Sex expression in the maize tassel (which only has male flowers) results from the halting of female organ development, but the genetic regulation of this process is unknown. Acosta et al. identify a major gene involved in male floral specificity by mapping and identifying the function of the tasselseed1 gene. Surprisingly, the gene is not a standard transcription factor but rather appears to be plastid localized and involved in the jasmonic acid pathway. The ts1 mutants have reduced amounts of jasmonate and flowers that contain both pistils and stamens, instead of male tassels. Exogenous jasmonate can rescue the mutant phenotype. Thus, jasmonate (or its metabolites) is required to suppress female development in male flowers in maize.
I. F. Acosta, H. Laparra, S. P. Romero, E. Schmelz, M. Hamberg, J. P. Mottinger, M. A. Moreno, S. L. Dellaporta, tasselseed1 is a lipoxygenase affecting jasmonic acid signaling in sex determination of maize. Science 323, 262–265 (2009). [Abstract] [Full Text]