Molecular evolution of the chalcone synthase multigene family in the morning glory genome
Molecular evolution of the chalcone synthase multigene family in the morning glory genome
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DOI：
10.1023/a:1006375904820
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发表时间：
2000-01-01
影响因子：
5.1
通讯作者：
Clegg, MT
中科院分区：
文献类型：
--
作者：
Durbin, ML;McCaig, B;Clegg, MT
植物基因组似乎利用基因复制过程作为获得生化和发育灵活性的主要手段。因此，例如，植物次生代谢的大多数酶成分都是由小基因家族编码的，这些基因起源于进化过程中的复制。编码查尔酮合成酶(CHS)的基因很好地说明了基因家族进化的动态，查尔酮合成酶是类黄酮生物合成的第一步。我们回顾了开花植物中CHS进化的相关事实，特别是牵牛花属，Ipomoea。我们的综述表明，在开花植物进化过程中，新的CHS基因被反复招募。在新的重复基因中，核苷酸替换的速度经常加快，而且有明确的证据表明，在CHS基因的重复副本中，酶功能反复发生变化。此外，我们还提供了有关常见牵牛花(I.Purpurea)CHS基因表达模式随组织和发育阶段变化的新数据。这些数据表明CHS基因的重复拷贝之间在基因表达上存在广泛的差异。我们还表明，阻止花瓣花青素生物合成的单个突变与牵牛花基因组中存在的六个重复CHS基因之一的表达缺失有关。这表明CHS的不同复制副本在进化过程中获得了特殊的功能角色。我们认为，重复基因复制和随后的分化是植物基因组进化的一种主要适应策略。
Plant genomes appear to exploit the process of gene duplication as a primary means of acquiring biochemical and developmental flexibility. Thus, for example, most of the enzymatic components of plant secondary metabolism are encoded by small families of genes that originated through duplication over evolutionary time. The dynamics of gene family evolution are well illustrated by the genes that encode chalcone synthase (CHS), the first committed step in flavonoid biosynthesis. We review pertinent facts about CHS evolution in flowering plants with special reference to the morning glory genus, Ipomoea. Our review shows that new CHS genes are recruited recurrently in flowering plant evolution. Rates of nucleotide substitution are frequently accelerated in new duplicate genes, and there is clear evidence for repeated shifts in enzymatic function among duplicate copies of CHS genes. In addition, we present new data on expression patterns of CHS genes as a function of tissue and developmental stage in the common morning glory (I. purpurea). These data show extensive differentiation in gene expression among duplicate copies of CHS genes. We also show that a single mutation which blocks anthocyanin biosynthesis in the floral limb is correlated with a loss of expression of one of the six duplicate CHS genes present in the morning glory genome. This suggests that different duplicate copies of CHS have acquired specialized functional roles over the course of evolution. We conclude that recurrent gene duplication and subsequent differentiation is a major adaptive strategy in plant genome evolution.