论文题目：Natural Variation in the ZmPIMT1 Promoter Enhances Seed Aging Tolerance by Regulating PABP2 Repair in Maize
论文作者：Yumin Zhang, Lynnette M.A. Dirk, Jingliang Zheng, Jiahao Chai, Xianbo Song,JieCao, Hao Wang, Yan Liu, Yunjun Liu, Sihan Zhen, Junjie Fu, Guoji Wang, Shixiao Li, Arthur G. Hunt, A. Bruce Downie, Tianyong Zhao
论文摘要：PROTEIN L-ISOASPARTYL O-METHYLTRANSFERASE (PIMT) promotes seed vigor by repairing damaged proteins. However, whether PIMT variants have arisen during maize (Zea mays) domestication remains unknown. Here, we found two variants in the ZmPIMT1 promoter. The ZmPIMT1 Hap C7-2 promoter exhibited stronger activity than the ZmPIMT1 Hap Z58 promoter. Maize inbred lines carrying the ZmPIMT1 Hap C7-2 promoter had greater seed vigor than ZmPIMT1 Hap Z58 lines in a population of Zhengdan 958 recombinant inbred lines (RILs) and a maize inbred population. By characterizing the maize zmpimt1 knockdown mutant, ZmPIMT1-overexpressing maize and Arabidopsis thaliana heterologous ZmPIMT1 overexpression lines, we demonstrated that ZmPIMT1 positively regulates seed vigor. Co-IP and LC-MS/MS assays showed that ZmPIMT1 interacts with and repairs damaged POLY(A) BINDING PROTEIN2 (PABP2). ZmPIMT1 stabilizes PABP2 RNA-binding activity and regulates the stability and translation efficiency of the mRNA during maize seed germination. Disruption of PABP2 decreases seed vigor in Arabidopsis thaliana. Furthermore, the F-statistics (Fixation index; FST) and nucleotide diversity (θπ) ratio between teosinte and maize lines showed that ZmPIMT1 likely has not undergone selection during maize domestication. Our findings unveil a molecular mechanism in which ZmPIMT1 regulates seed vigor in maize and highlight a potential application of the advantageous ZmPIMT1 haplotype for breeding new varieties with increased seed vigor.
蛋白质异天冬氨酸甲基转移酶（PIMT）通过修复受损蛋白质来提升种子活力，但该基因变异是否在玉米驯化过程中出现尚不明确。本研究发现ZmPIMT1启动子存在两种变异型，其中玉米ZmPIMT1单倍型C7-2启动子活性显著强于ZmPIMT1单倍型Z58启动子。在郑单958重组自交系群体和玉米自交系群体中，携带ZmPIMT1单倍型C7-2启动子的玉米品系表现出更强的种子活力。通过玉米zmpimt1基因敲低突变体、ZmPIMT1过表达玉米株系及拟南芥异源过表达株系的验证，证实ZmPIMT1对种子活力具有正向调控作用。Co-IP和LC-MS/MS分析表明，ZmPIMT1能与多聚腺苷酸结合蛋白2（PABP2）相互作用并修复其损伤，稳定PABP2的RNA结合活性，调控玉米种子萌发过程中mRNA的稳定性及翻译效率。拟南芥中PABP2功能缺失会降低种子活力。此外发现ZmPIMT1在玉米驯化过程中未经历选择。本研究揭示了ZmPIMT1调控玉米种子活力的分子机制，为利用优势单倍型ZmPIMT1培育玉米高活力种子新品种提供了潜在应用策略。
原文链接：https://academic.oup.com/plcell/advance-article/doi/10.1093/plcell/koaf217/8257766