Fine Mapping and Candidate Gene Validation of Tomato Gene Carpelloid Stamen and Parthenocarpy (CSP)

Abstract

Parthenocarpy and male sterility are highly desirable traits in tomato breeding and molecular study. The stamen carpelloid mutant generally displays male sterility. A natural mutant displaying carpelloid stamen and parthenocarpy (csp) was identified in our research group. In this study, the csp locus was finely mapped to a 65 kb interval, which contained six putative genes. One of them, Solyc04g081000, encodes the tomato class B MADS box gene TAP3 (syn. SlDEF). Sequencing data revealed that a copia long terminal repeat retrotransposon was inserted in the first intron of the TAP3 gene of the csp mutant. qRT-PCR showed that the expression of TAP3 was significantly down-regulated in the petals and stamens of the csp mutant. A phenotypic analysis of the TAP3 gene-edited mutants and allelism tests indicated that TAP3 was the gene underlying csp, and csp was a novel allelic mutation of TAP3. The results of this study will lay the foundation for a further analysis of the function of TAP3 and provide materials and a basis for a further study of the functional differentiation of tomato B-class genes.