Dynamics of volatilomes emitted during cross-talking of plant-growth-promoting bacteria and the phytopathogen, Fusarium solani

The dynamics of volatilomes emitted during the interaction between plant-growth-promoting bacteria (PGPB) and the phytopathogenFusarium solaniwere evaluated for 5 days. The first screening was done to evaluate the antagonist activity of volatile compounds emitted by PGPB againstF. solani. Volatilomes from 11 PGPB were determined individually and together withF. solaniby using solid-phase microextraction coupled to gas-chromatography-mass spectrometry. Isolates of PGPB belonged to theBacillusgenus and inhibited from 18 to 24% the fungal mycelium growth. The isolates also induced morphological alterations of fungal hyphae, like small globular vesicles and the formation of chlamydospores, suggesting a stress mechanism response by the fungus. Volatilome profile showed 49 different compounds that appeared in the bacterial-fungal interaction, such as ketones, sesquiterpenes, monoterpenoids, alkanes, alkenes, carboxylic acids, and fatty acids. Some ketones and alcohols were detected in high abundance only in the interaction PGPB-fungus at 3 and 5 days.Bacillus circulansA19,Bacillus amyloliquefaciensA21, andBacillus wiedmanniiS18 shared a group of emitted alcohols and ketones when they were exposed toF. solani.F. solaniproduced its own volatilome profile, with the presence of sesquiterpenes, such as alpha-cubebene and caryophyllene, which increased significantly in co-incubation with the tested bacteria, suggesting chemical communication between them. [GRAPHICS] .