CHLORIDE CHANNEL 1 promotes drought tolerance in rice, leading to increased grain yield

Abstract

Plant chloride channels (CLCs) localize to the plasma and organellar membranes; these channels play pivotal roles in the modulation of ion homeostasis and cell turgor. Recent studies have shown that the expression of CLCs is involved in plant responses to environmental stress. Here, we examined the rice (Oryza sativa) tonoplast-localized channel OsCLC1. OsCLC1 is preferentially expressed in roots, and therefore, we generated transgenic rice with root-specific overexpression of OsCLC1 (RCc3::OsCLC1). We also identified a T-DNA mutant line that lacks expression of OsCLC1 (osclc1). We found that RCc3::OsCLC1 rice plants showed increased tiller number and grain yield, whereas the osclc1 plants exhibited decreased tiller number and grain yield, compared with wild type. These observations suggest that expression of OsCLC1 affects rice growth and productivity. Furthermore, RCc3::OsCLC1 plants showed enhanced drought tolerance, leading to increased grain yield compared to wild-type plants grown under the same conditions. By contrast, osclc1 mutants exhibited reduced drought tolerance and productivity compared to wild-type plants. When expression of OsCLC1 was analyzed in drought, jasmonic acid (JA) or abscisic acid (ABA)-treated rice, expression of OsCLC1 was preferentially upregulated in roots in response to drought and JA, and was preferentially upregulated in shoots in response to ABA. Together with the finding that expression of OsCLC1 is positively correlated both with expressions of OsDREB1A and OsbHLH148, key transcription factors in drought and JA responses, respectively, these results suggest that OsCLC1 regulates drought tolerance in rice and JA signaling is involved in this process.