Identification and functional characterization of anaphase-promoting complex/cyclosome subunits in tomato

The anaphase-promoting complex/cyclosome (APC/C), a multiunit-E3 ligase, governs both mitotic and non-mitotic pathways by interacting with ubiquitinated proteins. However, developmental functions of APC/C subunits in tomato have been rarely studied. Here, we identified a total of nine APC/C subunits in tomato genome and established their functions in leaf and fruit development via VIGS gene silencing technology. Protein interactions between subunits revealed that tomato ‘Heinz 1706’ had a slightly different APC/C structure from other systems, in which APC8 and APC10 had the most interactions. Silencing APC/C subunits in tomato led to smaller plants with significantly reduced plant height, biomass, leaf area, flower size and fruit size. Cytological analyses confirmed that silencing APC/C subunits repressed both cell division and expansion in tomato leaves and fruits. Both flow cytometric and mitotic index analyses verified the positive role of APC/C in regulating M phase of cell cycle, which led to increased DNA contents in cells of silencing plants. APC1, APC2, APC4, APC11 and CDC27a had more impacts on the floral organ development than other subunits. Silencing APC/C subunits reduced the pollen viability due to unbalanced meiotic division. APC4 and APC6 were important for the fruit maturation while APC1, APC4 and APC10 modulated the fruit shape. Taken together, our findings illustrate that APC/C is essential for tomato development through the modulation of mitotic and meiotic division, and different subunits may have distinct or more profound impacts on the certain tissue development than others.