Publications by authors named "Dov Prusky"

60 Publications

Regulates Differentiation of Infection Structures Induced by Physicochemical Signals From Pear Fruit Cuticular Wax, Secondary Metabolism, and Pathogenicity of .

Front Plant Sci 2021 21;12:642601. Epub 2021 Apr 21.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China.

, the casual agent of black rot of pear fruit, can sense and respond to the physicochemical cues from the host surface and form infection structures during infection. To evaluate the role of cyclic AMP-dependent protein kinase (cAMP-PKA) signaling in surface sensing of , we isolated and functionally characterized the cyclic adenosine monophosphate-dependent protein kinase A catalytic subunit gene (). Gene expression results showed that was strongly expressed during the early stages of appressorium formation on hydrophobic surfaces. Knockout mutants Δ were generated by replacing the target genes via homologous recombination events. We found that intracellular cAMP content increased but PKA content decreased in Δ mutant strain. Appressorium formation and infection hyphae were reduced in the Δ mutant strain, and the ability of the Δ mutant strain to recognize and respond to high hydrophobicity surfaces and different surface waxes was lower than in the wild type (WT) strain. In comparison with the WT strain, the appressorium formation rate of the Δ mutant strain on high hydrophobicity and fruit wax extract surface was reduced by 31.6 and 49.3% 4 h after incubation, respectively. In addition, is required for the hypha growth, biomass, pathogenicity, and toxin production of . However, negatively regulated conidia formation, melanin production, and osmotic stress resistance. Collectively, is required for pre-penetration, developmental, physiological, and pathological processes in
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http://dx.doi.org/10.3389/fpls.2021.642601DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8096925PMC
April 2021

The Effect of Environmental pH during (Pers.:Fr.) Link Inoculation of Apple Fruits on the Host Differential Reactive Oxygen Species Metabolism.

Antioxidants (Basel) 2021 Apr 28;10(5). Epub 2021 Apr 28.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China.

is an important postharvest pathogen, belonging to an alkalizing group of pathogens secreting ammonia during fungal growth and colonization of apple fruits. Fungal pH modulation is usually considered a factor for improving fungal gene expression, contributing to its pathogenicity. However, the effects of inoculation with spore suspensions at increasing pH levels from pH 3 up to pH 7, on the reactive oxygen species (ROS) production and scavenging capability of the apple fruits, affecting host susceptibility, indicate that the pH regulation by the pathogens also affects host response and may contribute to colonization. The present results indicate that the inoculation of spores at pH 3 caused the lowest cell membrane permeability, and reduced malondialdehyde content, NADPH oxidases activity, O and HO production in the colonized fruit. Observations of the colonized area on the 9th day after inoculation at pH 3, showed that the rate of O production and HO content was reduced by 57% and 25%, compared to their activities at pH 7. In contrast, antioxidative activities of superoxide dismutase, catalase and peroxidases of fruit tissue inoculated with spores' suspension in the presence of a solution at pH 3.0 showed their highest activity. The catalase and peroxidases activities in the colonized tissue at pH 3 were higher by almost 58% and 55.9%, respectively, on the 6th day after inoculation compared to inoculation at pH 7. The activities of key enzymes of the ascorbate-glutathione (AsA-GSH) cycle and their substrates and products by the 9th day after fruit inoculation at pH 3 showed 150%, 31%, 16%, and 110% higher activities of ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase and glutathione reductase, respectively, compared to pH 7. A similar pattern of response was also observed in the accumulation of ascorbic acid and dehydroascorbate which showed a higher accumulation at pH 3 compared to the colonization at pH 7. The present results indicate that the metabolic regulation of the pH environment by the not only modulates the fungal pathogenicity factors reported before, but it induces metabolic host changes contributing both together to fungal colonization.
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http://dx.doi.org/10.3390/antiox10050692DOI Listing
April 2021

Special Issue "Interplay between Fungal Pathogens and Harvested Crops and Fruits".

Microorganisms 2021 Mar 8;9(3). Epub 2021 Mar 8.

Department of Food Sciences, Institute of Postharvest and Food Sciences, Agricultural Research Organization-The Volcani Center, Rishon LeZion 7505101, Israel.

The interplay between fungal pathogens and harvest crops is important in determining the extent of food losses following the storage and transport of crops to consumers. The specific factors modulating the activation of colonization are of key importance to determining the initiation of fungal colonization and host losses. It is clear nowadays from the wide number of transcription studies in colonized fruits that pathogenicity in postharvest produce is not only the result of activation of fungal pathogenicity factors but is significantly contributed to fruit maturity and ripening. In this editorial summary of the Special Issue "Interplay between Fungal Pathogens and Harvested Crops and Fruits", we present a short summary of future research directions on the importance of the interplay between fruit and pathogens and nine published papers (one review and eight original research papers), covering a wide range of subjects within the mechanism of pathogenicity by postharvest pathogens, including transcriptome analysis of pathogenesis, pathogenicity factors, new antifungal compounds and food toxin occurrence by pathogens. This summary may lead the reader to understand the key factors modulating pathogenicity in fruits.
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http://dx.doi.org/10.3390/microorganisms9030553DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7998692PMC
March 2021

Host Factors Modulating Ochratoxin A Biosynthesis during Fruit Colonization by .

J Fungi (Basel) 2020 Dec 28;7(1). Epub 2020 Dec 28.

Institute of Postharvest and Food Sciences, The Volcani Center, Agricultural Research Organization, Rishon LeZion 7528809, Israel.

is a strong and consistent ochratoxin A (OTA) producer and considered to be the main source of this toxic metabolite in grapes and grape products such as wine, grape juice and dried vine fruit. OTA is produced under certain growth conditions and its accumulation is affected by several environmental factors, such as growth phase, substrate, temperature, water activity and pH. In this study, we examined the impact of fruit host factors on regulation and accumulation of OTA in colonized grape berries, and assessed in vitro the impact of those factors on the transcriptional levels of the key genes and global regulators contributing to fungal colonization and mycotoxin synthesis. We found that limited sugar content, low pH levels and high malic acid concentrations activated OTA biosynthesis by , both in synthetic media and during fruit colonization, through modulation of global regulator of secondary metabolism, and OTA gene cluster expression. These findings indicate that fruit host factors may have a significant impact on the capability of to produce and accumulate OTA in grapes.
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http://dx.doi.org/10.3390/jof7010010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7823970PMC
December 2020

Functional roles of LaeA, polyketide synthase, and glucose oxidase in the regulation of ochratoxin A biosynthesis and virulence in Aspergillus carbonarius.

Mol Plant Pathol 2021 01 10;22(1):117-129. Epub 2020 Nov 10.

Institute of Postharvest and Food Sciences, The Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel.

Aspergillus carbonarius is the major producer of ochratoxin A (OTA) among Aspergillus species, but the contribution of this secondary metabolite to fungal virulence has not been assessed. We characterized the functions and addressed the roles of three factors in the regulation of OTA synthesis and pathogenicity in A. carbonarius: LaeA, a transcriptional factor regulating the production of secondary metabolites; polyketide synthase, required for OTA biosynthesis; and glucose oxidase (GOX), regulating gluconic acid (GLA) accumulation and acidification of the host tissue during fungal growth. Deletion of laeA in A. carbonarius resulted in significantly reduced OTA production in colonized nectarines and grapes. The ∆laeA mutant was unable to efficiently acidify the colonized tissue, as a direct result of diminished GLA production, leading to attenuated virulence in infected fruit compared to the wild type (WT). The designed Acpks-knockout mutant resulted in complete inhibition of OTA production in vitro and in colonized fruit. Interestingly, physiological analysis revealed that the colonization pattern of the ∆Acpks mutant was similar to that of the WT strain, with high production of GLA in the colonized tissue, suggesting that OTA accumulation does not contribute to A. carbonarius pathogenicity. Disruption of the Acgox gene inactivated GLA production in A. carbonarius, and this mutant showed attenuated virulence in infected fruit compared to the WT strain. These data identify the global regulator LaeA and GOX as critical factors modulating A. carbonarius pathogenicity by controlling transcription of genes important for fungal secondary metabolism and infection.
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http://dx.doi.org/10.1111/mpp.13013DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7749749PMC
January 2021

Modification performance and electrochemical characteristics of different groups of modified aptamers applied for label-free electrochemical impedimetric sensors.

Food Chem 2021 Feb 4;337:127761. Epub 2020 Aug 4.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, PR China; Department of Postharvest Science of Fresh Produce, the Volcani Center, Agricultural Research Organization, Bet Dagan 50250, Israel.

Amino and thiolated aptamers are the main aptamers used to construct label-free electrochemical impedimetric aptasensors. In this study, the modification performance and electrochemical properties of amino aptamers and thiolated aptamers were studied in the construction of label-free impedimetric sensors. The results showed that the initial modification density of amino aptamers was higher than that of thiol aptamers. Aptamers can recognize and bind OTA to generate electrical signals. The higher the density of aptamer modification was, the better the electric signals were. If only considering the initial modification density, amino aptamers were more suitable for the preparation of aptasensors than thiolated aptamers. However, the modification density of the amino aptamer decreased with the prolonged immersion time in 1 mM HCl solution, which suggests that the stability of this sensor was poor. However, the thiolated aptamer maintained relatively constant density and could be reused. Thus, the thiolated aptasensor had a wide range and good reproducibility and stability for the determination of ochratoxin A (OTA). In addition, this study proved that gold nanoparticles play an important role in signal amplification by increasing the effective gold surface to fix more aptamers in the process of sensor preparation.
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http://dx.doi.org/10.1016/j.foodchem.2020.127761DOI Listing
February 2021

Phospholipase C From Is Induced by Physiochemical Cues on the Pear Fruit Surface That Dictate Infection Structure Differentiation and Pathogenicity.

Front Microbiol 2020 30;11:1279. Epub 2020 Jun 30.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China.

To investigate the mechanisms of phospholipase C (PLC)-mediated calcium (Ca) signaling in , the regulatory roles of PLC were elucidated using neomycin, a specific inhibitor of PLC activity. Three isotypes of PLC designated , , and were identified in through genome sequencing. qRT-PCR analysis showed that fruit wax extracts significantly upregulated the expression of all three PLC genes . Pharmacological experiments showed that neomycin treatment led to a dose-dependent reduction in spore germination and appressorium formation in . Appressorium formation was stimulated on hydrophobic and pear wax-coated surfaces but was significantly inhibited by neomycin treatment. The appressorium formation rates of neomycin treated on hydrophobic and wax-coated surfaces decreased by 86.6 and 47.4%, respectively. After 4 h of treatment, exogenous CaCl could partially reverse the effects of neomycin treatment. Neomycin also affected mycotoxin production in alternariol (AOH), alternariol monomethyl ether (AME), altenuene (ALT), and tentoxin (TEN), with exogenous Ca partially reversing these effects. These results suggest that PLC is required for the growth, infection structure differentiation, and secondary metabolism of in response to physiochemical signals on the pear fruit surface.
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http://dx.doi.org/10.3389/fmicb.2020.01279DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7339947PMC
June 2020

Characterization of the Role of a Non-GPCR Membrane-Bound CFEM Protein in the Pathogenicity and Germination of .

Microorganisms 2020 Jul 14;8(7). Epub 2020 Jul 14.

Department of Vegetable and Field Crops, Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion 7505101, Israel.

The necrotrophic fungus , is considered a major cause of postharvest losses in a wide range of crops. The common fungal extracellular membrane protein (CFEM), containing a conserved eight-cysteine pattern, was found exclusively in fungi. Previous studies in phytopathogenic fungi have demonstrated the role of membrane-bound and secreted CFEM-containing proteins in different aspects of fungal virulence. However, non-G protein-coupled receptor (non-GPCR) membrane CFEM proteins have not been studied yet in phytopathogenic fungi. In the present study, we have identified a non-GPCR membrane-bound CFEM-containing protein, Bcin07g03260, in the genome, and generated deletion mutants, ΔCFEM-, to study its potential role in physiology and virulence. Three independent ΔCFEM- mutants showed significantly reduced progression of a necrotic lesion on tomato () leaves. Further analysis of the mutants revealed significant reduction (approximately 20-30%) in conidial germination and consequent germ tube elongation compared with the WT. Our data complements a previous study of secreted Δ mutants of that showed reduced progression of necrotic lesions on leaves, without effect on germination. Considering various functions identified for CFEM proteins in fungal virulence, our work illustrates a potential new role for a non-GPCR membrane CFEM in pathogenic fungi to control virulence in the fungus .
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http://dx.doi.org/10.3390/microorganisms8071043DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7409268PMC
July 2020

Transcriptome Profiling Data of Infection on Whole Plant .

Mol Plant Microbe Interact 2020 Sep 28;33(9):1103-1107. Epub 2020 Jul 28.

Department of Vegetable Research, Institute of Plant Sciences, Agricultural Research Organization, Volcani Center, 68 HaMaccabim Road, P.O. Box 15159, Rishon LeZion 7505101, Israel.

is a foliar necrotrophic fungal-pathogen capable of infecting >580 genera of plants, is often used as model organism for studying fungal-host interactions. We used RNAseq to study transcriptome of infection on a major (worldwide) vegetable crop, tomato (). Most previous works explored only few infection stages, using RNA extracted from entire leaf-organ diluting the expression of studied infected region. Many studied infection, on detached organs assuming that similar defense/physiological reactions occurs in the intact plant. We analyzed transcriptome of the pathogen and host in 5 infection stages of whole-plant leaves at the infection site. We supply high quality, pathogen-enriched gene count that facilitates future research of the molecular processes regulating the infection process.
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http://dx.doi.org/10.1094/MPMI-05-20-0109-ADOI Listing
September 2020

New Insight Into Pathogenicity and Secondary Metabolism of the Plant Pathogen Through Deletion of the Epigenetic Reader SntB.

Front Microbiol 2020 9;11:610. Epub 2020 Apr 9.

Department of Medical Microbiology and Immunology, University of Wisconsin - Madison, Madison, WI, United States.

is one of the most harmful post-harvest pathogens of pomaceous fruits and the causal agent of blue rot disease. During infection, produces the toxic secondary metabolites patulin and citrinin that can impact virulence and, further, render the fruit inedible. Several studies have shown that epigenetic machinery controls synthesis of secondary metabolites in fungi. In this regard, the epigenetic reader, SntB, has been reported to govern the production of multiple toxins in species, and impact virulence of plant pathogenic fungi. Here we show that deletion of in results in several phenotypic changes in the fungus including stunted vegetative growth, reduced conidiation, but enhanced germination rates as well as decreased virulence on Golden Delicious apples. In addition, a decrease in both patulin and citrinin biosynthesis and patulin in apples, was observed. SntB positively regulates expression of three global regulators of virulence and secondary metabolism (LaeA, CreA, and PacC) which may explain in part some of the phenotypic and virulence defects of the PeΔ strain. Lastly, results from this study revealed that the controlled environmental factors (low temperatures and high CO levels) to which is commonly exposed during fruit storage, resulted in a significant reduction of expression and consequent patulin and citrinin reduction. These data identify the epigenetic reader SntB as critical factor regulated in post-harvest pathogens under storage conditions and a potential target to control fungal colonization and decaying of stored fruit.
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http://dx.doi.org/10.3389/fmicb.2020.00610DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7160234PMC
April 2020

Sugar-regulated susceptibility of tomato fruit to Colletotrichum and Penicillium requires differential mechanisms of pathogenicity and fruit responses.

Environ Microbiol 2020 07 29;22(7):2870-2891. Epub 2020 Apr 29.

Department of Postharvest Science, Agricultural Research Organization, The Volcani Center, Rishon LeZion, 7505101, Israel.

Colletotrichum gloeosporioides and Penicillium expansum cause postharvest diseases in tropical and deciduous fruit. During colonization, C. gloeosporioides and P. expansum secrete ammonia in hosts with low sugar content (LowSC) and gluconic acid in hosts with high sugar content (HighSC), respectively, as a mechanism to modulate enhanced pathogenicity. We studied the pathogens interactions with tomato lines of similar genetic background but differing in their sugar content. Colletotrichum gloeosporioides showed enhanced colonization of the LowSC line with differential expression response of 15% of its genes including enhanced relative expression of glycosyl hydrolases, glucanase and MFS-transporter genes. Enhanced colonization of P. expansum occurred in the HighSC line, accompanied by an increase in carbohydrate metabolic processes mainly phosphoenolpyruvate carboxykinase, and only 4% of differentially expressed genes. Gene response of the two host lines strongly differed depending on the sugar level. Limited colonization of HighSC line by C. gloeosporioides was accompanied by a marked alteration of gene expression compared the LowSC response to the same pathogen; while colonization by P. expansum resulted in a similar response of the two different hosts. We suggest that this differential pattern of fungal/host responses may be the basis for the differential of host range of both pathogens in nature.
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http://dx.doi.org/10.1111/1462-2920.15031DOI Listing
July 2020

Editorial: Interplay Between Fungal Pathogens and Fruit Ripening.

Front Plant Sci 2020 24;11:275. Epub 2020 Mar 24.

Laboratory of Plant Pathology and Biotechnology, DISTAL- Alma Mater Studiorum University of Bologna, Bologna, Italy.

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http://dx.doi.org/10.3389/fpls.2020.00275DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7109395PMC
March 2020

The pH-Responsive Transcription Factor PacC Governs Pathogenicity and Ochratoxin A Biosynthesis in .

Front Microbiol 2020 13;11:210. Epub 2020 Feb 13.

Institute of Postharvest and Food Sciences, Agricultural Research Organization, Volcani Center, Rishon LeZion, Israel.

Pathogenic fungi must respond effectively to changes in environmental pH for successful host colonization, virulence and toxin production. is a mycotoxigenic pathogen with the ability to colonize many plant hosts and secrete ochratoxin A (OTA). In this study, we characterized the functions and addressed the role of PacC-mediated pH signaling in pathogenicity using designed gene knockout mutant. Δ mutant displayed an acidity-mimicking phenotype, which resulted in impaired fungal growth at neutral/alkaline pH, accompanied by reduced sporulation and conidial germination compared to the wild type (WT) strain. The Δ mutant was unable to efficiently acidify the growth media as a direct result of diminished gluconic and citric acid production. Furthermore, loss of resulted in a complete inhibition of OTA production at pH 7.0. Additionally, Δ mutant exhibited attenuated virulence compared to the WT toward grapes and nectarine fruits. Reintroduction of gene into Δ mutant restored the WT phenotype. Our results demonstrate important roles of PacC of in OTA biosynthesis and in pathogenicity by controlling transcription of genes important for fungal secondary metabolism and infection.
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http://dx.doi.org/10.3389/fmicb.2020.00210DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7031272PMC
February 2020

Mechanism of Ca-mediated NOX modulated in ROS metabolism induced by T-2 toxin in potato tuber.

Food Chem 2020 Jul 14;317:126416. Epub 2020 Feb 14.

College of Science, Gansu Agricultural University, Lanzhou 730070, PR China.

T-2 toxin at low concentrations can induce ROS accumulation and modulate host resistance in plants. NOX plays crucial roles in ROS production and is regulated by Cavia direct binding to EF-hand motifs. In this study, the effect of EGTA (Ca chelating agent) on the expression and enzymatic activity of NOX, as well as the activities and corresponding gene expressions involved in ROS metabolism and cell membrane integrity, were investigated in treated slices. Results indicated that EGTA treatment significantly affected gene expression and activity of NOX, and reduced ROS accumulation and cell membrane integrity and the enzymatic activities and gene expression involved in ROS metabolism when exposed to treatment. The addition of exogenous Ca restored the initial relative transcript abundance, ROS accumulation and their activities. Results suggest that Ca affected by EGTA plays a crucial role in NOX activity regulation, ultimately affecting ROS metabolism in slices induced by T-2 toxin.
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http://dx.doi.org/10.1016/j.foodchem.2020.126416DOI Listing
July 2020

Cuminal Inhibits Growth by Triggering Cell Starvation: Transcriptome and Proteome Analysis.

Microorganisms 2020 Feb 14;8(2). Epub 2020 Feb 14.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China.

is a harmful postharvest fungus causing serious damage, together with the secretion of insidious mycotoxins, on apples, melons, and other important fruits. Cuminal, a predominant component of essential oil has proven to successfully inhibit the growth of in vitro and in vivo. Electron microscopic observations revealed cuminal exposure impaired the fungal morphology and ultrastructure, particularly the plasmalemma. Transcriptome and proteome analysis was used to investigate the responses of to exposure of cuminal. In total, 2825 differentially expressed transcripts (1516 up and 1309 down) and 225 differentially expressed proteins (90 up and 135 down) were determined. Overall, notable parts of these differentially expressed genes functionally belong to subcellular localities of the membrane system and cytosol, along with ribosomes, mitochondria and peroxisomes. According to the localization analysis and the biological annotation of these genes, carbohydrate and lipids metabolism, redox homeostasis, and asexual reproduction were among the most enriched gene ontology (GO) terms. Biological pathway enrichment analysis showed that lipids and amino acid degradation, ATP-binding cassette transporters, membrane reconstitution, mRNA surveillance pathway and peroxisome were elevated, whereas secondary metabolite biosynthesis, cell cycle, and glycolysis/gluconeogenesis were down regulated. Further integrated omics analysis showed that cuminal exposure first impaired the polarity of the cytoplasmic membrane and then triggered the reconstitution and dysfunction of fungal plasmalemma, resulting in handicapped nutrient procurement of the cells. Consequently, fungal cells showed starvation stress with limited carbohydrate metabolism, resulting a metabolic shift to catabolism of the cell's own components in response to the stress. Additionally, these predicaments brought about oxidative stress, which, in collaboration with the starvation, damaged certain critical organelles such as mitochondria. Such degeneration, accompanied by energy deficiency, suppressed the biosynthesis of essential proteins and inhibited fungal growth.
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http://dx.doi.org/10.3390/microorganisms8020256DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7074788PMC
February 2020

Network analysis exposes core functions in major lifestyles of fungal and oomycete plant pathogens.

BMC Genomics 2019 Dec 26;20(1):1020. Epub 2019 Dec 26.

Department of Vegetable and Field Crops, Institute of Plant Sciences, Volcani Center, Agricultural Research Organization, Rishon LeZion, Israel.

Background: Genomic studies demonstrate that components of virulence mechanisms in filamentous eukaryotic pathogens (FEPs, fungi and oomycetes) of plants are often highly conserved, or found in gene families that include secreted hydrolytic enzymes (e.g., cellulases and proteases) and secondary metabolites (e.g., toxins), central to the pathogenicity process. However, very few large-scale genomic comparisons have utilized complete proteomes from dozens of FEPs to reveal lifestyle-associated virulence mechanisms. Providing a powerful means for exploration, and the discovery of trends in large-scale datasets, network analysis has been used to identify core functions of the primordial cyanobacteria, and ancient evolutionary signatures in oxidoreductases.

Results: We used a sequence-similarity network to study components of virulence mechanisms of major pathogenic lifestyles (necrotroph (ic), N; biotroph (ic), B; hemibiotroph (ic), H) in complete pan-proteomes of 65 FEPs and 17 saprobes. Our comparative analysis highlights approximately 190 core functions found in 70% of the genomes of these pathogenic lifestyles. Core functions were found mainly in: transport (in H, N, B cores); carbohydrate metabolism, secondary metabolite synthesis, and protease (H and N cores); nucleic acid metabolism and signal transduction (B core); and amino acid metabolism (H core). Taken together, the necrotrophic core contains functions such as cell wall-associated degrading enzymes, toxin metabolism, and transport, which are likely to support their lifestyle of killing prior to feeding. The biotrophic stealth growth on living tissues is potentially controlled by a core of regulatory functions, such as: small G-protein family of GTPases, RNA modification, and cryptochrome-based light sensing. Regulatory mechanisms found in the hemibiotrophic core contain light- and CO-sensing functions that could mediate important roles of this group, such as transition between lifestyles.

Conclusions: The selected set of enriched core functions identified in our work can facilitate future studies aimed at controlling FEPs. One interesting example would be to facilitate the identification of the pathogenic potential of samples analyzed by metagenomics. Finally, our analysis offers potential evolutionary scenarios, suggesting that an early-branching saprobe (identified in previous studies) has probably evolved a necrotrophic lifestyle as illustrated by the highest number of shared gene families between saprobes and necrotrophs.
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http://dx.doi.org/10.1186/s12864-019-6409-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6933724PMC
December 2019

The effect of benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) treatment on regulation of reactive oxygen species metabolism involved in wound healing of potato tubers during postharvest.

Food Chem 2020 Mar 16;309:125608. Epub 2019 Oct 16.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China; Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.

Benzo-(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH) can improve wound healing of potato tubers; however, how the chemical regulates reactive oxygen species (ROS) generation and scavenging during wound healing is not completely understood. BTH at 100 mg·L regulated changes in ROS generation and scavenging in healing tissues of potato tubers. A higher HO content was presented in healing tissues of potato tubers, while cell membrane permeability and malondialdehyde content declined due to BTH treatment. Additionally, the activities and transcript level of enzymes related with ROS generation, including NADPH oxidase, peroxidase and polyamine oxidase, as well as enzymes involved in ROS scavenging, such as superoxide dismutase, catalase, ascorbate peroxidase, and glutathione reductase, were significantly enhanced by BTH treatment. It is suggested that ROS metabolism might play a crucial role in wound healing of potato tubers mediated by BTH during postharvest.
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http://dx.doi.org/10.1016/j.foodchem.2019.125608DOI Listing
March 2020

Effect of benzothiadiazole treatment on improving the mitochondrial energy metabolism involved in induced resistance of apple fruit during postharvest storage.

Food Chem 2020 Jan 29;302:125288. Epub 2019 Jul 29.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, China. Electronic address:

The effects of benzothiadiazole (BTH) on Penicillium expansum development, mitochondria energy metabolism, and changes in the number and structure of mitochondria in apple fruit were investigated after the fruit were immersed in 100 mg L BTH for 10 min and then stored at 22 °C. The results indicated that BTH treatment significantly decreased the lesion diameter of fruit challenged with P. expansum; further, treatment enhanced the activities of mitochondrial respiratory metabolism-related enzymes, such as succinate dehydrogenase, cytochrome oxidase, H-ATPase and Ca-ATPase, along with high ATP level and energy status in apple fruit during storage. Moreover, transmission electron microscopy results indicated that BTH treatment was beneficial for maintaining the number and structure of mitochondria during storage. The results suggested that BTH treatment enhanced ATP levels via mitochondrial energy metabolism, which might contribute to the induced resistance in apple fruit during storage.
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http://dx.doi.org/10.1016/j.foodchem.2019.125288DOI Listing
January 2020

Exogenous polyamines enhance resistance to Alternaria alternata by modulating redox homeostasis in apricot fruit.

Food Chem 2019 Dec 31;301:125303. Epub 2019 Jul 31.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, PR China; Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Beit Dagan, Israel. Electronic address:

The effects of exogenous polyamines treatment on reactive oxygen species (ROS) metabolism in apricot fruits were systematically analyzed through the investigation of their curative and preventive effects on black spot disease. Results showed that 1.5 mM spermine (Spm), 1.5 mM spermidine (Spd) and 10 mM putrescine (Put) treatment significantly inhibited black spot development, additionally, the efficacy of this control was dependent upon the type of polyamines used and concentration level applied. Further studies have shown that exogenous polyamines treatments significantly improved production of O and HO, and increased the activities and gene expression levels of NADPH oxidase (NOX), super oxide dismutase (SOD), catalase (CAT) ascorbate peroxidase (AXP) and glutathione reductase (GR) in apricot fruit. Increased ascorbic acid (AsA) and reduced glutathione (GSH) content were also observed after exogenous polyamines treatment. These results have revealed that postharvest polyamines treatment effectively enhanced disease resistance through the maintenance of homeostasis in apricot fruits.
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http://dx.doi.org/10.1016/j.foodchem.2019.125303DOI Listing
December 2019

Sodium silicate prime defense responses in harvested muskmelon by regulating mitochondrial energy metabolism and reactive oxygen species production.

Food Chem 2019 Aug 13;289:369-376. Epub 2019 Mar 13.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou 730070, PR China; Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Beit Dagan, Israel.

The effects of postharvest treatment with sodium silicate (Si) (100 mM) on mitochondrial ROS production and energy metabolism of the muskmelon fruits (cv. Yujinxiang) on development of defense responses to Trichothecium roseum were studied. Si treatment decreased decay severity of inoculated muskmelons, enhanced the activities of energy metabolism of key enzymes and kept the intracellular ATP at a higher level; meanwhile, Si also induced the mtROS accumulation such as HO and superoxide anion. TMT-based quantitative proteomics analysis revealed that a total of 24 proteins with significant differences in abundance involved in energy metabolism, defense and stress responses, glycolytic and TCA cycle, and oxidation-reduction process. It is suggested by our study that melon fruit mitochondria, when induced by Si treatments, play a key role in priming of host resistance against T. roseum infection through the regulation of energy metabolism and ROS production in the pathogen infected muskmelon fruits.
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http://dx.doi.org/10.1016/j.foodchem.2019.03.058DOI Listing
August 2019

Both and Infections Promote the Ripening of Apples and Release Specific Volatile Compounds.

Front Plant Sci 2019 20;10:338. Epub 2019 Mar 20.

College of Food Science and Engineering, Gansu Agricultural University, Lanzhou, China.

Blue mold and core rot caused by and are major diseases of apple fruit in China; however, their differential aggressiveness in apples and effect on fruit postharvest physiology are unclear. The effects of colonization of apples cv. Red Delicious by both pathogens were compared to physiological parameters of ripening and release of volatile compounds (VOCs). colonization showed increased aggressiveness compared to colonization of apple fruits. enhanced colonization occurred with differential higher ethylene production and respiratory rate evolution, lower membrane integrity and fruit firmness in correspondence with the colonization pattern of inoculated apples. Moreover, caused lower contents of total soluble solid and titratable acid, and higher malondialdehyde compared with colonization. While both pathogen infections enhanced VOCs release, compared with inoculated apples, inoculated apple showed a higher total VOCs production including alcohols, aldehydes and esters, being the C6 alcohols, aldehydes and esters amount. PLS-DA analysis indicated that hexanoic acid was the most important factor to distinguish the inoculated fruits from the controls. Interestingly, propyl acetate and hexyl benzoate, and undecylenic acid and hexadecane were only identified in the and inoculated fruits, respectively. Taken together, our findings indicate that both fungi inoculations promote apple fruit ripening and release specific VOCs; moreover, apple fruits are more susceptible to colonization than .
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http://dx.doi.org/10.3389/fpls.2019.00338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6435981PMC
March 2019

Early Defense Responses Involved in Mitochondrial Energy Metabolism and Reactive Oxygen Species Accumulation in Harvested Muskmelons Infected by Trichothecium roseum.

J Agric Food Chem 2019 Apr 4;67(15):4337-4345. Epub 2019 Apr 4.

Department of Postharvest Science of Fresh Produce , Agricultural Research Organization, The Volcani Center , Beit Dagan 50250 , Israel.

Mitochondria play an essential part in fighting against pathogen infection in the defense responses of fruits. In this study, we investigated the reactive oxygen species (ROS) production, energy metabolism, and changes of mitochondrial proteins in harvested muskmelon fruits ( Cucumis melo cv. Yujinxiang) inoculated with Trichothecium roseum. The results indicated that the fungal infection obviously induced the HO accumulation in mitochondria. Enzyme activities were inhibited in the first 6 h postinoculation (hpi), including succinic dehydrogenase, cytochrome c oxidase, H-ATPase, and Ca-ATPase. However, the activities of Ca-ATPase and H-ATPase and the contents of intracellular adenosine triphosphate (ATP) were improved to a higher level at 12 hpi. A total of 42 differentially expressed proteins were identified through tandem mass tags-based proteomic analyses, which are mainly involved in energy metabolism, stress responses and redox homeostasis, glycolysis and tricarboxylic acid cycle, and transporter and mitochondria dysfunction. Taken together, our results suggest that mitochondria play crucial roles in the early defense responses of muskmelons against T. roseum infection through regulation of ROS production and energy metabolism.
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http://dx.doi.org/10.1021/acs.jafc.8b06333DOI Listing
April 2019

Apple Intrinsic Factors Modulating the Global Regulator, LaeA, the Patulin Gene Cluster and Patulin Accumulation During Fruit Colonization by .

Front Plant Sci 2018 27;9:1094. Epub 2018 Jul 27.

Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan, Israel.

The mycotoxin patulin is produced in colonized tissue by during storage of apples and is significantly affected by environmental factors that contribute to its accumulation. Few reports have, however, examined the effect of natural intrinsic factors associated with the fruit on the production of patulin. Here, we find that with advancing maturity, Golden Delicious apples show increased concentrations of total soluble solids (TSS) from 14 to 17% associated with the increased expression of the global transcription factor involved in regulation of secondary metabolite biosynthesis in filamentous fungi, expression and patulin accumulation. However, the apple cultivar Granny Smith, with similar TSS values but differing in pH levels and malic acid concentrations, showed reduced expression levels of and the patulin biosynthesis gene cluster ( genes) and patulin accumulation, suggesting a complexity of host factors contribution to patulin accumulation during colonization. To start elucidating these apple intrinsic factors, we examined their impact on and gene expression concomitant with patulin synthesis. Increasing sucrose concentrations from 15 to 175 mM repressed and gene expression and patulin production. However, this affect was modified and often reversed and sometimes accentuated by changes in pH, or the addition of malic acid or the major apple phenolic compounds, chlorogenic acid and epicatechin. While the increase in malic acid from 0 to 1% increased and gene expression, the decrease in pH from 3.5 to 2.5 reduced their expression. Also the increased and genes expressions at increasing epicatechin concentrations from 0 to 1 mM, was reversed by increasing sucrose concentrations, all together suggesting the complexity of the interactions .
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http://dx.doi.org/10.3389/fpls.2018.01094DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6073165PMC
July 2018

Fungal attack and host defence pathways unveiled in near-avirulent interactions of Penicillium expansum creA mutants on apples.

Mol Plant Pathol 2018 12 22;19(12):2635-2650. Epub 2018 Oct 22.

Department of Medical Microbiology and Immunology, University of Wisconsin - Madison, Madison 53706, WI, USA.

Amongst the universal diseases affecting apples, blue mould caused by Penicillium expansum is a major concern, resulting in yield and quality losses as a result of the production of the mycotoxin patulin. Despite the characterization of the patulin biosynthetic gene cluster at both the molecular and chemical levels, the underlying regulation of patulin biosynthesis in P. expansum and the mechanisms of apple colonization remain largely obscure. Recent work has indicated that sucrose, a carbon catabolite repressive metabolite, is a critical factor in the regulation of patulin synthesis. Here, CreA, the global carbon catabolite regulator, was assessed for virulence both in vitro and in vivo. We showed that loss-of-function creA strains were nearly avirulent and did not produce patulin in apples. On the basis of RNA-sequencing (RNA-seq) analysis and physiological experimentation, these mutants were unable to successfully colonize apples for a multitude of potential mechanisms including, on the pathogen side, a decreased ability to produce proteolytic enzymes and to acidify the environment and impaired carbon/nitrogen metabolism and, on the host side, an increase in the oxidative defence pathways. Our study defines CreA and its downstream signalling pathways as promising targets for the development of strategies to fight against the development and virulence of this post-harvest pathogen.
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http://dx.doi.org/10.1111/mpp.12734DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6638163PMC
December 2018

How alkalinization drives fungal pathogenicity.

PLoS Pathog 2017 11 9;13(11):e1006621. Epub 2017 Nov 9.

Departamento de Genética, Universidad de Córdoba, Córdoba, Spain.

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http://dx.doi.org/10.1371/journal.ppat.1006621DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5679519PMC
November 2017

Does the Host Contribute to Modulation of Mycotoxin Production by Fruit Pathogens?

Toxins (Basel) 2017 09 12;9(9). Epub 2017 Sep 12.

Department of Postharvest Science of Fresh Produce, The Volcani Center, Bet Dagan 50250, Israel.

Storage of freshly harvested fruit is a key factor in modulating their supply for several months after harvest; however, their quality can be reduced by pathogen attack. Fruit pathogens may infect their host through damaged surfaces, such as mechanical injuries occurring during growing, harvesting, and packing, leading to increased colonization as the fruit ripens. Of particular concern are fungal pathogens that not only macerate the host tissue but also secrete significant amounts of mycotoxins. Many studies have described the importance of physiological factors, including stage of fruit development, biochemical factors (ripening, C and N content), and environmental factors (humidity, temperature, water deficit) on the occurrence of mycotoxins. However, those factors usually show a correlative effect on fungal growth and mycotoxin accumulation. Recent reports have suggested that host factors can induce fungal metabolism, leading to the synthesis and accumulation of mycotoxins. This review describes the new vision of host-factor impact on the regulation of mycotoxin biosynthetic gene clusters underlying the complex regulation of mycotoxin accumulation in ripening fruit.
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http://dx.doi.org/10.3390/toxins9090280DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618213PMC
September 2017

Differential gene expression in tomato fruit and Colletotrichum gloeosporioides during colonization of the RNAi-SlPH tomato line with reduced fruit acidity and higher pH.

BMC Genomics 2017 08 4;18(1):579. Epub 2017 Aug 4.

Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, the Volcani Center, 7505101, Rishon LeZion, Israel.

Background: The destructive phytopathogen Colletotrichum gloeosporioides causes anthracnose disease in fruit. During host colonization, it secretes ammonia, which modulates environmental pH and regulates gene expression, contributing to pathogenicity. However, the effect of host pH environment on pathogen colonization has never been evaluated. Development of an isogenic tomato line with reduced expression of the gene for acidity, SlPH (Solyc10g074790.1.1), enabled this analysis. Total RNA from C. gloeosporioides colonizing wild-type (WT) and RNAi-SlPH tomato lines was sequenced and gene-expression patterns were compared.

Results: C. gloeosporioides inoculation of the RNAi-SlPH line with pH 5.96 compared to the WT line with pH 4.2 showed 30% higher colonization and reduced ammonia accumulation. Large-scale comparative transcriptome analysis of the colonized RNAi-SlPH and WT lines revealed their different mechanisms of colonization-pattern activation: whereas the WT tomato upregulated 13-LOX (lipoxygenase), jasmonic acid and glutamate biosynthesis pathways, it downregulated processes related to chlorogenic acid biosynthesis II, phenylpropanoid biosynthesis and hydroxycinnamic acid tyramine amide biosynthesis; the RNAi-SlPH line upregulated UDP-D-galacturonate biosynthesis I and free phenylpropanoid acid biosynthesis, but mainly downregulated pathways related to sugar metabolism, such as the glyoxylate cycle and L-arabinose degradation II. Comparison of C. gloeosporioides gene expression during colonization of the WT and RNAi-SlPH lines showed that the fungus upregulates ammonia and nitrogen transport and the gamma-aminobutyric acid metabolic process during colonization of the WT, while on the RNAi-SlPH tomato, it mainly upregulates the nitrate metabolic process.

Conclusions: Modulation of tomato acidity and pH had significant phenotypic effects on C. gloeosporioides development. The fungus showed increased colonization on the neutral RNAi-SlPH fruit, and limited colonization on the WT acidic fruit. The change in environmental pH resulted in different defense responses for the two tomato lines. Interestingly, the WT line showed upregulation of jasmonate pathways and glutamate accumulation, supporting the reduced symptom development and increased ammonia accumulation, as the fungus might utilize glutamate to accumulate ammonia and increase environmental pH for better expression of pathogenicity factors. This was not found in the RNAi-SlPH line which downregulated sugar metabolism and upregulated the phenylpropanoid pathway, leading to host susceptibility.
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http://dx.doi.org/10.1186/s12864-017-3961-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5545021PMC
August 2017

Cation-Stress-Responsive Transcription Factors SltA and CrzA Regulate Morphogenetic Processes and Pathogenicity of Colletotrichum gloeosporioides.

PLoS One 2016 28;11(12):e0168561. Epub 2016 Dec 28.

Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, the Volcani Center, Bet Dagan, Israel.

Growth of Colletotrichum gloeosporioides in the presence of cation salts NaCl and KCl inhibited fungal growth and anthracnose symptom of colonization. Previous reports indicate that adaptation of Aspergillus nidulans to salt- and osmotic-stress conditions revealed the role of zinc-finger transcription factors SltA and CrzA in cation homeostasis. Homologs of A. nidulans SltA and CrzA were identified in C. gloeosporioides. The C. gloeosporioides CrzA homolog is a 682-amino acid protein, which contains a C2H2 zinc finger DNA-binding domain that is highly conserved among CrzA proteins from yeast and filamentous fungi. The C. gloeosporioides SltA homolog encodes a 775-amino acid protein with strong similarity to A. nidulans SltA and Trichoderma reesei ACE1, and highest conservation in the three zinc-finger regions with almost no changes compared to ACE1 sequences. Knockout of C. gloeosporioides crzA (ΔcrzA) resulted in a phenotype with inhibited growth, sporulation, germination and appressorium formation, indicating the importance of this calciu006D-activated transcription factor in regulating these morphogenetic processes. In contrast, knockout of C. gloeosporioides sltA (ΔsltA) mainly inhibited appressorium formation. Both mutants had reduced pathogenicity on mango and avocado fruit. Inhibition of the different morphogenetic stages in the ΔcrzA mutant was accompanied by drastic inhibition of chitin synthase A and B and glucan synthase, which was partially restored with Ca2+ supplementation. Inhibition of appressorium formation in ΔsltA mutants was accompanied by downregulation of the MAP kinase pmk1 and carnitine acetyl transferase (cat1), genes involved in appressorium formation and colonization, which was restored by Ca2+ supplementation. Furthermore, exposure of C. gloeosporioides ΔcrzA or ΔsltA mutants to cations such as Na+, K+ and Li+ at concentrations that the wild type C. gloeosporioides is not affected had further adverse morphogenetic effects on C. gloeosporioides which were partially or fully restored by Ca2+. Overall results suggest that both genes modulating alkali cation homeostasis have significant morphogenetic effects that reduce C. gloeosporioides colonization.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0168561PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5193415PMC
July 2017

Mutation of AREA affects growth, sporulation, nitrogen regulation, and pathogenicity in Colletotrichum gloeosporioides.

Fungal Genet Biol 2017 02 25;99:29-39. Epub 2016 Dec 25.

Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel. Electronic address:

The GATA transcription factor AreA is a global nitrogen regulator that restricts the utilization of complex and poor nitrogen sources in the presence of good nitrogen sources in microorganisms. In this study, we report the biological function of an AreA homolog (the CgareA gene) in the fruit postharvest pathogen Colletotrichum gloeosporioides. Targeted gene deletion mutants of areA exhibited significant reductions in vegetative growth, increases in conidia production, and slight decreases in conidial germination rates. Quantitative RT-PCR (qRT-PCR) analysis revealed that the expression of AreA was highly induced under nitrogen-limiting conditions. Moreover, compared to wild-type and complemented strains, nitrogen metabolism-related genes were misregulated in ΔareA mutant strains. Pathogenicity assays indicated that the virulence of ΔareA mutant strains were affected by the nitrogen content, but not the carbon content, of fruit hosts. Taken together, our results indicate that CgareA plays a critical role in fungal development, conidia production, regulation of nitrogen metabolism and virulence in Colletotrichum gloeosporioides.
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http://dx.doi.org/10.1016/j.fgb.2016.12.006DOI Listing
February 2017

Genome Sequence of a Potential New Benyvirus Isolated from Mango RNA-seq Data.

Genome Announc 2016 Nov 10;4(6). Epub 2016 Nov 10.

Department of Plant Pathology and Weed Research, Institute of Plant Protection, ARO, Volcani Center, Rishon LeZion, Israel.

We report here the sequence of a new benyvirus found through mango cultivar Shelly RNA-seq analysis in Israel. This is the first virus strain reported in mango trees.
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http://dx.doi.org/10.1128/genomeA.01250-16DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5105099PMC
November 2016