[P3] Abiotic Stress for Crop Production

[P3-19] NaCl-Stimulated ATP Synthesis in a Halophyte (Mesembryanthemum crystallinum L.)

*Nominated for Presentation Awards

^○Ryoma Sato¹, Kazuki Yoshida¹, Ayako Konishi², Dan Q. Tran³, Kazuyuki Saito⁴, John C. Cushman⁵, Sakae Agarie⁴ (1.Graduate school of Bioresource and Bioenvironmental Sciences, Kyushu University, Japan, 2.Faculty of Agriculture, Kagawa University, Japan, 3.The United Graduate School of Agricultural Sciences, Ehime University, Japan, 4.Faculty of Agriculture, Kyushu University, Japan, 5.Department of Biochemistry and Molecular Biology, University of Nevada, United States)

NaCl is one of the factors causing damages in plants that severely impedes their growth and reduces crop productivity. Halophyte, a group of salt-tolerant plants, evolved sophisticated mechanisms to survive under the severe salinity conditions, and they also show halophilism, which is a growth response that increases in the presence of NaCl at a concentration in which almost all crops die. The salt-tolerant and halophilic reactions require a large amount of ATP. In the previous study, we found that the ATP synthesis increased with increasing NaCl concentration in the mitochondria isolated from a halophyte, the common ice plant (Mesembryanthemum crystallinum L.). In the present study, RNA-Seq analysis was performed to determine the genes related to NaCl-stimulated ATP synthesis in the NaCl-treated cultured cells of the ice plant. We found that mRNA encoding the subunit B of ATP synthase is expressed at a higher level with NaCl. We also identified a specific amino acid sequence of the ice plant that shows high homology with vacuolar ATPase (V-ATPase, a member of ATP synthase superfamily) using BLASTP and the amino acid sequences of Na⁺-driven ATP synthases isolated from archaea. Besides, we found that ATP synthesis of the mitochondria treated with uncoupling agent to dissipate H⁺ gradient between the mitochondrial matrix and intermembrane space was maintained with NaCl. In the presentation, we will discuss the possibility of Na⁺-driven ATP synthesis and the mechanism of increased H⁺-driven ATP synthesis in the halophyte.