[P3] Abiotic Stress for Crop Production

[P3-20] Expression Analysis of Genes Involved in Removal of Na⁺ and Cl^– by Leaf Sheath in Rice

^○Sarin Neang^1,3, Nicola Stephanie Skoulding¹, Joyce A. Cartagena¹, Mana Kano-Nakata², Akira Yamauchi¹, Shiro Mitsuya¹ (1.Graduate School of Bioagricultural Sciences, Nagoya University, Japan, 2.International Center for Research and Education in Agriculture, Nagoya University, Japan, 3.Department of Agro-Industry, Ministry of Agriculture, Forestry and Fisheries, Cambodia)

A significant mechanism of salt-tolerance in rice is the ability to remove Na⁺ and Cl^– in the leaf sheath, which limits the entry of these toxic ions into the leaf blade. The leaf sheath removes Na⁺ and Cl^– in the basal and tip parts, respectively, by unloading them from xylem vessels and sequestering them into the fundamental parenchyma cells (Neang et al. 2019). This study aimed to identify Na⁺ and Cl^– transporter genes, their distribution patterns of Na⁺ and Cl^– along the longitudinal axis of leaves and in the internal tissues of leaf sheaths, and the genes that increase their expression levels under salinity. Our results indicated that OsHKT1;1, OsHKT1;5, OsNHX1, 2, 3 and 5 might be involved in the Na⁺ accumulation in basal parts of leaf sheaths under salinity. Additionally, OsHKT1;5 may be involved in Na⁺ unloading from xylem vessels. The Na⁺ accumulation in fundamental parenchyma cells is probably mediated by OsNHX3 in the central parts and OsNHX5 in the peripheral parts under salinity. Furthermore, our results indicated that Cl^– removal in leaf sheaths is possibly regulated by OsNPF2;4, OsCLC1, OsCLC2, OsSLAH1 and OsSLAH2. Cl^– accumulation in fundamental parenchyma cells might be associated with OsNPF2;4 and OsCLC2 under salinity.