Characterization of the tomato water stress response mediated by the beneficial fungus of the rizosphere trichoderma longibrachiatum

Water deficiency is one of the primary causes of tomato yield reduction. Fungi belonging to the Trichoderma genus known to be efficient "plant growth promoters" (PGPF), play a key role in improving plant growth and resistance to environmental stresses. Although this interaction occurs at the root level, its beneficial effects spread through the whole organism, potentially involving a systemic regulation of plant gene expression.Recently the use of the Next Generation Sequencing (NGS) technology and the availability of several functional genetics tools have revolutionized the way to investigate complex biological systems. We studied the Trichoderma-mediated water stress response of three-week-old plants of Solanum lycopersicum L. in a hydroponic growing system. In order to mimic water deficiency, a 15% polyethyleneglycole (PEG) solution was added to the growing media of T. longibrachiatum MK1-treated and non-treated (control) plants for 24, 48 and 72 h. Biometric and physiological analyses were conducted to evaluate the effects of the fungus and/or of water stress on the host plants. The results confirmed the positive effects of Trichoderma on tomato plants, both in terms of growth promotion and of protective role during the abiotic stress. High-throughput transcriptomic data were produced from tomato shoots bio-stimulated by T. longibrachiatum MK1 or treated with PEG for 24 h in the presence or not of the fungus. A global expression profile for each condition was obtained and key regulatory elements were identified.Understanding the mechanisms underlying the cross talk between tomato plant and Trichoderma spp. will be crucial not only to gain insights into the mechanisms of plant-microbe interactions, but also to sustainably improve crop quality and productivity in the light of climate change.This work was supported by the Project GenoPOM-pro PON02_00395_3082360, funded by the Italian Ministry of Education, University and Research (MIUR), PON R&C 2007-2013.