Breeding Systems, Mating Systems, and Genomics of Gender Determination in Angiosperm Trees

Abstract

Angiosperm trees and non-woody plants differ in the prevalence of different genetic transmission systems with the potential to result in categorical differences in adaptive capacity and genomic structure. Decades of careful investigations have revealed that although most tree species are hermaphroditic (perfect flowers), dioecy (unisexual individuals) is more common than throughout the angiosperms, and self-fertilization is exceedingly rare. These patterns indicate that the benefits of outcrossing are strong drivers of the evolution of angiosperm trees. Moreover, patterns of the evolution of genetic sex determination regions in dioecious trees are highly dynamic, including differences between closely related species and genera in the genetic characteristics and location of sex determination regions and which sex is heterogametic (XY vs. ZW). This short review emphasizes that investigations of factors influencing genetic transmission are likely to provide answers to fundamental questions regarding genomic and phenotypic evolution in angiosperm trees.