P119: Interaction between soil fungi, Trichoderma and plants through volatile signaling

One of the most frequently isolated genus of free-living soil fungi, Trichoderma species, are well studied for their ability to reduce plant disease and promote plant growth and productivity.  In addition, Trichoderma species produce volatile organic compounds (VOCs) and these compounds have shown self inhibitory effects and inhibition on other microorganisms and animals.  However, the mechanisms involved in Trichoderma VOCs and the potential for the fungal VOCs to induce beneficial plant responses is yet to be determined.  Our research has shown that VOCs emitted by T. viride have plant growth promoting effects on Arabidopsis thaliana.  Plants and fungi were grown together in a glass exposure chamber that provided physical separation while allowing gas exchange to occur.  A. thaliana exposed to T. viride VOCs exhibited growth promotion and developmental changes including large leaf size, increased shoot and root weight, increased lateral root branching, and earlier formation of flowers.  The average root mass of VOC exposed plants was 0.77g, showing a 113% increase compare to control plants at 0.36g.  There was a 60% increase in chlorophyll concentration (5.5mg/g control, 8.8mg/g VOC exposed plants).  Other physiological assays such as plant electrolyte leakage (at 12% ± 2%), Trypan Blue staining for presence of necrotic lesions, and DAB staining for the presence of hydrogen peroxide, were same in both control and test plants.  Understanding the possible mechanisms involved in plant response to fungal VOCs will aid in and advance our current understanding of the usage of biological agents in agricultural practices.