Effects of fungal volatile organic compounds on Arabidopsis thaliana growth and gene expression

Many microorganisms produce volatile organic compounds (VOCs) with biological effects on plants. In this study, Arabidopsis seeds or 14-day-old vegetative plants were exposed to 0.5 μg/l of chemical standards of 26 VOCs previously identified from the biocontrol fungus Trichoderma. Seven compounds (1-decene, 2-heptylfuran, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1- butanol, 2-heptanone, and 1-octen-3-ol) were further tested at the physiological concentration (10 ng/l) and 3-methyl-1-butanol, 1-decene, and 2-heptylfuran induced significant increases in fresh weight and total chlorophyll content. Plants exposed to 1-decene had the greatest increase in plant fresh shoot weight (38.9%) and chlorophyll content (67.8%). An RNA sequencing analysis was performed on plants treated with vapors of 1-decene. The expression of 123 genes was differentially affected, encompassing genes involved in cell wall modification, auxin induction, stress, and defense responses, with several major classes of stress-related genes showing down-regulation. To our knowledge, this is the first report of the effect of a plant growth promoting VOC on gene expression in Arabidopsis thaliana. As the role of fungal VOCs in biocontrol moves from correlative studies to more hypothesis driven approaches, our findings can guide both basic and applied studies in agricultural research.