Abstract
CBL-interacting protein kinases are involved in plant responses to abiotic stresses, including salt stress. However, the negative regulating mechanism of this gene family in response to salinity is less reported. In this study, we evaluated the role of TaCIPK25 in regulating salt response in wheat. Under conditions of high salinity, TaCIPK25 expression was markedly down-regulated in roots. Overexpression of TaCIPK25 resulted in hypersensitivity to Na+ and superfluous accumulation of Na+ in transgenic wheat lines. TaCIPK25 expression did not decline in transgenic wheat and remained at an even higher level than that in wild-type wheat controls under high-salinity treatment. Furthermore, transmembrane Na+/H+ exchange was impaired in the root cells of transgenic wheat. These results suggested that TaCIPK25 negatively regulated salt response in wheat. Additionally, yeast-one-hybrid, β-glucuronidase activity and DNA-protein-interaction-enzyme-linked-immunosorbent assays showed that the transcription factor TaWRKY9 bound W-box in the TaCIPK25 promoter region. Quantitative real-time polymerase chain reaction assays showed concomitantly inverted expression patterns of TaCIPK25 and TaWRKY9 in wheat roots under salt treatment, ABA application and inhibition of endogenous ABA condition. Overall, based on our results, in a salt stress condition, the negative salt response in wheat involved TaCIPK25 with the expression regulated by TaWRKY9.
Highlights
Acid (ABA)-dependent and -independent pathways, several transcription factors and promoter elements have been identified in salt-stress signaling of plants[28]
We demonstrated that TaWRKYs were involved in improving stress tolerance in transgenic tobacco[33,34]; we selected three representative TaWRKY transcription factors (TaWRKY1, TaWRKY9 and TaWRKY44) to verify the interactions with promoters of TaCIPK25
The expression patterns of TaWRKY9 were in contrast to those of TaCIPK25 (Fig. 3B)
Summary
Acid (ABA)-dependent and -independent pathways, several transcription factors and promoter elements have been identified in salt-stress signaling of plants[28]. The detailed regulation of CIPKs in these signaling pathways is less characterized. We isolated a wheat CIPK, i.e., TaCIPK25 (homology to AtCIPK12, 18 and 19)[29]. In this study, based on our results, the overexpression of TaCIPK25 impaired salt tolerance, which was mediated by a WRKY transcription factor in an ABA-dependent pathway under saline conditions
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