Functional Characterization of Wheat TaAPC11-5B in Regulating Grain Size and Weight

The anaphase-promoting complex/cyclosome (APC/C) is a conserved multisubunit Cullin-RING-type E3 ubiquitin ligase complex. It regulates mitotic progression by ubiquitinating key cell cycle regulators, thereby modulating plant growth and development. In this study, the RING domain-containing subunit TaAPC11-5B of the APC/C E3 ligase was functionally characterized as a critical regulator of wheat grain development. TaAPC11-5B was highly expressed in wheat grains at 25 days after anthesis. TaAPC11-5B exhibited intrinsic E3 ligase activity and interacted with TaAPC2. Heterologous overexpression of TaAPC11-5B in rice increased grain length, width, and weight by enhancing longitudinal cell division and lateral cell expansion, as well as promoting starch accumulation. These findings revealed the role of TaAPC11-5B in modulating grain size and weight through cell division, cell expansion, and starch accumulation, providing potential for wheat yield improvement.