Devos Katrien M, Brown James K M, Bennetzen Jeffrey L
John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom.
Genome Res. 2002 Jul;12(7):1075-9. doi: 10.1101/gr.132102.
Genome size varies greatly across angiosperms. It is well documented that, in addition to polyploidization, retrotransposon amplification has been a major cause of genome expansion. The lack of evidence for counterbalancing mechanisms that curtail unlimited genome growth has made many of us wonder whether angiosperms have a "one-way ticket to genomic obesity." We have therefore investigated an angiosperm with a well-characterized and notably small genome, Arabidopsis thaliana, for evidence of genomic DNA loss. Our results indicate that illegitimate recombination is the driving force behind genome size decrease in Arabidopsis, removing at least fivefold more DNA than unequal homologous recombination. The presence of highly degraded retroelements also suggests that retrotransposon amplification has not been confined to the last 4 million years, as is indicated by the dating of intact retroelements.
被子植物的基因组大小差异很大。有充分的文献记载，除了多倍体化之外，逆转座子扩增一直是基因组扩张的主要原因。由于缺乏抑制基因组无限制增长的平衡机制的证据，我们许多人不禁要问，被子植物是否走上了“通往基因组肥胖的单程票”。因此，我们研究了一种基因组特征明确且特别小的被子植物——拟南芥，以寻找基因组DNA丢失的证据。我们的结果表明， illegitimate重组是拟南芥基因组大小减小的驱动力，其去除的DNA至少比不等位同源重组多五倍。高度降解的逆转录元件的存在也表明，逆转座子扩增并不局限于过去400万年，这是完整逆转录元件的年代测定所表明的。
