虎眼万年青核型分析及B染色体研究

Karyotype Analysis and B-Chromosomes Study of Ornithogalum caudatum Ait.

对虎眼万年青的染色体核型进行了分析，结果表明：该物种的体细胞染色体组包括18条数目稳定的A染色体和28-36条数目不等的B染色体，各A染色体之间形态差异不明显，均为中着丝粒染色体或近中着丝粒染色体，最长与最短染色体相对长度比仅为1．35，核型类型为较对称的2A型，核型公式为2n=18=4m＋14sm＋（28-36）Bs。B染色体在不同细胞间却表现出明显的遗传多态性，文中还讨论了B染色体的大数量出现和数目变异与虎眼万年青具有抗旱、抗逆等生理适应性之间的关系。

Analysis of the karyotype of Ornithogalum caudatum Ait. showed that the somatic cells genome consists of 18 A-chromosomes and 28-36 B-chromosomes. No obvious difference was found in morphology among the Achromosomes, all of which are median and submedian centromeric chromosomes. The relative length ratio between the longest and the shortest chromosomes is 1.35, and the karyotype type is 2A, which is quite bilateral. The karyotype formula is 2 n= 18=4 m＋ 14 sm＋（28-36）Bs. The B-chromosomes showed obvious genetic polymorphism in different cells from the same root tip. Some genetic traits of B-chromosomes,such as appearance of large number of the B-chromosomes and their changes,were discussed in this paper,which might be cytological evidences to explain their physiological adaptation related with drought and stress resistance in Ornithogalum caudatum Air.