SlCCS52B, an activator of the APC/C complex, regulates fruit shape in Tomato
Résumé
Cell cycle progression is controlled by the tight regulation of the amount and activity of the main cell cycle regulators, the CYCLIN-DEPENDENT KINASEs and CYCLINs. Specific ubiquitination and targeting to degradation of these proteins participate in this regulation and are executed by the E3 ubiquitin ligase Anaphase Promoting Complex/Cyclosome (APC/C). In plants, the CCS52 proteins are activators of the APC/C complex and allow the specific targeting of proteins to be degraded by the 26S proteasome. While the involvement of CCS52A in the regulation of the endocycle, a process triggering DNA replication without mitosis, and its targeted proteins are pretty well described in several species, including tomato, only little information is available about the function of CCS52B.
We produced ccs52b mutants in tomato by CRISPR-CAS9 gene editing and studied their growth-related phenotypes. We observed that these mutants produced elongated fruit with heart-like shape, compared to control plants. Through a detailed cellular analysis overtime, we found that the altered shape is already present during ovary development and probably results from a change in cell division orientation.
To identify SlCCS52B targets potentially involved in this cell division regulation, mutant and WT ovaries at stage 11 were harvested and used for proteomic analysis. We found 789 proteins differentially accumulating with 37 increased by more than two fold in the mutant, potentially due to a lack of degradation. We are currently studying the direct interaction between SlCCS52B and these candidate targets.