Functional analysis ofSalix purpureagenes support roles forARR17andGATA15as master regulators of sex determination

Abstract

AbstractThe Salicaceae family is of growing interest in the study of dioecy in plants because the sex determination region (SDR) has been shown to be highly dynamic, with differing locations and heterogametic systems between species. Without the ability to transform and regenerateSalixin tissue culture, previous studies investigating the mechanisms regulating sex in the genusSalixhave been limited to genome resequencing and differential gene expression, which are mostly descriptive in nature, and functional validation of candidate sex determination genes has not yet been conducted. Here we used Arabidopsis to functionally characterize a suite of previously identified candidate genes involved in sex determination and sex dimorphism in the bioenergy shrub willowSalix purpurea. Six candidate master regulator genes for sex determination were heterologously expressed in Arabidopsis, followed by floral proteome analysis. In addition, 11 transcription factors with predicted roles in mediating sex dimorphism downstream of the SDR were tested using DAP-Seq in both male and femaleS. purpureaDNA. The results of this study provide further evidence to support models for the roles ofARR17andGATA15as master regulator genes of sex determination inS. purpurea, contributing to a regulatory system that is notably different from that of its sister genusPopulus. Evidence was also obtained for the roles of two transcription factors, anAP2/ERFfamily gene and a homeodomain-like transcription factor, in downstream regulation of sex dimorphism.