Cell cycle progression is tightly regulated through the control of both the amount and activity of key regulators, CYCLIN-DEPENDENT KINASEs (CDKs) and CYCLINs. A critical aspect of this regulation involves the targeted degradation of these proteins by the 26S proteasome via ubiquitination mediated by the E3 ubiquitin ligase complex known as the Anaphase Promoting Complex/Cyclosome (APC/C). In plants, APC/C activity is modulated by CCS52 proteins, which act as activators enabling the selective degradation of target proteins.In our study, we identified a third CCS52 homologue in the tomato genome, SlCCS52A2, which shares high amino acid sequence similarity with SlCCS52A1. Building on previous research on SlCCS52A1 and the known partially redundant functions of the two AtCCS52A homologues in Arabidopsis, we performed a comparative phenotypic analysis of knockout lines for both SlCCS52A genes. Our aim was to clarify the role of SlCCS52A2.Our findings indicate that SlCCS52A1 and SlCCS52A2 in tomato retain conserved functions similar to their Arabidopsis counterparts but also exhibit distinct roles. Specifically, SlCCS52A1 is a positive regulator of endoreduplication and inhibits cell division in endoreduplicated cells, whereas SlCCS52A2 appears to play a key role in maintaining meristem function and inhibits cell division in the ovary.Read less <