The capacity of isoprene emission largely influences the proteome of Arabidopsis plants both under well-watered and water-stress conditions

Isoprene is a small lipophilic molecule synthetized at chloroplast level and released into the atmosphere. Isoprene-emitting plants are believed to be better protected against abiotic stresses (i.e. temperature, oxidative stress, drought). The mechanism of action of isoprene is still under debate. In this study we compared the physiological responses and proteomic profile of isoprene-emitting (ISPS) and non-emitting (WT and EV) Arabidopsis thaliana plants subjected to a moderate water stress and in control conditions. Our aim was to investigate if isoprene-emitting plants displayed a different proteomic profile which may help explain how isoprene protects plants from stresses. Only ISPS plants were able to maintain the same photosynthesis and fresh weight in water stress and in control condition. To better understand the molecular mechanism underlying isoprene emission, we performed a LC-MS/MS-based proteomic analysis to explore the changes in protein abundance between WT and EV both under control and moderate water stress conditions. Our data suggest that isoprene exerts its protective mechanism at different levels rather than on a single mode, triggering significant changes in chloroplast protein profiles, but also playing important roles in modulating signaling and hormone pathways and even membrane trafficking.