Microbial Volatiles (mVOCs) Induce Tomato Plant Growth and Disease Resistance Against Wilt Pathogen Fusarium oxysporum f.sp. lycopersici

Microbial volatile organic compounds (mVOCs) and its potentiality in plant growth and development is still an unexplored area. The in vitro study on bipartite plate showed inhibition of Fusarium oxysporum f.sp lycopersici (FOL) by volatiles of Trichoderma asperellum BHU P1 and Ochrobactrum sp. BHU-PB1 over control. The seed germination and seedling growth was recorded maximum in plant exposed to VOCs of Ochrobactrum sp. in both magenta box (in vitro) and pot (in vivo) experiment. The growth parameters as seed germination, shoot length, root length, fresh weight, dry weight, number of lateral roots and number of leaflets was compared to be higher in microbial volatile metabolites treated plants as compared to control. Disease incidence in T. asperellum and Ochrobactrum sp. volatile treated tomato plants were 43.66% and 41.33%, respectively at 20 days post inoculation (dpi) whereas untreated control showed disease incidence up to 79.16%. GC-MS analysis of volatile metabolite of T. asperellum BHU P1 detected 42 compounds and Ochrobactrum sp. BHU-PB1 detected 50 compounds over PDB and NB control. HPLC analysis of volatile treated tomato leaves showed enhanced concentration of gallic acid, t-chlorogenic acid, rutin, p-caumeric acid, cinnamic acid, ferulic acid, capsacin, salicylic acid, syringic acid and quercetin over control at 0, 48 and 72 h of FOL challenge. Above observations led to the conclusion that tomato roots which perceived the volatiles of Ochrobactrum sp. BHU-PB1 showed better plant growth promotion and enhanced plant defense, revealed by higher phenolic compound production followed by T. asperellum BHU P1 volatile treated plant.

Automated summary

Microbial volatile organic compounds (mVOCs) and their potential in plant growth and development remains understudied. In vitro experiments demonstrated that volatiles from Trichoderma asperellum BHU P1 and Ochrobactrum sp. BHU-PB1 inhibited the growth of Fusarium oxysporum f.sp lycopersici (FOL). Exposure to volatiles from Ochrobactrum sp. resulted in the highest seed germination and seedling growth. Compared to the control, plants treated with microbial volatile metabolites exhibited better growth parameters and lower disease incidence.