崇州枇杷茶野生大茶树染色体核型分析

Karyotype Analysis of Chongzhou Loquat Wild Tea Plants

【目的】通过核型分析实验,了解6种不同类型崇州枇杷茶树的进化和变异情况,为其起源、进化和亲缘关系的研究提供一些细胞学依据。【方法】选取6种不同类型的四川崇州枇杷茶野生大茶树(依次编号为A类、B类、C类、D类、E类、F类),以芽叶原基为供试材料,采用去壁低渗法进行染色体核型分析实验。【结果】6种不同类型的大茶树染色体为二倍体的小型染色体,核型公式均为2n=2x=30=22m+8sm,属Stebbins标准中较原始的2A型。【结论】根据核型对称性程度、平均臂比、核型不对称系数推断,F类、A类茶树较为原始,E类茶树进化程度相对较高。核型分析表明,分布在四川崇州区域的枇杷茶树既具有较原始的对称性核型性状,又具有较不对称性的进化型或派生型核型,表现为一种渐变的趋势。

[Objective] The purpose of the article was to understand the evolution and variability of six different types of Chongzhou loquat tea plants and provide some cytological basis for its origin, evolution and genetic relationship by karyotype analysis. [Method] Six different types of wild lo- quat tea from Sichuan Chongzhou, named as class A, B, C, D, E, F, respectively, were used in karyotype analysis. We used shoots primordia of loquat tea by the wall degradation hypotonic method. [Results] Chromosomes of six types of loquat tea were small chromosomes and varied morphologically. The karyotype formulas of them are 2n=2x=30=22m＋8sm. It was the origi- nal type 2A according to the Stebbins standard. [Conclusion]According to symmetry of karyo- type, average arm ratio, and karyotype asymmetry index, it is concluded that the class F and class A tea are the original types, while the E-class tea are newly evolved. The present cytological evi- dence supported that the Sichuan Chongzhou loquat tea since both they appeared original symme- try of their karyotype, but also contained more asymmetry and evolutionarily derived karyotypes, showing a gradual evolutionary trend.