《植物生理学报》 2015, 51(10): 1719-1728

拟南芥PKS5激酶磷酸化ABI5参与植物ABA响应

赵菲佚^*, 焦成瑾, 陈荃, 王太术, 田春芳, 高雅梅

天水师范学院生物工程与技术学院, 甘肃天水741001

通信作者：赵菲佚；E-mail: tspaulzhao@163.com；Tel: 0938-8362830

摘　要：

植物激素脱落酸(abscisic acid, ABA)在植物生长、发育及环境胁迫中起着重要的作用。本研究发现拟南芥PKSes (SOS2-like protein kinases)蛋白激酶家族成员PKS5 (SOS2-like protein kinase 5)参与植物ABA响应。PKS5功能获得性点突变体pks5-3与pks5-4表现出对ABA的敏感表型。在外源ABA处理下, pks5-3与pks5-4种子萌发率降低, 幼苗生长矮小、黄化。体外磷酸化测试显示, PKS5特异磷酸化ABA响应元件ABI5 (ABA-insensitive 5) N末端多肽(1~211 aa)。qRT-PCR分析表明pks5-3与pks5-4突变体中ABI5下游ABA响应基因RAB18 (RESPONSIVE TO ABA18)与EM6 (LATE EMBRYOGENESIS ABUNDANT 6)表达均发生改变。这些研究结果表明, 拟南芥PKS5通过磷酸化ABI5的N末端参与植物ABA响应过程。

关键词：PKS5; ABI5; ABA响应; 磷酸化

收稿：2015-05-15   修定：2015-08-25

PKS5 Kinase is Involved in ABA Response through Phosphorylating ABI5 in Arabidopsis

ZHAO Fei-Yi^*, JIAO Cheng-Jin, CHEN Quan, WANG Tai-Shu, TIAN Chun-Fang, GAO Ya-Mei

School of Bioengineering & Biotechnology, Tianshui Normal University, Tianshui, Gansu 741001, China

Corresponding author: ZHAO Fei-Yi; E-mail: tspaulzhao@163.com; Tel: 0938-8362830

Abstract:

The phytohormone abscisic acid (ABA) plays an essential role in plant growth and development as well as abiotic stress responses. In this study, we found that PKS5 (SOS2-like protein kinase 5), a family member of PKSes (SOS2-like protein kinases), involved in ABA response in Arabidopsis. PKS5 gain-of-function point mutants pks5-3 and pks5-4 exhibited hypersensitive to ABA in the phenotypic test. Additionally, seed germinations of pks5-3 and pks5-4 decreased and seedlings of them showed stunted growth and leaf chlorotic symptoms under exogenous ABA treatment. In vitro phosphorylation assay indicated that PKS5 specifically phosphorylates the ABA-responsive component ABI5 (ABA-insensitive 5) N terminus fragment range from 1 to 211 amino acids. Moreover, the relative expression levels of RAB18 and EM6, which are the downstream ABA-responsive genes of ABI5, significantly altered in pks5-3 and pks5-4 mutants compared with the wildtype plants by quantitative real-time PCR using gene-specific primers. Taken together, the results of this study revealed that PKS5 involves in ABA response via phosphorylating the N-terminus of ABI5 in Arabidopsis.

Key words: PKS5; ABI5; ABA response; phosphorylation