慈姑基因组大小鉴定及核型分析

Genome size identification and karyotype analysis of Sagittaria trifolia

【目的】慈姑是中国重要的园艺经济作物,其基因组大小的鉴定和核型分析对慈姑基因组学研究及分子遗传学研究必不可少,现阶段慈姑的基因组大小及染色体形态未知,本研究将为慈姑的育种和物种进化研究提供更多细胞学的参考。【方法】采用流式细胞技术、荧光原位杂交技术,参考裂解液配方、探针配置,对慈姑品种‘紫金星’(ZJX)的根尖基因组大小进行鉴定,并对其染色体形态进行分析观察。【结果】(1)所测慈姑为二倍体植物,‘紫金星’慈姑基因组为16 Gb左右。(2)用DAPI荧光染色获得其染色体数目稳定,且与端粒荧光原位杂交的结果完全吻合,均为22条;染色体类型有中部着丝粒、近中部着丝粒以及近端部着丝粒,近端部着丝粒最多,且未发现随体;核型公式为:2n=2x=22=6m+4sm+12st,属于Stebbins类型中的3B型,核型不对称系数为99.13。【结论】慈姑基因组大小中等,核型极不对称,进化程度较高。

[Objective]Sagittaria trifolia is an important horticultural and cash crop in China.Identification of genome size and analysis of karyotype are essential for genome research and molecular genetics of S.trifolia.Currently,the genome size and chromosome morphology of S.trifolia are unclear.The present study provides cytological references to S.trifolia breeding and species evolution analysis.[Methods]Using flow cytometry and fluorescence in situ hybridization,together with reference to the lysate formulation to probe configuration,the genome size of the root tips of S.trifolia variety‘Zijinxing’(ZJX)was identified and the chromosome morphology was analyzed.[Results](1)The tested cecropia was a diploid plant,and the genome of‘Zijinxing’cecropia was about 16 Gb.(2)Using DAPI fluorescence staining,the number of chromosomes was identified to be stable,consistent with the results of telomeric fluorescence in situ hybridization.The chromosome types were middle mitotic(metacentric chromosome),near-middle mitotic(submetacentric chromosome),and proximal mitotic(acrocentric chromosome), with the most centromere was found in the proximal part, and no satellite was found. The karyotypeformula was 2n=2x=22=6m+4sm+12st, belonging to the type 3B of Stebbins, with the asymmetrycoefficient of 99.13. [Conclusion] The study concludes that the genome of S. trifolia is of mediumsize, with a highly asymmetric karyotype and a high degree of evolution.