Genome-wide identification and functional characterization of pectin methylesterase inhibitors associated with male sterility in wheat

Pectin methylesterase inhibitors (PMEIs) can specifically bind to pectin methylesterases (PMEs) and regulate their enzymatic activities to control the status of pectin methyl esterification, which plays crucial roles in stabilizing the cell wall properties during plant growth and development. Although the evolution and biological functions of the PMEI gene family in various plants have been well characterized, the role of PMEI genes in wheat was poorly understood. In this study, a total of 237 PMEI genes (TaPMEIs) were identified in wheat (Triticum aestivum L.), which were dispersed irregularly over 22 chromosomes and tissue-specific in their expression. They were divided into nine groups based on similar motif number and composition. Using quantitative real-time PCR analysis, we discovered that TaPMEI23 as the most abundant-expressed PMEI in anther and significantly upregulated expression in fertile anthers. Moreover, subcellular localization analysis indicated that TaPMEI23 was localized on the plasma membrane or cell wall. Effective silencing of the TaPMEI23 significantly influences the anther dehiscence, pollen activity, seed setting rate, and male fertility, suggesting that PMEIs are necessary for pollen development and male sterility. Our work provides novel insights into the functions of PMEIs in wheat.