The formation and evolution of polyploid genomes in plants

YANG Ji

Abstract:

Polyploidy is widely acknowledged as a major mechanism of adaptation and speciation in

plants. Recent estimates suggest that 70% of all angiosperms have experienced one or more episodes

of polyploidization. Interdisciplinary approaches combining phylogenetic and molecular genetic per-

spectives have enhanced our awareness of the myriad genetic interactions made possible by

polyploidy. In this paper, cytological mechanisms of polyploid formation and processes and mecha-

nisms of gene and genome evolution in polyploids are reviewed. In many cases, spontaneous

polyploids have cytotypes that appear to have been formed by the union of reduced and unreduced

gametes. Recent studies demonstrate that most polyploid species have formed recurrently from differ-

ent populations of their progenitors. Genes duplicated by polyploidy may retain their original or simi-

lar function, undergo diversification in protein function or regulation, or one copy may become si-

lenced through mutational or epigenetic means. Duplicated genes also may interact through inter-lo-

cus recombination, gene conversion, or concerted evolution. Extensive and rapid genome restructur-

ing can occur after polyploidization. These include inter-genomic chromosomal exchanges, non-Men-

delian genomic evolution in nascent polyploids, inter-genomic invasion, and cytonuclear stabiliza-

tion. Continued application of molecular genetic approaches to questions of polyploid genome evolu-

tion holds promise for producing lasting insight into processes by which novel genotypes are generated

and ultimately into how polyploidy facilitates evolution and adaptation.

Key words: Polyploid plants, Multiple origins, Genome evolution

YANG Ji. The formation and evolution of polyploid genomes in plants[J]. , 2001, 39(4): 357-372.

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