Molecular systematics, GISH and the origin of hybrid taxa in Nicotiana (Solanaceae)
Molecular systematics, GISH and the origin of hybrid taxa in Nicotiana (Solanaceae)
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DOI：
10.1093/aob/mcg087
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发表时间：
2003-07-01
期刊：
影响因子：
4.2
通讯作者：
Parokonny, AS
中科院分区：
文献类型：
--
作者：
Chase, MW;Knapp, S;Parokonny, AS
利用核糖体DNA （nrDNA）内部转录间隔区（ITS）的简约性分析，研究了烟草属植物的系统发育关系。此外，本文还利用基因组原位杂交（GISH）技术对烟草中某些双二倍体类群的起源进行了研究，并利用两组分析的结果对以往关于这些类群起源的假设进行了验证。利用ITS nrDNA数据对包括二倍体和多倍体分类群的77个自然物种中的66个进行了系统发育分析，并对二倍体分类群中的35个物种进行了系统发育分析，以检验两二倍体对亲缘关系估计的影响。所有分类群，不论倍性如何，产出干净。尽管有些分类群是杂交的，但它们是ITS区域的单一副本。结果与已发表的质体（matK）系统发育进行了比较，使用较少但许多相同的分类群。在这两种分析中可以看到，烟叶的关系模式在很大程度上与彼此以及先前基于形态学和细胞学的进化观点一致，但一些重要的差异是明显的。目前公认的烟草亚属中没有一个是单系的，尽管大多数目前公认的部分是连贯的，但其他部分显然是多系的。仅仅依靠ITS的nrDNA分析来揭示烟草等复杂属的系统发育模式是不够的，而且很明显，对单一数据集的传统分析，如ITS，至少在进化史的某些方面可能会产生误导。它的自然和充分记录的双二倍体序列与双亲中的一方相似或完全相同——通常是，但不总是，母亲的父母——并且在任何意义上本身都不是“杂交”。了解人工双二倍体中ITS的进化过程，有助于深入了解ITS分析可能揭示的未知来源的自然双二倍体，从这个角度来看，ITS序列分析具有很高的信息量。(C) 2003年植物学年鉴。
Phylogenetic relationships in the genus Nicotiana were investigated using parsimony analyses of the internal transcribed spacer (ITS) regions of nuclear ribosomal DNA (nrDNA). In addition, origins of some amphidiploid taxa in Nicotiana were investigated using the techniques of genomic in situ hybridization (GISH), and the results of both sets of analyses were used to evaluate previous hypotheses about the origins of these taxa. Phylogenetic analyses of the ITS nrDNA data were performed on the entire genus (66 of 77 naturally occurring species, plus three artificial hybrids), comprising both diploid and polyploid taxa, and on the diploid taxa only (35 species) to examine the effects of amphidiploids on estimates of relationships. All taxa, regardless of ploidy, produced clean. single copies of the ITS region, even though some taxa are hybrids. Results are compared with a published plastid (matK) phylogeny using fewer, but many of the same, taxa. The patterns of relationships in Nicotiana, as seen in both analyses, are largely congruent with each other and previous evolutionary ideas based on morphology and cytology, but some important differences are apparent. None of the currently recognized subgenera of Nicotiana is monophyletic and, although most of the currently recognized sections are coherent, others are clearly polyphyletic. Relying solely upon ITS nrDNA analysis to reveal phylogenetic patterns in a complex genus such as Nicotiana is insufficient, and it is clear that conventional analysis of single data sets, such as ITS, is likely to be misleading in at least some respects about evolutionary history. ITS sequences of natural and well-documented amphidiploids are similar or identical to one of their two parents-usually, but not always, the maternal parent-and are not in any sense themselves 'hybrid'. Knowing how ITS evolves in artificial amphidiploids gives insight into what ITS analysis might reveal about naturally occurring amphidiploids of unknown origin, and it is in this perspective that analysis of ITS sequences is highly informative. (C) 2003 Annals of Botany Company.