AUTHOR=Wang Beifang , Zhang Yingxin , Bi Zhenzhen , Liu Qunen , Xu Tingting , Yu Ning , Cao Yongrun , Zhu Aike , Wu Weixun , Zhan Xiaodeng , Anis Galal Bakr , Yu Ping , Chen Daibo , Cheng Shihua , Cao Liyong 

TITLE=Impaired Function of the Calcium-Dependent Protein Kinase, OsCPK12, Leads to Early Senescence in Rice (Oryza sativa L.)

JOURNAL=Frontiers in Plant Science

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2019.00052

DOI=10.3389/fpls.2019.00052

ISSN=1664-462X

ABSTRACT=<p>Premature leaf senescence affects plant yield and quality, and numerous researches about it have been conducted until now. In this study, we identified an early senescent mutant <italic>es4</italic> in rice (<italic>Oryza sativa</italic> L.); early senescence appeared approximately at 60 dps and became increasingly senescent with the growth of <italic>es4</italic> mutant. We detected that content of reactive oxygen species (ROS) and malondialdehyde (MDA), as well as activity of superoxide dismutase (SOD) were elevated, while chlorophyll content, soluble protein content, activity of catalase (CAT), activity of peroxidase (POD) and photosynthetic rate were reduced in the <italic>es4</italic> mutant leaves. We mapped <italic>es4</italic> in a 33.5 Kb physical distance on chromosome 4 by map-based cloning. Sequencing analysis in target interval indicated there was an eight bases deletion mutation in <italic>OsCPK12</italic> which encoded a calcium-dependent protein kinase. Functional complementation of <italic>OsCPK12</italic> in <italic>es4</italic> completely restored the normal phenotype. We used CRISPR/Cas9 for targeted disruption of <italic>OsCPK12</italic> in ZH8015 and all the mutants exhibited the premature senescence. All the results indicated that the phenotype of <italic>es4</italic> was caused by the mutation of <italic>OsCPK12</italic>. Overexpression of <italic>OsCPK12</italic> in ZH8015 enhanced the net photosynthetic rate (<italic>P</italic><sub>n</sub>) and chlorophyll content. <italic>OsCPK12</italic> was mainly expressed in green organs. The results of qRT-PCR analysis showed that the expression levels of some key genes involved in senescence, chlorophyll biosynthesis, and photosynthesis were significantly altered in the <italic>es4</italic> mutant. Our results demonstrate that the mutant of <italic>OsCPK12</italic> triggers the premature leaf senescence; however, the overexpression of <italic>OsCPK12</italic> may delay its growth period and provide the potentially positive effect on productivity in rice.</p>