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Department of Plant Pathology and Microbiology
The Robert H. Smith Faculty of Agriculture, Food & Environment
The Hebrew University of Jerusalem

P.O. Box 12 
Rehovot 76100 
ISRAEL

Tel: 08-9489219
Fax: 08-9466794
rakefetk@savion.huji.ac.il

Publications

2019
Vela-Corcía, D. ; Aditya Srivastava, D. ; Dafa-Berger, A. ; Rotem, N. ; Barda, O. ; Levy, M. MFS transporter from Botrytis cinerea provides tolerance to glucosinolate-breakdown products and is required for pathogenicity. 2019, 10, 2886. Publisher's VersionAbstract
Glucosinolates accumulate mainly in cruciferous plants and their hydrolysis-derived products play important roles in plant resistance against pathogens. The pathogen Botrytis cinerea has variable sensitivity to glucosinolates, but the mechanisms by which it responds to them are mostly unknown. Exposure of B. cinerea to glucosinolate-breakdown products induces expression of the Major Facilitator Superfamily transporter, mfsG, which functions in fungitoxic compound efflux. Inoculation of B. cinerea on wild-type Arabidopsis thaliana plants induces mfsG expression to higher levels than on glucosinolate-deficient A. thaliana mutants. A B. cinerea strain lacking functional mfsG transporter is deficient in efflux ability. It accumulates more isothiocyanates (ITCs) and is therefore more sensitive to this compound in vitro; it is also less virulent to glucosinolates-containing plants. Moreover, mfsG mediates ITC efflux in Saccharomyces cerevisiae cells, thereby conferring tolerance to ITCs in the yeast. These findings suggest that mfsG transporter is a virulence factor that increases tolerance to glucosinolates.
Calderón, C. E. ; Rotem, N. ; Harris, R. ; Vela-Corcía, D. ; Levy, M. Pseudozyma aphidis activates reactive oxygen species production, programmed cell death and morphological alterations in the necrotrophic fungus Botrytis cinerea. Molecular Plant Pathology 2019, 20, 562 - 574. Publisher's VersionAbstract
Summary Many types of yeast have been studied in the last few years as potential biocontrol agents against different phytopathogenic fungi. Their ability to control plant diseases is mainly through combined modes of action. Among them, antibiosis, competition for nutrients and niches, induction of systemic resistance in plants and mycoparasitism have been the most studied. In previous work, we have established that the epiphytic yeast Pseudozyma aphidis inhibits Botrytis cinerea through induced resistance and antibiosis. Here, we demonstrate that P. aphidis adheres to B. cinerea hyphae and competes with them for nutrients. We further show that the secreted antifungal compounds activate the production of reactive oxygen species and programmed cell death in B. cinerea mycelium. Finally, P. aphidis and its secreted compounds negatively affect B. cinerea hyphae, leading to morphological alterations, including hyphal curliness, vacuolization and branching, which presumably affects the colonization ability and infectivity of B. cinerea. This study demonstrates additional modes of action for P. aphidis and its antifungal compounds against the plant pathogen B. cinerea.
2017
Polturak, G. ; Grossman, N. ; Vela-Corcia, D. ; Dong, Y. ; Nudel, A. ; Pliner, M. ; Levy, M. ; Rogachev, I. ; Aharoni, A. Engineered gray mold resistance, antioxidant capacity, and pigmentation in betalain-producing crops and ornamentals. Proceedings of the National Academy of Sciences 2017, 114, 9062–9067. Publisher's VersionAbstract
In plants, three major classes of pigments are generally responsible for colors seen in fruits and flowers: anthocyanins, carotenoids, and betalains. Betalains are red-violet and yellow plant pigments that have been reported to possess strong antioxidant and health-promoting properties, including anticancer, antiinflammatory, and antidiabetic activity. Here, heterologous betalain production was achieved for the first time in three major food crops: tomato, potato, and eggplant. Remarkably, betalain production in tobacco resulted in significantly enhanced resistance toward gray mold (Botrytis cinerea), a plant pathogen responsible for major crop losses. Considering the significant characteristics of these molecules, heterologous betalain production now offers exciting opportunities for creating new value for consumers, producers, and suppliers of food crops and ornamental plants.Betalains are tyrosine-derived red-violet and yellow plant pigments known for their antioxidant activity, health-promoting properties, and wide use as food colorants and dietary supplements. By coexpressing three genes of the recently elucidated betalain biosynthetic pathway, we demonstrate the heterologous production of these pigments in a variety of plants, including three major food crops: tomato, potato, and eggplant, and the economically important ornamental petunia. Combinatorial expression of betalain-related genes also allowed the engineering of tobacco plants and cell cultures to produce a palette of unique colors. Furthermore, betalain-producing tobacco plants exhibited significantly increased resistance toward gray mold (Botrytis cinerea), a pathogen responsible for major losses in agricultural produce. Heterologous production of betalains is thus anticipated to enable biofortification of essential foods, development of new ornamental varieties, and innovative sources for commercial betalain production, as well as utilization of these pigments in crop protection.
2016
Ogran, A. ; Landau, N. ; Hanin, N. ; Levy, M. ; Gafni, Y. ; Barazani, O. Intraspecific variation in defense against a generalist lepidopteran herbivore in populations of Eruca sativa (Mill.). Ecology and EvolutionEcology and EvolutionEcol Evol 2016, 6 363 - 374. Publisher's VersionAbstract
Abstract Populations of Eruca sativa (Brassicaceae) from desert and Mediterranean (Med) habitats in Israel differ in their defense against larvae of the generalist Spodoptera littoralis but not the specialist Pieris brassicae. Larvae of the generalist insect feeding on plants of the Med population gained significantly less weight than those feeding on the desert plants, and exogenous application of methyl jasmonate (MJ) on leaves of the Med plants significantly reduced the level of damage created by the generalist larvae. However, MJ treatment significantly induced resistance in plants of the desert population, whereas the generalist larvae caused similar damage to MJ-induced and noninduced plants. Analyses of glucosinolates and expression of genes in their synthesis pathway indicated that defense in plants of the Med population against the generalist insect is governed by the accumulation of glucosinolates. In plants of the desert population, trypsin proteinase inhibitor activity was highly induced in response to herbivory by S. littoralis. Analysis of genes in the defense-regulating signaling pathways suggested that in response to herbivory, differences between populations in the induced levels of jasmonic acid, ethylene, and salicylic acid mediate the differential defenses against the insect. In addition, expression analysis of myrosinase-associated protein NSP2 suggested that in plants of the desert population, glucosinolates breakdown products were primarily directed to nitrile production. We suggest that proteinase inhibitors provide an effective defense in the desert plants, in which glucosinolate production is directed to the less toxic nitriles. The ecological role of nitrile production in preventing infestation by specialists is discussed.