CsCLE3 delays female flower anthesis in cucumber

A corolla opening is a necessary process affecting the quality of fruits and market competitiveness in cucumber (Cucumis sativus). In the previous paper, we identified a unique cucumber line (‘6457’) that possesses extra-long ovaries and shows a delayed corolla opening when nutrient supplies are abundant. We also previously showed that the expression of CsCLE3 (Csa4G627800) is correlated with the delayed opening of the female corolla. Here, we investigated the function of CsCLE3 in cucumber by conducting transgenic experiments and phenotypic analysis. The results showed that the expression of CsCLE3 in the extra-long ovary was significantly lower than in the typical ovary. In CsCLE3-overexpressed plants, the capacity to produce extra-long ovaries was lost, and the average rates of the extra-long ovary and the extra-long ovary plant were both 0%. In the CsCLE3 knockout plants obtained by the CRISPR/Cas9 system, the average extra-long ovary and extra-long ovary plant rates were significantly higher- 66.67% and 100%, respectively. Our study proved a negative regulating corolla opening time factor and provides new insight into the molecular basis of cucumber reproduction, producing fruits with flowers remaining on the tip.