaticus' and two strains of Citrus Tristeza Virus.

Science.gov (United States)

Fu, Shimin; Shao, Jonathan; Zhou, Changyong; Hartung, John S

2016-05-11

Huanglongbing (HLB) and tristeza, are diseases of citrus caused by a member of the α-proteobacteria, 'Candidatus Liberibacter asiaticus' (CaLas), and Citrus tristeza virus (CTV) respectively. HLB is a devastating disease, but CTV strains vary from very severe to very mild. Both CaLas and CTV are phloem-restricted. The CaLas-B232 strain and CTV-B6 cause a wide range of severe and similar symptoms. The mild strain CTV-B2 doesn't induce significant symptoms or damage to plants. Transcriptome profiles obtained through RNA-seq revealed 611, 404 and 285 differentially expressed transcripts (DETs) after infection with CaLas-B232, CTV-B6 and CTV-B2. These DETs were components of a wide range of pathways involved in circadian rhythm, cell wall modification and cell organization, as well as transcription factors, transport, hormone response and secondary metabolism, signaling and stress response. The number of transcripts that responded to both CTV-B6 and CaLas-B232 was much larger than the number of transcripts that responded to both strains of CTV or to both CTV-B2 and CaLas-B232. A total of 38 genes were assayed by RT-qPCR and the correlation coefficients between Gfold and RT-qPCR were 0.82, 0.69, 0.81 for sweet orange plants infected with CTV-B2, CTV-B6 and CaLas-B232, respectively. The number and composition of DETs reflected the complexity of symptoms caused by the pathogens in established infections, although the leaf tissues sampled were asymptomatic. There were greater similarities between the sweet orange in response to CTV-B6 and CaLas-B232 than between the two CTV strains, reflecting the similar physiological changes caused by both CTV-B6 and CaLas-B232. The circadian rhythm system of plants was perturbed by all three pathogens, especially by CTV-B6, and the ion balance was also disrupted by all three pathogens, especially by CaLas-B232. Defense responses related to cell wall modification, transcriptional regulation, hormones, secondary metabolites, kinases and

Asian citrus psyllid RNAi pathway - RNAi evidence

Science.gov (United States)

In silico analyses of the draft genome of Diaphorina citri, the Asian citrus psyllid, for genes within the Ribonucleic acid interference(RNAi), pathway was successful. The psyllid is the vector of the plant-infecting bacterium, Candidatus Liberibacter asiaticus (CLas), which is linked to citrus gree...

Somatic Embryogenesis: Still a Relevant Technique in Citrus Improvement.

Science.gov (United States)

Omar, Ahmad A; Dutt, Manjul; Gmitter, Frederick G; Grosser, Jude W

2016-01-01

The genus Citrus contains numerous fresh and processed fruit cultivars that are economically important worldwide. New cultivars are needed to battle industry threatening diseases and to create new marketing opportunities. Citrus improvement by conventional methods alone has many limitations that can be overcome by applications of emerging biotechnologies, generally requiring cell to plant regeneration. Many citrus genotypes are amenable to somatic embryogenesis, which became a key regeneration pathway in many experimental approaches to cultivar improvement. This chapter provides a brief history of plant somatic embryogenesis with focus on citrus, followed by a discussion of proven applications in biotechnology-facilitated citrus improvement techniques, such as somatic hybridization, somatic cybridization, genetic transformation, and the exploitation of somaclonal variation. Finally, two important new protocols that feature plant regeneration via somatic embryogenesis are provided: protoplast transformation and Agrobacterium-mediated transformation of embryogenic cell suspension cultures.

Proximity to citrus influences Pierce's disease in Temecula Valley vineyards

OpenAIRE

Perring, Thomas M.; Farrar, Charles A.; Blua, Matthew

2001-01-01

Pierce's disease has caused extensive losses to grapes in the Temecula Valley. The primary vector of Pierce's disease in the region is the glassy-winged sharpshooter (GWSS), which has been found in large numbers in citrus trees. We examined the role of citrus in the Temecula Valley Pierce's disease epidemic and found that citrus groves have influenced the incidence and severity of Pierce's disease in grapes. Because GWSS inhabit citrus in large numbers, California grape growers should take ad...

Overexpression of NPR1 in Brassica juncea Confers Broad Spectrum Resistance to Fungal Pathogens

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Sajad Ali

2017-10-01

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.

Citrus paradisi: an effective bio-adsorbent for arsenic (v) remediation

International Nuclear Information System (INIS)

Khaskheli, M.I.; Memon, S.Q.; Parveen, S.

2014-01-01

In the present study As(V) was removed by citrus paradise (grape fruit) peel. Kinetics of the adsorption reaction was analyzed by the Pseudo second order and Morris-weber equations. Freundlich and Langmuir isotherm models were utilized for understanding of the relationship between the arsenic ions and citrus paradise peel adsorbent. The maximum measured uptake capacity of citrus paradise was 37.76 mg.g/sup -1/ at pH 4. FT-IR characterization of unloaded and As (V) loaded citrus paradisi peel adsorbent showed the participation of carbonyl (CO) and hydroxyl (OH) groups in adsorption process. The proposed citrus paradis peel adsorbent with optimized parameters was used for the removal of arsenic from arsenic contaminated real water samples. (author)

Metalized polyethylene mulch to repel Asian citrus psyllid, slow spread of huanglongbing and improve growth of new citrus plantings.

Science.gov (United States)

Croxton, Scott D; Stansly, Philip A

2014-02-01

Greening or huanglongbing (HLB) is a debilitating disease of citrus caused by Candidatus Liberibactor asiaticus and transmitted by the Asian citrus psyllid (ACP), Diaphorina citri. HLB now occurs worldwide in all major citrus growing regions except the Mediterranean and Australia. Management relies principally on insecticidal control of the ACP vector, but is insufficient, even for young trees which are most susceptible to the disease. We tested the ability of metalized polyethylene mulch to repel adult ACP as well as effects on incidence of HLB and early tree growth. Metalized mulch significantly reduced ACP populations and HLB incidence compared to whiteface mulch or bare ground. In addition, metalized mulch, together with the associated drip irrigation and fertigation system, increased soil moisture, reduced weed pressure, and increased tree growth rate. Metalized mulch slows spread of ACP and therefore HLB pressure on young citrus trees. Metalized mulch can thereby augment current control measures for young trees based primarily on systemic insecticides. Additional costs could be compensated for by increased tree growth rate which would shorten time to crop profitability. These advantages make a compelling case for large-scale trials using metalized mulch in young citrus plantings threatened by HLB. © 2013 Society of Chemical Industry.

Citrus peel extract incorporated ice cubes to protect the quality of common pandora: Fish storage in ice with citrus.

Science.gov (United States)

Yerlikaya, Pinar; Ucak, Ilknur; Gumus, Bahar; Gokoglu, Nalan

2015-12-01

The objective of this study was to investigate the effects of ice with albedo and flavedo fragments of Citrus (Grapefruit (Citrus paradisi) and Bitter orange (Citrus aurantium L.)) extracts on the quality of common pandora (Pagellus erythrinus). Concentrated citrus extracts were diluted with distilled water (1/100 w/v) before making of ice. The ice cubes were spread on each layer of fishes and stored at 0 °C for 15 days. The pH value showed a regular increase in all samples. TVB-N levels of bitter orange treatment groups were recorded lower than the other groups reaching to 25.11 ± 0.02 mg/100 g at the end of the storage. The TMA-N values of bitter orange treatment groups were lower than that of control and grapefruit treatment groups. In terms of TBARS value, alteration was observed in the control samples and this value significantly (p extracts treatment groups at the end of storage since their antioxidant capacity. The oxidation was suppressed in citrus extracts treatment groups, especially in bitter orange flavedo treatment. The results showed the bitter orange albedo and bitter orange flavedo extracts in combination with ice storage have more effectiveness in controlling the biochemical indices in common pandora.

Detection of Citrus psorosis virus in the northwestern citrus production area of Argentina by using an improved TAS-ELISA.

Science.gov (United States)

Zanek, Maria Cecilia; Peña, Eduardo; Reyes, Carina Andrea; Figueroa, Julia; Stein, Beatriz; Grau, Oscar; Garcia, Maria Laura

2006-11-01

Citrus Psorosis in Argentina is a serious disease. Citrus is produced in two regions located in the northeast (NE) and northwest (NW) area of the country. These two areas have different climates and soil types, and therefore different citrus species and varieties are cultivated. In the NE region, Psorosis is epidemic, and in the NW region, the disease was described on several occasions since 1938, but it is not observed commonly in the orchards. Recently, trees with symptoms of Psorosis were observed in the Tucumán and Salta Provinces located in the NW region. Epidemiological studies in Argentina and Texas suggested that the disease is spread naturally by an unknown vector. The causal agent of the disease is the Citrus psorosis virus (CPsV), which can be detected by TAS-ELISA, RT-PCR and indicator plants. A new more rapid TAS-ELISA-HRP (horseradish peroxidase) is described which is more reliable, faster and more sensitive than the currently used for this virus, the TAS-ELISA-AP (alkaline phosphatase). Psorosis was detected by this improved method in few trees in the orchards of the Tucumán Province, in the NW citrus region, although natural spread does not seem to occur.

Comparative analysis of juice volatiles in selected mandarins, mandarin relatives and other citrus genotypes.

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Yu, Yuan; Bai, Jinhe; Chen, Chunxian; Plotto, Anne; Baldwin, Elizabeth A; Gmitter, Frederick G

2018-02-01

Citrus fruit flavor is an important attribute prioritized in variety improvement. The present study compared juice volatiles compositions from 13 selected citrus genotypes, including six mandarins (Citrus reticulata), three sour oranges (Citrus aurantium), one blood orange (Citrus sinensis), one lime (Citrus limonia), one Clementine (Citrus clementina) and one satsuma (Citrus unshiu). Large differences were observed with respect to volatile compositions among the citrus genotypes. 'Goutou' sour orange contained the greatest number of volatile compounds and the largest volatile production level. 'Ponkan' mandarin had the smallest number of volatiles and 'Owari' satsuma yielded the lowest volatile production level. 'Goutou' sour orange and 'Moro' blood orange were clearly distinguished from other citrus genotypes based on the analysis of volatile compositions, even though they were assigned into one single group with two other sour oranges by the molecular marker profiles. The clustering analysis based on the aroma volatile compositions was able to differentiate mandarin varieties and natural sub-groups, and was also supported by the molecular marker study. The gas chromatography-mass spectrometry analysis of citrus juice aroma volatiles can be used as a tool to distinguish citrus genotypes and assist in the assessment of future citrus breeding programs. The aroma volatile profiles of the different citrus genotypes and inter-relationships detected among volatile compounds and among citrus genotypes will provide fundamental information on the development of marker-assisted selection in citrus breeding. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Degradation of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking.

Science.gov (United States)

Siegel, David; Feist, Michael; Proske, Matthias; Koch, Matthias; Nehls, Irene

2010-09-08

The stability of the Alternaria mycotoxins alternariol, alternariol monomethyl ether, and altenuene upon bread baking was investigated by model experiments using a spiked wholemeal wheat flour matrix. For alternariol and alternariol monomethyl ether, but not for altenuene, degradation products, formed through a sequence of hydrolysis and decarboxylation, could be identified in pilot studies. The simultaneous quantification of alternariol, alternariol monomethyl ether, altenuene, and the degradation products was achieved by a newly developed high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) multimethod. The obtained quantitative data indicate that the Alternaria mycotoxins are barely degraded during wet baking, while significant degradation occurs upon dry baking, with the stability decreasing in the order alternariol monomethyl ether>alternariol>altenuene. The novel degradation products could be detected after the wet baking of flour spiked with alternariol and in a sample survey of 24 commercial cereal based baking products.

Activation of Melanin Synthesis in Alternaria infectoria by Antifungal Drugs.

Science.gov (United States)

Fernandes, Chantal; Prados-Rosales, Rafael; Silva, Branca M A; Nakouzi-Naranjo, Antonio; Zuzarte, Mónica; Chatterjee, Subhasish; Stark, Ruth E; Casadevall, Arturo; Gonçalves, Teresa

2015-12-28

The importance of Alternaria species fungi to human health ranges from their role as etiological agents of serious infections with poor prognoses in immunosuppressed individuals to their association with respiratory allergic diseases. The present work focuses on Alternaria infectoria, which was used as a model organism of the genus, and was designed to unravel melanin production in response to antifungals. After we characterized the pigment produced by A. infectoria, we studied the dynamics of 1,8-dihydroxynaphthalene (DHN)-melanin production during growth, the degree of melanization in response to antifungals, and how melanization affected susceptibility to several classes of therapeutic drugs. We demonstrate that A. infectoria increased melanin deposition in cell walls in response to nikkomycin Z, caspofungin, and itraconazole but not in response to fluconazole or amphotericin B. These results indicate that A. infectoria activates DHN-melanin synthesis in response to certain antifungal drugs, possibly as a protective mechanism against these drugs. Inhibition of DHN-melanin synthesis by pyroquilon resulted in a lower minimum effective concentration (MEC) of caspofungin and enhanced morphological changes (increased hyphal balloon size), characterized by thinner and less organized A. infectoria cell walls. In summary, A. infectoria synthesizes melanin in response to certain antifungal drugs, and its susceptibility is influenced by melanization, suggesting the therapeutic potential of drug combinations that affect melanin synthesis. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

Necrotrophic pathogens use the salicylic acid signaling pathway to promote disease development in tomato.

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Rahman, Taha Abd El; Oirdi, Mohamed El; Gonzalez-Lamothe, Rocio; Bouarab, Kamal

2012-12-01

Plants use different immune pathways to combat pathogens. The activation of the jasmonic acid (JA)-signaling pathway is required for resistance against necrotrophic pathogens; however, to combat biotrophic pathogens, the plants activate mainly the salicylic acid (SA)-signaling pathway. SA can antagonize JA signaling and vice versa. NPR1 (noninducible pathogenesis-related 1) is considered a master regulator of SA signaling. NPR1 interacts with TGA transcription factors, ultimately leading to the activation of SA-dependent responses. SA has been shown to promote disease development caused by the necrotrophic pathogen Botrytis cinerea through NPR1, by suppressing the expression of two JA-dependent defense genes, proteinase inhibitors I and II. We show here that the transcription factor TGA1.a contributes to disease development caused by B. cinerea in tomato by suppressing the expression of proteinase inhibitors I and II. Finally, we present evidence that the SA-signaling pathway contributes to disease development caused by another necrotrophic pathogen, Alternaria solani, in tomato. Disease development promoted by SA through NPR1 requires the TGA1.a transcription factor. These data highlight how necrotrophs manipulate the SAsignaling pathway to promote their disease in tomato.

Effect of intercropping of maize in citrus orchards on citrus leaf miner infestation and population of its natural enemies

International Nuclear Information System (INIS)

Ahmed, S.; Khan, M.A.; Qasam, M.

2012-01-01

An experiment was conducted to determine the effect of intercropping of maize fodder in months of monsoon (July to October), in Faisalabad, Pakistan, on infestation of citrus leaf miner (CLM) (Phyllocnistis citrella Stanton) and its predators. Lemon, Kinnow, Grapefruit and Musambi intercropped with and without maize were selected for recording data on these insects. Percent leaf miner infestation and number of predators were recorded from randomly selected branches of citrus trees. Results showed that intercropped plots of each variety had low infestation of citrus miner and high population of coccinellids and Chrysoperla carnea and Musambi was 8.40+-0.144 and 12.72+-0.171 in intercropped and 9.12+-0.169 and 14.52+-0.200 in wihtout intercropped plots, respectively. Interaction of population of Chrysoperla carnea and coccinellids was non-significant for months, varieties and intercropping but was significant within months, varieties and intercropping. The possibility of using maize fodder as intercrop in autumn in citrus is discussed. (author)

Current Situation of Citrus Huanglongbing in Guangdong, P. R. China

Science.gov (United States)

Guangdong Province is an important citrus production region in China. Citrus Huanglongbing (HLB, yellow shoot disease) was observed in Guangdong probably in the late 1800’s and the disease was first studied there. Since the 1990’s, citrus production in Guangdong has gradually shifted from the coasta...

Control of Citrus Huanglongbing via Trunk Injection of Plant Defense Activators and Antibiotics.

Science.gov (United States)

Hu, J; Jiang, J; Wang, N

2018-02-01

Citrus huanglongbing (HLB) or greening is a devastating disease of citrus worldwide and no effective control measure is currently available. Plant defense activators environmentally friendly compounds capable of inducing resistance against many plant pathogens. Earlier studies showed that foliar spray of plant defense inducers could slow down HLB disease progress. In this study, eight plant defense activators and three antibiotics were evaluated in three field trials for their effect to control HLB by trunk injection of young and mature sweet orange trees. Results showed that four trunk injections of several activators, including salicylic acid, oxalic acid, acibenzolar-S-methyl, and potassium phosphate, provided significant control of HLB by suppressing 'Candidatus Liberibacter asiaticus' titer and disease progress. Trunk injection of penicillin, streptomycin, and oxytetracycline hydrochloride resulted in excellent control of HLB. In general, antibiotics were more effective in reduction of 'Ca. L. asiaticus' titer and HLB symptom expressions than plant defense activators. These treatments also resulted in increased yield and better fruit quality. Injection of both salicylic acid and acibenzolar-S-methyl led to significant induction of pathogenesis-related (PR) genes PR-1 and PR-2 genes. Meanwhile, injection of either potassium phosphate or oxalic acid resulted in significant induction of PR-2 or PR-15 gene expression, respectively. These results suggested that HLB diseased trees remained inducible for systemic acquired resistance under field conditions. In summary, this study presents information regarding controlling HLB via trunk injection of plant defense activators and antibiotics, which helps citrus growers in decision making regarding developing an effective HLB management program.

Citrus paradisi: An Effective bio-adsorbent for Arsenic (V Remediation

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Mazhar I. Khaskheli

2014-06-01

Full Text Available In the present study As (V was removed by citrus paradisi (grape fruit peel. Kinetics of the adsorption reaction was analyzed by the Pseudo second order and Morris-weber equations. Freundlich and Langmuir isotherm models were utilized for understanding of the relationship between the arsenic ions and citrus paradisi peel adsorbent. The maximum measured uptake capacity of citrus paradisi was 37.76 mg.g-1 at pH 4. FT-IR characterization of unloaded and As (V loaded citrus paradisi peel adsorbent showed the participation of carbonyl (CO and hydroxyl (OH groups in adsorption process. The proposed citrus paradisi peel adsorbent with optimized parameters was used for the removal of arsenic from arsenic contaminated real water samples.

Fungi isolated from Stewartia pseudocamellia Max. seeds and their pathogenesis

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Halina Kurzawińska

2012-12-01

Full Text Available The aim of studies was to determine typical composition of fungi occurring on seeds of Stewartia pseudocamellia.The studies conducted on 100 disinfected and 100 nondisinfected seeds of these plants.Isolates of Alternaria alternata, Fusarium oxysporum, Cylindrocarpon radicicola and Rhizoctonia solani were characterized by pathogenicity towards the investigated Stewartia pseudocamellia. In the laboratory experiment, 204 isolations of microorganisms were obtained that belonged to 20 species and form of fungi and bacteria. Among fungi there were both of parasite (Alternaria alternata, Botrytis cinerea, Fusarium spp., Rhizoctonia solani and typical saprophytic (Cladosporium spp., Penicillium spp., Aspergillus spp., Epicoccum spp., Mucor spp.. The dominant fungus on seeds was Alternaria alternata. Among the investigated isolates only one isolate (R4 Rhizoctonia solani, was strongly pathogenic, isolates (A1 Alternaria alternata were weakly pathogenic to seedlings of Stewartia pseudocamellia.

Combination of UV-C treatment and Metschnikowia pulcherrimas for controlling Alternaria rot in postharvest winter jujube fruit.

Science.gov (United States)

Guo, Dongqi; Zhu, Lixia; Hou, Xujie

2015-01-01

The potential of using antagonistic yeast Metschnikowia pulcherrimas alone or in combination with ultraviolet-C (UV-C) treatment for controlling Alternaria rot of winter jujube, and its effects on postharvest quality of fruit was investigated. The results showed that spore germination of Alternaria alternata was significantly inhibited by each of the 3 doses (1, 5, and 10 kJ m(-2) ) in vitro. In vivo, UV-C treatment (5 kJ m(-2) ) or antagonist yeast was capable of reducing the percentage of infected wounds and lesion diameter in artificially inoculated jujube fruits, however, in fruit treated with combination of UV-C treatment and M. pulcherrima, the percentage of infected wounds and lesion diameter was only 16.0% and 0.60 cm, respectively. The decay incidence on winter jujube fruits treated with the combination of UV-C treatment and M. pulcherrima was 23% after storage at 0 ± 1 °C for 45 d followed by 22 °C for 7 d. None of the treatments impaired quality parameters of jujube fruit. Thus, the combination of UV-C radiation and M. pulcherrima could be an alternative to synthetic fungicides for controlling postharvest Alternaria rot of winter jujube. © 2014 Institute of Food Technologists®

Citrus plastid-related gene profiling based on expressed sequence tag analyses

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Tercilio Calsa Jr.

2007-01-01

Full Text Available Plastid-related sequences, derived from putative nuclear or plastome genes, were searched in a large collection of expressed sequence tags (ESTs and genomic sequences from the Citrus Biotechnology initiative in Brazil. The identified putative Citrus chloroplast gene sequences were compared to those from Arabidopsis, Eucalyptus and Pinus. Differential expression profiling for plastid-directed nuclear-encoded proteins and photosynthesis-related gene expression variation between Citrus sinensis and Citrus reticulata, when inoculated or not with Xylella fastidiosa, were also analyzed. Presumed Citrus plastome regions were more similar to Eucalyptus. Some putative genes appeared to be preferentially expressed in vegetative tissues (leaves and bark or in reproductive organs (flowers and fruits. Genes preferentially expressed in fruit and flower may be associated with hypothetical physiological functions. Expression pattern clustering analysis suggested that photosynthesis- and carbon fixation-related genes appeared to be up- or down-regulated in a resistant or susceptible Citrus species after Xylella inoculation in comparison to non-infected controls, generating novel information which may be helpful to develop novel genetic manipulation strategies to control Citrus variegated chlorosis (CVC.

THE USE OF AZADIRACHTA INDICA EXTRACT TO DECREASE OF ALTERNARIA PORRI DISEASE ON ONION

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Loso Winarto

2013-01-01

Full Text Available Purple spot caused by Alternaria porri a major disease in the onion crop in the world. The disease is also widespread in the onion crop in Indonesia. This research aim was to know the effect of mimba leaf (Azadirachta indica extract concentration to decrease of Alternaria porri on onion (Allium ascalonicum L.This research conducted at Research Garden of the Center of Agricultural Technology Assessment of North Sumatra Province, from October 2010 until January 2011.The research used non factorial Block Randomized Design (BRD and four replications.The treatment consisted of six levels of Azadirachta indica which is dissolved in one litre of water each treatment. The number of replication are four each treatment. Treatment applied were 0 g plot-1 (control; 100 g plot-1; ; 150 g plot-1 ; 200 g plot-1 ; 250 g plot-1 ; 300 g plot-1 . The results showed that mimba leaf extract significantly affect the intensity of the purple spot disease and onion production.

Citrus Tristeza Virus: An Increasing Trend in the Virus Occurrence ...

African Journals Online (AJOL)

Citrus tristeza clostervirus (CTV) is one of the most damaging fruit viruses playing havoc in citrus orchards around the world. Here, we report, an ELISA-based indexing of citrus trees over a period of eight years (2002 to 2010) in Northwest Pakistan, revealing that the incidence of CTV is increasing mainly with the distribution ...

Detection of Citrus Trees from Uav Dsms

Science.gov (United States)

Ok, A. O.; Ozdarici-Ok, A.

2017-05-01

This paper presents an automated approach to detect citrus trees from digitals surface models (DSMs) as a single source. The DSMs in this study are generated from Unmanned Aerial Vehicles (UAVs), and the proposed approach first considers the symmetric nature of the citrus trees, and it computes the orientation-based radial symmetry in an efficient way. The approach also takes into account the local maxima (LM) information to verify the output of the radial symmetry. Our contributions in this study are twofold: (i) Such an integrated approach (symmetry + LM) has not been tested to detect (citrus) trees (in orchards), and (ii) the validity of such an integrated approach has not been experienced for an input, e.g. a single DSM. Experiments are performed on five test patches. The results reveal that our approach is capable of counting most of the citrus trees without manual intervention. Comparison to the state-of-the-art reveals that the proposed approach provides notable detection performance by providing the best balance between precision and recall measures.

Entomopathogens Associated to Citrus and Their Pathogenicity on Compsus viridivittatus Guérin-Méneville (Coleoptera: Curculionidae: Entiminae

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Paola Andrea Zuluaga Cárdenas

2015-07-01

Full Text Available C. viridivittatus, citrus weevil distributed throughoutthe coffee maker and Andean region of Colombia. Thelarvae feed on roots and adults on leaves and flowers. On three citrus farms of the Valley were isolate and evaluated fungi and entompathogenic nematodes M. anisopliaeand B. bassiana and Steinernema sp. and Heterorabditis sp. on larvae of C. viridivittatus 26, 36, 48 and 53 days of age. In 120 from 132 soil samples were found 21 fungi and none nematodes. Commercial B. bassiana B9 and B10 caused 100 % adult mortality in a time of 4.3 and 4 days. M. anisopliae M6 y M7 caused 94 % and 97 % of mortality to the 4.3 and 5 days. Steinernema sp. UNS09 caused 65 % of mortality on larvae of 48 and 53 days of age, seven days later. No were differences between UNS09 Steinernema and Heterorhabditis UNH16. Steinernema sp. UNS09 caused 85.7 % of mortality on 53 days larvae and 81.9 % and 81.1 % to larvae of 36 and 26 days. Heterorhabditis sp. UNH16 killed larvae of 36, 26 and 56 days was 79 %, 81 % and 75.4 % seven days later. In conclusion, fungi and nematodes can be an alternative to management of C. viridivittatus larvae.

Comparison of Potato and Asian Citrus Psyllid Adult and Nymph Transcriptomes Identified Vector Transcripts with Potential Involvement in Circulative, Propagative Liberibacter Transmission

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Tonja W. Fisher

2014-11-01

Full Text Available The potato psyllid (PoP Bactericera cockerelli (Sulc and Asian citrus psyllid (ACP Diaphorina citri Kuwayama are the insect vectors of the fastidious plant pathogen, Candidatus Liberibacter solanacearum (CLso and Ca. L. asiaticus (CLas, respectively. CLso causes Zebra chip disease of potato and vein-greening in solanaceous species, whereas, CLas causes citrus greening disease. The reliance on insecticides for vector management to reduce pathogen transmission has increased interest in alternative approaches, including RNA interference to abate expression of genes essential for psyllid-mediated Ca. Liberibacter transmission. To identify genes with significantly altered expression at different life stages and conditions of CLso/CLas infection, cDNA libraries were constructed for CLso-infected and -uninfected PoP adults and nymphal instars. Illumina sequencing produced 199,081,451 reads that were assembled into 82,224 unique transcripts. PoP and the analogous transcripts from ACP adult and nymphs reported elsewhere were annotated, organized into functional gene groups using the Gene Ontology classification system, and analyzed for differential in silico expression. Expression profiles revealed vector life stage differences and differential gene expression associated with Liberibacter infection of the psyllid host, including invasion, immune system modulation, nutrition, and development.

Reinvestigation of structure of porritoxin, a phytotoxin of Alternaria porri.

Science.gov (United States)

Horiuchi, Masayuki; Maoka, Takashi; Iwase, Noriyasu; Ohnishi, Keiichiro

2002-08-01

The structure of porritoxin, a phytotoxin of Alternaria porri, was reinvestigated by detailed 2D NMR analysis including (1)H-(13)C and (1)H-(15)N HMBC experiments. The structure of porritoxin was determined to be 2-(2'-hydroxyethyl)-4-methoxy-5-methyl-6-(3' '-methyl-2' '-butenyloxy)-2,3-dihydro-1H-isoindol-1-one (1). Thus our previous proposed structure, 8-(3',3'-dimethylallyloxy)-10-methoxy-9-methyl-1H-3,4-dihydro-2,5-benzoxazocin-6(5H)-one (2), is incorrect.

Alternaria resistance of Brassicae campestris L. improved by induced mutations

International Nuclear Information System (INIS)

Das, M.L.; Rahman, A.

1989-01-01

Full text: Seeds of 'YS 52', a cultivar susceptible to Alternaria brassicae (Berk.) Sacc., were exposed to gamma rays (30-90 kR). Eight more resistant mutants were selected in M3 and subjected to further field evaluation. The best mutant '17-5-83' appeared resistant and gave 44% higher yield than the parent, mutant '70-7-82' was found to be moderately resistant and gave a yield 21% higher than the parent. The yield increases seem to be connected with plant architecture changes. (author)

Priming by Hexanoic acid induce activation of mevalonic and linolenic pathways and promotes the emission of plant volatiles.

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Eugenio eLlorens

2016-04-01

Full Text Available Hexanoic acid is a short natural monocarboxylic acid present in some fruits and plants. Previous studies reported that soil drench application of this acid induces effective resistance in tomato plants against Botrytis cinerea and Pseudomonas syringae and in citrus against Alternaria alternata and Xanthomonas citri. In this work, we performed an in deep study of the metabolic changes produced in citrus by the application of hexanoic acid in response to the challenge pathogen Alternaria alternata, focusing on the response of the plant. Moreover, we used 13C labeled hexanoic to analyze its behavior inside the plants. Finally, we studied the volatile emission of the treated plants after the challenge inoculation. Drench application of 13C labeled hexanoic demonstrated that this molecule stays in the roots and is not mobilized to the leaves, suggesting long distance induction of resistance. Moreover, the study of the metabolic profile showed an alteration of more than two hundred molecules differentially induced by the application of the compound and the inoculation with the fungus. Bioinformatics analysis of data showed that most of these altered molecules could be related with the mevalonic and linolenic pathways suggesting the implication of these pathways in the induced resistance mediated by hexanoic acid. Finally, the application of this compound showed an enhancement of the emission of 17 volatile metabolites. Taken together, this study indicates that after the application of hexanoic acid this compound remains in the roots, provoking molecular changes that may trigger the defensive response in the rest of the plant mediated by changes in the mevalonic and linolenic pathways and enhancing the emission of volatile compounds, suggesting for the first time the implication of mevalonic pathway in response to hexanoic application.

Compatibility and Efficacy of Isaria fumosorosea with Horticultural Oils for Mitigation of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae

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Vivek Kumar

2017-10-01

Full Text Available Horticultural oils are an important component of integrated management programs of several phytophagous arthropods and pathogens affecting fruit, ornamentals and vegetables in greenhouse and field production systems. Although effective against the target pest, their incompatibility with biological control agents can compromise efforts to develop eco-friendly management programs for important agricultural pests. In this study, we assessed the in vitro effect of selected refined petroleum oils used in citrus and other horticultural crops with a biopesticide containing the entomopathogenic fungi, Isaria fumosorosea (PFR-97 under laboratory conditions. Further, we used leaf disk bioassays to evaluate the combined efficacy of petroleum oils and I. fumosorosea against the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae, a major pest of citrus in the United States. All five petroleum oil treatments (Orchex, Sun Pure, Conoco Blend -1, Conoco Blend -2, and JMS were compatible with I. fumosorosea blastospores, as none of them were found to affect I. fumosorosea colony-forming units and radial fungal growth measured at 3, 6, 9, and 12 days post-inoculation. All mixed treatments performed better than I. fumosorosea alone against D. citri, where the highest mean survival time of D. citri was 12.5 ± 0.7 days. No significant differences in D. citri survival time and I. fumosorosea growth (fungal development index on dead cadavers, which is important for determining their horizontal transmission, were observed when mixed with Orchex, Sun Pure, Conoco Blend -2, and JMS. Results indicated that horticultural oils in combination with I. fumosorosea could offer citrus growers an alternative treatment for integrating into their current management programs while battling against D. citri in citrus production systems. Due to their eco-friendly, broad-spectrum effect, it could provide control against various citrus pests, while also encouraging the

Compatibility and Efficacy of Isaria fumosorosea with Horticultural Oils for Mitigation of the Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae).

Science.gov (United States)

Kumar, Vivek; Avery, Pasco B; Ahmed, Juthi; Cave, Ronald D; McKenzie, Cindy L; Osborne, Lance S

2017-10-31

Horticultural oils are an important component of integrated management programs of several phytophagous arthropods and pathogens affecting fruit, ornamentals and vegetables in greenhouse and field production systems. Although effective against the target pest, their incompatibility with biological control agents can compromise efforts to develop eco-friendly management programs for important agricultural pests. In this study, we assessed the in vitro effect of selected refined petroleum oils used in citrus and other horticultural crops with a biopesticide containing the entomopathogenic fungi, Isaria fumosorosea (PFR-97) under laboratory conditions. Further, we used leaf disk bioassays to evaluate the combined efficacy of petroleum oils and I. fumosorosea against the Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae), a major pest of citrus in the United States. All five petroleum oil treatments (Orchex, Sun Pure, Conoco Blend -1, Conoco Blend -2, and JMS) were compatible with I. fumosorosea blastospores, as none of them were found to affect I. fumosorosea colony-forming units and radial fungal growth measured at 3, 6, 9, and 12 days post-inoculation. All mixed treatments performed better than I. fumosorosea alone against D. citri , where the highest mean survival time of D. citri was 12.5 ± 0.7 days. No significant differences in D. citri survival time and I. fumosorosea growth (fungal development index) on dead cadavers, which is important for determining their horizontal transmission, were observed when mixed with Orchex, Sun Pure, Conoco Blend -2, and JMS. Results indicated that horticultural oils in combination with I. fumosorosea could offer citrus growers an alternative treatment for integrating into their current management programs while battling against D. citri in citrus production systems. Due to their eco-friendly, broad-spectrum effect, it could provide control against various citrus pests, while also encouraging the retention of effective

The effect of pre spring spray to reduce of citrus important pests.

Science.gov (United States)

Hashemi, B; Damavandian, M R; Shoushtaril, R Vafaei; Tafaghodynia, B

2008-10-01

The importance of pre spring spray against citrus aphids, Pulvinaria aurantii Cockerell and Panonychus citri McGregor that are the most important pest of citrus during spring was tested. In this research, 150 trees ten years old sweet orange (Thomson navel on Citrus aurantium (root stocks)) in a citrus orchard approximately three hectares sampled. The experiment was laid out in a totally randomized (one-way) design replicated five times. According to the results, the pre spring spray do not effect on population density of citrus aphids and P. aurantii during March, April, May and June. However, the P. citri population decreased. Therefore, it seems the pre spring spray in citrus orchards is not necessary, but if P. citri is observed, the pre spring spray should be recommended.

The Types of Essentials Oil Components Isolated From the Leaves of Citrus Aurantifolia and Citrus Nobilis

OpenAIRE

Wulandari, Mutiara Juni; Mohammad Anwar Jamaludin,, Lailatul Riska, Agustin Laela Prunama; Mumun Nurmilawati, Indra Fauzi

2015-01-01

Essential oil or known as the eteris oil (etheric oil) was result from secondary metabolism of a plant. In general essential oil contains of citronellal, Citronelal, Citronelol, Limonen, β-Pinene dan sabinene. The components essential oil derived from citrus plants commonly used by perfume industry, on other hand it is used as essentials oil orange flavour addition in some drinks and food, and also as an antioxidant and anti cancer. One of the essential oil is produced by Citrus aurantifolia ...

Genome-wide identification of sweet orange (Citrus sinensis) histone modification gene families and their expression analysis during the fruit development and fruit-blue mold infection process.

Science.gov (United States)

Xu, Jidi; Xu, Haidan; Liu, Yuanlong; Wang, Xia; Xu, Qiang; Deng, Xiuxin

2015-01-01

In eukaryotes, histone acetylation and methylation have been known to be involved in regulating diverse developmental processes and plant defense. These histone modification events are controlled by a series of histone modification gene families. To date, there is no study regarding genome-wide characterization of histone modification related genes in citrus species. Based on the two recent sequenced sweet orange genome databases, a total of 136 CsHMs (Citrus sinensis histone modification genes), including 47 CsHMTs (histone methyltransferase genes), 23 CsHDMs (histone demethylase genes), 50 CsHATs (histone acetyltransferase genes), and 16 CsHDACs (histone deacetylase genes) were identified. These genes were categorized to 11 gene families. A comprehensive analysis of these 11 gene families was performed with chromosome locations, phylogenetic comparison, gene structures, and conserved domain compositions of proteins. In order to gain an insight into the potential roles of these genes in citrus fruit development, 42 CsHMs with high mRNA abundance in fruit tissues were selected to further analyze their expression profiles at six stages of fruit development. Interestingly, a numbers of genes were expressed highly in flesh of ripening fruit and some of them showed the increasing expression levels along with the fruit development. Furthermore, we analyzed the expression patterns of all 136 CsHMs response to the infection of blue mold (Penicillium digitatum), which is the most devastating pathogen in citrus post-harvest process. The results indicated that 20 of them showed the strong alterations of their expression levels during the fruit-pathogen infection. In conclusion, this study presents a comprehensive analysis of the histone modification gene families in sweet orange and further elucidates their behaviors during the fruit development and the blue mold infection responses.

Citrus fruit quality assessment; producer and consumer perspectives

Science.gov (United States)

Consumption of citrus fruit and juices is popular with consumers worldwide and makes an important contribution to a healthy diet. Nevertheless, consumer preferences for citrus have undergone significant changes over the last twenty years and it is important to understand what consumers are looking ...

Citrus Seed Oils Efficacy against Larvae of Aedes aegypti

Directory of Open Access Journals (Sweden)

Hazrat Bilal

2017-10-01

Full Text Available Background: Dengue fever is a serious public health issue in Pakistan for many years. Globally plants have been reported to contain compounds with insecticidal properties. These properties have been demonstrated more recently on the larval stages of mosquitoes. Therefore, Citrus cultivar seeds were evaluated for larvicidal potential against the primary dengue vector Aedes aegypti.Methods: Extraction of oil was done by a steam distillation method and oils were evaluated according to WHO guidelines for larvicides 2005 for evaluation of insecticidal properties of citrus seed extracts against mosquito larvae.Result: Among the Citrus cultivar seed oil, rough lemon (Citrus jambhiri had the lowest LC50 value (200.79ppm, while musambi (C. sinensis var musambi had the highest LC50 value (457.30ppm after 24 h of exposure.Conclusion: Citrus cultivars have some larvicidal potential but C. jambhiri had the greatest potential against A. ae­gypti larvae. Further small-scale field trials using the extracts of C. jambhiri will be conducted to determine opera­tional feasibility.

Monitoring Citrus Soil Moisture and Nutrients Using an IoT Based System

Directory of Open Access Journals (Sweden)

Xueyan Zhang

2017-02-01

Full Text Available Chongqing mountain citrus orchard is one of the main origins of Chinese citrus. Its planting terrain is complex and soil parent material is diverse. Currently, the citrus fertilization, irrigation and other management processes still have great blindness. They usually use the same pattern and the same formula rather than considering the orchard terrain features, soil differences, species characteristics and the state of tree growth. With the help of the ZigBee technology, artificial intelligence and decision support technology, this paper has developed the research on the application technology of agricultural Internet of Things for real-time monitoring of citrus soil moisture and nutrients as well as the research on the integration of fertilization and irrigation decision support system. Some achievements were obtained including single-point multi-layer citrus soil temperature and humidity detection wireless sensor nodes and citrus precision fertilization and irrigation management decision support system. They were applied in citrus base in the Three Gorges Reservoir Area. The results showed that the system could help the grower to scientifically fertilize or irrigate, improve the precision operation level of citrus production, reduce the labor cost and reduce the pollution caused by chemical fertilizer.

Development of sparse-seeded mutant kinnow (Citrus reticulata ...

African Journals Online (AJOL)

... crops like citrus, induced mutation for seedlessness in Kinnow with gamma irradiation of dormant bud which was attempted at the Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad. Dormant bud irradiation-cum-grafting technique was employed, using the Citrus jambhiri rootstock for propagation of the scion.

Near ultraviolet radiation (280-400 nm): Direct and indirect effects on microbial pathogens

International Nuclear Information System (INIS)

Asthana, A.

1993-01-01

Responses of pigmented pathogenic fungi and E. coli strains differing in DNA repair and catalase proficiency to direct and indirect effects of ultraviolet radiation were evaluated. Pigments in the four fungal pathogens of Citrus differed in their ability to protect against direct UV and damage by UV-A -mediated phototoxins of both host and non-host origin. UV-A and UV-B did not inactivate the fungal species. Differential protection in wild type strains of the two Fusarium spp. and in the wild type strains of the two Penicilium spp. against UV-C was observed. Wild type and mutants with altered coloration in Penicilium spp. protected to varying extent against both α-T and 8-MOP in the presence of UV-A. UV-B irradiation of E. coli resulted in inactivation of strains deficient in DNA excision repair. Plasmid DNA damaged in vitro by UV-B from lamp systems as well as by sunlight, and transformed in vivo into bacterial cells lacking specific nucleases showed reduced transformation in DNA excision repair strains. UV-B enriched wavelengths isolated from a solar simulator affected plasmid DNA in a similar manner as UV-B from lamp systems. Sunlight, however affected the membrane of whole cells. Concentration of foliar furanocoumarins of Citrus jambhiri decreased with UV-B irradiation. Phototoxicity to Fusarium spp. was accounted for, in part, by furanocoumarins, psoralen and bergapten (5-MOP) and others. Pure psoralen and 5-MOP affected both Fusarium spp. similarly and carotenoids protected only partially in the wild type strains. Citrus targetted the cell membrane in Fusarium spp.l and in E. coli strains; carotenoids in both of which protected against such damage. Loss in structural integrity of plasmid DNA when treated with citral and UV-A correlated with loss in transforming activity. Biological damage to membrane and DNA was due to the production of hydrogen peroxide. Fruit-rot pathogens Penicilium spp. were not affected by either furanocoumarins or citrals

Consumer preferences for fresh citrus: Impacts of demographic and behavioral characteristics

Science.gov (United States)

From 2000 to 2006, per capita consumption of fresh citrus fruit increased by 11.0%, but the relative shares of types of citrus consumed changed. Per capita consumption of the historically dominant citrus fruit, fresh oranges, experienced a continuous decline from 12.4 pounds to 7.4 pounds from 1990 ...

Early events of citrus greening (Huanglongbing) disease development at the ultrastructural level.

Science.gov (United States)

Folimonova, Svetlana Y; Achor, Diann S

2010-09-01

Citrus greening (Huanglongbing [HLB]) is one of the most destructive diseases of citrus worldwide. The causal agent of HLB in Florida is thought to be 'Candidatus Liberibacter asiaticus'. Understanding of the early events in HLB infection is critical for the development of effective measures to control the disease. In this work, we conducted cytopathological studies by following the development of the disease in citrus trees graft inoculated with 'Ca. L. asiaticus'-containing material under greenhouse conditions to examine the correlation between ultrastructural changes and symptom production, with the main objective of characterizing the early events of infection. Based on our observations, one of the first degenerative changes induced upon invasion of the pathogen appears to be swelling of middle lamella between cell walls surrounding sieve elements. This anatomical aberration was often observed in samples from newly growing flushes in inoculated sweet orange and grapefruit trees at the early "presymptomatic" stage of HLB infection. Development of symptoms and their progression correlated with an increasing degree of microscopic aberrations. Remarkably, the ability to observe the bacterium in the infected tissue also correlated with the degree of the disease progression. Large numbers of bacterial cells were found in phloem sieve tubes in tissue samples from presymptomatic young flushes. In contrast, we did not observe the bacteria in highly symptomatic leaf samples, suggesting a possibility that, at more advanced stages of the disease, a major proportion of 'Ca. L. asiaticus' is present in a nonviable state. We trust that observations reported here advance our understanding of how 'Ca. L. asiaticus' causes disease. Furthermore, they may be an important aid in answering a question: when and where within an infected tree the tissue serves as a better inoculum source for acquisition and transmission of the bacterium by its psyllid vector.

Potato carrot agar with manganese as an isolation medium for Alternaria, Epicoccum and Phoma

DEFF Research Database (Denmark)

Sørensen, Jens Laurids; Mogensen, Jesper Mølgaard; Thrane, Ulf

2009-01-01

A semi-selective medium for isolation of Alternaria spp., Epicoccum sp. and Phoma spp. from soil and plant samples was developed. The basal medium was a modified potato carrot agar (PCA), containing 10 g/L of potato and carrot. It is known that the target genera sporulate well on standard PCA when...

Sclerenchymatous ring as a barrier to phloem feeding by Asian citrus psyllid: Evidence from electrical penetration graph and visualization of stylet pathways.

Directory of Open Access Journals (Sweden)

Justin George

Full Text Available Asian citrus psyllid (Diaphorina citri feeding behaviors play a significant role in the transmission of the phloem-limited Candidatus Liberibacter asiaticus (CLas bacterium that causes the economically devastating citrus greening disease. Sustained phloem ingestion by D. citri on CLas infected plants is required for pathogen acquisition and transmission. Recent studies have shown a fibrous ring of thick-walled sclerenchyma around the phloem in mature, fully expanded citrus leaves that is more prominent on the abaxial compared with the adaxial side. The composition and thickness of this fibrous ring may have an important role in selection of feeding sites by D. citri based on leaf age and leaf surface, which in turn can affect pathogen acquisition and transmission. We measured feeding behavior using electrical penetration graph (EPG recordings of individual D. citri adults placed on abaxial or adaxial surfaces of young or mature Valencia orange leaves to study the role of the sclerenchymatous ring in modifying D. citri feeding behavior. Feeding sites on the same leaf tissues were then sectioned and examined by epifluorescence microscopy. The duration of phloem ingestion (E2 waveform by psyllids was significantly reduced on mature compared with young leaves, and on abaxial compared with adaxial leaf surfaces. The longest duration of phloem ingestion was observed from psyllids placed on the adaxial side of young leaves that had the least developed sclerenchyma. Bouts of phloem salivation (E1 waveform, however, were significantly longer on mature leaves compared with young leaves. D. citri adults made consecutive phloem feeding attempts (bouts on the abaxial side of mature leaves and those bouts resulted in unsuccessful or shorter periods of phloem ingestion. Adults also made more frequent and longer bouts of xylem ingestion on mature leaves compared with adult psyllids placed on young leaves. Epifluorescence microscopy showed that the fibrous ring

Sclerenchymatous ring as a barrier to phloem feeding by Asian citrus psyllid: Evidence from electrical penetration graph and visualization of stylet pathways

Science.gov (United States)

George, Justin; Ammar, El-Desouky; Hall, David G.

2017-01-01

Asian citrus psyllid (Diaphorina citri) feeding behaviors play a significant role in the transmission of the phloem-limited Candidatus Liberibacter asiaticus (CLas) bacterium that causes the economically devastating citrus greening disease. Sustained phloem ingestion by D. citri on CLas infected plants is required for pathogen acquisition and transmission. Recent studies have shown a fibrous ring of thick-walled sclerenchyma around the phloem in mature, fully expanded citrus leaves that is more prominent on the abaxial compared with the adaxial side. The composition and thickness of this fibrous ring may have an important role in selection of feeding sites by D. citri based on leaf age and leaf surface, which in turn can affect pathogen acquisition and transmission. We measured feeding behavior using electrical penetration graph (EPG) recordings of individual D. citri adults placed on abaxial or adaxial surfaces of young or mature Valencia orange leaves to study the role of the sclerenchymatous ring in modifying D. citri feeding behavior. Feeding sites on the same leaf tissues were then sectioned and examined by epifluorescence microscopy. The duration of phloem ingestion (E2 waveform) by psyllids was significantly reduced on mature compared with young leaves, and on abaxial compared with adaxial leaf surfaces. The longest duration of phloem ingestion was observed from psyllids placed on the adaxial side of young leaves that had the least developed sclerenchyma. Bouts of phloem salivation (E1 waveform), however, were significantly longer on mature leaves compared with young leaves. D. citri adults made consecutive phloem feeding attempts (bouts) on the abaxial side of mature leaves and those bouts resulted in unsuccessful or shorter periods of phloem ingestion. Adults also made more frequent and longer bouts of xylem ingestion on mature leaves compared with adult psyllids placed on young leaves. Epifluorescence microscopy showed that the fibrous ring in young

Survey of current crop management practices in a mixed-ricefield landscape, Mekong Delta, Vietnam - potential of habitat manipulation for improved control of citrus leafminer and citrus red mite

NARCIS (Netherlands)

Mele, van P.; Lenteren, van J.C.

2002-01-01

In the Mekong Delta, Vietnam, the citrus leafminer Phyllocnistis citrella (CLM) and the citrus red mite Panonychus citri are major pests in both sweet orange (Citrus sinensis) and Tieu mandarin (C. reticulata). Survey data indicate that these pest problems might be aggravated after farmers have

7 CFR 319.56-41 - Citrus from Peru.

Science.gov (United States)

2010-01-01

... 7 Agriculture 5 2010-01-01 2010-01-01 false Citrus from Peru. 319.56-41 Section 319.56-41... from Peru. Grapefruit (Citrus paradisi), limes (C. aurantiifolia), mandarins or tangerines (C... States from Peru under the following conditions: (a) The fruit must be accompanied by a permit issued in...

Citrus Production, Constraints and Management Practices in Ethiopia

African Journals Online (AJOL)

Citrus is economically important fruit crop in Ethiopia. However, its production is seriously constrained by various diseases including Pseudocercospora leaf and fruit spot. Surveys were conducted between June 2012 and May 2013 in the main citrus production areas of the country to assess the spread of the disease, and to ...

Sensivity of Jordanian Isolates of Alternaria solani to Manchotane

OpenAIRE

K.I. Al-Mughrabi

2004-01-01

Early blight of potato, caused by Alternaria solani, poses a significant risk to potato crops worldwide. Fifty A. solani isolates representing a population were collected from the Jordan Valley, purified, and tested for their sensitivity to the fungicide mancothane. The isolates were tested against a series of concentrations of 0, 0.1, 1, 10, 100, and 1000 mg mancothane ml-1 in 5% sodium dodecyl sulfate (SDS). Some A. solani isolates tolerated up to 1000 mg mancothane ml-1. Isolat...

Risk assessment of various insecticides used for management of Asian citrus psyllid, Diaphorina citri in Florida citrus, against honey bee, Apis mellifera.

Science.gov (United States)

Chen, Xue Dong; Gill, Torrence A; Pelz-Stelinski, Kirsten S; Stelinski, Lukasz L

2017-04-01

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is a major pest of citrus trees worldwide. A wide variety of insecticides are used to manage D. citri populations within citrus groves in Florida. However, in areas shared by citrus growers and beekeepers the use of insecticides may increase the risks of Apis mellifera  L. (Hymenoptera: Apidae) loss and contaminated honey. The objective of this research was to determine the environmental toxicity of insecticides, spanning five different modes of action used to control D. citri, to A. mellifera. The insecticides investigated were imidacloprid, fenpropathrin, dimethoate, spinetoram and diflubenzuron. In laboratory experiments, LD 50 values were determined and ranged from 0.10 to 0.53 ng/μl for imidacloprid, fenpropathrin, dimethoate and spinetoram. LD 50 values for diflubenzuron were >1000 ng/μl. Also, a hazard quotient was determined and ranged from 1130.43 to 10893.27 for imidacloprid, fenpropathrin, dimethoate, and spinetoram. This quotient was mellifera 3 and 7 days after application. Spinetoram and imidacloprid were moderately toxic to A. mellifera at the recommended rates for D. citri. Diflubenzuron was not toxic to A. mellifera in the field as compared with untreated control plots. Phenoloxidase (PO) activity of A. mellifera was higher than in untreated controls when A. mellifera were exposed to 14 days old residues. The results indicate that diflubenzuron may be safe to apply in citrus when A. mellifera are foraging, while most insecticides used for management of D. citri in citrus are likely hazardous under various exposure scenarios.

Towards the identification of flower-specific genes in Citrus spp

Directory of Open Access Journals (Sweden)

Marcelo Carnier Dornelas

2007-01-01

Full Text Available Citrus sinensis is a perennial woody species, for which genetic approaches to the study of reproductive development are not readily amenable. Here, the usefulness of the CitEST Expressed Sequence Tag (EST database is demonstrated as a reliable new resource for identifying novel genes exclusively related to Citrus reproductive biology. We performed the analysis of an EST dataset of the CitEST Project containing 4,330 flower-derived cDNA sequences. Relying on bioinformatics tools, sequences exclusively present in this flower-derived sequence collection were selected and used for the identification of Citrus putative flower-specific genes. Our analysis revealed several Citrus sequences showing significant similarity to conserved genes known to have flower-specific expression and possessing functions related to flower metabolism and/or reproductive development in diverse plant species. Comparison of the Citrus flower-specific sequences with all available plant peptide sequences unraveled 247 unique transcripts not identified elsewhere within the plant kingdom. Additionally, 49 transcripts, for which no biological function could be attributed by means of sequence comparisons, were found to be conserved among plant species. These results allow further gene expression analysis and possibly novel approaches to the understanding of reproductive development in Citrus.

Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis) Ciferri.

Science.gov (United States)

Nanda, Satyabrata; Chand, Subodh Kumar; Mandal, Purander; Tripathy, Pradyumna; Joshi, Raj Kumar

2016-12-01

Purple blotch, caused by Alternaria porri (Ellis) Cifferi, is a serious disease incurring heavy yield losses in the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification of effective resistance sources for use in host resistance breeding. A total of 43 Allium genotypes were screened for purple blotch resistance under field conditions. Allium cepa accession 'CBT-Ac77' and cultivar 'Arka Kalyan' were observed to be highly resistant. In vitro inoculation of a selected set of genotypes with A. porri , revealed that 7 days after inoculation was suitable to observe the disease severity. In vitro screening of 43 genotypes for resistance to A. porri revealed two resistant lines. An additional 14 genotypes showed consistent moderate resistance in the field as well as in vitro evaluations. Among the related Allium species, A. schoenoprasum and A. roylei showed the least disease index and can be used for interspecific hybridization with cultivated onion. Differential reaction analysis of three A. porri isolates ( Apo-Chiplima, Apn-Nasik, Apg-Guntur ) in 43 genotypes revealed significant variation among the evaluated Allium species ( P = 0.001). All together, the present study suggest that, the newly identified resistance sources can be used as potential donors for ongoing purple blotch resistance breeding program in India.

Citrus Tristeza Virus on the Island of Crete

DEFF Research Database (Denmark)

Shegani, M.; Tsikou, D.; Velimirovic, A.

2012-01-01

Over a period of two years, more than 5,000 citrus trees were tested for the presence of Citrus tristeza virus (CTV) on the island of Crete, resulting in thirty eight positives. Comparisons of the relative transcript levels of CTV p23, coat protein (CP), polymerase (POL) and an intergenic (POL/p3...

Factors affecting transmission rates of 'Candidatus Liberibacter asiaticus' by Asian citrus psyllid

Science.gov (United States)

The Asian citrus psyllid (ACP), Diaphorina citri, is an important pest because it transmits a bacterium ‘Candidatus Liberibacter asiaticus’ (CLas) responsible for a serious disease of citrus known as Asiatic huanglongbing (citrus greening disease). USDA-ARS researchers recently established a program...

Citrus stand ages regulate the fraction alteration of soil organic carbon under a citrus/Stropharua rugodo-annulata intercropping system in the Three Gorges Reservoir area, China.

Science.gov (United States)

Zhang, Yang; Ni, Jiupai; Yang, John; Zhang, Tong; Xie, Deti

2017-08-01

Soil carbon fractionation is a valuable indicator in assessing stabilization of soil organic matter and soil quality. However, limited studies have addressed how different vegetation stand ages under intercropping agroforestry systems, could affect organic carbon (OC) accumulation in bulk soil and its physical fractions. A field study thus investigated the impact of citrus plantation age (15-, 25-, and 45-year citrus) on the bulk soil organic carbon (SOC) and SOC fractions and yields of Stropharia rugoso-annulata (SRA) in the Three Gorges Reservoir area, Chongqing, China. Results indicated that the intercropping practice of SRA with citrus significantly increased the SOC by 57.4-61.6% in topsoil (0-10 cm) and by 24.8-39.9% in subsoil (10-30 cm). With a significantly higher enhancement under the 25-year citrus stand than the other two stands, all these citrus stands of three ages also resulted in a significant increase of free particulate OC (fPOC, 60.1-62.4% in topsoil and 34.8-46.7% in subsoil), intra-micro aggregate particulate OC (iPOC, 167.6-206.0% in topsoil and 2.77-61.09% in subsoil), and mineral-associated OC (MOC, 43.6-46.5% in topsoil and 26.0-51.5% in subsoil). However, there were no significant differences in yields of SRA under three citrus stands. Our results demonstrated that citrus stand ages did play an important role in soil carbon sequestration and fractionation under a citrus/SRA intercropping system, which could therefore provide a sustainable agroforestry system to enhance concurrently the SOC accumulation while mitigating farmland CO 2 emission.

(Liberibacter spp.) associated with citrus greening disease in Uganda

African Journals Online (AJOL)

ACSS

Citrus is one of the largest fruit crops grown in Uganda ... of several citrus industries in Asia and. Africa (da Graca ... role in transmission of HLB, psyllid feeding ... The Indian Ocean islands of Reunion and ..... Pacific Grove, California: Duxbury ...

Overexpression of a citrus NDR1 ortholog increases disease resistance in Arabidopsis

Science.gov (United States)

Emerging devastating diseases, such as Huanglongbing (HLB) and citrus canker, have caused tremendous losses to the citrus industry worldwide. Genetic engineering is a powerful approach that could allow us to increase citrus resistance against these diseases. The key to the success of this approach r...

Descriptions of new varieties recently distributed from the Citrus Clonal Protection Program

Science.gov (United States)

The Citrus Clonal Protection Program (CCPP) is operated through the Department of Plant Pathology and Microbiology at University of California (UC) Riverside and is funded in large part by The California Citrus Research Board (CRB). The CCPP processes citrus propagative material in two phases. First...

Identification of zygotic and nucellar seedlings in citrus interspecific ...

African Journals Online (AJOL)

ajl yemi

2011-12-19

Dec 19, 2011 ... Department of Plant Breeding and Improvement, Iran Citrus Research Institute, Mottahari Street, Ramsar, .... (C. aurantium) rootstock plants for further agronomic evaluation .... literatures may be attributed to pollination efficiency and ... zygotic seedlings in Swingle citromelo Citrus paradisi × Poncirus tifoliata.

Penicillium digitatum metabolites on synthetic media and citrus fruits

DEFF Research Database (Denmark)

Ariza, M.R.; Larsen, Thomas Ostenfeld; Petersen, Bent O.

2002-01-01

Penicillium digitatum has been cultured on citrus fruits and yeast extract sucrose agar media (YES).Cultivation of fungal cultures on solid medium allowed the isolation of two novel tryptoquivaline-like metabolites, tryptoquialanine A (1) and tryptoquialanine B (2), also biosynthesized on citrus...

The dual nature of trehalose in citrus canker disease: a virulence factor for Xanthomonas citri subsp. citri and a trigger for plant defence responses

KAUST Repository

Piazza, A.

2015-03-14

Xanthomonas citri subsp. citri (Xcc) is a bacterial pathogen that causes citrus canker in susceptible Citrus spp. The Xcc genome contains genes encoding enzymes from three separate pathways of trehalose biosynthesis. Expression of genes encoding trehalose-6-phosphate synthase (otsA) and trehalose phosphatase (otsB) was highly induced during canker development, suggesting that the two-step pathway of trehalose biosynthesis via trehalose-6-phosphate has a function in pathogenesis. This pathway was eliminated from the bacterium by deletion of the otsA gene. The resulting XccΔotsA mutant produced less trehalose than the wild-type strain, was less resistant to salt and oxidative stresses, and was less able to colonize plant tissues. Gene expression and proteomic analyses of infected leaves showed that infection with XccΔotsA triggered only weak defence responses in the plant compared with infection with Xcc, and had less impact on the host plant\\'s metabolism than the wild-type strain. These results suggested that trehalose of bacterial origin, synthesized via the otsA-otsB pathway, in Xcc, plays a role in modifying the host plant\\'s metabolism to its own advantage but is also perceived by the plant as a sign of pathogen attack. Thus, trehalose biosynthesis has both positive and negative consequences for Xcc. On the one hand, it enables this bacterial pathogen to survive in the inhospitable environment of the leaf surface before infection and exploit the host plant\\'s resources after infection, but on the other hand, it is a tell-tale sign of the pathogen\\'s presence that triggers the plant to defend itself against infection. © The Author 2015. Published by Oxford University Press on behalf of the Society for Experimental Biology.

Stylet morphometrics and citrus leaf vein structure in relation to feeding behavior of the Asian citrus psyllid Diaphorina citri, vector of citrus huanglongbing bacterium.

Directory of Open Access Journals (Sweden)

El-Desouky Ammar

Full Text Available The Asian citrus psyllid (ACP, Diaphorina citri (Hemiptera: Psyllidae, is the primary vector of the phloem-limited bacterium Candidatus Liberibacter asiaticus (LAS associated with huanglongbing (HLB, citrus greening, considered the world's most serious disease of citrus. Stylet morphometrics of ACP nymphs and adults were studied in relation to citrus vein structure and to their putative (histologically verified feeding sites on Valencia orange leaves. ACP nymphs preferred to settle and feed on the lower (abaxial side of young leaves either on secondary veins or on the sides of the midrib, whereas adults preferred to settle and feed on the upper (adaxial or lower secondary veins of young or old leaves. Early instar nymphs can reach and probe the phloem probably because the distance to the phloem is considerably shorter in younger than in mature leaves, and is shorter from the sides of the midrib compared to that from the center. Additionally, the thick-walled 'fibrous ring' (sclerenchyma around the phloem, which may act as a barrier to ACP stylet penetration into the phloem, is more prominent in older than in younger leaves and in the center than on the sides of the midrib. The majority (80-90% of the salivary sheath termini produced by ACP nymphs and adults that reached a vascular bundle were associated with the phloem, whereas only 10-20% were associated with xylem vessels. Ultrastructural studies on ACP stylets and LAS-infected leaves suggested that the width of the maxillary food canal in first instar nymphs is wide enough for LAS bacteria to traverse during food ingestion (and LAS acquisition. However, the width of the maxillary salivary canal in these nymphs may not be wide enough to accommodate LAS bacteria during salivation (and LAS inoculation into host plants. This may explain the inability of early instar nymphs to transmit LAS/HLB in earlier reports.

Sulfur volatiles from Allium spp. affect Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), response to citrus volatiles.

Science.gov (United States)

Mann, R S; Rouseff, R L; Smoot, J M; Castle, W S; Stelinski, L L

2011-02-01

The Asian citrus psyllid, Diaphorina citri Kuwayama, vectors Candidatus Liberibacter asiaticus (Las) and Candidatus Liberibacter americanus (Lam), the presumed causal agents of huanglongbing. D. citri generally rely on olfaction and vision for detection of host cues. Plant volatiles from Allium spp. (Alliaceae) are known to repel several arthropod species. We examined the effect of garlic chive (A. tuberosum Rottl.) and wild onion (A. canadense L.) volatiles on D. citri behaviour in a two-port divided T-olfactometer. Citrus leaf volatiles attracted significantly more D. citri adults than clean air. Volatiles from crushed garlic chive leaves, garlic chive essential oil, garlic chive plants, wild onion plants and crushed wild onion leaves all repelled D. citri adults when compared with clean air, with the first two being significantly more repellent than the others. However, when tested with citrus volatiles, only crushed garlic chive leaves and garlic chive essential oil were repellent, and crushed wild onions leaves were not. Analysis of the headspace components of crushed garlic chive leaves and garlic chive essential oil by gas chromatography-mass spectrometry revealed that monosulfides, disulfides and trisulfides were the primary sulfur volatiles present. In general, trisulfides (dimethyl trisulfide) inhibited the response of D. citri to citrus volatiles more than disulfides (dimethyl disulfide, allyl methyl disulfide, allyl disulfide). Monosulfides did not affect the behaviour of D. citri adults. A blend of dimethyl trisulfide and dimethyl disulfide in 1:1 ratio showed an additive effect on inhibition of D. citri response to citrus volatiles. The plant volatiles from Allium spp. did not affect the behaviour of the D. citri ecto-parasitoid Tamarixia radiata (Waterston). Thus, Allium spp. or the tri- and di-sulphides could be integrated into management programmes for D. citri without affecting natural enemies.

Botanical insecticides in controlling Kelly's citrus thrips (Thysanoptera: Thripidae) on organic grapefruits.

Science.gov (United States)

Vassiliou, V A

2011-12-01

Kelly's citrus thrips, Pezothrips kellyanus (Bagnall) (Thysanoptera: Thripidae) was first recorded in Cyprus in 1996 and became an economic citrus pest. In Cyprus, Kelly's citrus thrips larvae cause feeding damage mainly on immature lemon and grapefruit fruits. Use of botanical insecticides is considered an alternative tool compared with synthetic chemicals, in offering solutions for healthy and sustainable citrus production. During 2008-2010, the efficacy of the botanical insecticides azadirachtin (Neemex 0.3%W/W and Oikos 10 EC), garlic extract (Alsa), and pyrethrins (Vioryl 5%SC) was evaluated in field trials against Kelly's citrus thrips larval stage I and II aiming at controlling the pest's population and damage to organic grapefruit fruits. In each of the trial years treatments with pyrethrins and azadirachtin (Neemex 0.3%W/W) were the most effective against Kelly's citrus thrips compared with the untreated control (for 2008: P extract showed the lowest effect from all the botanicals used compared with the untreated control.

The wild tomato species Solanum chilense shows variation in pathogen resistance between geographically distinct populations.

Science.gov (United States)

Stam, Remco; Scheikl, Daniela; Tellier, Aurélien

2017-01-01

Wild tomatoes are a valuable source of disease resistance germplasm for tomato ( Solanum lycopersicum ) breeders. Many species are known to possess a certain degree of resistance against certain pathogens; however, evolution of resistance traits is yet poorly understood. For some species, like Solanum chilense , both differences in habitat and within species genetic diversity are very large. Here we aim to investigate the occurrence of spatially heterogeneous coevolutionary pressures between populations of S. chilense . We investigate the phenotypic differences in disease resistance within S. chilense against three common tomato pathogens ( Alternaria solani , Phytophthora infestans and a Fusarium sp .) and confirm high degrees of variability in resistance properties between selected populations. Using generalised linear mixed models, we show that disease resistance does not follow the known demographic patterns of the species. Models with up to five available climatic and geographic variables are required to best describe resistance differences, confirming the complexity of factors involved in local resistance variation. We confirm that within S. chilense , resistance properties against various pathogens show a mosaic pattern and do not follow environmental patterns, indicating the strength of local pathogen pressures. Our study can form the basis for further investigations of the genetic traits involved.

Inhibitory effect of Epstein-Barr virus activation by Citrus fruits, a cancer chemopreventor.

Science.gov (United States)

Iwase, Y; Takemura, Y; Ju-ichi, M; Kawaii, S; Yano, M; Okuda, Y; Mukainaka, T; Tsuruta, A; Okuda, M; Takayasu, J; Tokuda, H; Nishino, H

1999-05-24

To search useful compounds in Citrus fruit for cancer chemoprevention, we carried out a primary screening of extracts of fruit peels and seeds from 78 species of the genus Citrus and those from two Fortunella and one Poncirus species, which were closely related to the genus Citrus. These Citrus extracts inhibited the Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA) as a useful screening method for anti-tumor promoters. Our results indicated that Citrus containing substances may be inhibit susceptibility factors involved in the events leading to the development of cancer.

ENZYMATIC KINETIC STUDY HYDROLASE FROM CITRUS

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Israel Hernández

2015-09-01

Full Text Available In this paper the degrading activity of enzymes derived from orange peels (Citrus x sinensis, grapefruit (Citrus paradise and pineapple (Ananas comosus on the organic matter in wastewater is evaluated. This activity is measured indirectly by quantifying the biochemical oxygen demand (COD before and after degradation process based on a period of time using the HACH DR / 2010, and then the kinetic study was performed by the differential method and integral with the experimental data, obtaining a reaction order of 1 to pectinase (orange, and order 2 for bromelain (pineapple.

Evaluation of non-chemical seed treatment methods for control of Alternaria brassicicola on cabbage seeds

NARCIS (Netherlands)

Amein, T.; Wright, Al S.; Wikstrom, M.; Koch, E.; Schmitt, A.; Stephan, D.; Jahn, M.; Tinivella, F.; Gullino, M.L.; Forsberg, G.; Werner, S.; Wolf, van der J.M.; Groot, S.P.C.

2011-01-01

Due to the lack of foliar fungicide use, the organic production of Brassica seeds free of Alternaria spp. is difficult. Therefore, effective seed treatments certified for use in organic farming are needed to eradicate or at least effec­tively reduce the seed-borne inoculum. We here report results of

In vitro activity of glucosinolates and their degradation products against brassica-pathogenic bacteria and fungi.

Science.gov (United States)

Sotelo, T; Lema, M; Soengas, P; Cartea, M E; Velasco, P

2015-01-01

Glucosinolates (GSLs) are secondary metabolites found in Brassica vegetables that confer on them resistance against pests and diseases. Both GSLs and glucosinolate hydrolysis products (GHPs) have shown positive effects in reducing soil pathogens. Information about their in vitro biocide effects is scarce, but previous studies have shown sinigrin GSLs and their associated allyl isothiocyanate (AITC) to be soil biocides. The objective of this work was to evaluate the biocide effects of 17 GSLs and GHPs and of leaf methanolic extracts of different GSL-enriched Brassica crops on suppressing in vitro growth of two bacterial (Xanthomonas campestris pv. campestris and Pseudomonas syringae pv. maculicola) and two fungal (Alternaria brassicae and Sclerotinia scletoriorum) Brassica pathogens. GSLs, GHPs, and methanolic leaf extracts inhibited the development of the pathogens tested compared to the control, and the effect was dose dependent. Furthermore, the biocide effects of the different compounds studied were dependent on the species and race of the pathogen. These results indicate that GSLs and their GHPs, as well as extracts of different Brassica species, have potential to inhibit pathogen growth and offer new opportunities to study the use of Brassica crops in biofumigation for the control of multiple diseases. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

Comparative study on the effect of chemicals on Alternaria blight in Indian mustard--a multi-location study in India.

Science.gov (United States)

Meena, P D; Chattopadhyay, C; Kumar, A; Awasthi, R P; Singh, R; Kaur, S; Thomas, L; Goyal, P; Chand, P

2011-05-01

High severity of Altemaria blight disease is a major constraint in production of rapeseed-mustard in India. The aim of this study was to investigate the suppressive potential of chemicals viz., zinc sulphate, borax, sulphur, potash and calcium sulphate, aqueous extracts viz., Eucalyptus globosus (50 g l-1) leaf extract and garlic (Allium sativum) bulb (20 g l-1) extract, cow urine and bio-agents Trichoderma harzianum, Pseudomonas fluorescence in comparison with the recommended chemical fungicide (mancozeb), against foliar disease Alternaria blight of Indian mustard [Brassica juncea (L.) Czern. and Coss] under five different geographical locations of India. Mancozeb recorded the lowest mean severity (leaf: 33.1%; pod: 26.3%) of Alternaria blight with efficacy of garlic bulb extract alone (leaf = 34.4%; pod = 27.3%) or in combination with cow urine (leaf = 34.2%; pod = 28.6%) being statistically at par with the recommended chemical fungicide. Chemicals also proved effective in reducing Alternaria blight severity on leaves and pods of Indian mustard (leaf = 36.3-37.9%; pod = 27.5-30.1%). The effective treatments besides providing significant reduction in disease severity also enabled increase in dry seed yield of the crop (mancozeb = 2052 kg ha-1; garlic = 2006 kg ha-1; control = 1561 kg ha-1).

Weed Biomass and Weed Species Diversity of Juvenile Citrus Trees Intercrop with some Arable Crops

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Patience Mojibade OLORUNMAIYE

2012-02-01

Full Text Available A preliminary study was carried out to evaluate the performances of eight crops in the intercrop of citrus with arable crops at the National Horticultural Research Institute (NIHORT Ibadan, Nigeria. Eight arable crops: maize, cucumber, sweet potato, Corchorus olitorius, large green, grain amaranth, Mucuna pruriens var. utilis, and groundnut were intercropped with young citrus trees in the early planting season of 2010 with sole citrus as control. The experiment was laid out in a completely randomized block design with three replicates. Data were collected on weed flora, weed density and weed dry weight. Results showed that the relative frequencies of weeds in all the plots were less than 4% at both 6 and 9WAP. Gomphrena celosoides, Oldenlandia corymbosa and Tridax procumbens were most preponderant in appearing in all the plots. Tridax procumbens had a consistent relative frequency (2.34% in all the plots except in citrus/maize plot (0.78% at 9 WAP. Significantly lower broadleaf weed densities were obtained in citrus/sweet potato, citrus/large green, control plot and citrus/cucumber (28.67, 45.00, 50.00 and 76.33 m-2 respectively than in citrus/groundnut plot (143.00 m-2. Similarly, significantly lower grass weed densities were produced in citrus/Mucuna and citrus/sweet potato (0.33 m-2 each plots than the control plot (11.33 m-2. Whereas citrus/corchorus plot produced significantly lower broadleaf weed dry weight (37.59 g m-2 than citrus/Mucuna plot (126.47 g m-2 at 3WAP, citrus/large green plot (16.15 g m-2 and citrus/groundnut plot (123.25 g m-2 followed the same trend at 6 WAP. Sedges dry weights were less than 7 g m-2 in all the plots compared with control plot.

Chlorophyll Fluorescence Imaging Uncovers Photosynthetic Fingerprint of Citrus Huanglongbing

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Haiyan Cen

2017-08-01

Full Text Available Huanglongbing (HLB is one of the most destructive diseases of citrus, which has posed a serious threat to the global citrus production. This research was aimed to explore the use of chlorophyll fluorescence imaging combined with feature selection to characterize and detect the HLB disease. Chlorophyll fluorescence images of citrus leaf samples were measured by an in-house chlorophyll fluorescence imaging system. The commonly used chlorophyll fluorescence parameters provided the first screening of HLB disease. To further explore the photosynthetic fingerprint of HLB infected leaves, three feature selection methods combined with the supervised classifiers were employed to identify the unique fluorescence signature of HLB and perform the three-class classification (i.e., healthy, HLB infected, and nutrient deficient leaves. Unlike the commonly used fluorescence parameters, this novel data-driven approach by using the combination of the mean fluorescence parameters and image features gave the best classification performance with the accuracy of 97%, and presented a better interpretation for the spatial heterogeneity of photochemical and non-photochemical components in HLB infected citrus leaves. These results imply the potential of the proposed approach for the citrus HLB disease diagnosis, and also provide a valuable insight for the photosynthetic response to the HLB disease.

QTL identification for early blight resistance (Alternaria solani) in a Solanum lycopersicum x S. arcanum cross.

NARCIS (Netherlands)

Chaerani, R.; Smulders, M.J.M.; Linden, van der C.G.; Vosman, B.; Stam, P.; Voorrips, R.E.

2007-01-01

Alternaria solani (Ellis and Martin) Sorauer, the causal agent of early blight (EB) disease, infects aerial parts of tomato at both seedling and adult plant stages. Resistant cultivars would facilitate a sustainable EB management. EB resistance is a quantitatively expressed character, a fact that

Genetic variability in the endophytic fungus Guignardia citricarpa isolated from citrus plants

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Chirlei Glienke-Blanco

2002-01-01

Full Text Available During some phases of of their life-cycle endophytic fungi colonize plants asymptomatically being found most frequently inside the aerial part of plant tissues. After surface disinfection of apparently healthy leaves from three varieties of mandarin orange and one tangor, and after incubation on appropriate culture medium, 407 fungal isolates were obtained, giving a total infection frequency of 81%. No fungal growth was observed from disinfected seeds, indicating that fungi are probably not transmitted via seeds. Of the fungal isolates, 27% belonged to the genus Guignardia, with 12 isolates being identified as Guignardia citricarpa Kiely, which is described as a citrus pathogen. The isolates were variable in respect to the presence of sexual structures and growth rates. Most of the isolates produces mature asci, supporting the hypothesis that they are nonpathogenic endophytes, which recently were identified as G. mangiferae. High intraspecific genetic variability (an average similarity coefficient of 0.6 was detected using random amplified polymorphic DNA (RAPD markers generated by seven different primers. The highest similarity coefficient (0.9 was between isolates P15 and M86 and the smallest (0.22 between isolates P15 and C145. These results did not allow us to establish an association between genetic similarity of the fungal isolates and the citrus varieties from which they were obtained.

Production of transgenic brassica juncea with the synthetic chitinase gene (nic) conferring resistance to alternaria brassicicola

International Nuclear Information System (INIS)

Munir, I.; Hussan, W.; Kazi, M.; Mian, A.

2016-01-01

Brassica juncea is an important oil seed crop throughout the world. The demand and cultivation of oil seed crops has gained importance due to rapid increase in world population and industrialization. Fungal diseases pose a great threat to Brassica productivity worldwide. Absence of resistance genes against fungal infection within crossable germplasms of this crop necessitates deployment of genetic engineering approaches to produce transgenic plants with resistance against fungal infections. In the current study, hypocotyls and cotyledons of Brassica juncea, used as explants, were transformed with Agrobacterium tumefacien strain EHA101 harboring binary vector pEKB/NIC containing synthetic chitinase gene (NIC), an antifungal gene under the control of cauliflower mosaic virus promoter (CaMV35S). Bar genes and nptII gene were used as selectable markers. Presence of chitinase gene in trangenic lines was confirmed by PCR and southern blotting analysis. Effect of the extracted proteins from non-transgenic and transgenic lines was observed on the growth of Alternaria brassicicola, a common disease causing pathogen in brassica crop. In comparison to non-transgenic control lines, the leaf tissue extracts of the transgenic lines showed considerable resistance and antifungal activity against A. brassicicola. The antifungal activity in transgenic lines was observed as corresponding to the transgene copy number. (author)

COMPLEX OF PATHOGENES ON VEGETABLE CROPS IN CONDITION OF CENTRAL REGION OF RUSSIA

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L. T. Timina

2015-01-01

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.

Alternative oxidase (AOX) constitutes a small family of proteins in Citrus clementina and Citrus sinensis L. Osb.

Science.gov (United States)

Araújo Castro, Jacqueline; Gomes Ferreira, Monique Drielle; Santana Silva, Raner José; Andrade, Bruno Silva; Micheli, Fabienne

2017-01-01

The alternative oxidase (AOX) protein is present in plants, fungi, protozoa and some invertebrates. It is involved in the mitochondrial respiratory chain, providing an alternative route for the transport of electrons, leading to the reduction of oxygen to form water. The present study aimed to characterize the family of AOX genes in mandarin (Citrus clementina) and sweet orange (Citrus sinensis) at nucleotide and protein levels, including promoter analysis, phylogenetic analysis and C. sinensis gene expression. This study also aimed to do the homology modeling of one AOX isoform (CcAOXd). Moreover, the molecular docking of the CcAOXd protein with the ubiquinone (UQ) was performed. Four AOX genes were identified in each citrus species. These genes have an open reading frame (ORF) ranging from 852 bp to 1150 bp and a number of exons ranging from 4 to 9. The 1500 bp-upstream region of each AOX gene contained regulatory cis-elements related to internal and external response factors. CsAOX genes showed a differential expression in citrus tissues. All AOX proteins were predicted to be located in mitochondria. They contained the conserved motifs LET, NERMHL, LEEEA and RADE-H as well as several putative post-translational modification sites. The CcAOXd protein was modeled by homology to the AOX of Trypanosona brucei (45% of identity). The 3-D structure of CcAOXd showed the presence of two hydrophobic helices that could be involved in the anchoring of the protein in the inner mitochondrial membrane. The active site of the protein is located in a hydrophobic environment deep inside the AOX structure and contains a diiron center. The molecular docking of CcAOXd with UQ showed that the binding site is a recessed pocket formed by the helices and submerged in the membrane. These data are important for future functional studies of citrus AOX genes and/or proteins, as well as for biotechnological approaches leading to AOX inhibition using UQ homologs.

β-Cryptoxanthin and Zeaxanthin Pigments Accumulation to Induce Orange Color on Citrus Fruits

Science.gov (United States)

Hidayati Sumiasih, Inanpi; Poerwanto, Roedhy; Efendi, Darda; Agusta, Andria; Yuliani, Sri

2018-01-01

Degreening, a transformation process of green color on citrus peel to be orange color on tropical low-land citrus fruits often fails. Orange color of the citrus peel comes from the mixture carotenoid pigments, such as zeaxanthine and mainly β-cryptoxanthin and β-citraurin. The accumulation of β-citraurin occurs when the fruits are exposed to low temperature, and otherwise, it will fail to occur. Precooling treatment on lowland tropical citrus fruits is expected to stimulate the accumulation of β-citraurin. The results showed the most favorable color obtained from precooling and 24-hour ethylene exposure duration. This treatment could decrease total chlorophyll and β-carotene content as well as proven to increase 3 times the accumulation of β-cryptoxanthin in accelerating the appearance of bright orange color on citrus peel. Degreening gave no significant effect to internal quality of Citrus reticulata.

Effectiveness of Postharvest Treatment with Chitosan to Control Citrus Green Mold

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Mohamed El Guilli

2016-03-01

Full Text Available Control of green mold, caused by Penicillium digitatum, by fungicides raises several problems, such as emergence of resistant pathogens, as well as concerns about the environment and consumers’ health. As potential alternatives, the effects of chitosan on green mold disease and the quality attributes of citrus fruits were investigated. Fruits were wounded then treated with different concentrations of chitosan 24 h before their inoculation with P. digitatum. The results of in vitro experiment demonstrated that the antifungal activity against P. digitatum was improved in concert to the increase of chitosan concentration. In an in vivo study, green mold was significantly reduced by chitosan treatments. In parallel, chitinase and glucanase activities were enhanced in coated fruits. Evidence suggested that effects of chitosan coating on green mold of mandarin fruits might be related to its fungitoxic properties against the pathogen and/or the elicitation of biochemical defense responses in coated fruits. Further, quality attributes including fruit firmness, surface color, juice content, and total soluble solids, were not affected by chitosan during storage. Moreover, the loss of weight was even less pronounced in chitosan-coated fruit.

First record of Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) in citrus in Brazil.

Science.gov (United States)

Lemos, W P; da Silva, R A; Araújo, S C A; Oliveira, E L A; da Silva, W R

2011-01-01

Anastrepha serpentina (Wiedemann) is recorded for the first time in citrus (Rutaceae) in Brazil. Specimens were obtained from sweet orange (Citrus sinensis) sampled in the municipalities of Belém and Capitão Poço, and from mandarin orange (Citrus reticulata) from Tomé-Açu, state of Pará, Brazil.

First record of Anastrepha serpentina (Wiedemann) (Diptera: Tephritidae) in citrus in Brazil

OpenAIRE

Lemos, WP; Silva, RA da; Araújo, SCA; Oliveira, ELA; Silva, WR da

2011-01-01

Anastrepha serpentina (Wiedemann) is recorded for the first time in citrus (Rutaceae) in Brazil. Specimens were obtained from sweet orange (Citrus sinensis) sampled in the municipalities of Belém and Capitão Poço, and from mandarin orange (Citrus reticulata) from Tomé-Açu, state of Pará, Brazil.

Citrus leprosis and its status in Florida and Texas: past and present.

Science.gov (United States)

Childers, C C; Rodrigues, J C V; Derrick, K S; Achor, D S; French, J V; Welbourn, W C; Ochoa, R; Kitajima, E W

2003-01-01

According to published reports from 1906 to 1968, leprosis nearly destroyed the Florida citrus industry prior to 1925. This was supported with photographs showing typical leprosis symptoms on citrus leaves, fruit, and twigs. Support for the past occurrence of citrus leprosis in Florida includes: (1) presence of twig lesions in affected orange blocks in addition to lesions on fruits and leaves and corresponding absence of similar lesions on grapefruit; (2) yield reduction and die-back on infected trees; and (3) spread of the disease between 1906 and 1925. Transmission electron microscopy (TEM) examination of tissue samples from leprosis-like injuries to orange and grapefruit leaves from Florida in 1997, and fruits from grapefruit and sweet orange varieties from Texas in 1999 and 2000 did not contain leprosis-like viral particles or viroplasm inclusions. In contrast, leprosis viroplasm inclusions were readily identified by TEM within green non-senescent tissues surrounding leprosis lesions in two of every three orange leaf samples and half of the fruit samples obtained from Piracicaba, Brazil. Symptoms of leprosis were not seen in any of the 24,555 orange trees examined across Florida during 2001 and 2002. The authors conclude that citrus leprosis no longer exists in Florida nor occurs in Texas citrus based on: (1) lack of leprosis symptoms on leaves, fruit, and twigs of sweet orange citrus varieties surveyed in Florida: (2) failure to find virus particles or viroplasm inclusion bodies in suspect samples from both Florida and Texas examined by TEM; (3) absence of documented reports by others on the presence of characteristic leprosis symptoms in Florida; (4) lack of its documented occurrence in dooryard trees or abandoned or minimal pesticide citrus orchard sites in Florida. In view of the serious threat to citrus in the U.S., every effort must be taken to quarantine the importation of both citrus and woody ornamental plants that serve as hosts for Brevipalpus

CHEMICAL COMPOSITION AND TOXICITY OF CITRUS ESSENTIAL OILS ON Dysmicoccus brevipes (HEMIPTERA: PSEUDOCOCCIDAE)

OpenAIRE

MARTINS, GISELE DOS SANTOS OLIVEIRA; ZAGO, HUGO BOLSONI; COSTA, ADILSON VIDAL; ARAUJO JUNIOR, LUIS MOREIRA DE; CARVALHO, JOSÉ ROMÁRIO DE

2017-01-01

ABSTRACT The insect Dysmicoccus brevipes (Hemiptera: Pseudococcidae) has been reported as an important pest for several crops, especially coffee. The citrus essential oils can be obtained as by-products of the citrus-processing industry and have been tested as an alternative to control different insect groups. Therefore, the objective of this work was to determine the chemical composition and evaluate the toxicity of commercial sweet orange (Citrus sinensis), bitter orange (Citrus aurantium) ...

(JASR) VOL. 10, No. 2, 2010 69 CITRUS FARMERS PRODUCTION

African Journals Online (AJOL)

oma

Emerging trends and advances in the citrus industry globally necessitates updating ... citrus is ranked first among other fruit crops by farmers (NIHORT, 2000). .... the arduous task of producing horticultural crops which are pest, diseases and ...

Complex history of admixture during citrus domestication revealed by genome analysis

Energy Technology Data Exchange (ETDEWEB)

Wu, G. Albert; Prochnik, Simon; Jenkins, Jerry; Salse, Jerome; Hellsten, Uffe; Murat, Florent; Perrier, Xavier; Ruiz, Manuel; Scalabrin, Simone; Terol, Javier; Takita, Marco Aur& #233; lio,; Labadie, Karine; Poulain, Julie; Couloux, Arnaud; Jabbari, Kamel; Cattonaro, Federica; Fabbro, Cristian Del; Pinosio, Sara; Zuccolo, Andrea; Chapman, Jarrod; Grimwood, Jane; Tadeo, Francisco; Estornell, Leandro H.; Mu?oz-Sanz, Juan V.; Ibanez, Victoria; Herrero-Ortega, Amparo; Aleza, Pablo; P& #233; rez, Juli& #225; n P& #233; rez,; Ramon, Daniel; Brunel, Dominique; Luro, Francois; Chen, Chunxian; Farmerie, William G.; Desany, Brian; Kodira, Chinnappa; Mohiuddin, Mohammed; Harkins, Tim; Fredrikson, Karin; Burns, Paul; Lomsadze, Alexandre; Borodovsky, Mark; Reforgiato, Giuseppe; Freitas-Astua, Juliana; Quetier, Francis; Navarro, Luis; Roose, Mikeal; Wincker, Patrick; Schmutz, Jeremy; Morgante, Michele; Machado, Marcos Antonio; Talon, Manuel; Jaillon, Olivier; Ollitrault, Patrick; Gmitter, Frederick; Rokhsar, Daniel

2014-06-30

Although Citrus is the most globally significant tree fruit, its domestication history is poorly understood. Cultivated citrus types are believed to comprise selections from and/or hybrids of several wild progenitor species, but the identities of these progenitors, and their contribution to modern cultivars, remain controversial. Here we report the genomes of a collection of mandarins, pummelos, and oranges, including a high quality reference sequence from a haploid Clementine mandarin. By comparative genome analysis we show that these cultivated types can be derived from two progenitor species. Cultivated pummelos represent selections from a single progenitor species C. maxima. Unexpectedly, however, we find that cultivated mandarins are introgressions of C. maxima into a distinct second population that we identify with the ancestral wild mandarin species C. reticulata. Sweet and sour oranges are found to be interspecific hybrids. Sweet orange, the most widely cultivated citrus, arose as the offspring of previously admixed individuals. In contrast, sour (or Seville) orange is an F1 hybrid of pure C. maxima and C. reticulata parents, implying that wild mandarins were part of the early breeding germplasm. Surprisingly, we also find that a wild Chinese mandarin from Mangshan, China shows substantial sequence divergence from C. reticulata and appears to represent a distinct taxon. Understanding the relationships and phylogeny of cultivated citrus through genome analysis will clarify taxonomic relationships and enable previously inconceivable opportunities for sequence-directed genetic improvement. Citrus are widely consumed worldwide as juice or fresh fruit, providing important sources of vitamin C and other health-promoting compounds. Global production in 2012 exceeded 86 million metric tons, with an estimated value of US$9 billion (http://www.fas.usda.gov/psdonline/circulars/citrus.pdf). The very narrow genetic diversity of cultivated citrus makes it highly

Saving Citrus: Does the Next Generation See GM Science as a Solution?

Science.gov (United States)

Rumble, Joy N.; Ruth, Taylor K.; Owens, Courtney T.; Lamm, Alexa J.; Taylor, Melissa R.; Ellis, Jason D.

2016-01-01

Citrus is one of Florida's most prominent commodities, providing 66% of the total United States' value for oranges. Florida's citrus production decreased 21% in 2014 from the previous season, partly due to the disease citrus greening. The science of genetic modification (GM) is one of the most promising solutions to the problem. However, a…

Repellency of Selected Psidium guajava cultivars to the Asian citrus psyllid, Diaphorina citri

Science.gov (United States)

Asiatic huanglongbing (HLB)(also known as citrus greening disease) is the most devastating disease of citrus worldwide. It is caused by a bacterium ‘Candidatus Liberibacter asiaticus’ and transmitted by the Asian citrus psyllid (ACP), Diaphorina citri. Considerable research has been conducted toward...

Identification of Novel Source of Resistance and Differential Response of Allium Genotypes to Purple Blotch Pathogen, Alternaria porri (Ellis Ciferri

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Satyabrata Nanda

2016-12-01

Full Text Available Purple blotch, caused by Alternaria porri (Ellis Cifferi, is a serious disease incurring heavy yield losses in the bulb and seed crop of onion and garlic worldwide. There is an immediate need for identification of effective resistance sources for use in host resistance breeding. A total of 43 Allium genotypes were screened for purple blotch resistance under field conditions. Allium cepa accession ‘CBT-Ac77’ and cultivar ‘Arka Kalyan’ were observed to be highly resistant. In vitro inoculation of a selected set of genotypes with A. porri, revealed that 7 days after inoculation was suitable to observe the disease severity. In vitro screening of 43 genotypes for resistance to A. porri revealed two resistant lines. An additional 14 genotypes showed consistent moderate resistance in the field as well as in vitro evaluations. Among the related Allium species, A. schoenoprasum and A. roylei showed the least disease index and can be used for interspecific hybridization with cultivated onion. Differential reaction analysis of three A. porri isolates (Apo-Chiplima, Apn-Nasik, Apg-Guntur in 43 genotypes revealed significant variation among the evaluated Allium species (P = 0.001. All together, the present study suggest that, the newly identified resistance sources can be used as potential donors for ongoing purple blotch resistance breeding program in India.

DNA microarray-based genome comparison of a pathogenic and a nonpathogenic strain of Xylella fastidiosa delineates genes important for bacterial virulence.

Science.gov (United States)

Koide, Tie; Zaini, Paulo A; Moreira, Leandro M; Vêncio, Ricardo Z N; Matsukuma, Adriana Y; Durham, Alan M; Teixeira, Diva C; El-Dorry, Hamza; Monteiro, Patrícia B; da Silva, Ana Claudia R; Verjovski-Almeida, Sergio; da Silva, Aline M; Gomes, Suely L

2004-08-01

Xylella fastidiosa is a phytopathogenic bacterium that causes serious diseases in a wide range of economically important crops. Despite extensive comparative analyses of genome sequences of Xylella pathogenic strains from different plant hosts, nonpathogenic strains have not been studied. In this report, we show that X. fastidiosa strain J1a12, associated with citrus variegated chlorosis (CVC), is nonpathogenic when injected into citrus and tobacco plants. Furthermore, a DNA microarray-based comparison of J1a12 with 9a5c, a CVC strain that is highly pathogenic and had its genome completely sequenced, revealed that 14 coding sequences of strain 9a5c are absent or highly divergent in strain J1a12. Among them, we found an arginase and a fimbrial adhesin precursor of type III pilus, which were confirmed to be absent in the nonpathogenic strain by PCR and DNA sequencing. The absence of arginase can be correlated to the inability of J1a12 to multiply in host plants. This enzyme has been recently shown to act as a bacterial survival mechanism by down-regulating host nitric oxide production. The lack of the adhesin precursor gene is in accordance with the less aggregated phenotype observed for J1a12 cells growing in vitro. Thus, the absence of both genes can be associated with the failure of the J1a12 strain to establish and spread in citrus and tobacco plants. These results provide the first detailed comparison between a nonpathogenic strain and a pathogenic strain of X. fastidiosa, constituting an important step towards understanding the molecular basis of the disease.

Cholinesterase inhibitor (Altenuene) from an endophytic fungus Alternaria alternata: optimization, purification and characterization.

Science.gov (United States)

Bhagat, J; Kaur, A; Kaur, R; Yadav, A K; Sharma, V; Chadha, B S

2016-10-01

The aim of this study was to screen endophytic fungi isolated from Vinca rosea for their potential to produce acetylcholinesterase (AChE) inhibitors. Endophytic fungi isolated from V. rosea (Catharanthus roseus), were screened for AChE inhibitor production using Ellman's method. Maximum inhibition against AChE (78%) was observed in an isolate VS-10, identified to be Alternaria alternata on morphological and molecular basis. The isolate also inhibited butyrylcholinesterase (73%). Significant increase (1·3 fold) was achieved after optimization of process parameters using one variable at time approach. The inhibitor was purified using chromatographic techniques. The structure elucidation of the inhibitor was carried out using spectroscopic techniques and was identified to be 'altenuene'. The purified inhibitor possessed antioxidant potential as revealed by dot blot assay. The insecticidal potential of purified inhibitor was evaluated by feeding Spodoptora litura on diet amended with inhibitor. It evinced significant larval mortality. Endophytic A. alternata can serve as a source of dual cholinesterase inhibitor 'altenuene' with significant antioxidant and insecticidal activity. This is the first report on acetylcholinestearse inhibitory activity of altenuene. Alternaria alternata has the potential to produce a dual ChE inhibitor with antioxidant activity useful in the treatment of neurodegenerative disorders and in agriculture as biocontrol agent. © 2016 The Society for Applied Microbiology.

Living on the Edges: Spatial Niche Occupation of Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), in Citrus Groves.

Science.gov (United States)

Sétamou, Mamoudou; Bartels, David W

2015-01-01

The spatial niche occupation of the Asian citrus psyllid, Diaphorina citri Kuwayama, 1908, was evaluated to determine its field colonization and food resource exploitation strategies in citrus groves. Mature grapefruit and sweet orange groves were surveyed as part of an area-wide program in 2009-2010 to determine D. citri population densities and between-tree distribution. In both cultivars, significantly more psyllids were found on perimeter trees throughout the study period suggesting a strong edge effect in D. citri distribution in the groves. D. citri densities and infestation levels gradually declined from the edge to the center of grove. Higher numbers of D. citri were recorded on trees located on the east and south sides of the groves than those on the west and north sides. Citrus groves located at the outer edge of the study with at least one side non-surrounded to other citrus groves harbored significantly more D. citri than groves located within the block cluster and entirely surrounded by other groves. In detailed field studies during 2012, infestation of D. citri started from border trees in the grove where possibly one generation is completed before inner trees become infested. In addition, psyllid densities decreased significantly with increasing distance from the grove edge. Using the selection index, D citri exhibited a strong niche occupation preference for border trees.

Living on the Edges: Spatial Niche Occupation of Asian Citrus Psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae, in Citrus Groves.

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Mamoudou Sétamou

Full Text Available The spatial niche occupation of the Asian citrus psyllid, Diaphorina citri Kuwayama, 1908, was evaluated to determine its field colonization and food resource exploitation strategies in citrus groves. Mature grapefruit and sweet orange groves were surveyed as part of an area-wide program in 2009-2010 to determine D. citri population densities and between-tree distribution. In both cultivars, significantly more psyllids were found on perimeter trees throughout the study period suggesting a strong edge effect in D. citri distribution in the groves. D. citri densities and infestation levels gradually declined from the edge to the center of grove. Higher numbers of D. citri were recorded on trees located on the east and south sides of the groves than those on the west and north sides. Citrus groves located at the outer edge of the study with at least one side non-surrounded to other citrus groves harbored significantly more D. citri than groves located within the block cluster and entirely surrounded by other groves. In detailed field studies during 2012, infestation of D. citri started from border trees in the grove where possibly one generation is completed before inner trees become infested. In addition, psyllid densities decreased significantly with increasing distance from the grove edge. Using the selection index, D citri exhibited a strong niche occupation preference for border trees.

RNA-Seq analysis of Citrus reticulata in the early stages of Xylella fastidiosa infection reveals auxin-related genes as a defense response.

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Rodrigues, Carolina M; de Souza, Alessandra A; Takita, Marco A; Kishi, Luciano T; Machado, Marcos A

2013-10-03

Citrus variegated chlorosis (CVC), caused by Xylella fastidiosa, is one the most important citrus diseases, and affects all varieties of sweet orange (Citrus sinensis L. Osb). On the other hand, among the Citrus genus there are different sources of resistance against X. fastidiosa. For these species identifying these defense genes could be an important step towards obtaining sweet orange resistant varieties through breeding or genetic engineering. To assess these genes we made use of mandarin (C. reticulata Blanco) that is known to be resistant to CVC and shares agronomical characteristics with sweet orange. Thus, we investigated the gene expression in Ponkan mandarin at one day after infection with X. fastidiosa, using RNA-seq. A set of genes considered key elements in the resistance was used to confirm its regulation in mandarin compared with the susceptible sweet orange. Gene expression analysis of mock inoculated and infected tissues of Ponkan mandarin identified 667 transcripts repressed and 724 significantly induced in the later. Among the induced transcripts, we identified genes encoding proteins similar to Pattern Recognition Receptors. Furthermore, many genes involved in secondary metabolism, biosynthesis and cell wall modification were upregulated as well as in synthesis of abscisic acid, jasmonic acid and auxin. This work demonstrated that the defense response to the perception of bacteria involves cell wall modification and activation of hormone pathways, which probably lead to the induction of other defense-related genes. We also hypothesized the induction of auxin-related genes indicates that resistant plants initially recognize X. fastidiosa as a necrotrophic pathogen.

Systemic translocation and metabolism of 14C-metalaxyl in citrus

International Nuclear Information System (INIS)

Musumeci, M.R.; Ruegg, E.F.

1984-01-01

Systemic uptake and translocation of 14 C-metalaxyl to citrus seedlings from soils (Humic Gley and Yellow Red Latosol) with different physical - chemical properties are studied. Seedlings of Citrus limonia are treated with 14 C-metalaxyl. (M.A.C.) [pt

Incidence of 'Candidatus Liberibacter asiaticus' in a Florida population of Asian citrus psyllid

Science.gov (United States)

A study was conducted to assess the incidence of a bacterium ‘Candidatus Liberibacter asiaticus’ in a Florida population of Asian citrus psyllid (ACP), Diaphorina citri. The bacterium is the presumed causal agent of Asiatic huanglongbing, a serious citrus disease also known as citrus greening or yel...

Bacterial brown leaf spot of citrus, a new disease caused by Burkholderia andropogonis

Science.gov (United States)

A new bacterial disease of citrus was recently identified in Florida and named as bacterial brown leaf spot (BBLS) of citrus. BBLS-infected citrus displayed flat, circular and brownish lesions with water-soaked margins surrounded by a chlorotic halo on leaves. Based on Biolog carbon source metabolic...

Authenticity analysis of citrus essential oils by HPLC-UV-MS on oxygenated heterocyclic components

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Hao Fan

2015-03-01

Full Text Available Citrus essential oils are widely applied in food industry as the backbone of citrus flavors. Unfortunately, due to relatively simple chemical composition and tremendous price differences among citrus species, adulteration has been plaguing the industry since its inception. Skilled blenders are capable of making blends that are almost indistinguishable from authentic oils through conventional gas chromatography analysis. A reversed-phase high performance liquid chromatography (HPLC method was developed for compositional study of nonvolatile constituents in essential oils from major citrus species. The nonvolatile oxygenated heterocyclic components identified in citrus oils were proved to be more effective as markers in adulteration detection than the volatile components. Authors are hoping such an analysis procedure can be served as a routine quality control test for authenticity evaluation in citrus essential oils.

Identification and Characterization of Pathogenic and Endophytic Fungal Species Associated with Pokkah Boeng Disease of Sugarcane

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Angelyn Hilton

2017-06-01

Full Text Available Pokkah Boeng is a serious disease of sugarcane, which can lead to devastating yield losses in crop-producing regions, including southern China. However, there is still uncertainty about the causal agent of the disease. Our aim was to isolate and characterize the pathogen through morphological, physiological, and molecular analyses. We isolated sugarcane-colonizing fungi in Fujian, China. Isolated fungi were first assessed for their cell wall degrading enzyme capabilities, and five isolates were identified for further analysis. Internal transcribed spacer sequencing revealed that these five strains are Fusarium, Alternaria, Phoma, Phomopsis, and Epicoccum. The Fusarium isolate was further identified as F. verticillioides after Calmodulin and EF-1α gene sequencing and microscopic morphology study. Pathogenicity assay confirmed that F. verticillioides was directly responsible for disease on sugarcane. Co-inoculation of F. verticillioides with other isolated fungi did not lead to a significant difference in disease severity, refuting the idea that other cellulolytic fungi can increase disease severity as an endophyte. This is the first report characterizing pathogenic F. verticillioides on sugarcane in southern China.

In vitro Propagation of Citrus limonia Osbeck Through Nucellar Embryo Culture

OpenAIRE

Alka Jajoo

2010-01-01

Citrus limonia Osbeck is a promising rootsctock for commercial citrus species with sturdy anddisease and drought resistant characters. A n efficient and highly reproducible plant regeneration protocol hasbeen developed from nucellar embryo of Citrus limonia. Murashige and Skoogs medium was used for plantregeneration from nucellar embryos. It was noted that 6-benzylaminopurine at a concentration of 2.22 mMinduced highest number of multiple shoots as 18.26 shoots per explant. O n transfer of in...

Innate and Conditioned Responses to Chemosensory and Visual Cues in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae), Vector of Huanglongbing Pathogens.

Science.gov (United States)

Patt, Joseph M; Stockton, Dara; Meikle, William G; Sétamou, Mamoudou; Mafra-Neto, Agenor; Adamczyk, John J

2014-11-19

Asian citrus psyllid (Diaphorina citri) transmits Huanglongbing, a devastating disease that threatens citrus trees worldwide. A better understanding of the psyllid's host-plant selection process may lead to the development of more efficient means of monitoring it and predicting its movements. Since behavioral adaptations, such as associative learning, may facilitate recognition of suitable host-plants, we examined whether adult D. citri could be conditioned to visual and chemosensory stimuli from host and non-host-plant sources. Response was measured as the frequency of salivary sheaths, the residue of psyllid probing activity, in a line of emulsified wax on the surface of a test arena. The psyllids displayed both appetitive and aversive conditioning to two different chemosensory stimuli. They could also be conditioned to recognize a blue-colored probing substrate and their response to neutral visual cues was enhanced by chemosensory stimuli. Conditioned psyllids were sensitive to the proportion of chemosensory components present in binary mixtures. Naïve psyllids displayed strong to moderate innate biases to several of the test compounds. While innate responses are probably the psyllid's primary behavioral mechanism for selecting host-plants, conditioning may enhance its ability to select host-plants during seasonal transitions and dispersal.

Insecticidal activity of some citrus oils against culex quinquefasciatus

International Nuclear Information System (INIS)

Saeed, H. M. A.

2009-01-01

The present study deals with the larvicidal potency of peel oils of grapefruit (Citrus paradise), sweet orange (Citrus sinensis) and lime (Citrus aurantifolia) on 4''th instar larvae of the mosquito, Culex quinquefasciatus. Orange oil was the most effective followed by grapefruit oil and then lime oil. The toxicity of the oils applied to the 4''th instar larval stage was extended to pupal and adult stages. All oils produced deleterious effects on fecundity of survivors of sublethal doses. By the aid of chemical analysis of oils, the active compound was found to be limonene, a monoterpene compound. The percentages limonene were 97.15%, 92.46% and 32.29% for orange, grapefruit and lime respectively.(Author)

7 CFR 301.75-15 - Funds for the replacement of commercial citrus trees.

Science.gov (United States)

2010-01-01

... 7 Agriculture 5 2010-01-01 2010-01-01 false Funds for the replacement of commercial citrus trees... trees. Subject to the availability of appropriated funds, the owner of a commercial citrus grove may be eligible to receive funds to replace commercial citrus trees in accordance with the provisions of this...

History and Diversity of Citrus leprosis virus Recorded in Herbarium Specimens.

Science.gov (United States)

Hartung, John S; Roy, Avijit; Fu, Shimin; Shao, Jonathan; Schneider, William L; Brlansky, Ronald H

2015-09-01

Leprosis refers to two diseases of citrus that present similar necrotic local lesions, often surrounded by chlorotic haloes on citrus. Two distinct viruses are associated with this disease, one that produces particles primarily in the nucleus of infected plant cells (Citrus leprosis virus nuclear type [CiLV-N]; Dichorhavirus) and another type that produces particles in the cytoplasm of infected plant cells (Citrus leprosis virus cytoplasmic type [CiLV-C]; Cilevirus). Both forms are transmitted by Brevipalpid mites and have bipartite, single-stranded, RNA genomes. CiLV-C and CiLV-N are present in South and Central America and as far north as parts of Mexico. Although leprosis disease was originally described from Florida, it disappeared from there in the 1960s. The United States Department of Agriculture-Agricultural Research Service maintains preserved citrus specimens identified at inspection stations 50 or more years ago with symptoms of citrus leprosis. We isolated RNA from these samples and performed degradome sequencing. We obtained nearly full-length genome sequences of both a typical CiLV-C isolate intercepted from Argentina in 1967 and a distinct CiLV-N isolate obtained in Florida in 1948. The latter is a novel form of CiLV-N, not known to exist anywhere in the world today. We have also documented the previously unreported presence of CiLV-N in Mexico in the mid-20th century.

Exogenous application of methyl jasmonate and salicylic acid on citrus foliage: Effecs on foliar volatiles and aggregation behavior of Asian citrus psyllid (Diaphorina citri)

Science.gov (United States)

Methyl jasmonate (MeJA) and salicylic acid (SA) are well-known activators of chemical defenses in plants. The SA pathway is involved in citrus response to infection by Candidatus Liberibacter asiaticus (CLas); less is known about the role of jasmonates in citrus defense response. We examined the eff...

Behavioral assay on Asian citrus psyllid attraction to orange jasmine

Science.gov (United States)

The Asian citrus psyllid (ACP) is an important pest because it transmits a bacterium putatively responsible for huanglongbing, a devastating citrus disease. Research on ACP chemical ecology is of interest with respect to identifying attractants and repellents for managing the psyllid. We report on a...

Assessment of citrus marketing in Benue and Kano states of Nigeria ...

African Journals Online (AJOL)

Assessment of citrus marketing in Benue and Kano states of Nigeria. ... tends towards pure competition. Keywords: Benue, citrus, gini coefficient, Kano, marketing, pure competition, traders. Full Text: EMAIL FULL TEXT EMAIL FULL TEXT

Diversity of endophytic bacterial populations and their interaction with Xylella fastidiosa in citrus plants

NARCIS (Netherlands)

Araujo, W.L.; Marcon, J.; jr. Maccheroni, W.; Elsas, van J.D.; Vuurde, van J.W.L.; Azevedo, de J.L.

2002-01-01

Citrus variegated chlorosis (CVC) is caused by Xylella fastidiosa, a phytopathogenic bacterium that can infect all Citrus sinensis cultivars. The endophytic bacterial communities of healthy, resistant, and CVC-affected citrus plants were studied by using cultivation as well as

Studies on the development of functional powder from citrus peel.

Science.gov (United States)

Kang, H J; Chawla, S P; Jo, C; Kwon, J H; Byun, M W

2006-03-01

The suitability of citrus peels, generated as a by-product of the juice industry, as a source of antioxidants was investigated. Citrus peel powder was prepared by lyophilizing 70% ethanol extract from citrus peels. Extraction was carried out at room temperature (20 degrees C) for 72 h. The extract was subjected to gamma-irradiation treatment (20 kGy). The aqueous solutions of citrus peel powder were examined for color characteristics and antioxidant potential in terms of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging, beta-carotene bleaching and nitrite scavenging activities. There were significant changes in Hunter color values due to irradiation. The a*- and b*-values decreased due to radiation treatment. DPPH radical scavenging, beta-carotene bleaching and nitrite scavenging activities were not affected by irradiation treatment. Nitrite scavenging activity was the highest in the extract at pH 1.2 followed by pH 4.2 and 6.0. These functional properties of the aqueous solution were found to be stable in heat treatment. It could significantly improve oxidative stability of lipids in fish meat system. Based on these results there may be opportunities to use citrus peel powder as a functional component in the food processing industry with gamma irradiation treatment improving its color characteristics without adversely influencing the functional properties.

An association of Alternaria alternata and Scopulariopsis brevicaulis in cutaneous phaeohyphomycosis

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Anandan V

2008-01-01

Full Text Available Rare molds are increasingly emerging as a cause of deep and invasive fungal infections. We report here a rare case of cutaneous phaeohyphomycosis of the lower limbs due to Alternaria alternata associated with extra-ungual localization of Scopulariopsis brevicaulis. Diagnosis was made based on repeated, direct, microscopic mycological and histological examinations. The study revealed hyphae and fungal cells in a granulomatous dermal infiltrate. Identification of the molds was based on macroscopic appearance on culture of samples from the lesions on Sabouraud′s dextrose agar and microscopic appearance on Lactophenol cotton blue following slide culture.

Determination of limonin and nomilin contents in different citrus cultivars using high performance liquid chromatography

International Nuclear Information System (INIS)

Bilal, H.; Hassan, S.; Sahar, S.; Akram, W.; Sahar, S.

2013-01-01

High perlorrnance liquid chromatography (HPLC) analysis was done to quantify the amount of limonoids (nomilin and nomilin) in seven selected citrus cultivars. According to the HPLC analysis red blood orange (Citrus sinensis var red blood orange) had maximum amount of limonin (479.77 ug/rnl.), while rough lemon (Citrus jambhiri) had no limonin content. in case of nomonin, rough lemon (Citrus jambhir) had maximum amount of nomilin (54.23 micro g/ML)) while succari (citrus sinensis var succari) had very low amount of nomilin (0.37 micro g/Ml). (author)

Sensitivities of baseline isolates and boscalid-resistant mutants of Alternaria alternata from pistachio to fluopyram, penthiopyrad, and fluxapyroxad

NARCIS (Netherlands)

Avenot, H.F.; Biggelaar, van den H.; Morgan, D.P.; Moral, J.; Joosten, M.H.A.J.; Michailides, T.J.

2014-01-01

Resistance of Alternaria alternata to boscalid, the first succinate dehydrogenase inhibitor (SDHI) fungicide labeled on pistachio, has become a common occurrence in California pistachio orchards and affects the performance of this fungicide. In this study, we established the baseline sensitivities

Java project on periodontal diseases: effect of vitamin C/calcium threonate/citrus flavonoids supplementation on periodontal pathogens, CRP and HbA1c

NARCIS (Netherlands)

Amaliya, A.; Laine, M.L.; Loos, B.G.; van der Velden, U.

2015-01-01

Objective To assess in a periodontally diseased rural population deprived from regular dental care and having poor dietary conditions, the effect of vitamin C/calcium threonate/citrus flavonoids (VitC/Ca/Fl) supplementation on subgingival microbiota and plasma levels of vitamin C, HbA1c and hsCRP.

First records of parasitoids attacking the Asian citrus psyllid in Ecuador

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Diego E. Portalanza

Full Text Available ABSTRACT First records of parasitoids attacking the Asian citrus psyllid in Ecuador. The objective of the current study was to investigate the presence of natural enemies of Diaphorina citri (Hemiptera: Liviidae (the Asian citrus psyllid in Ecuador. Incidence of parasitoid Diaphorencyrtus aligarhensis (Hymenoptera: Encyrtidae was assessed between November 2015 and March 2016, in Letamendi, Febres-Cordero and Tarqui, urban districts of Guayaquil. Highest incidence of parasitism occurred in those regions and seasons of the year with the highest temperatures commensurate with increase of citrus plant shoots. Similar to their host, these parasitoids appear to have established in Ecuador by accident, and were not the result of purposeful introduction. This fortuitous introduction is a potentially helpful tool in controlling the Asian citrus psyllid, and potentially Huanglongbing.

EPIDEMIOLOGICAL ASPECTS OF LEAF BLIGHT OF CARROT (Daucus carota L. CAUSED BY Alternaria dauci (KÜHN GROVES & SKOLKO: SURVIVAL OF Alternaria dauci IN VEGETAL RESIDUES OF CARROT (Daucus carota L. CROP ASPECTOS EPIDEMIOLÓGICOS DA QUEIMA DAS FOLHAS DA CENOURA (Daucus carota L. CAUSADA POR Alternaria dauci (Kühn GROVES & SKOLKO: Sobrevivência de Alternaria dauci (Kühn Groves & SKOLKO em restos culturais da cenoura (Daucus carota L.

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Geraldo Martins Chaves

2007-09-01

Full Text Available

The spore viability of Alternaria dauci (Kühn Groves & Skolko in carrot (Daucus carota L. debris which were kept at different levels of temperature and relative humidity, without light, was studied. The temperature levels tested were 8, 16, 24 and 32°C, and the relative humidity levels 3, 18, 51, 73 and 100%. The treatments were different combinations of these levels. Humidity was the more important factor in preserving the fungus spore ability to germinate and its infectivity. Under conditions of high relative humidity and temperatures of 24 and 32°C, the spores rapidly lost their viability. This did not happen when the relative humidity was equal to, or below, 51%. The survival of fungus mycelium on carrot petioles was studied in non-treated organic soil, at different humidity levels, at three different depths, during a period of 120 days. Soil humidity was the factor of major significance in the persistence of the mycelium, followed by depths and time factors. In petioles kept at depths of 10 and 20 cm in humid soil, the survival was greatly reduced, while survival was markedly higher in those kept at the surface of dry soil. The effect of humidity on the viability of mycelium was studied also under soiless condition. Petioles were maintained in relative humidity controlled chamber, at 24°C. In saturated atmosphere (100% humidity, the mycelium viability was lost in less than 20 days. It was concluded that both, the conidial and mycelial form of Alternaria dauci are quite sensitive to high humidity levels.

Estudou-se a sobrevivência das formas conidial e miceliana de Alternaria dauci, respectivamente, sobre folhas necrosadas e pecíolos de cenoura, sob diferentes condições mesológicas. Os esporos do fungo sobre conidióforos em folhas necrosadas de cenoura foram mantidos por 120 dias sob condi

The Composition, Antioxidant and Antibacterial Activities of Cold-Pressed and Distilled Essential Oils of Citrus paradisi and Citrus grandis (L. Osbeck

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Ming-Chiu Ou

2015-01-01

Full Text Available The chemical composition and functional activities of cold-pressed and water distilled peel essential oils of Citrus paradisi (C. paradisi and Citrus grandis (L. Osbeck (C. grandis were investigated in present study. Yields of cold-pressed oils were much higher than those of distilled oils. Limonene was the primary ingredient of essential oils of C. paradisi (cold 92.83%; distilled 96.06% and C. grandis (cold 32.63%; distilled 55.74%. In addition, C. grandis oils obtained were rich in oxygenated or nitrogenated compounds which may be involved in reducing cardiovascular diseases or enhancing sleep effectiveness. The order of free radical scavenging activities of 4 citrus oils was distilled C. paradisi oil > cold-pressed C. paradisi oil > distilled C. grandis oil > cold-pressed C. grandis oil. Cold-pressed C. grandis oil exhibited the lowest activity in all antioxidative assays. The order of antimicrobial activities of 4 citrus oils was distilled C. grandis oil, cold-pressed C. paradisi oil > distilled C. paradisi oil > cold-pressed C. paradisi oil. Surprisingly, distilled C. grandis oil exhibited better antimicrobial activities than distilled C. paradisi oil, especially against Escherichia coli and Salmonella enterica subsp. The results also indicated that the antimicrobial activities of essential oils may not relate to their antioxidative activities.

Acquisition, Replication and Inoculation of Candidatus Liberibacter asiaticus following Various Acquisition Periods on Huanglongbing-Infected Citrus by Nymphs and Adults of the Asian Citrus Psyllid.

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El-Desouky Ammar

Full Text Available The Asian citrus psyllid, Diaphorina citri (Hemiptera: Liviidae, is the primary vector of Candidatus Liberibacter asiaticus (Las implicated as causative agent of citrus huanglongbing (citrus greening, currently the most serious citrus disease worldwide. Las is transmitted by D. citri in a persistent-circulative manner, but the question of replication of this bacterium in its psyllid vector has not been resolved. Thus, we studied the effects of the acquisition access period (AAP by nymphs and adults of D. citri on Las acquisition, multiplication and inoculation/transmission. D. citri nymphs or adults (previously non-exposed to Las were caged on Las-infected citrus plants for an AAP of 1, 7 or 14 days. These 'Las-exposed' psyllids were then transferred weekly to healthy citrus or orange jasmine plants, and sampled via quantitative polymerase chain reaction (qPCR analysis 1-42 days post-first access to diseased plants (padp; all tested nymphs became adults 7-14 days padp. Our results indicate that following 1 or 7 day AAP as nymphs 49-59% of Las-exposed psyllids became Las-infected (qPCR-positive, whereas only 8-29% of the psyllids were infected following 1-14 day AAP as adults. Q-PCR analysis also indicated that Las titer in the Las-exposed psyllids (relative to that of the psyllid S20 ribosomal protein gene was: 1 significantly higher, and increasing at a faster rate, following Las acquisition as nymphs compared to that following Las acquisition as adults; 2 higher as post-acquisition time of psyllids on healthy plants increased reaching a peak at 14-28 days padp for nymphs and 21-35 days padp for adults, with Las titer decreasing or fluctuating after that; 3 higher with longer AAP on infected plants, especially with acquisition as adults. Our results strongly suggest that Las multiplies in both nymphs and adults of D. citri but attains much higher levels in a shorter period of time post-acquisition when acquired by nymphs than when acquired by

Phylogenetic Relationships of Citrus and Its Relatives Based on matK Gene Sequences

Science.gov (United States)

Penjor, Tshering; Uehara, Miki; Ide, Manami; Matsumoto, Natsumi; Matsumoto, Ryoji

2013-01-01

The genus Citrus includes mandarin, orange, lemon, grapefruit and lime, which have high economic and nutritional value. The family Rutaceae can be divided into 7 subfamilies, including Aurantioideae. The genus Citrus belongs to the subfamily Aurantioideae. In this study, we sequenced the chloroplast matK genes of 135 accessions from 22 genera of Aurantioideae and analyzed them phylogenetically. Our study includes many accessions that have not been examined in other studies. The subfamily Aurantioideae has been classified into 2 tribes, Clauseneae and Citreae, and our current molecular analysis clearly discriminate Citreae from Clauseneae by using only 1 chloroplast DNA sequence. Our study confirms previous observations on the molecular phylogeny of Aurantioideae in many aspects. However, we have provided novel information on these genetic relationships. For example, inconsistent with the previous observation, and consistent with our preliminary study using the chloroplast rbcL genes, our analysis showed that Feroniella oblata is not nested in Citrus species and is closely related with Feronia limonia. Furthermore, we have shown that Murraya paniculata is similar to Merrillia caloxylon and is dissimilar to Murraya koenigii. We found that “true citrus fruit trees” could be divided into 2 subclusters. One subcluster included Citrus, Fortunella, and Poncirus, while the other cluster included Microcitrus and Eremocitrus. Compared to previous studies, our current study is the most extensive phylogenetic study of Citrus species since it includes 93 accessions. The results indicate that Citrus species can be classified into 3 clusters: a citron cluster, a pummelo cluster, and a mandarin cluster. Although most mandarin accessions belonged to the mandarin cluster, we found some exceptions. We also obtained the information on the genetic background of various species of acid citrus grown in Japan. Because the genus Citrus contains many important accessions, we have

Phylogenetic relationships of citrus and its relatives based on matK gene sequences.

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Tshering Penjor

Full Text Available The genus Citrus includes mandarin, orange, lemon, grapefruit and lime, which have high economic and nutritional value. The family Rutaceae can be divided into 7 subfamilies, including Aurantioideae. The genus Citrus belongs to the subfamily Aurantioideae. In this study, we sequenced the chloroplast matK genes of 135 accessions from 22 genera of Aurantioideae and analyzed them phylogenetically. Our study includes many accessions that have not been examined in other studies. The subfamily Aurantioideae has been classified into 2 tribes, Clauseneae and Citreae, and our current molecular analysis clearly discriminate Citreae from Clauseneae by using only 1 chloroplast DNA sequence. Our study confirms previous observations on the molecular phylogeny of Aurantioideae in many aspects. However, we have provided novel information on these genetic relationships. For example, inconsistent with the previous observation, and consistent with our preliminary study using the chloroplast rbcL genes, our analysis showed that Feroniella oblata is not nested in Citrus species and is closely related with Feronia limonia. Furthermore, we have shown that Murraya paniculata is similar to Merrillia caloxylon and is dissimilar to Murraya koenigii. We found that "true citrus fruit trees" could be divided into 2 subclusters. One subcluster included Citrus, Fortunella, and Poncirus, while the other cluster included Microcitrus and Eremocitrus. Compared to previous studies, our current study is the most extensive phylogenetic study of Citrus species since it includes 93 accessions. The results indicate that Citrus species can be classified into 3 clusters: a citron cluster, a pummelo cluster, and a mandarin cluster. Although most mandarin accessions belonged to the mandarin cluster, we found some exceptions. We also obtained the information on the genetic background of various species of acid citrus grown in Japan. Because the genus Citrus contains many important accessions

Phylogenetic relationships of citrus and its relatives based on matK gene sequences.

Science.gov (United States)

Penjor, Tshering; Yamamoto, Masashi; Uehara, Miki; Ide, Manami; Matsumoto, Natsumi; Matsumoto, Ryoji; Nagano, Yukio

2013-01-01

The genus Citrus includes mandarin, orange, lemon, grapefruit and lime, which have high economic and nutritional value. The family Rutaceae can be divided into 7 subfamilies, including Aurantioideae. The genus Citrus belongs to the subfamily Aurantioideae. In this study, we sequenced the chloroplast matK genes of 135 accessions from 22 genera of Aurantioideae and analyzed them phylogenetically. Our study includes many accessions that have not been examined in other studies. The subfamily Aurantioideae has been classified into 2 tribes, Clauseneae and Citreae, and our current molecular analysis clearly discriminate Citreae from Clauseneae by using only 1 chloroplast DNA sequence. Our study confirms previous observations on the molecular phylogeny of Aurantioideae in many aspects. However, we have provided novel information on these genetic relationships. For example, inconsistent with the previous observation, and consistent with our preliminary study using the chloroplast rbcL genes, our analysis showed that Feroniella oblata is not nested in Citrus species and is closely related with Feronia limonia. Furthermore, we have shown that Murraya paniculata is similar to Merrillia caloxylon and is dissimilar to Murraya koenigii. We found that "true citrus fruit trees" could be divided into 2 subclusters. One subcluster included Citrus, Fortunella, and Poncirus, while the other cluster included Microcitrus and Eremocitrus. Compared to previous studies, our current study is the most extensive phylogenetic study of Citrus species since it includes 93 accessions. The results indicate that Citrus species can be classified into 3 clusters: a citron cluster, a pummelo cluster, and a mandarin cluster. Although most mandarin accessions belonged to the mandarin cluster, we found some exceptions. We also obtained the information on the genetic background of various species of acid citrus grown in Japan. Because the genus Citrus contains many important accessions, we have

An integrated in silico/in vitro approach to assess the xenoestrogenic potential of Alternaria mycotoxins and metabolites.

Science.gov (United States)

Dellafiora, Luca; Warth, Benedikt; Schmidt, Verena; Del Favero, Giorgia; Mikula, Hannes; Fröhlich, Johannes; Marko, Doris

2018-05-15

Xenoestrogenic mycotoxins may contaminate food and feed posing a public health issue. Besides the zearalenone group, the Alternaria toxin alternariol (AOH) has been described as a potential mycoestrogen. However, the estrogenicity of Alternaria toxins is still largely overlooked and further data are needed to better describe the group toxicity. In the frame of risk assessment, mixed in silico/in vitro approaches already proved to be effective first-line analytical tools. An integrated in silico/in vitro approach was used to investigate the effects of metabolic and chemical modifications on the estrogenicity of AOH. Among the considered modifications, methylation was found critical for enhancing estrogenicity (as seen for alternariol monomethyl ether (AME)) while hydroxylation and glucuronidation had the opposite effect (as seen for 4-hydroxy AOH and 4-hydroxy AME). The structure-activity relationship analysis provided the structural rationale. Our results provide insights to design more efficient risk assessment studies expanding knowledge over the group toxicity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Survey of huanglongbing associated with ‘Candidatus Liberibacter’ species in Spain: analyses of citrus plants and Trioza erytreae

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Felipe SIVERIO

2017-05-01

Full Text Available The disease huanglongbing (HLB, caused by the phloem-limited and psyllid-vectored ‘Candidatus Liberibacter’ spp., is threatening the Mediterranean citrus industry. The African psyllid (Trioza erytreae vector of the pathogen was detected in Madeira (Portugal in 1994 and in the Canary Islands (Spain in 2002, and its arrival in 2014 in northwest Spain and Portugal along the Atlantic coast instigated a biological alert, and a contingency management plan was developed. Extensive surveys were conducted in Canary Islands from 2009 to 2015 and in the northwest mainland Spain (Galicia since the first detection of T. erytreae. Symptoms of the psyllid were observed in most sweet orange orchards of five islands in Canary Islands (93% of the inspected plots. In northwest mainland Spain, 65% of the inspected plots up to 2016 showed T. erytreae symptoms. During the surveys, ten leaves/tree from trees showing suspicious symptoms and from symptomless trees, as well as adult psyllids, were collected and analysed by real-time PCR using a universal ‘Ca. Liberibacter’ spp. kit, according to the EPPO standard. Suspected samples from other surveyed Spanish regions free of the vector were also analysed. The few samples that were positive in the screening test were tested by species-specific real-time PCR protocols, and they did not show amplification. These data confirm that the Spanish citrus industry is currently free of the ‘Ca. Liberibacter’ spp., but strict measures to prevent the introduction of this pathogen are required as the presence of T. erytreae increases the risk of its dissemination.

Yield loss assessment due to Alternaria blight and its management in linseed.

Science.gov (United States)

Singh, R B; Singh, H K; Parmar, Arpita

2014-04-01

Field experiments were conducted during 2010-11 and 2011-12 to assess the yield losses due to Alternaria blight disease caused by Alternaria lini and A. linicola in recently released cultivars and their management with the integration of Trichoderma viride, fungicides and plant extract. Disease severity on leaves varied from 41.07% (Parvati) to 65.01% (Chambal) while bud damage per cent ranged between 23.56% (Shekhar) to 46.12% (T-397), respectively in different cultivars. Maximum yield loss of 58.44% was recorded in cultivar Neelum followed by Parvati (55.56%), Meera (55.56%) and Chambal (51.72%), respectively while minimum loss was recorded in Kiran (19.99%) and Jeevan (22.22%). Minimum mean disease severity (19.47%) with maximum disease control (69.74%) was recorded with the treatment: seed treatment (ST) with vitavax power (2 g kg(-1) seed) + 2 foliar sprays (FS) of Saaf (a mixture of carbendazim+mancozeb) 0.2% followed by ST with Trichoderma viride (4g kg(-1) seed) + 2 FS of Saaf (0.2%). Minimum bud damage (13.75%) with maximum control (60.94%) was recorded with treatment of ST with vitavax power+2 FS of propiconazole (0.2%). Maximum mean seed yield (1440 kg ha(-1)) with maximum net return (Rs. 15352/ha) and benefit cost ratio (1:11.04) was obtained with treatment ST with vitavax power + 2 FS of Neem leaf extract followed by treatment ST with vitavax power+2 FS of Saaf (1378 kg ha(-1)).

Effect of limonene on anaerobic digestion of citrus waste and pretreatments for its improvement

OpenAIRE

RUIZ FUERTES, BEGOÑA

2016-01-01

[EN] Anaerobic digestion is a sustainable and technically sound way to valorise citrus waste if the inhibitory effect of the citrus essential oil (CEO) is controlled. Several strategies have been proposed to overcome these difficulties: keeping the organic loading rate (OLR) in low values to avoid excess dosage of inhibitor, supplementing the citrus waste with nutrient and buffering solutions or pre-treating the citrus waste in order to reduce the CEO concentration, either by recovery or by d...

The wild tomato species Solanum chilense shows variation in pathogen resistance between geographically distinct populations

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Remco Stam

2017-01-01

Full Text Available Wild tomatoes are a valuable source of disease resistance germplasm for tomato (Solanum lycopersicum breeders. Many species are known to possess a certain degree of resistance against certain pathogens; however, evolution of resistance traits is yet poorly understood. For some species, like Solanum chilense, both differences in habitat and within species genetic diversity are very large. Here we aim to investigate the occurrence of spatially heterogeneous coevolutionary pressures between populations of S. chilense. We investigate the phenotypic differences in disease resistance within S. chilense against three common tomato pathogens (Alternaria solani, Phytophthora infestans and a Fusarium sp. and confirm high degrees of variability in resistance properties between selected populations. Using generalised linear mixed models, we show that disease resistance does not follow the known demographic patterns of the species. Models with up to five available climatic and geographic variables are required to best describe resistance differences, confirming the complexity of factors involved in local resistance variation. We confirm that within S. chilense, resistance properties against various pathogens show a mosaic pattern and do not follow environmental patterns, indicating the strength of local pathogen pressures. Our study can form the basis for further investigations of the genetic traits involved.

The wild tomato species Solanum chilense shows variation in pathogen resistance between geographically distinct populations

Science.gov (United States)

Scheikl, Daniela; Tellier, Aurélien

2017-01-01

Wild tomatoes are a valuable source of disease resistance germplasm for tomato (Solanum lycopersicum) breeders. Many species are known to possess a certain degree of resistance against certain pathogens; however, evolution of resistance traits is yet poorly understood. For some species, like Solanum chilense, both differences in habitat and within species genetic diversity are very large. Here we aim to investigate the occurrence of spatially heterogeneous coevolutionary pressures between populations of S. chilense. We investigate the phenotypic differences in disease resistance within S. chilense against three common tomato pathogens (Alternaria solani, Phytophthora infestans and a Fusarium sp.) and confirm high degrees of variability in resistance properties between selected populations. Using generalised linear mixed models, we show that disease resistance does not follow the known demographic patterns of the species. Models with up to five available climatic and geographic variables are required to best describe resistance differences, confirming the complexity of factors involved in local resistance variation. We confirm that within S. chilense, resistance properties against various pathogens show a mosaic pattern and do not follow environmental patterns, indicating the strength of local pathogen pressures. Our study can form the basis for further investigations of the genetic traits involved. PMID:28133579

Digestion kinetics of carbohydrate fractions of citrus by-products

DEFF Research Database (Denmark)

Lashkari, Saman; Taghizadeh, Akbar

2015-01-01

The present experiment was carried out to determine the digestion kinetics of carbohydrate fractions of citrus by-products. Grapefruit pulp (GP), lemon pulp (LE), lime pulp (LI) and orange pulp (OP) were the test feed. Digestion kinetic of whole citrus by-products and neutral detergent fiber (NDF......) fraction and acid detergent fiber (ADF) fractions of citrus by-products were measured using the in vitro gas production technique. Fermentation kinetics of the neutral detergent soluble carbohydrates (NDSC) fraction and hemicelluloses were calculated using a curve subtraction. The fermentation rate...... of whole was the highest for the LE (p by-products lag time was longer for hemicellulose than other carbohydrate fractions. There was no significant difference among potential gas production (A) volumes of whole test feeds (p

Taxonomy and phylogeny of the genus citrus based on the nuclear ribosomal dna its region sequence

International Nuclear Information System (INIS)

Sun, Y.L.

2015-01-01

The genus Citrus (Aurantioideae, Rutaceae) is the sole source of the citrus fruits of commerce showing high economic values. In this study, the taxonomy and phylogeny of Citrus species is evaluated using sequence analysis of the ITS region of nrDNA. This study is based on 26 plants materials belonging to 22 Citrus species having wild, domesticated, and cultivated species. Through DNA alignment of the ITS sequence, ITS1 and ITS2 regions showed relatively high variations of sequence length and nucleotide among these Citrus species. According to previous six-tribe discrimination theory by Swingle and Reece, the grouping in our ITS phylogenetic tree reconstructed by ITS sequences was not related to tribe discrimination but species discrimination. However, the molecular analysis could provide more information on citrus taxonomy. Combined with ITS sequences of other subgenera in then true citrus fruit tree group, the ITS phylogenetic tree indicated subgenera Citrus was monophyletic and nearer to Fortunella, Poncirus, and Clymenia compared to Microcitrus and Eremocitrus. Abundant sequence variations of the ITS region shown in this study would help species identification and tribe differentiation of the genus Citrus. (author)

AN EXPLORATION OF FACTORS AFFECTING DEVELOPMENT OF CITRUS INDUSTRY IN TANZANIA: EMPIRICAL EVIDENCE FROM MUHEZA DISTRICT, TANGA REGION

Directory of Open Access Journals (Sweden)

Robert Makorere

2014-04-01

Full Text Available The paper stresses on understanding factors affecting development of citrus industry in Tanzania particularly in Muheza District, in Tanga region. Citrus fruit is one of the most important crops in Muheza District of Tanga region in Tanzania particularly in improving rural farmers’ income. The study employed institutional framework methodology. The study disclosed that the government of Tanzania has been implementing various agricultural development programmes in improving citrus fruit production as well as to enhance farmers’ income. However, yet the results reveal that the citrus farming practices in the surveyed area are not well developed. And these are because citruses are still grown under rain fed regime without any form of irrigation, citrus seedlings are produced by individual farmers locally in their backyard nurseries. There is no professional company responsible for seedling production. Also, citrus farmers’ skills in citrus husbandry practices are limited. Lastly, all citrus varieties used contain many seeds in the citrus fruits whereas the market demands seedless citrus fruits. It is therefore, recommended that the policy maker should focus on development of citrus industry in Tanzania using proper institutional framework support, which could increase growth and development of citrus production through the provision of subsides for inputs to reduce cost of production and enlightenment campaigns to improve farmer’s knowledge and technical skills on how to reach lucrative markets.

GABA Pathway Rate-Limit Citrate Degradation in Postharvest Citrus Fruit Evidence from HB Pumelo (Citrus grandis) × Fairchild (Citrus reticulata) Hybrid Population.

Science.gov (United States)

Sheng, Ling; Shen, Dandan; Yang, Wei; Zhang, Mingfei; Zeng, Yunliu; Xu, Juan; Deng, Xiuxin; Cheng, Yunjiang

2017-03-01

Organic acids are a major index of fresh fruit marketing properties. However, the genetic effects on the organic acid level in postharvest citrus fruit still remain unknown. Here, we used the fruits of about 40 lines in a hybrid population (high-acid "HB Pumelo" × low-acid "Fairchild") to analyze the organic acid metabolism of postharvest citrus fruit. A transgressive content of titratable acid (TA) was observed, which was attributed to citrate accumulation. High- and low-acid fruits (No. 130, 168 and No. 080, 181, respectively) were chosen for further study. Gene expression analysis on citrate metabolism showed that the high accumulation of citrate could be attributed to the low activity of γ-aminobutyric acid (GABA) shunt, and was partially due to the block of tricarboxylic acid (TCA) cycle by low mitochondrial aconitase (m-ACO) expression. TA level was significantly negatively correlated with weight loss in fruits during postharvest storage, implying a close relationship between organic acid and water metabolism.

Correlation of electronic monitoring and stylet pathways elucidate the role of sclerenchymatous ring as a barrier to phloem feeding on citrus leaves by Asian citrus psyllid

Science.gov (United States)

Asian citrus psyllid (ACP, Diaphorina. citri) feeding behaviors play a significant role in the transmission of the phloem-limited Candidatus Liberibacter asiaticus (CLas) bacterium that causes the economically devastating citrus greening disease. Recent studies have shown a fibrous ring of thick-wal...

Utilization of founder lines for improved Citrus biotechnology via RMCE

Science.gov (United States)

On October 1st 2011 the CRB chose to fund a unique research project, the development of citrus cultivars specifically for genetic engineering (GE). The objective of this research was to develop GE citrus ‘Founder Lines’ containing DNA sequences that will allow the precise insertion of genes for de...

(JASR) VOL. 10, No. 2, 2010 69 CITRUS FARMERS PRODUCTION

African Journals Online (AJOL)

oma

models of citrus, production of bottled citrus juice, jams and marmalades. Although a lot of work has been done in development of improved technologies for ..... Acta. Horticulturae 123:23-27. Owoeye, T (2010) Nigeria: Training farmers will boost agricultural production. www.freshplaza.com/news_detail. Umeh, V.C, Garcia ...

Comparative Evaluation of Biochemical Changes in Tomato (Lycopersicon esculentum Mill.) Infected by Alternaria alternata and Its Toxic Metabolites (TeA, AOH, and AME).

Science.gov (United States)

Meena, Mukesh; Zehra, Andleeb; Dubey, Manish K; Aamir, Mohd; Gupta, Vijai K; Upadhyay, Ram S

2016-01-01

In the present study, we have evaluated the comparative biochemical defense response generated against Alternaria alternata and its purified toxins viz. alternariol (AOH), alternariol monomethyl ether (AME), and tenuazonic acid (TeA). The necrotic lesions developed due to treatment with toxins were almost similar as those produced by the pathogen, indicating the crucial role of these toxins in plant pathogenesis. An oxidative burst reaction characterized by the rapid and transient production of a large amount of reactive oxygen species (ROS) occurs following the pathogen infection/toxin exposure. The maximum concentration of hydrogen peroxide (H 2 O 2 ) produced was reported in the pathogen infected samples (22.2-fold) at 24 h post inoculation followed by TeA (18.2-fold), AOH (15.9-fold), and AME (14.1-fold) in treated tissues. 3,3'- Diaminobenzidine staining predicted the possible sites of H 2 O 2 accumulation while the extent of cell death was measured by Evans blue dye. The extent of lipid peroxidation and malondialdehyde (MDA) content was higher (15.8-fold) at 48 h in the sample of inoculated leaves of the pathogen when compared to control. The cellular damages were observed as increased MDA content and reduced chlorophyll. The activities of antioxidative defense enzymes increased in both the pathogen infected as well as toxin treated samples. Superoxide dismutase (SOD) activity was 5.9-fold higher at 24 h post inoculation in leaves followed by TeA (5.0-fold), AOH (4.1-fold) and AME (2.3-fold) treated leaves than control. Catalase (CAT) activity was found to be increased upto 48 h post inoculation and maximum in the pathogen challenged samples followed by other toxins. The native PAGE results showed the variations in the intensities of isozyme (SOD and CAT) bands in the pathogen infected and toxin treated samples. Ascorbate peroxidase (APx) and glutathione reductase (GR) activities followed the similar trend to scavenge the excess H 2 O 2 . The reduction in CAT

Resistance of citrus genotypes to Phyllocnitis citrella Stainton (Lepidoptera: Gracillariidae).

Science.gov (United States)

Santos, M S; Vendramim, J D; Lourenção, A L; Pitta, R M; Martins, E S

2011-01-01

The development and reproduction of the citrus leafminer (CLM), Phyllocnistis citrella Stainton, were evaluated in six citrus genotypes in order to identify genotypes with resistance traits that could be applied in a program for the development of citrus varieties resistant to the citrus leafminer. Tests were conducted under controlled laboratory conditions (25 ± 1ºC, 70 ± 10% RH, and 14h photophase). Seedlings of each genotype tested were infested with eggs obtained from a stock colony of CLM maintained on 'Cravo' lemon (Citrus limonia L. Osbeck), and the duration and survival of the eggs, larval and pupal stages, pupal size and weight, fecundity and longevity of adults, and sex ratio were evaluated. No influence was observed on the duration and survival of eggs, larvae and pupae of P. citrella. However, pupae obtained in the hybrid C x R(4) were significantly smaller and lighter than pupae from the remaining treatments. Adult females from the hybrids C x R(4) and C x R(315) were the least fecund. However, the lowest value for the corrected reproductive potential (CRP) was recorded in the hybrid C x R(315), suggesting that this genotype is the least favorable for the development and reproduction of CLM. On the other hand, the highest CRP value obtained in the 'Rugoso' lemon confirms the susceptibility of this genotype, indicating it as the most suitable for CLM.

7 CFR 301.75-17 - Funds for the replacement of certified citrus nursery stock.

Science.gov (United States)

2010-01-01

... 7 Agriculture 5 2010-01-01 2010-01-01 false Funds for the replacement of certified citrus nursery... nursery stock. Subject to the availability of appropriated funds, a commercial citrus nursery may be eligible to receive funds to replace certified citrus nursery stock in accordance with the provisions of...

Detection of mechanical and disease stresses in citrus plants by fluorescence spectroscopy

Science.gov (United States)

Belasque, J., Jr.; Gasparoto, M. C. G.; Marcassa, L. G.

2008-04-01

We have investigated the detection of mechanical and disease stresses in citrus plants (Citrus limonia [L.] Osbeck) using laser-induced fluorescence spectroscopy. Due to its economic importance we have chosen to investigate the citrus canker disease, which is caused by the Xanthomonas axonopodis pv. citri bacteria. Mechanical stress was also studied because it plays an important role in the plant's infection by such bacteria. A laser-induced fluorescence spectroscopy system, composed of a spectrometer and a 532 nm10 mW excitation laser was used to perform fluorescence spectroscopy. The ratio of two chlorophyll fluorescence bands allows us to detect and discriminate between mechanical and disease stresses. This ability to discriminate may have an important application in the field to detect citrus canker infected trees.

Innate and Conditioned Responses to Chemosensory and Visual Cues in Asian Citrus Psyllid, Diaphorina citri (Hemiptera: Liviidae, Vector of Huanglongbing Pathogens

Directory of Open Access Journals (Sweden)

Joseph M. Patt

2014-11-01

Full Text Available Asian citrus psyllid (Diaphorina citri transmits Huanglongbing, a devastating disease that threatens citrus trees worldwide. A better understanding of the psyllid’s host-plant selection process may lead to the development of more efficient means of monitoring it and predicting its movements. Since behavioral adaptations, such as associative learning, may facilitate recognition of suitable host-plants, we examined whether adult D. citri could be conditioned to visual and chemosensory stimuli from host and non-host-plant sources. Response was measured as the frequency of salivary sheaths, the residue of psyllid probing activity, in a line of emulsified wax on the surface of a test arena. The psyllids displayed both appetitive and aversive conditioning to two different chemosensory stimuli. They could also be conditioned to recognize a blue-colored probing substrate and their response to neutral visual cues was enhanced by chemosensory stimuli. Conditioned psyllids were sensitive to the proportion of chemosensory components present in binary mixtures. Naïve psyllids displayed strong to moderate innate biases to several of the test compounds. While innate responses are probably the psyllid’s primary behavioral mechanism for selecting host-plants, conditioning may enhance its ability to select host-plants during seasonal transitions and dispersal.

DNA Barcode Reference Library for the African Citrus Triozid, Trioza erytreae (Hemiptera: Triozidae): Vector of African Citrus Greening.

Science.gov (United States)

Khamis, F M; Rwomushana, I; Ombura, L O; Cook, G; Mohamed, S A; Tanga, C M; Nderitu, P W; Borgemeister, C; Sétamou, M; Grout, T G; Ekesi, S

2017-12-05

Citrus (Citrus spp.) production continues to decline in East Africa, particularly in Kenya and Tanzania, the two major producers in the region. This decline is attributed to pests and diseases including infestation by the African citrus triozid, Trioza erytreae (Del Guercio) (Hemiptera: Triozidae). Besides direct feeding damage by adults and immature stages, T. erytreae is the main vector of 'Candidatus Liberibacter africanus', the causative agent of Greening disease in Africa, closely related to Huanglongbing. This study aimed to generate a novel barcode reference library for T. erytreae in order to use DNA barcoding as a rapid tool for accurate identification of the pest to aid phytosanitary measures. Triozid samples were collected from citrus orchards in Kenya, Tanzania, and South Africa and from alternative host plants. Sequences generated from populations in the study showed very low variability within acceptable ranges of species. All samples analyzed were linked to T. erytreae of GenBank accession number KU517195. Phylogeny of samples in this study and other Trioza reference species was inferred using the Maximum Likelihood method. The phylogenetic tree was paraphyletic with two distinct branches. The first branch had two clusters: 1) cluster of all populations analyzed with GenBank accession of T. erytreae and 2) cluster of all the other GenBank accession of Trioza species analyzed except T. incrustata Percy, 2016 (KT588307.1), T. eugeniae Froggatt (KY294637.1), and T. grallata Percy, 2016 (KT588308.1) that occupied the second branch as outgroups forming sister clade relationships. These results were further substantiated with genetic distance values and principal component analyses. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America.

Transcriptional Responses of the Bdtf1-Deletion Mutant to the Phytoalexin Brassinin in the Necrotrophic Fungus Alternaria brassicicola

Directory of Open Access Journals (Sweden)

Yangrae Cho

2014-07-01

Full Text Available Brassica species produce the antifungal indolyl compounds brassinin and its derivatives, during microbial infection. The fungal pathogen Alternaria brassicicola detoxifies brassinin and possibly its derivatives. This ability is an important property for the successful infection of brassicaceous plants. Previously, we identified a transcription factor, Bdtf1, essential for the detoxification of brassinin and full virulence. To discover genes that encode putative brassinin-digesting enzymes, we compared gene expression profiles between a mutant strain of the transcription factor and wild-type A. brassicicola under two different experimental conditions. A total of 170 and 388 genes were expressed at higher levels in the mutants than the wild type during the infection of host plants and saprophytic growth in the presence of brassinin, respectively. In contrast, 93 and 560 genes were expressed, respectively, at lower levels in the mutant than the wild type under the two conditions. Fifteen of these genes were expressed at lower levels in the mutant than in the wild type under both conditions. These genes were assumed to be important for the detoxification of brassinin and included Bdtf1 and 10 putative enzymes. This list of genes provides a resource for the discovery of enzyme-coding genes important in the chemical modification of brassinin.

Exploiting fruit byproducts for eco-friendly nanosynthesis: Citrus × clementina peel extract mediated fabrication of silver nanoparticles with high efficacy against microbial pathogens and rat glial tumor C6 cells.

Science.gov (United States)

Saratale, Rijuta Ganesh; Shin, Han-Seung; Kumar, Gopalakrishnan; Benelli, Giovanni; Ghodake, Gajanan S; Jiang, Yuan Yuan; Kim, Dong Su; Saratale, Ganesh Dattatraya

2018-04-01

Process byproducts from the fruit industry may represent a cheap and reliable source of green reducing agents to be used in current bio-nanosynthesis. This study reports the use of orange (Citrus × clementina) peel aqueous extract (OPE) for one-pot green synthesis of silver nanoparticles (AgNPs) with high effectiveness against various microbial pathogens as well as rat glial tumor C6 cells. The effects of various operational parameters on the synthesis of AgNPs were systematically investigated. The morphology, particle size, and properties of synthesized AgNPs were characterized using UV-visible spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy, field emission scanning electron microscopy, energy-dispersive x-ray spectroscopy, and Fourier transform infrared spectroscopy. High-resolution transmission electron microscopy shows that the nanoparticles are mostly spherical in shape and monodispersed, with an average particle size of 15-20 nm. Notably, the OPE-synthesized AgNPs were stable up to 6 months without change in their properties. Low doses of OPE-AgNPs inhibited the growth of human pathogens Escherichia coli, Bacillus cereus, and Staphylococcus aureus. The minimum inhibitory concentration and minimum bactericidal concentration of AgNPs against selected pathogenic bacteria were determined. OPE-AgNPs exhibited strong antioxidant activity in terms of ABTS (2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) radical scavenging (IC 50 49.6 μg/mL) and DPPH (1,1-diphenyl-2-picrylhydrazyl) radical scavenging (IC 50 63.4 μg/mL). OPE-AgNPs showed dose-dependent response against rat glial tumor C6 cells (LD 50 60 μg/mL) showing a promising potential as anticancer agents. Overall, the current investigation highlighted a cheap green technology route to synthesize AgNPs using OPE byproducts and could potentially be utilized in biomedical, cosmetic, and pharmaceutical industry.

In vitro pollen germination of five citrus species

International Nuclear Information System (INIS)

Khan, S.A.; Perveen, A.

2014-01-01

The aim of present study is In vitro germination of the pollen grains of five Citrus species belonging to the family Rutaceae viz., Citrus aurantium L. var., aurantium Hook.f., C. limon (L.) Brum. f., C. paradisii Macfad, C. reticulata Blanco and C. sinensis (L.) Osbeck. using hanging drop technique. The germination was checked up to 48 weeks, for the pollen stored at different temperatures like 4 degree C, -20 degree C, -30 degree C and -60 degree C. The study indicates that low temperature and low relative humidity is better than high temperature and humidity with respect to pollen germination capacity and viability. Freeze dryer (-60 degree C) seems to be the best method to maintain pollen viability of stored pollen grains for a long period of time. Among five species Citrus aurantium, C. limon and C. sinensis showed high percentage of germination as compared to C. reticulata and C. paradisii. (author)

Exposure to Guava Affects Citrus Olfactory Cues and Attractiveness to Diaphorina citri (Hemiptera: Psyllidae).

Science.gov (United States)

Barman, Jagadish Chandra; Campbell, Stuart A; Zeng, Xinnian

2016-06-01

Intercropping can reduce agricultural pest incidence, and represents an important sustainable alternative to conventional pest control methods. Understanding the ecological mechanisms for intercropping could help optimize its use, particularly in tropical systems which present a large number of intercropping possibilities. Citrus is threatened worldwide by greening disease (huanglongbing, HLB) vectored by the Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae). Control of HLB and citrus psyllid can be partially achieved through intercropping with guava, Psidium guajava L., but the mechanisms remain unclear. We tested the hypothesis that guava olfactory cues affect psyllid behavior by altering the attractiveness of citrus through plant-plant interactions. In choice and no-choice cage experiments, psyllid settlement was reduced on citrus shoots that had been exposed to guava shoot odors for at least 2 h. In Y-tube olfactometer experiments, psyllids oriented to odors of unexposed, compared with guava-exposed, citrus shoots. These behavioral results indicate that a mechanism for the success of guava intercropping for sustainable, ecological disease management may be the indirect effect of guava on citrus attractiveness. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

7 CFR 905.149 - Procedure for permitting growers to ship tree run citrus fruit.

Science.gov (United States)

2010-01-01

... Fruit § 905.149 Procedure for permitting growers to ship tree run citrus fruit. (a) Tree run citrus fruit. Tree run citrus fruit as referenced in this section is defined in the Florida Department of... grower shall apply to ship tree run fruit using a Grower Tree Run Certificate Application, furnished by...

A new perylenequinone from a halotolerant fungus, Alternaria sp. M6.

Science.gov (United States)

Zhang, Song-Ya; Li, Zhan-Lin; Bai, Jiao; Wang, Yu; Zhang, Li-Min; Wu, Xin; Hua, Hui-Ming

2012-01-01

To study the metabolites of a halotolerant fungus Alternaria sp. M6. The metabolites were isolated and purified by various chromatographic techniques. Their structures were determined on the basis of physical properties and spectroscopic data. Nine compounds were isolated and identified as 8β-chloro-3, 6aα, 7β, 9β, 10-pentahydroxy-9, 8, 7, 6a-tetrahydroperylen-4(6aH)-one (1), alterperylenol (2), dihydroalterperylenol (3), adenine (4), adenosine (5), deoxyadenosine (6), guanosine (7), tryptophan (8), and hexadecanoic acid (9). Compound 1 is a new perylenequinone. Copyright © 2012 China Pharmaceutical University. Published by Elsevier B.V. All rights reserved.

Land cover classification of VHR airborne images for citrus grove identification

Science.gov (United States)

Amorós López, J.; Izquierdo Verdiguier, E.; Gómez Chova, L.; Muñoz Marí, J.; Rodríguez Barreiro, J. Z.; Camps Valls, G.; Calpe Maravilla, J.

Managing land resources using remote sensing techniques is becoming a common practice. However, data analysis procedures should satisfy the high accuracy levels demanded by users (public or private companies and governments) in order to be extensively used. This paper presents a multi-stage classification scheme to update the citrus Geographical Information System (GIS) of the Comunidad Valenciana region (Spain). Spain is the first citrus fruit producer in Europe and the fourth in the world. In particular, citrus fruits represent 67% of the agricultural production in this region, with a total production of 4.24 million tons (campaign 2006-2007). The citrus GIS inventory, created in 2001, needs to be regularly updated in order to monitor changes quickly enough, and allow appropriate policy making and citrus production forecasting. Automatic methods are proposed in this work to facilitate this update, whose processing scheme is summarized as follows. First, an object-oriented feature extraction process is carried out for each cadastral parcel from very high spatial resolution aerial images (0.5 m). Next, several automatic classifiers (decision trees, artificial neural networks, and support vector machines) are trained and combined to improve the final classification accuracy. Finally, the citrus GIS is automatically updated if a high enough level of confidence, based on the agreement between classifiers, is achieved. This is the case for 85% of the parcels and accuracy results exceed 94%. The remaining parcels are classified by expert photo-interpreters in order to guarantee the high accuracy demanded by policy makers.

A new modified resource budget model for nonlinear dynamics in citrus production

International Nuclear Information System (INIS)

Ye, Xujun; Sakai, Kenshi

2016-01-01

Highlights: • A theoretical modeling and simulation study of the nonlinear dynamics in citrus is conducted. • New leaf growth is incorporated into the model as a major factor responsible for the yield oscillations. • A Ricker-type equation for the relationship between costs for flowering and fruiting is proposed. • A generic form of the resource budget model for the nonlinear dynamics in citrus is obtained. • The new model is tested with experimental data for two citrus trees. - Abstract : Alternate bearing or masting is a general yield variability phenomenon in perennial tree crops. This paper first presents a theoretical modeling and simulation study of the mechanism for this dynamics in citrus, and then provides a test of the proposed models using data from a previous 16-year experiment in a citrus orchard. Our previous studies suggest that the mutual effects between vegetative and reproductive growths caused by resource allocation and budgeting in plant body might be considered as a major factor responsible for the yield oscillations in citrus. Based on the resource budget model proposed by Isagi et al. (J Theor Biol. 1997;187:231-9), we first introduce the new leaf growth as a major energy consumption component into the model. Further, we introduce a nonlinear Ricker-type equation to replace the linear relationship between costs for flowering and fruiting used in Isagi's model. Model simulations demonstrate that the proposed new models can successfully simulate the reproductive behaviors of citrus trees with different fruiting dynamics. These results may enrich the mechanical dynamics in tree crop reproductive models and help us to better understand the dynamics of vegetative-reproductive growth interactions in a real environment.

Antimicrobial activities of Streptomyces pulcher, S. canescens and S. citreofluorescens against fungal and bacterial pathogens of tomato in vitro.

Science.gov (United States)

el-Abyad, M S; el-Sayed, M A; el-Shanshoury, A R; el-Sabbagh, S M

1996-01-01

Thirty-seven actinomycete species isolated from fertile cultivated soils in Egypt were screened for the production of antimicrobial compounds against a variety of test organisms. Most of the isolates exhibited antimicrobial activities against Gram-positive, Gram-negative, and acid-fast bacteria, yeasts and filamentous fungi, with special attention to fungal and bacterial pathogens of tomato. On starch-nitrate agar, 14 strains were active against Fusarium oxysporum f.sp. lycopersici (the cause of Fusarium wilt), 18 against Verticillium albo-atrum (the cause of Verticillium wilt), and 18 against Alternaria solani (the cause of early blight). In liquid media, 14 isolates antagonized Pseudomonas solanacearum (the cause of bacterial wilt) and 20 antagonized Clavibacter michiganensis ssp. michiganensis (the cause of bacterial canker). The most active antagonists of the pathogenic microorganisms studied were found to be Streptomyces pulcher, S. canescens (syn. S. albidoflavus) and S. citreofluorescens (syn. S. anulatus). The antagonistic activities of S. pulcher and S. canescens against pathogenic fungi were assessed on solid media, and those of S. pulcher and S. citreofluorescens against pathogenic bacteria in liquid media under shaking conditions. The optimum culture conditions were determined.

Carcass characteristics and meat quality of heavy swine fed different citrus pulp levels

Directory of Open Access Journals (Sweden)

P.H. Watanabe

2010-08-01

Full Text Available An assay with 36 swine initially weighting 83.7±5.1kg body weight (BW was carried out to evaluate the effects of the use of different dietary citrus pulp levels, 0, 10%, 20%, and 30%, upon digestive organs weights, carcass characteristics, and meat quality of animals subjected to qualitative feed restriction program, and slaughtered at 130kg BW. Linear response (P0.05. Higher levels of citrus pulp neither decreased backfat thickness nor increased amount of lean meat, indicative that qualitative feed restriction was not efficient. Positive linear effect (P<0.05 on pH measured 24 hours after slaughter and negative linear effect (P<0.05 on color characteristics as function of citrus pulp dietary levels were verified. Citrus pulp addition in qualitative feed restriction program may not be effective. As no deleterious effects upon meat qualities were observed, citrus pulp can be used as an alternative feedstuff for finishing swine.