Table_2_Genome-Wide Identification of the PMEI Gene Family in Tea Plant and Functional Analysis of CsPMEI2 and CsPMEI4 Through Ectopic Overexpression.XLSX

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 CsPMEIs genes were identified from tea plant genome. CsPMEI1-4 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 CsPMEI4 slightly decreased cold tolerance of transgenic Arabidopsis 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, CsPMEI2/4 promoted early flowering phenotypes in transgenic Arabidopsis along with higher expression levels of many flowering-related genes. Moreover, overexpression of CsPMEI2/4 decreased PME activity, but increased sugars contents (sucrose, glucose, and fructose) in transgenic Arabidopsis as compared with wild type plants under short-day condition. These results indicate that CsPMEIs are widely involved in tea plant vegetative and reproductive processes, and also in various stress responses. Moreover, CsPMEI4 negatively regulated cold response, meanwhile, CsPMEI2/4 promoted early flowering of transgenic Arabidopsis via the autonomous pathway. Collectively, these results open new perspectives on the roles of PMEIs in tea plant.

果胶甲酯酶抑制剂（Pectin methylesterase inhibitor, PMEI）可在翻译后水平抑制果胶甲酯酶（Pectin methylesterase, PME）的活性，在植物的营养与生殖过程以及各类胁迫响应中发挥核心作用。然而，PMEI家族在茶树中的功能仍未被阐明。本研究从茶树基因组中共鉴定得到51个CsPMEI家族基因。CsPMEI1至CsPMEI4的转录本在茶树不同组织中存在表达差异，并受多种处理调控，涵盖生物胁迫、非生物胁迫、糖处理、冷驯化与芽休眠诱导。过表达CsPMEI4会轻微降低转基因拟南芥的耐寒性，与野生型植株相比，转基因株系的电解质渗漏率、可溶性糖含量以及多个冷诱导基因的转录水平均更低。在长日照与短日照培养条件下，过表达CsPMEI2/4可使转基因拟南芥呈现早花表型，同时多个开花相关基因的表达水平显著上调。此外，在短日照条件下，与野生型植株相比，CsPMEI2/4过表达可降低转基因拟南芥体内的PME活性，并提升蔗糖、葡萄糖与果糖的含量。上述结果表明，CsPMEI家族广泛参与茶树的营养与生殖过程，同时也参与各类胁迫响应；其中CsPMEI4负调控低温响应，而CsPMEI2/4则通过开花自主通路促进转基因拟南芥提早开花。综上，本研究结果为解析PMEI家族在茶树中的功能提供了全新的研究视角。