乐昌含笑(木兰科)的核型研究(英文)

Karyotypical Studies on Michelia chapensis Dandy (Magnoliaceae)

首次报道了乐昌含笑(Micheliachapensis)的染色体数目和核型。核型公式为2n=38=28m+6sm+4st(2SAT)。与前人认为整个含笑属都为单一的2A型不同,乐昌含笑的核型属于Stebbins的2B型,具有2对近端着丝粒染色体。而且发现在第9对染色体上有小随体的存在。这些表明在含笑属内含有不同的核型。乐昌含笑在细胞学意义上可能是属内比较进化的类群。对染色体结构的细微改变在木兰科植物的种属进化上的作用进行了简要讨论。

Michelia chapensis Dandy is firstly karyomorphologically studied. Its karyotype can be formulated as 2n=38=28 m+6 sm+4 st (2SAT), belonging to Stebbins's 2B type. This is a new karyotype report, which, different from the previous confirmation that in Michelia group, the whole karyotypes of genus are of uniform 2A and there is no st chromosome occurred. There might be different karyotypes within Michelia, and M. chapensis is probably a relatively advanced species. We briefly discuss the role of minor chromosomal structural alterations played in evolution of genus or species in Magnoliaceae.