平邑甜茶后代双胚苗的倍性鉴定及核型分析

Ploidy identification and karyotype analysis on the seedlings from di-embryonic seeds of Pingyi Tiancha(Malus hupehensis var.pingyiensis)

为了确定平邑甜茶双胚苗的倍性特征和核型特点,采用压片和流式细胞仪观测的方法对平邑甜茶后代中双胚苗进行染色体倍性观察和核型分析。结果表明:4株供试材料均为三倍体,2n=3x=51,染色体为小型,染色体长度比差异不大;核型组成由中部着丝点染色体(m)和亚中部着丝点染色体(sm)组成;株系8-1、8-2、12-1和12-2的核型公式分别为2n=3x=45m+6sm,2n=3x=48m+3sm,2n=3x=27m+24sm,2n=3x=33m+18sm;染色体相对长度和着丝点指数的变异范围分别为1.21%～2.68%和34.19%～42.37%,1.44%～2.63%和35.59%～44.08%,1.36%～3.02%和32.85%～42.18%,1.43%～2.87%和34.23%～44.02%;核型分别属于1B、1A、2B和1B类型,表现为株系之间的核型不完全相同。本研究为丰富无融合生殖型砧木的育种理论,获得新的苹果无融合生殖型砧木提供有益的借鉴。

Using the seedlings from di-embryonic seeds of Pingyi Tiancha （Malus hupehensis var. pingyiensis ） as materials, the chromosome number was observed and the karyotype was analysed by the methods of Squash and Cytometer. The results indicated that the ploidy of observed 4 seedlings （8-1, 8-2, 12-1 and 12-2） were all triploidy and composed of metacentric chromosomes and submetacentric chromosomes： 2n=3x=51 which were all small chromosomes and whose morphological variations and relative length ratios were not obvious. The karyotype formulas of them were 2n=3x=45m＋6sm, 2n=3x=48m＋3sm, 2n=3x=27m＋24sm and 2n=3x=33m＋18sm, respectively. The ranges of variation in the chromosome relative length and cen- tromere index were 1.21% to 2.68% and 34.19% to 42.37%, 1.44% to 2.63% and 35.59% to 44.08%, 1.36% to 3.02% and 32.85% to 42.18%, 1.43% to 2.87% and 34.23% to 44.02%, respectively. The karyotypes of the 4 seedlings were 1B, 1A, 2B and 1B, respectively, which indicated that the karyotypes were not identical completely among the 4 seedlings. This research enriched the breeding methods and offered some new apomictic stocks in Malus for the utilization in fruit production.