作 者 ：YANG Ji
期 刊 ：植物分类学报 2001年 4期
Keywords:Multiple origins, Genome evolution,
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.