不同倍性云南山茶染色体核型分析

Chromosome karyotype analysis of Camellia reticulata with different ploidy

【目的】采用流式细胞术(Flow cytometry,FCM)对不同倍性云南山茶进行倍性鉴定,并通过采用常规压片法对其结果进行验证及核型分析,研究其染色体特性及进化程度。【方法】以不同倍性云南山茶叶片为实验材料采用流式细胞术对其进行倍性鉴定,及采用不同倍性云南山茶根尖为实验材料,采用常规压片法进行核型分析。【结果】1)流式细胞术结果显示G0/G1期荧光强度峰值比值分别为二倍体对照组的1.94、2.78,不同倍性云南山茶细胞核DNA含量差异显著,3种倍性云南山茶随着倍性水平的增加,其细胞核DNA相对含量也成倍增加。2)二倍体云南山茶染色体数目为30条,基数为15,核型公式为2n=2x=30=22m(2sat)+8sm,在第2和13对染色体短臂上附有随体,核型不对称系数为60.56%,属于2A型,四倍体云南山茶染色体数目为60条,基数为15,核型公式为2n=4x=60=44m(2sat)+14sm+2st,在第12对染色体短臂上附有随体,核型不对称系数为61.38%,属于2B型,六倍体云南山茶染色体数目为90条,基数为15,核型公式为2n=6x=90=66m+24sm,核型不对称系数为61.47%,属于2B型。3种倍性云南山茶核型不对称系数为60.56%~61.47%,【结论】流式细胞仪结果证明其3种云南山茶倍性分别为二倍体、四倍体、六倍体。进化趋势分析推测进化水平从高到低排序为:六倍体、四倍体、二倍体。其中二倍体云南山茶进化程度较低,六倍体云南山茶最为进化。

【Objective】The ploidy of different kinds of Camellia reticulata was identified by Flow cytometry(FCM),and the results were verified by the conventional pressing method and karyotype analysis,so as to study their chromosome characteristics and evolution degrees.【Method】The ploidy of different kinds of C.reticulata leaves was identified by flow cytometry,and the karyotype of different kinds of C.reticulata root tips was analyzed by the conventional tablet pressing method.【Result】1)Flow cytometry showed that compared with the diploid control group,the ratios of peak fluorescence intensity at the G0/G1 phase were 1.94 and 2.78,respectively.There were significant differences in the contents of nuclear DNA in different ploidy types.With the increase of ploidy level,the relative contents of nuclear DNA in the three types of C.reticulata increased exponentially.2)The chromosome number of diploid C.reticulata was 30,and its cardinal number was 15.The karyotype formula was 2n=2x=30=22m(2sat)+8sm.The appendage was attached to the short arms of chromosome 2 and chromosome 13.The karyotype asymmetry coefficient was 60.56%,belonging to type 2A.The chromosome number of tetraploid C.reticulata was 60,and its cardinal number was 15.The karyotype formula was 2n=4x=60=44m(2sat)+14sm+2st,and the satellite was attached to the short arm of chromosome 12.The karyotype asymmetry coefficient was 61.38%,belonging to type 2B.The chromosome number of hexaploid C.reticulata was 90,its cardinal number was 15,and the karyotype formula was 2n=6x=90=66m+24sm.The karyotype asymmetry coefficient was 61.47%,belonging to type 2B.The karyotype asymmetry coefficients of the three ploidy types of C.reticulata ranged from 60.56%to 61.47%.【Conclusion】The results of flow cytometry showed that the three ploidy of C.reticulata were diploid,tetraploid and hexaploid,respectively.The evolutionary trend analysis suggested that the evolutionary level from high to low was hexaploid,tetraploid and diploid.Among them,diploid C.reticulata has a low evolution degree,while hexaploid C.reticulata evolves the most.