古蔺牛皮茶染色体制片条件优化及核型分析

Optimization of Chromosome Preparation Conditions and Karyotype Analysis of Camellia sinensis cv. Gulin-niupicha

利用常规压片法对古蔺牛皮茶进行染色体制片条件优化与核型分析,结果表明,与顶芽和嫩叶相比,古蔺牛皮茶根尖的分裂相及中期分裂相细胞比例最高,是最合适的取材部位;1 mol/L盐酸解离16分钟染色体形态及分散效果最好。核型分析结果显示,其染色体数目为30条,核型公式2 n=2 x=30=18 m(2SAT)+10 sm+2 st,染色体相对长度变化范围为4.87%~8.58%,其相对长度组成2L+6M2+6M1+1S,染色体着丝粒指数范围为24.83%~45.82%,最长染色体与最短染色体长度比为1.76,臂比>2的染色体比例为6.7%,平均臂比值为1.60,核型类型为2A,核型不对称系数为60.93%,在50种茶树中处于中等进化程度。本研究为古蔺牛皮茶的进化分类、遗传育种、种质资源鉴定等研究提供了细胞学依据。

In the present study,the traditional squash method was used to carry out chromosome preparation conditions optimization and karyotype analysis of Camellia sinensis.The results showed that compared with terminal buds and tender leaves,the percentage of cells at the mitotic and metaphase stage was the highest at root tip.The best chromosome morphology and effect of chromosome dispersion were determined at dissociation for 16 min with 1 mol/L HCl.Karyotype analysis showed that the chromosome number was 30 and the karyotype formula was 2n=2x=30=18 m（2 SAT）＋10 sm＋2 st.The relative lengths of chromosome ranged from 4.87% to 8.58%,and the constitution of the relative length was 2 L＋6M2＋6M1＋1 S.The centromeric index of chromosome was 24.83%～45.82%,and the ratio of chromosome length（L/S） was 1.76.The percentage of arm ratio 2 was 6.7%,with the average arm ratio of 1.60,and the karyotype type was 2 A.The karyotype asymmetry index was 60.93%,which was in the middle of evolution level in 50 tea trees.In conclusion,the results provided a cytological theoretical basis for Camellia sinensis in evolutionary classification,genetic breeding,and germplasm identification.