中山杉401无性系的染色体核型分析

The karyotype analysis of T. × Zhongsannica CL'401'

观察分析了中山杉401无性系(Taxodium ascendens Brongn×Taxodium mueyonatum Tenore CL'401')的染色体核型,并与亲本的染色体核型进行了比较。结果表明,中山杉401无性系的染色体数目为2n=22,核型公式为K(2n)=20m+2sm。杂种后代有两条大小、形态不同的近中部着丝点染色体,一条为第11条,一条为第17条,仅第17条具大着丝点的特征。中山杉401无性系确系种间杂种,在该无性系中未发生染色体加倍、缺失的变异。

T. × Zhongshannica CL' 401' is an excellent individual,selected from the interspecific hybrid (? Taxodium ascendens Brongn × ? Taxodium mucronatum Tenore) seedlings. The chromosome number and karyotype of the hybrid in root-tip cells were studied, compared with the karyotype of their parents. The result shows that the chromosome number is 2n = 22, according to the terminology defined by Levan et al, the karyotype formula is K(2n) = 20m + 2sm. The absolute length, relative length and arm ratio of hybrid chromosome are 6.63~10.54 μm,7.40%~11.77% and 1.04~1.71, respectively. The two submetacentric chromosomes of interspecific hybrid appears the differences in chromosome size and morphology. The absolute length, relative length and arm ratio of the 11th chromosome and the 17th chromosome are 7.92μm,8.67%,1.70 and 7.34μm,8.14%,1.71,respectively. Only the17th chromosome has long kinetochore region. The fact that T. × Zhongshannica CL'401' is a interspecific hybrid is proven by karyotype analysis. Chromosome doubling and deficiency have not been found in the T.× Zhongshannica CL '401'.