Asymmetric hybridization in Rhododendron agastum: a hybrid taxon comprising mainly F1s in Yunnan, China
Asymmetric hybridization in Rhododendron agastum: a hybrid taxon comprising mainly F1s in Yunnan, China
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DOI：
10.1093/aob/mcp267
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发表时间：
2010-01-01
期刊：
影响因子：
4.2
通讯作者：
Sun, Hang
中科院分区：
文献类型：
--
作者：
Zha, Hong-Guang;Milne, Richard I.;Sun, Hang
杜鹃属(杜鹃科)是一个大型木本植物属，杂交在进化和物种形成中发挥着重要作用，特别是在中国-喜马拉雅地区，许多相互干扰的物种经常共存。高山杜鹃是一种可能的杂交种，发生在云南西部的中国，是红毛杜鹃和德州杜鹃的混合种群。利用cpDNA和内转录间隔区(ITS)序列和扩增片段长度多态(AFLP)基因座对两个相距400公里的地点(朱建园，ZJY和花甸坝，HDB)的材料进行了分析，以验证高山杜鹃实际上是其他两个物种之间的杂交。根据叶绿体trnL-F和trns-trnG序列的不同，分别获得了红毛刺参、德拉瓦依刺参和大叶刺参的部分亲本材料，从HDB站点获得的14株刺参植株都具有delavayi cpDNA单倍型，而在ZJY站点有17株刺参植株具有该单倍型，4株具有刺参单倍型。在ITS序列中有5个明确的点突变，从而区分了伊氏红曲霉和德拉瓦伊红曲霉；每一次红曲霉的加入都有一个相加的模式(双峰)。来自AFLP基因座的数据从每个地点的每个分类单元的10到21个植物中获得，并使用由程序Newhydds实现的贝叶斯方法进行分析。该程序确认了Delavayi的所有材料和除1个可能是回交的外，所有的R.irratum的身份。高山杜鹃和ZJY 21株高山杜鹃均被归类为F-1杂交种，其余两株不能归为一类。高山杜鹃代表的是红花杜鹃和德拉瓦伊杜鹃的杂交群体，主要或仅含有F(1)S。这两个位点的不同之处在于，在HDB中没有检测到cpDNA类型或杂交类的变异，而在ZJY中两者都有变异。
Rhododendron (Ericaceae) is a large woody genus in which hybridization is thought to play an important role in evolution and speciation, particularly in the Sino-Himalaya region where many interfertile species often occur sympatrically. Rhododendron agastum, a putative hybrid species, occurs in China, western Yunnan Province, in mixed populations with R. irroratum and R. delavayi.Material of these taxa from two sites 400 km apart (ZhuJianYuan, ZJY and HuaDianBa, HDB) was examined using cpDNA and internal transcribed spacer (ITS) sequences, and amplified fragment length polymorphism (AFLP) loci, to test the possibility that R. agastum was in fact a hybrid between two of the other species. Chloroplast trnL-F and trnS-trnG sequences together distinguished R. irroratum, R. delavayi and some material of R. decorum, which is also considered a putative parent of R. agastum.All 14 R. agastum plants from the HDB site had the delavayi cpDNA haplotype, whereas at the ZJY site 17 R. agastum plants had this haplotype and four had the R. irroratum haplotype. R. irroratum and R. delavayi are distinguished by five unequivocal point mutations in their ITS sequences; every R. agastum accession had an additive pattern (double peaks) at each of these sites. Data from AFLP loci were acquired for between ten and 21 plants of each taxon from each site, and were analysed using a Bayesian approach implemented by the program NewHybrids. The program confirmed the identity of all accessions of R. delavayi, and all R. irroratum except one, which was probably a backcross. All R. agastum from HDB and 19 of 21 from ZJY were classified as F-1 hybrids; the other two could not be assigned a class.Rhododendron agastum represents populations of hybrids between R. irroratum and R. delavayi, which comprise mostly or only F(1)s, at the two sites examined. The sites differ in that at HDB there was no detected variation in cpDNA type or hybrid class, whereas at ZJY there was variation in both.