S11 - Session O5 - When things get too salty: use forest residue extracts! In vitro screening of plant-based compounds for increased salt stress tolerance in A. thaliana, S. Lycopersicum and L. Sativa

Authors: Eva Ors *, Barrada Adam, Martine Dorais, Maxime Delisle-Houde, Thi Thuy An Nguyen, Russell J. Tweddell, Veedaa Soltaniband, Robab Mahmoudi

As extreme climatic events become more and more frequent all over the world due to climate change, drought and salinity are among the main environmental stresses that negatively affect productivity of various crops and pose a threat to food safety. During the last decades, many efforts have been put into the time-consuming task of breeding new drought and salinity tolerant genotypes. However, the emergency of the problem requires short-term measures such as the use of plant extracts which may activate stress adaptation mechanisms in plants, thus increasing their resilience to adverse environmental conditions. Our goal was to study the effect of compounds triggering the abscisic acid (ABA) pathway on plant salt stress response. To this end, we first used the transgenic RD29b::LUC Arabidopsis thaliana line which carries the firefly luciferase (LUC) reporter gene fused to an ABA-inducible promoter to screen, in vitro, for the activation of LUC expression by ten forest residue extracts and two protein hydrolysates. The studied plant-based compounds causing the highest LUC activity were then used to pre-treat 5-day-old in vitro grown Arabidopsis thaliana , Solanum lycopersicum (cv. Micro Tom) and Lactuca sativa (cv. Salanova Red Batavia) seedlings, which were transferred two days later onto half-strength MS medium plates supplemented or not with NaCl. In order to determine salt sensitivity, root length and plant fresh weight were measured after 10 days and growth inhibition was calculated for each treatment. Finally, we determined salt stress sensitivity of ABA deficient Arabidopsis thaliana aba2-1 and aba1-1 mutants after pretreatment with compounds allowing for the lowest root growth inhibitions in order to assess the importance of ABA in salt stress tolerance. Ultimately, this approach would allow us to identify bio-based treatments which increase salt stress tolerance of two major greenhouse crop species, as well as determine their efficiency and mode of action.