GT1 regulates maize sex determination by affecting the jasmonate pathway

SUMMARY Maize ( Zea mays L.) is a monoecious plant with male and female flowers physically separated on different inflorescences—the tassel and the ear. Maize sex determination is controlled by a series of complicated developmental signals. Here, we characterized an EMS‐induced maize feminized tassel mutant, tasselsilk1 ( tsk1 ), and identified GRASSY TILLERS1 ( GT1 ) as the causative gene. Phenotypic analysis of tsk1 mutants revealed that pistils fail to abort in both the tassel and ear, resulting in long sterile silks in the tassel and the development of an extra small kernel from the lower floret in the ear. RNA‐seq and CUT&Tag analysis indicated that GT1 functioned as a repressor for flower organ development by regulating the JA biosynthesis and signaling pathways, specifically by directly promoting the expression of TASSELSEED1 ( TS1 ), ZmMYC2A , ZmMYC2B. Together, we identified a new allele of GT1 and proposed that GT1 functions through JA biosynthesis and signaling pathways to regulate sex determination in maize.