A unique transposable element insertion affecting CmaCPK4 leads to subgynoecy in pumpkin (Cucurbita maxima D.)

Pumpkin (C. maxima D.) is an important Cucurbitaceae family member and an important worldwide vegetable whose yield is related to its degree of femaleness. Although some quantitative trait loci that affect subgynoecy properties in pumpkin have been reported, the genes responsible and the underlying mechanisms remain poorly understood. In this study, we identified a pumpkin novel subgynoecy (sg1) mutant that exhibited a distinctive phenotypic trait, including produce few male flowers in the beginning nodes and all female unisexual flowers in the later nodes. We clarified CmaCPK4 was the candidate causal gene, and a retrotransposon insertion identified within promoter elevated CmaCPK4 expression in the sg1 mutant.