A Y-chromosome–encoded small RNA acts as a sex determinant in persimmons

Y male plants affect female development Although most plants have both male and female organs within a single flower, some produce separate male and female plants. In some cases, such as persimmons, males are determined by a Y chromosome. Akagi et al. examined the gene transcript differences between male and female persimmons. A gene on the Y chromosome regulated a non–sex chromosome–linked small RNA that suppresses female organ development. This small RNA was localized to male flowers and could affect female development in other plant species. The evolutionary history of these genes suggests that they are tied to the origin of the separation of sexes in the persimmon family. Science , this issue p. 646