Nobuhiro Suzuki

Title : Mechanisms underlying the tolerance of plants to a combination of heat stress and drought

Abstract:

Plants as sessile organisms are exposed to multiple abiotic stresses that simultaneously occur under natural environmental conditions. Studies deciphering acclimation of plants to stress combinations are however still scarce. Here, we report the characteristics of Arabidopsis mutants with enhanced tolerance to a combination of heat stress and drought. ISOCHORISMATE SYNTHASE 1 (ICS1) is known as a crucial enzyme required for the synthesis of salicylic acid and phylloquinone, one of the components of the photosystem I complex in the chloroplast. We revealed enhanced tolerance of an Arabidopsis mutant deficient in ICS1 (sid2-1) to a combination of heat stress and drought, accompanied by enhanced H₂O₂-dependent stomatal closure and accumulation of total soluble sugars. In addition, sid2-1 plants showed higher accumulation of reaction centre proteins in the photosystem II compared to WT plants as well as enhanced expression of transcripts involved in the turnover of these reaction centre proteins. Taken together, our findings suggest that maintenance of photosynthetic apparatus as well as prevention of excess water loss might enhance the tolerance of sid2-1 plants to a combination of heat stress and drought. Elm2 gene in Arabidopsis was previously shown to be up-regulated in response to a combination of heat stress and drought. Here, we demonstrated enhanced tolerance of an Arabidopsis mutant deficient in Elm2 gene (elm2) to this stress combination. However, the mechanisms underlying this enhanced stress tolerance of elm2 mutant might be different from that of sid2-1 mutant. elm2 mutant showed lower accumulation of oxidized lipid and superoxide compared to WT plants under a combination of heat stress and drought. In addition, expression of transcript encoding a ROS producing NADPH oxidase was lower in elm2 mutant compared to WT plants under this stress combination. Thus, the enhanced tolerance of elm2 mutant to combined stress might be due to attenuation of oxidative damage caused by superoxide. Our researches demonstrated the different mechanisms that are significant for the tolerance of plants to a combination of heat stress and drought. It should be interesting to address how these different mechanisms are integrated in future studies

Biography:

Nobuhiro Suzuki obtained Master’s degree from Kagawa University in Japan, and Ph.D from University of Nevada, Reno in USA. Then, he worked as a postdoctoral fellow in Prof. Ron Mittler’s lab in University of Nevada, Reno and University of North Texas. He is currently working as an assistant professor in Sophia University, Tokyo, Japan, mainly studying response of plants to heat stress and stress combinations. He published 29 peer-reviewed article and 1 book chapter.