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Title: Trichothecenes and aspinolides produced by Trichoderma arundinaceum regulate expression of Botrytis cinerea genes involved in virulence and growth

item MALMIERCA, MONICA - University Of Leon
item BARUA, JAVIER - University Of Cadiz
item McCormick, Susan
item CARDOZA, ROSA - University Of Leon
item ALEXANDER, NANCY - Retired ARS Employee
item IZQUIERDO-BUENO, INMACULADA - University Of Cadiz
item CASQUERO, PEDRO - University Of Leon
item COLLADO, ISIDRO - University Of Cadiz
item MONTE, ENRIQUE - University Of Salamanca
item GUTIERREZ, SANTIAGO - University Of Leon

Submitted to: Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/6/2016
Publication Date: 11/9/2016
Publication URL:
Citation: Malmierca, M.G., Izquierdo-Bueno, I., McCormick, S.P., Cardoza, R.E., Alexander, N.J., Barua, J., Lindo, L., Casquero, P.A., Collado, I.G., Monte, E., Gutierrez, S. 2016. Trichothecenes and aspinolides produced by Trichoderma arundinaceum regulate expression of Botrytis cinerea genes involved in virulence and growth. Environmental Microbiology. 18(11):3991-4004.

Interpretive Summary: In this research we found that both the biocontrol fungus Trichoderma arundinaceum and the plant pathogen Botrytis cinerea have an arsenal of chemical weapons that they use to interact with each other and plants. T. arundinaceum produces the trichothecene sesquiterpene harzianum A (HA) which is toxic to other fungi but not toxic to plants and helps turn on genes for natural defenses that plants use to fight fungal pathogens. B. cinerea is an airborne fungus that causes pre-harvest soft rotting of field and greenhouse grown horticultural crops and post harvest rotting of vegetable, fruits and flowers. We found that HA and other T. arundinaceum chemical weapons affect the genes for production of botrydial, a sesquiterpene toxin produced by B. cinerea that helps it invade and kill plant tissues, as well as fight back against the biocontrol fungus. This research provides scientists with tools to understand the complex interactions between these fungi and their chemical weapons. Knowledge of how pathogenic and biocontrol fungi interact will aid in designing effective biocontrol strategies to combat plant fungal diseases.

Technical Abstract: Trichoderma arundinaceum (Ta37) and Botrytis cinerea (B05.10) produce the sesquiterpenoids harzianum A (HA) and botrydial (BOT), respectively. Ta'Tri5, an HA non-producer mutant, produces high levels of the polyketide compounds aspinolides (Asp) B and C. We analyzed the role of HA and Asp in the B. cinerea-T. arundinaceum interaction, including changes in BOT production as well as transcriptomic changes of BcBOT genes involved in BOT biosynthesis, and also of genes associated with virulence and ergosterol biosynthesis. We found that exogenously added HA up-regulated the expression of the BcBOT and all the virulence genes analyzed when B. cinerea was grown alone. However, a decrease in the amount of BOT and a down-regulation of BcBOT gene expression was observed in the interaction zone of B05.10-Ta37 dual cultures, compared to Ta'Tri5. Thus, the confrontation with T. arundinaceum results in an up-regulation of most of the B. cinerea genes involved in virulence yet the presence of T. arundinaceum secondary metabolites, HA and AspC, act separately and together to down-regulate the B. cinerea genes analyzed. The present work emphasizes the existence of a chemical cross-regulation between B. cinerea and T. arundinaceum and contributes to understanding how a biocontrol fungus and its prey interact with each other.