多倍体茶树的细胞学研究(一)

对从二倍体茶树品种凤凰水仙中获得的1株高度不孕的三倍体茶树的形态特征特性、核型和减数分裂的染色体行为进行观察表明:其核型组成为2n=3x=45=36M+9SM。可区分出3个基本相同的染色体组,同源染色体组3个成员的形态极为相似。终变期观察到1—9价体、多价体环或链等构型,所有细胞可见1—12个三价体,三价体在每个细胞中平均出现次数较高,为6.13次。后期Ⅰ∶86％的细胞具有1—6条落后染色体;到达每极区染色体数变化于12—29之间,82％的细胞具有18—24条染色体。后期Ⅱ∶93％的纺锤体中具有1—4条落

Cytology Studies on the Polyploid Tea (I)

A highly sterile triploid tea plant (Camellia sinensis), selected from a diploid tea variety (Fenghuang Shuixian), was used to study its characteristics, karyotype and meiotic chromosomal behavior. The formula of the karyotype was 2n=3x=45=36M+9SM.Fourty five chromosomes can be divided into 3 identical genomes and the shapes of the homologous chromosomes were very similar. It was observed that in diakinesis, there existed 9 forms of valents (from univalent to nine-valent), some multivalents had the shape of closed ring or open chain, the frequency of trivalents in each PMC examined ranged from 1 to 12, and the average frequency was 6.13, which was the highest among all mean frequencies of valents. In A I, the numbers of the chromosomes reached each polar region ranged from 12 to 29, 82% of the polar regions were 18 to 24. There were 1 to 6 laggards in about 86%of the PMC. In AⅡ, the numbers of the chromosomes reached each polar region ranged from 8 to 27, 76% of the polar regions were 16 to 22. There were 1 to 4 laggards in about 93% of the spindles examined, only 6% of the polar regions having 15 chromosomes were normal. In addition, the chromosome bridge can be observed in A I and AⅡ. The chromosomal synapsis and segregation of the triploid tea plant were abnormal. After meiosis, different microspores were formed and grew into the varied pollen grains. The percentage of germinative pollen was about 9%. On the basis of the genome analysis and the chromosomal configurations in diakinesis, it was regarded that the triploid tea plant may be an autotriploid. The reason of why the triploid tea plant was highly sterile was the irregularities of chromosomal behavior in the meiotic process.