MhCLC-c1, a Cl channel c homolog from Malus hupehensis, alleviates NaCl-induced cell death by inhibiting intracellular Cl– accumulation

Abstract

Abstract Background Overaccumulation of chloride (Cl) when plants suffer NaCl causes cell damage and death, and is regulated by Cl– channel protein (CLC). Apple roots are very sensitive to Cl–, but information associated with CLC is limited in apple crop that widely cultivated in the world. Results We identified 9 CLCs from the apple genome and divided them into two subclasses. Among them, MdCLC-c1 promoter contained the largest number of cis-acting elements associated with NaCl stress, and only the MdCLC-c1, MdCLC-d, and MdCLC-g were predicted that may be Cl– antiporters or channels. Expression analysis of MdCLCs homologs in the roots of Malus hupehensis showed that most of the MhCLCs expression were response to NaCl stress, especially MhCLC-c1 expression was upregulated continuously and rapidly expressed during NaCl treatment. Therefore, we isolated MhCLC-c1 and observed it was a plasma membrane-localized protein. The MhCLC-c1 suppression significantly increased sensitivity, reactive oxygen species content, and cell death of apple calli; while MhCLC-c1 overexpression decreased sensitivity, reactive oxygen species content, and cell death of apple calli and Arabidopsis by inhibiting intracellular Cl– accumulation under NaCl stress. Conclusions The study selected and isolated a CLC-c gene MhCLC-c1 from Malus hupehensis based on identification of CLCs gene family in apple, and their homologs MhCLCs expression patterns during NaCl treatments, revealing that MhCLC-c1 alleviates NaCl-induced cell death by inhibiting intracellular Cl– accumulation. Our findings confer the comprehensive and in-depth upstanding of the mechanism that plants resist salt stress, and might also confer genetic improvement of salt tolerance in horticultural crops and the development and utilization of saline–alkali land.