Publications by authors named "Dov B Prusky"

13 Publications

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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

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

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

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

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

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

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

How Does Host Carbon Concentration Modulate the Lifestyle of Postharvest Pathogens during Colonization?

Front Plant Sci 2016 1;7:1306. Epub 2016 Sep 1.

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

Postharvest pathogens can penetrate fruit by breaching the cuticle or directly through wounds, and they show disease symptoms only long after infection. During ripening and senescence, the fruit undergo physiological processes accompanied by a decline in antifungal compounds, which allows the pathogen to activate a mechanism of secretion of small effector molecules that modulate host environmental pH. These result in the activation of genes under their optimal pH conditions, enabling the fungus to use a specific group of pathogenicity factors at each particular pH. New research suggests that carbon availability in the environment is a key factor triggering the production and secretion of small pH-modulating molecules: ammonia and organic acids. Ammonia is secreted under limited carbon and gluconic acid under excess carbon. This mini review describes our most recent knowledge of the mechanism of activation of pH-secreted molecules and their contribution to colonization by postharvest pathogens to facilitate the transition from quiescence to necrotrophic lifestyle.
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http://dx.doi.org/10.3389/fpls.2016.01306DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5007722PMC
September 2016