Evidences for a role of two Y-specific genes in sex determination in Populus deltoides
Liang‐Jiao Xue, Huaitong Wu, Yingnan Chen, Xiaoping Li, Jing Hou, Jing Lü, Suyun Wei, Xiaogang Dai, Matthew S. Olson, Jianquan Liu, Mingxiu Wang, Deborah Charlesworth, Tongming Yin
Abstract
Almost all plants in the genus Populus are dioecious (i.e. trees are either male or female), but it is unknown whether dioecy evolved in a common ancestor or independently in different subgenera. Here, we sequence the small peritelomeric X- and Y-linked regions of P. deltoides chromosome XIX. Two genes are present only in the Y-linked region. One is a duplication of a non-Y-linked, female-specifically expressed response regulator, which produces siRNAs that block this gene's expression, repressing femaleness. The other is an LTR/Gypsy transposable element family member, which generates long non-coding RNAs. Overexpression of this gene in A. thaliana promotes androecium development. We also find both genes in the sex-determining region of P. simonii, a different poplar subgenus, which suggests that they are both stable components of poplar sex-determining systems. By contrast, only the duplicated response regulator gene is present in the sex-linked regions of P. davidiana and P. tremula. Therefore, findings in our study suggest dioecy may have evolved independently in different poplar subgenera.