Park Sung-chul;Yu Yi-cheng;Kou Meng;Yan Hui;Tang Wei;Wang Xin;Liu Ya-ju;Zhang Yun-gang;Sang-soo, Kwak;Ma Dai-fu;Sun Jiang;Li Qiang

Korea Res Inst Biosci & Biotechnol, Plant Syst Engn Res Ctr, Daejeon 305806, South Korea;Chinese Acad Agr Sci, Xuzhou Inst Agr Sci Jiangsu Xuhuai Dist, Key Lab Biol & Genet Breeding Sweet Potato, Minist Agr,Sweet Potato Res Inst, Xuzhou 221131, Peoples R China;Jiangsu Normal Univ, Inst Integrat Plant Biol, Sch Life Sci, Xuzhou 221116, Peoples R China

IbHKT1;Na+/K+ transporter;salt stress;sweet potato

Soil salinity causes the negative effects on the growth and yield of crops. In this study, two sweet potato (Ipomoea batatas L.) cultivars, Xushu 28 (X-28) and Okinawa 100 (O-100), were examined under 50 and 100 mmol L-1 NaCl stress. X-28 cultivar is relatively high salt tolerant than O-100 cultivar. Interestingly, real-time quantitative polymerase chain reaction (RT-qPCR) results indicated that sweet potato high-affinity K+ transporter 1 (IbHKT1) gene expression was highly induced by 50 and 100 mmol L-1 NaCl stress in the stems of X-28 cultivar than in those of O-100 cultivar, but only slightly induced by these stresses in the leaves and fibrous roots in both cultivars. To characterize the function of IbHKT1 transporter, we performed ion-flux analysis in tobacco transient system and yeast complementation. Tobacco transient assay showed that IbHKT1 could uptake sodium (Na+). Yeast complementation assay showed that IbHKT1 could take up K+ in 50 mmol L-1 K+ medium without the presence of NaCl. Moreover, Na+ uptake significantly increased in yeast overexpressing IbHKT1. These results showed that IbHKT1 transporter could have K+-Na+ symport function in yeast. Therefore, the modes of action of IbHKT1 in transgenic yeast could differ from the mode of action of the other HKT1 transporters in class I. Potentially, IbHKT1 could be used to improve the salt tolerance nature in sweet potato.