Volatile organic compounds for plant disease management

ESPAÑOL, LAUREANO A.; RAMOS, ROCÍO S.; LUQUE, ALICIA G.; SCANDIANI, MARÍA M.; SPAMPINATO, CLAUDIA P.

Viena

Conferencia; World Soybean Research Conference 11 (WSRC11); 2023

Plant responses to pathogens are known to be mediated by volatile organic compounds (VOCs). Here, we investigated VOC emission from soybean roots infected by Fusarium tucumaniae (Ft). This pathogen is the main causal agent of sudden death syndrome (SDS) of soybean in Argentina. For plant infection, inoculum was prepared by culturing Ft on potato dextrose agar (PDA) for 1 week at 25°C in the dark. Five agar plugs (6 mm diameter) with mycelium were added to autoclaved sorghum grain and incubated at 25°C in the dark for 2 weeks. Then, a layer of infected sorghum was distributed in pots on top of a nursery substrate and covered with the same substrate. Five susceptible SDS genotype seeds were placed and covered with substrate again. Once foliar symptoms appear, VOCs were identified in soybean infected root segments and in the rhizosphere soil by head space solid phase microextraction coupled to gas chromatography-mass spectrometer and compared with VOC emission from PDA mycelium plugs. Identified VOCs were classified into acids, terpenes, aldehydes, ketones and alcohols. Some chemical compounds differ between pathogen growth conditions. Among these, benzaldehyde was only found in the rhizosphere and in infected roots, thus suggesting a role for this VOC in early plant defense signalling. We then analyzed changes in Ft growth by benzaldehyde. The experiment was performed by growing a Ft plug on PDA at 25°C in dark in the presence of an imbibed filter paper with benzaldehyde on the lid of the plate. Plates were joined using sealing tape and the radii of fungal colonies were measured at different times. We found that benzaldehyde could effectively inhibit fungal growth in a concentration dependent manner. In conclusion, Ft triggers changes in soybean root VOC production highlighting the biological relevance of VOCs as a new strategy for SDS management.