Abstract

Chloride channels (CLCs) are kinds of anion transport protein family members that are mainly distributed in cell endomembrane systems of prokaryotic and eukaryotic organisms and mediate anion (Cl − , as a representative) transport and homeostasis. Some CLC genes have been reported to be involved in Cl − /salt tolerance of plants exposed to NaCl stress. Through BLAST in cotton database, a total of 22 CLC s were identified in genomes A and D in upland cotton ( Gossypium hirsutum L.), and except for GhCLC6 and GhCLC17 , they formed highly similar homologous genes pairs. According to the prediction in PlantCARE database, many cis-acting elements related to abiotic stress responses, including ABREs, AREs, GT-1s, G-boxes, MYBs, MYCs, etc., were found in the promoters of GhCLC s. qRT-PCR revealed that most GhCLC gene expression was upregulated in the roots and leaves of cotton seedlings under salt stress, and those of homologous GhCLC4/15 , GhCLC5/16 , and GhCLC7/18 displayed more obvious expression. Furthermore, according to leaf virus-induced gene silencing (VIGS) assay and compared with the salt-stressed GhCLC4/15- and GhCLC7/18- silenced cotton plants, the salt-stressed GhCLC5/16- silenced plants displayed relatively better growth with significant increases in both Cl − content and Cl − /NO 3 − ratio in the roots and drop of the same parameters in the leaves. These results indicate that homologous GhCLC5/16 , with the highest NaCl − induced upregulation of expression and the maximum number of MYC cis-acting elements, might be the key members contributing to cotton Cl − /salt tolerance by regulating the transport, interaction and homeostasis of Cl − and NO 3 − .