Tasselseed5 encoding a cytochrome C oxidase affects jasmonate catabolism in sex determination of maize.

Maize is a bisexual grass plant. The mature male and female florets form in tassel and ear respectively, thus maize is a model plant used to study flower development. Several tasselseed mutants have a reversal in sex determination, which leads to the generation of kernels in tassel eventually, such as two recessive mutants, tasselseed1(ts1) and tasselseed2(ts2). The phenotype of Tasselseed5 (Ts5) mutant is similar with ts2, and it is a dominant mutant. We positionally cloned the responsible gene and characterized the function of Ts5. There is an overexpression of GRMZM2G177668 gene in Ts5 mutant. This gene encodes a cytochrome C oxidase, which can transform jasmonoyl-L-isoleucine (JA-Ile) to 12OH-JA-Ile. Consistent with this, there is no JA-Ile peak in Ts5 mutant tassel during sex determinate period compared with wide type. Furthermore, overexpression of GRMZM2G177668 in transgenic maize plants generates tassel seed phenotype similar as Ts5. These results indicate that JA-Ile peak in tassels during sex determinate period is critical for sex determination, and Ts5 mutant phenotype results from the interruption of JA-Ile peak in tassels during sex determination. This article is protected by copyright. All rights reserved.