Molecular Evidence for the Hybrid Origin of Ilex dabieshanensis (Aquifoliaceae).
Molecular Evidence for the Hybrid Origin of Ilex dabieshanensis (Aquifoliaceae).
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Ilex Dabieshanensis（Aquifoliaceae）杂种起源的分子证据。
DOI：
10.1371/journal.pone.0147825
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发表时间：
2016
期刊：
影响因子：
3.7
通讯作者：
Zhou R
中科院分区：
文献类型：
--
作者：
Shi L;Li N;Wang S;Zhou Y;Huang W;Yang Y;Ma Y;Zhou R
冬青属是雌雄异株木本植物中最大的属，是研究杂交在物种形成和进化中的作用的一个很好的研究体系。大别山冬青（Ilex dab别山）是大别山地区特有的乔木，最初被描述为新种。根据其形态中间性及其与假定的亲本种角叶和大叶的同域分布，我们认为它是它们之间的天然杂交种。本研究对大别山猕猴桃及其可能亲本种的1个叶绿体基因间隔序列（trnH-psbA）和2个核基因（gapC和negs）进行了测序，以验证杂交起源假说。结果表明，在这两个核基因上，山茱萸和油葵之间存在1 ~ 2个差异固定序列差异。大别山猿猴14个个体中有12个个体在两个核基因的差异固定位点上表现出可加性，其余2个个体仅在negs基因的固定位点上表现出可加性。除了在negs基因上的一个单倍型外，两个核基因上的所有单倍型都与荷叶有很好的分离，而且大别山荷叶的大部分单倍型与荷叶和荷叶的单倍型相同。这些单倍型的系统发育分析与单倍型网络分析基本一致。大别山金银花与金银花叶绿体基因间间隔有2个核苷酸替换，其中12个与金银花序列相同，其余2个与金银花序列相同。这些分子数据为大别山赤杨的杂交起源和杂交方向的不对称提供了有说服力的证据。在negs基因上的一个单倍型与油叶的单倍型嵌套在一起，表明对油叶的遗传渐渗。
Ilex, the largest genus of dioecious woody plants, is a good study system to assess the role of hybridization in speciation and evolution. Ilex dabieshanensis, a tree endemic to Dabieshan Mountains region, was initially described as a new species. Based on morphological intermediacy and sympatric distribution with its putative parental species, I. cornuta and I. latifolia, we proposed it as a natural hybrid between them. In this study, we sequenced one chloroplast intergenic spacer (trnH-psbA) and two nuclear genes (gapC and nepGS) in I. dabieshanensis and its putative parental species to test the hybrid origin hypothesis. Our results showed that there were one to two differentially fixed sequence differences between I. cornuta and I. latifolia at the two nuclear genes. Twelve of the 14 individuals of I. dabieshanensis exhibited additivity in chromatograms on these differentially fixed sites at both nuclear genes, and the remaining two exhibited additivity in chromatograms on the fixed site at only the nepGS gene. Except one haplotype of I. cornuta at the nepGS gene, all of the haplotypes of I. cornuta at the two nuclear genes were well separated from those of I. latifolia, and most haplotypes of I. dabieshanensis were shared with those of I. cornuta and I. latifolia. Phylogenetic analysis of these haplotypes was largely consistent with haplotype network analysis. I. cornuta and I. latifolia differed by two nucleotide substitutions in the chloroplast intergenic spacer, and 12 individuals of I. dabieshanensis had the same sequences as I. latifolia, while the remaining two were identical with I. cornuta. The molecular data provide convincing evidence for the hybrid origin of I. dabieshanensis and asymmetrical direction of hybridization. One haplotype of I. cornuta at the nepGS gene was nested with those of I. latifolia, indicating introgression to I. cornuta.