Role of botrydial in the interaction between Botrytis cinerea and Bacillus spp.

VIGNATTI P; GONZALEZ ME; ROMERO FM; JOFRÉ E; BOLIVAR-ANILLO H; GONZÁLEZ COLLADO I; VIAUD M; PIECKENSTAIN FL

Congreso; XXIII Congreso Latinoamericano de Microbiologia; 2016

Introduction: Botrytis cinerea is a necrotrophic fungus that infects hundreds of plant species. This fungus feeds on dead host tissue derived fromthe action of cell wall?]degrading enzymes and toxic metabolites. B. cinerea produces several phytotoxins, such as the sesquiterpene botrydial and related compounds. The relevance of botrydial as a virulence factor is well established, but its role in the interaction between B. cinereaand other microorganisms has not been studied in depth. In this regard, botrydial was shown to inhibit growth of Bacillus subtilis in vitro, but itstoxicity has not been tested on other Bacillus spp. B. subtilis, B. methylotrophicus and B. amyloliquefaciens are known for their potential asbiological control agents (BCAs) of plant diseases caused by several pathogens, including B. cinerea. Thus, it is of interest to determine ifbotrydial production by B. cinerea strains renders them more resistant to the antagonistic effects of Bacillus spp, an issue that could decreasethe efficacy of these bacteria as BCAs.Aim: General aim: to analyze the role of botrydial in the interaction between B. cinerea and Bacillus spp with the potential to act as BCAs.Specifics aims of this work are: a) To analyze if wild?]type (WT) B. cinerea strains inhibit growth of Bacillus spp in vitro. b) To determine if mutant(bot?]) B. cinerea strains unable to synthesize botrydial maintain their ability to inhibit Bacillus spp in vitro. c) To evaluate the toxicity of purebotrydial towards Bacillus spp in vitro.Methodology: Petri dishes containing potato dextrose agar were inoculated with different strains of B. subtilis, B. amyloliquefaciens and B.methylotrophicus previously detected to antagonize B. cinerea. Bacterial suspensions were spread over the surface of the culture medium andplates were then inoculated with a disc of mycelium of either WT or bot?] B. cinerea strains. The presence of haloes of bacterial growth inhibitionaround the colony of B. cinerea was analyzed after 48 h incubation. Inhibitory effects of botrydial towards Bacillus methylotrophicus wasevaluated by analyzing bacterial growth in tryptein soybean broth amended with different concentrations of this toxin.Results: WT strains of B. cinerea inhibited growth of B. methylotrophicus and B. amyloliquefaciens, but not B. subtilis strains. B. cinerea mutantswere found to lack the ability to inhibit growth of B. methylotrophicus and B. amyloliquefaciens. Botrydial inhibited growth of B.methylotrophicus in a dose dependent manner.Conclusion: Botrydial confers B. cinerea strains the ability to inhibit in vitro growth of B. methylotrophicus and B. amyloliquefaciens, thusdemonstrating that in addition to its well?]known role as a virulence factor, botrydial can also play a role in the interaction between B. cinereaand other microorganisms. Further work is in progress to address the role of botrydial in the interaction between B. cinerea and Bacillus spp in planta.