中国山茶属4种2变种核型研究

本文采用去壁低渗法研究了我国山茶属植物4种2变种的核型。根据Levan等的命名系统,各个种的核型可简式为大理茶2n=20m+2m(SAT)+8sm;勐腊茶2n=20m+2m(SAT)+6sm+2sm(SAT);德宏茶2n=20m+8sm+2sm(SAT);苦茶2n=20m+9sm+1sm(SAT);茶2n=18m+2m(SAT)+12sm;白毛茶2n=18m十2m(SAT)+9sm+1sm(SAT)。这些种都是二倍体种(2n=2x=30),未发现多倍体。在勐腊茶核型中发现2个超数染色体(B-chromosome)。核型的不对称性表明,这些种均属于Stebbins核型分类的2A型核型。这些种在“随体数目和位置,最长染色体与最短染色体之比,臂比大于2:1的染色体比例,着丝点端化值,染色体绝对长度”方面的变异是清楚易见的。核型的变异表明,这些种的染色体进化顺序为大理茶—→勐腊茶—→德宏茶—→普洱茶—→白毛茶—→苦茶—→茶。这一结果与张宏达提出的山茶属植物的分类系统基木吻合。本文还讨论了山茶属植物核型的杂合性和多态性。本文中勐腊茶、德宏茶、苦茶的染色体数目和核型及大理茶的核型为首次报道。

KARYOTYPE STUDIES ON SIX TAXA OF CAMELLIA IN CHINA

The present paper deals with the karyotypes of 4 species and 2 varieties of Camellia in China by wall degradation hypotonic treatment and flame-drying method. According to the classification systems given by Levan et al. the karyotype formula of C. taliensis with 2n=20m+2m ( SAT )+8sm; C. manglaensis with 2n=20m+2m ( SAT ) +6sm+2sm ( SAT ); C. dehungensis with 2n= 20m+8sm+2sm ( SAT ) ; C. assamica var. kucha with 2n=20m+9sm+1sm ( SAT ); C. sinensis with 2n=16m+2m ( SAT ) +12sm; C. sinensis var. pubilimba with 2n=18m + 2m ( SAT ) +9sm+1sm (SAT). All of these species were diploid (2n=2X=30), no polyploid wal found. Two B-chromosomes were found in the karyotype of C. manglaensis. The karyotype asymmetry demonstrates that all of these species belong to 2A type of Stebbins karyotype symmetry. The variation in number and position of SAT-chromosome; the longest chromosome/the shortest chromosome; proportion of chromosome with arm ratio> 2:1 (%) ; centromeric ter-minalization value; the chromosome length " among these species are obvious. The variation in karyotype demonstrates that the chromosomal evolution in these species are C. taliensis-→C. manglaensis-→C. dehungensis-→C. assamica-→ C. sinensis var. pubilimba-→C. assamica var. kucha-→C. sinensis. The results basically tallied with viewpoint in "A Taxonomy of the Genus Camellia" of Chang Hunta. The heterozygosity and polymorphism of karyotype on Camellia plants are also discussed in this paper. The chromosome number and karyotype of C. manglaensis, C. dehungensis, C. assamica, var. kucha and C. taliensis are reported here for the first time.