Thwin Myo1,2, Baoming Tian1,2, Qi Zhang1,2, Shasha Niu1,2, Zhixian Liu1,3, Yinghui Shi3, Gangqiang Cao1,2, Hua Ling3, Fang Wei4,5, Gongyao Shi6,7. 1. Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China. 2. Henan International Joint Laboratory of Crop Gene Resources and Improvement, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, Henan, China. 3. Department of Biochemistry, National University of Singapore, Singapore, 117597, Singapore. 4. Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China. fangwei@zzu.edu.cn. 5. Henan International Joint Laboratory of Crop Gene Resources and Improvement, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, Henan, China. fangwei@zzu.edu.cn. 6. Research Base, State Key Laboratory of Cotton Biology, Zhengzhou University, Zhengzhou, 450001, Henan, China. shigy@zzu.edu.cn. 7. Henan International Joint Laboratory of Crop Gene Resources and Improvement, School of Agricultural Sciences, Zhengzhou University, Zhengzhou, 450001, Henan, China. shigy@zzu.edu.cn.
Abstract
MAIN CONCLUSION: GhBASS5 is a member of the bile acid sodium symporter (BASS) gene family from cotton and a plastid-localized Na+ transporter that negatively regulates salt tolerance of plants. Soil salinization is a major constraint on global cotton production, and Na+ is the most dominant toxic ion in salinity stress. Hence, insights into the identities and properties of transporters that catalyze Na+ movement between different tissues and within the cell compartments are vital to understand the salt-tolerant mechanisms of plants. Here, we identified the GhBASS5 gene, a member of the bile acid sodium symporter (BASS) gene family from cotton, served as a plastidic Na+ transporter. GhBASS5 encodes a membrane protein localized in the plastid envelope. It was highly expressed in cotton roots and predominantly existed in the vascular cylinder. Heterogenous expression of GhBASS5 in Arabidopsis chloroplasts promoted Na+ uptake into chloroplasts, which contributed to an increased cytoplasmic Na+ concentration. And GhBASS5-overexpressed transgenic plants showed an increase in Na+ translocation from roots to shoots and an elevated Na+ content in both roots and shoots, but a dramatic decrease in the Na+ efflux from root tissues and the K+/Na+ ratio, especially under salt stress conditions. Furthermore, overexpressing GhBASS5 greatly damaged plastid functions and enhanced salt sensitivity in transgenic Arabidopsis when compared with wild-type plants under salt stress. Additionally, the salt-responsive transporter genes that regulate K+/Na+ homeostasis were dramatically expressed in GhBASS5-overexpressed lines, especially under salt stress conditions. Taken together, our results suggest that GhBASS5 is a plastid-localized Na+ transporter, and high expression of GhBASS5 impairs salt tolerance of plants via increasing Na+ transportation and accumulation at both cell and tissue levels.
MAIN CONCLUSION: GhBASS5 is a member of the bile acid sodium symporter (BASS) gene family from cotton and a plastid-localized Na+ transporter that negatively regulates salt tolerance of plants. Soil salinization is a major constraint on global cotton production, and Na+ is the most dominant toxic ion in salinity stress. Hence, insights into the identities and properties of transporters that catalyze Na+ movement between different tissues and within the cell compartments are vital to understand the salt-tolerant mechanisms of plants. Here, we identified the GhBASS5 gene, a member of the bile acid sodium symporter (BASS) gene family from cotton, served as a plastidic Na+ transporter. GhBASS5 encodes a membrane protein localized in the plastid envelope. It was highly expressed in cotton roots and predominantly existed in the vascular cylinder. Heterogenous expression of GhBASS5 in Arabidopsis chloroplasts promoted Na+ uptake into chloroplasts, which contributed to an increased cytoplasmic Na+ concentration. And GhBASS5-overexpressed transgenic plants showed an increase in Na+ translocation from roots to shoots and an elevated Na+ content in both roots and shoots, but a dramatic decrease in the Na+ efflux from root tissues and the K+/Na+ ratio, especially under salt stress conditions. Furthermore, overexpressing GhBASS5 greatly damaged plastid functions and enhanced salt sensitivity in transgenic Arabidopsis when compared with wild-type plants under salt stress. Additionally, the salt-responsive transporter genes that regulate K+/Na+ homeostasis were dramatically expressed in GhBASS5-overexpressed lines, especially under salt stress conditions. Taken together, our results suggest that GhBASS5 is a plastid-localized Na+ transporter, and high expression of GhBASS5 impairs salt tolerance of plants via increasing Na+ transportation and accumulation at both cell and tissue levels.
Entities:
Keywords:
Gossypium hirsutum bile acid sodium symporter 5 (GhBASS5); Overexpression; Plastid-localized Na+ transporter; Salt stress; Transgenic arabidopsis