AUTHOR=Li Bo , Wang Huan , He Shan , Ding Zhaotang , Wang Yu , Li Nana , Hao Xinyuan , Wang Lu , Yang Yajun , Qian Wenjun 

TITLE=Genome-Wide Identification of the PMEI Gene Family in Tea Plant and Functional Analysis of CsPMEI2 and CsPMEI4 Through Ectopic Overexpression

JOURNAL=Frontiers in Plant Science

VOLUME=12

YEAR=2022

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2021.807514

DOI=10.3389/fpls.2021.807514

ISSN=1664-462X

ABSTRACT=<p>Pectin methylesterase inhibitor (PMEI) inhibits pectin methylesterase (PME) activity at post-translation level, which plays core roles in vegetative and reproductive processes and various stress responses of plants. However, the roles of PMEIs in tea plant are still undiscovered. Herein, a total of 51 <italic>CsPMEIs</italic> genes were identified from tea plant genome. <italic>CsPMEI1</italic>-<italic>4</italic> transcripts were varied in different tea plant tissues and regulated by various treatments, including biotic and abiotic stresses, sugar treatments, cold acclimation and bud dormancy. Overexpression of <italic>CsPMEI4</italic> slightly decreased cold tolerance of transgenic <italic>Arabidopsis</italic> associated with lower electrolyte leakage, soluble sugars contents and transcripts of many cold-induced genes as compared to wild type plants. Under long-day and short-day conditions, <italic>CsPMEI2</italic>/<italic>4</italic> promoted early flowering phenotypes in transgenic <italic>Arabidopsis</italic> along with higher expression levels of many flowering-related genes. Moreover, overexpression of <italic>CsPMEI2</italic>/<italic>4</italic> decreased PME activity, but increased sugars contents (sucrose, glucose, and fructose) in transgenic <italic>Arabidopsis</italic> as compared with wild type plants under short-day condition. These results indicate that <italic>CsPMEIs</italic> are widely involved in tea plant vegetative and reproductive processes, and also in various stress responses. Moreover, <italic>CsPMEI4</italic> negatively regulated cold response, meanwhile, <italic>CsPMEI2</italic>/<italic>4</italic> promoted early flowering of transgenic <italic>Arabidopsis</italic> via the autonomous pathway. Collectively, these results open new perspectives on the roles of PMEIs in tea plant.</p>