Significance and biological consequences of polyploidization in land plant evolution

Abstract

Although plant polyploidization is ubiquitous in nature, polyploidy has long been considered an evolutionary dead end, precluding further species diversification. However, recent genome sequencing projects have revealed that most, if not all angiosperms are in fact ancient polyploids, and that many plant species have undergone multiple whole-genome duplications (WGDs) in their evolutionary history. Moreover, studies investigating the genomic remains of WGDs have revealed that genome duplications have been essential for the expansion of developmentally important gene families, that they may have been crucial for plant speciation, diversification and evolutionary innovation, and that they may have facilitated the survival of plant species following large-scale ecological catastrophes. Although the significance of polyploidy in the evolution of angiosperms is now undeniable, many questions remain unanswered. A better understanding of WGDs and their consequences is crucial to really understand plant evolution. In this chapter, we discuss how genomic traces of ancient WGDs can be identified and dated, we describe the molecular biological consequences of polyploidization on shorter and longer evolutionary timescales, and we discuss in detail how WGDs might have contributed to the evolutionary success of descendant plant lineages.