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.