葱属根茎组8种21居群植物的核型研究

对葱属根茎组Allium sect.Rhiziridium的8种21个地方居群的核型进行研究，以期为解决该组的种间亲缘关系和物种进化机制提供依据。贺兰韭A.eduardii和阿拉善韭A．flavovirens2个种的核型以及辉韭A．strictum的六倍体核型均属首次报道。研究结果表明：贺兰韭A.eduardii、阿拉善韭A.tlavovirens、北韭A.lineare、蒙古韭A.mongolicum和滩地韭A．oreoprasum的各居群均为二倍体，核型类型为Stebbins的2A型；韭A．tuberosum和野韭A.ramosum的各个居群均为四倍体，核型类型为2A型：辉韭A．Jtrictum的4个居群均为六倍体，核型类型为2B型。通过研究可以得出如下推论：（1）该组植物中存在着大量的多倍体或多倍体系列，染色体数目变化与物种进化具有密切相关性，多倍化可能是根茎组植物核型进化的重要机制之一；（2）随体染色体多为st或t染色体，均位于短臂末端；（3）可以认为辉韭是以增加倍性来克服该物种扩大新的生存空间所带来的困难；（4）现今栽培的韭可能是由野生的二倍体韭和四倍体韭经过长期人工驯化而来的，现今栽培的三倍体韭可能是二倍体韭和四倍体韭杂交而来，并且以无性繁殖方式保存三倍体类群的存在。

Karyotype studies on twenty-one populations of eight species in Allium section Rhiziridium

In this paper, karyotypes from twenty-one populations in eight species of Allium section Rhiziridium from China were investigated. The karyotypes of two species, A. eduardii and A. flavovirens, and the hexaploidy karyotype of A. strictum are reported for the first time. By studying karyotypes of this section in Allium, we hope to understand evolutionary mechanisms and relationships among the taxa in this section. We find that five species, A. eduardii, A. flavovirens, A. lineare, A. mongolicum and A. oreoprasum are diploid, and that their karyotypes are the 2A type of Stebbins. The two species, A. tuberosum and A. ramosum, are tetraploid and their karyotypes are also the 2A type. Four populations of the species A. strictum are hexaploid and their karyotypes are the 2B type. From the karyotype analysis we obtain the following results: (1) In this section, there are many polyploids and polyploid series. The variation in the chromosome number in this section is closely related to the evolution history of the species. Therefore polyploidization might be one of the important evolutionary mechanisms that has shaped species diversity in sect. Rhiziridium. (2) The satellite chromosomes are either subterminal or terminal chromosomes and satellites are located in the short arm. (3) It is suggested that A. strictum might represent an incipient species and has exploited a new niche through ployploidization. (4) The cultivated species A. tuberosum might be derived from the artificial naturalization of the wild diploid and tetraploid ancestors. The cultivated triploid species is suggested to have originated from the hybridization between the wild diploid and tetraploid ancestors, and its survival and widespread cultivation might have been achieved through asexual reproduction.