向日葵染色体核型特征及rDNA分布分析

Karyotype Characteristics and rDNA Distribution Analysis of Sunflower(Helianthus annuus L.)Chromosomes

为揭示向日葵染色体核型和结构特征特性,以栽培种向日葵白葵杂6号(H-01A×RHA-K)为试验材料,采用改良的酶解去壁低渗法和涂片技术,进行向日葵染色体形态观察和核型分析。同时,以45S和5S rDNA重复序列为探针,采用荧光原位杂交(Fluorescence in situ hybridization,FISH)技术,对向日葵染色体rDNA分布进行物理定位和分析。染色体形态观察结果显示,白葵杂6号有3对染色体为随体染色体。栽培种向日葵染色体长度介于3.87~5.37μm;染色体多为中等染色体(M1和M2类型);相对长度组成为16M2+18M1。白葵杂6号(2n=34)染色体组核型公式为2n=2x=34=32m+2M,染色体组为1A核型,核型不对称系数为50.51%。rDNA FISH结果显示,栽培种向日葵有3对染色体(第5、9、13对染色体)携带有45S rDNA,荧光信号分布在染色体短臂末端;2对染色体(第5、7对染色体)携带有5S rDNA,分布在染色体短臂端部;1对染色体(第5对染色体)同时携带有45S rDNA和5S rDNA。

In order to explore the chromosome karyotype and structure characters in sunflower(Helianthus annuus L.),the modified wall degradation hypotonic method and smear chromosome preparation technique were applied to observe the chromosome and analyze the karyotype characteristics of the sunflower hybrid Baikuiza No.6(H‐01A×RHA‐K).Meanwhile,the physical location of rDNAs in sunflower chromosomes was mapped and analyzed using FISH(fluorescence in situ hybridization)technique with 45S and 5S rDNA repeats as probes.Chromosome morphology observation results showed that there were three pairs of satellite chromosomes in Baikuiza No.6.The chromosome length ranged from 3.87 to 5.37μm.Most of the chromosomes were medium in size(M1 and M2 types).The formula of relative chromosome length was 16M2+18M1.The karyotype formula of chromosome of Baikuiza No.6 was 2n=2x=34=32m+2M,which belonged to 1A karyotype with the asymmetrical karyotype coefficient value as 50.51%.The FISH results of rDNAs indicated that three pairs(5th,9th,and 13th)carried 45S rDNA and the hybridization signals were detected at the end of shot arms of the specific chromosomes;two pairs(5th and 7th)carried 5S rDNA with fluorescence signals at the end of the short arms;one pair of chromosomes(5th)carried both 45S and 5S rDNAs.