Soybean CHX-type ion transport protein GmSALT3 confers leaf Na⁺ exclusion via a root derived mechanism, and Cl⁻ exclusion via a shoot derived process | Soybean CHX-type ion transport protein GmSALT3 confers leaf Na(+) exclusion via a root derived mechanism, and Cl(-) exclusion via a shoot derived process
2021
Qu, Y. | Guan, R. | Bose, J. | Henderson, S.W. | Wege, S. | Qiu, L. | Gilliham, M.
Soybean (Glycine max) yields are threatened by multiple stresses including soil salinity. GmSALT3 (a cation-proton exchanger protein) confers net shoot exclusion for both Na⁺ and Cl⁻ and improves salt tolerance of soybean; however, how the ER-localised GmSALT3 achieves this is unknown. Here, GmSALT3's function was investigated in heterologous systems and near-isogenic lines that contained the full-length GmSALT3 (NIL-T; salt-tolerant) or a truncated transcript Gmsalt3 (NIL-S; salt-sensitive). GmSALT3 restored growth of K⁺ -uptake-defective E. coli and contributed toward net influx and accumulation of Na⁺ , K⁺ , and Cl⁻ in Xenopus laevis oocytes, while Gmsalt3 was non-functional. Time-course analysis of NILs confirmed shoot Cl⁻ exclusion occurs distinctly from Na⁺ exclusion. Grafting showed that shoot Na⁺ exclusion occurs via a root xylem-based mechanism; in contrast, NIL-T plants exhibited significantly greater Cl⁻ content in both the stem xylem and phloem sap compared to NIL-S, indicating that shoot Cl⁻ exclusion likely depends upon novel phloem-based Cl⁻ recirculation. NIL-T shoots grafted on NIL-S roots contained low shoot Cl⁻ , which confirmed that Cl⁻ recirculation is dependent on the presence of GmSALT3 in shoots. Overall, these findings provide new insights on GmSALT3's impact on salinity tolerance and reveal a novel mechanism for shoot Cl⁻ exclusion in plants.
Show more [+] Less [-]Yue Qu, Rongxia Guan, Jayakumar Bose, Sam W. Henderson, Stefanie Wege, Lijuan Qiu, Matthew Gilliham
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