Morphological, karyological and molecular delimitation of two gentians: Gentiana crassicaulis versus G. tibetica (Gentianaceae)

NWIPB OpenIR

	Morphological, karyological and molecular delimitation of two gentians: Gentiana crassicaulis versus G. tibetica (Gentianaceae)
	Zhang Xiao-Lan ; Ge Xue-Jun ; Liu Jian-Quan ; Yuan Yong-Ming
	2006-11-01
发表期刊	ACTA PHYTOTAXONOMICA SINICA
卷号	44 期号:6 页码:627-640
文章类型	Article
摘要	Gentiana crassicaulis Duthie ex Burk. and G tibetica King ex Hook. f. are confusing gentians. The former has smaller corolla and blue-purple limbs whereas the latter has larger corolla and purple-brown limbs. Intermediate types are often found in southeast Xizang where both species are putatively considered to occur. A question has been raised whether these intermediate types were produced by introgression between the two species, which further contribute to the taxonomic ambiguity. In the present study, we comprehensively compared morphological variations, chromosome numbers, and sequences of two DNA fragments from populations of the intermediate types and those of the two typical species. We sequenced cpDNA trnS-G and nuclear ITS fragments of 69 individuals of 10 populations, counted chromosome number of 26 individuals of six populations and measured morphological variation of 54 specimens. We found that corolla size is highly correlated with ploidy level. The populations of typical G crassicaulis from Yunnan were diploid (2n=26) with small corolla while those of G tibetica from western Xizang were tetraploid (2n=52) with large corolla. The populations of the intermediate types from southeast Xizang were tetraploid with large corolla, and a few individuals with purple to brown limbs. These features suggest that the intermediate types show more similarities to G tibetica. However, DNA sequence evidence unambiguously grouped those populations with G crassicaulis. Both nuclear and chloroplast DNA showed consistent results: the intermediate populations showed identical cpDNA and very similar ITS sequences to typical G crassicaulis. No sequence variation beyond what occurred in typical G crassicaulis and G tibetica was found from multiple individuals of the intermediate types. Thus the hypothesis of a recent introgression or hybridization between the two species could be rejected. Our results demonstrated that polyploidization had contributed to the intraspecific variation in G crassicaulis and that the tetraploid individuals of this species showed morphological convergence with tetraploid G tibetica, which blurred the morphological delimitations of the two species in southeast Xizang. Nevertheless, molecular markers can discriminate convergence and correctly attribute the intermediate populations or individuals to the correct species circumscription. Our results provided a case study to circumscribe the closely related species based on a comprehensive combination of morphological, karyological and molecular evidence. In addition, the geographical distributions of diploids and tetraploids within G crassicaulis and the implications for the origin and dispersals of this alpine species were also discussed.
关键词	Gentiana Crassicaulis Gentiana Tibetica Polyploidization Morphological Convergence Species Delimitation
WOS标题词	Science & Technology ; Life Sciences & Biomedicine
关键词[WOS]	NUCLEAR RIBOSOMAL DNA ; INTERNAL TRANSCRIBED SPACERS ; NUCLEOTIDE-SEQUENCES ; CONCERTED EVOLUTION ; PHYLOGENY ; GENUS ; ASTERACEAE ; CHINA ; DIVERSIFICATION ; RADIATION
收录类别	SCI
语种	英语
WOS研究方向	Plant Sciences
WOS类目	Plant Sciences
WOS记录号	WOS:000242416100002
引用统计	被引频次：16[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://210.75.249.4/handle/363003/6854
专题	中国科学院西北高原生物研究所
作者单位	1.Chinese Acad Sci, NW Plateau Inst Biol, Lab Biol Evolut & Adaptat, Xining 810001, Peoples R China 2.Chinese Acad Sci, S China Bot Garden, Guangzhou 510650, Guangdong, Peoples R China 3.Beijing Normal Univ, Coll Life Sci, Beijing 100875, Peoples R China
推荐引用方式 GB/T 7714	Zhang Xiao-Lan,Ge Xue-Jun,Liu Jian-Quan,et al. Morphological, karyological and molecular delimitation of two gentians: Gentiana crassicaulis versus G. tibetica (Gentianaceae)[J]. ACTA PHYTOTAXONOMICA SINICA,2006,44(6):627-640.
APA	Zhang Xiao-Lan,Ge Xue-Jun,Liu Jian-Quan,&Yuan Yong-Ming.(2006).Morphological, karyological and molecular delimitation of two gentians: Gentiana crassicaulis versus G. tibetica (Gentianaceae).ACTA PHYTOTAXONOMICA SINICA,44(6),627-640.
MLA	Zhang Xiao-Lan,et al."Morphological, karyological and molecular delimitation of two gentians: Gentiana crassicaulis versus G. tibetica (Gentianaceae)".ACTA PHYTOTAXONOMICA SINICA 44.6(2006):627-640.