植物基因组大小进化的研究进展

Recent progress in plant genome size evolution

不同的真核生物之间基因组大小差异很大,并与生物体复杂性不相关,在基因组中存在大量的非编码DNA序列是造成这种差异的主要原因,特别是转座子序列。文章综述了植物基因组大小差异以及引起这种差异的主要进化动力的最新研究进展。植物基因组多倍化和转座子积累是导致基因组增大的主要动力,而同源不平等重组和非正规重组则是驱动基因组DNA丢失的潜在动力,以制约基因组无限制地增大。文中还讨论了植物基因组大小进化方向,即总体趋势是朝着增大的方向进化,某些删除机制主要是削弱这种增大作用但不能逆转。

It has been known that eukaryotic genomes span a wide range of sizes regardless of organism complexity. The observed differences in genome size are primarily due to polyploidy level and abundance of non-coding DNA, especially the contribution of transposable elements （TEs）. Here we reviewed the current progress in genome size variation of plant species and the underlying evolutionary forces that contribute to genome expansion or contraction. Polyploidization and the accumulation of transposable element are the primary contributors to genome expansion. As to the mechanisms of DNA loss, unequal homologous recombination and illegitimate recombination are thought to be the counterbalances to the unlimited expansion of a genome. The evolutionary direction of plant genome size is also discussed, which tends to favor larger genomes with deletion mechanisms acting to only attenuate genome expansion but not reverse.