Cytology and its systematic implications in Sinosenecio (Senecioneae-Asteraceae) and two closely related genera
Cytology and its systematic implications in Sinosenecio (Senecioneae-Asteraceae) and two closely related genera
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千里光属（Senecioneae-Asteraceae）和两个密切相关属的细胞学及其系统意义
DOI：
10.1007/s00606-010-0365-3
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发表时间：
2011-01-01
影响因子：
1.9
通讯作者：
Yang, Qin-Er
中科院分区：
文献类型：
--
作者：
Liu, Ying;Yang, Qin-Er
本文报道了中国千里光属28种植物、狗舌草属2种植物和假千里光属1种植物的染色体形态和数目。结果表明，中国千里光属植物具有4种基本染色体数目：x = 13，24，29和30，其中24和30为优势染色体，13和29各见于一种。多倍体的发生率是低的属。染色体数目相似的物种，其核型都相当对称，染色体组成一般相当一致，但种间染色体大小有一定差异。基本染色体数目的模式在很大程度上是一致的花微形态和分子系统发育研究的结果，并强烈表明，Sinosenecio作为目前解释是一个多系群，迫切需要在属的水平上的分类重新界定。我们认为只有x = 30的种才应该保留在新定义的属中，而x = 24（很少有13）的种（除了S. newcombei和S. koreanus可能在毛豆属中找到家）可以被描述为一个新属或优选地转移到Nemosenecio属中，并且S.海南千里光属（Sinoseneciohainanensis）是中国千里光属中唯一的一个x = 29的种，具有一系列独特的形态学和孢粉学特征，应被描述为一个新的单种属，海南千里光属（Hainanecio），可能位于千里光亚族（Senecioninae）。当Sinosenecio以这种方式重新界定时，不仅Sinosenecio属本身倾向于单系，而且由Nemosenecio，Sinosenecio和Tephroseris组成的灰毛豆亚族也可能因此成为一个更好的特征，从而更容易接受的组。
Chromosome morphology and number in 28 species of Sinosenecio, two of Tephroseris and one of Nemosenecio (Senecioneae-Asteraceae) from China were investigated. Sinosenecio is revealed to have four basic chromosome numbers: x = 13, 24, 29, and 30, with 24 and 30 being predominant and 13 and 29 each occurring in one species only. The incidence of polyploidy is low in the genus. The karyotypes are all rather symmetrical and generally quite uniform in the species of similar chromosome number in respect of chromosome constitution, albeit with some variation in chromosome size among species. The pattern of basic chromosome numbers is largely congruent with results of floral micromorphological and molecular phylogenetic studies, and strongly indicates that Sinosenecio as currently construed is a polyphyletic group, badly needing a taxonomic re-circumscription at the generic level. We propose that only those Sinosenecio species with x = 30 should be retained in the newly defined genus, whereas those with x = 24 (rarely 13) (except for S. newcombei and S. koreanus which may find a home in Tephroseris) may be described as a new genus or preferably transferred to the genus Nemosenecio, and that S. hainanensis, the only Sinosenecio species having x = 29 and a suite of unique morphological and palynological characters, should be described as a new monospecific genus, Hainanecio, possibly positioned in the subtribe Senecioninae. When Sinosenecio is re-circumscribed in this way, not only does the genus Sinosenecio itself tend to be monophyletic, but the subtribe Tephroseridinae, which is composed of Nemosenecio, Sinosenecio, and Tephroseris, also may consequently become a better characterized and thus more acceptable group.