Tomato SIPP2C5 Is Involve in the Regulation of Fruit Development and Ripening

Abscisic acid (ABA) regulates plant development mainly through its signaling, in which ABA binds to receptors to inhibit type 2C protein phosphatases (PP2Cs). The exact roles of PP2Cs in fruit development are still unclear. In this work, we verify that tomato SIPP2CS works as a negative regulator in ABA signaling during fruit development. SIPP2C5 was inhibited by both monomeric and dimeric ABA receptors SIPYLs through ABA dose-dependent way, and it interacted physically with SIPYLs and SISnRK2s. SIPP2C5 was highly expressed in fruits induced by exogenous ABA. Plants with overexpressed SIPP2C5 had lower sensitivity to ABA, which showed faster seed germination and primary root growth compared to Wild type (WT), while SIPP2C5-suppressed plants were more sensitive to ABA. SIPP2C5-overexpression (OE) delayed fruit ripening onset, while SIPP2CSRNAi advanced fruit ripening. Alteration of SIPP2C5 expression impacts fruit quality parameters as well, including pericarp thickness, fruit shape index, seed number and weight and the soluble solid content. RNA-seq analysis revealed that there were significant expression differences of genes related to ethylene release and lycopene synthesis between WT and both SIPP2CS-OE and SIPP2C5-RNAi lines with an inversed variation. Taken together, our findings demonstrate that SIPP2C5 plays an important role in the regulation of fruit development, ripening and quality.