江元清等《Journal of Experimental Botany》2019

　　论文题目：Arabidopsis CPK6 positively regulates ABA signaling and drought tolerance through phosphorylating ABA-responsive element binding factors

　　论文作者：Hanfeng Zhang, Daoyin Liu, Bo Yang, Wu-Zhen Liu, Bangbang Mu,Huaxin Song, Bingyou Chen, Yuan Li, Dongtao Ren, Hanqing Deng,Yuan-Qing Jiang

　　论文摘要：Abscisic acid (ABA) regulates numerous developmental processes and drought tolerance in plants. Calcium-dependent protein kinases (CPKs) are important Ca2+ sensors playing crucial roles in plant growth and development as well as responses to stresses. However, the molecular mechanisms of many CPKs in ABA signalings and drought tolerance remain largely unknown. Here we combined protein interaction studies, biochemical and genetic approaches to identify and characterize substrates that were phosphorylated by CPK6 and elucidated the mechanism that underlines role of CPK6 in ABA signaling and drought tolerance. The expression of CPK6 is induced by ABA and dehydration. Two cpk6T-DNA insertion mutants are insensitive to ABA during seed germination and root elongation of seedlings, in contrast, overexpression of CPK6 showed the opposite phenotype. Moreover, CPK6-overexpressing lines showed enhanced drought tolerance. CPK6 interacts with and phosphorylates a subset of core ABA signaling-related transcription factors, ABA-responsive element binding factors (ABFs/AREBs) and enhances their transcriptional activities. The phosphorylation sites in ABF3 and ABI5 were also identified through mass spectrometry and mutational analyses. Taken together, we present evidences that CPK6 mediates ABA signaling and drought tolerance through phosphorylating ABFs/AREBs. This work thus uncovers a rather conserved mechanism of calcium-dependent Ser/Thr kinases in ABA signaling.

　　论文链接：https://doi.org/10.1093/jxb/erz432