苜蓿核糖体基因物理定位及染色体荧光分带

Physical Localization of Ribosomal Genes and Chromosome DAPI Banding by in situ Hybridization in Medicago sativa L.

利用核糖体基因为探针对,二倍体和四倍体苜蓿(Medicagosativa)进行原位杂交,结果表明,45s在四倍体、二倍体种中总是以单位点位于核仁组织区,5s则有2～3个位点;以二倍体种的基因组DNA为探针的原位杂交表明,蓝花苜蓿(M.coerulea)和黄花苜蓿(M.falcata)均能与四倍体染色体进行杂交,仅杂交信号强弱的染色体数目有差别;荧光染料DAPI使苜蓿的染色体显示带纹,蓝花苜蓿的DAPI带与C带基本一致。文章对四倍体苜蓿的可能来源进行了讨论。

Physical localization of ribosomal genes in diploid and tetraploid alfalfa（ Medicogo. sativa） was studied using fluorescent in situ hybridization （FISH）. It was revealed that 45s gene was only located at nucleolus organizer region （NOR） with a single locus in both diploid and tetraploid alfalfa, while 5s gene had 2～3 loci on chromosomes. Using the genomic DNA from M. coerulea and M. falcota as probe to hybridize with tetraploid species in alfalfa, both diploid species were successfully hybridized with tetraploid chromosomes, only showing the difference in hybridization signals in different numbers of chromosomes. Chromosomes of alfalfa exhibited DAPI banding by FISH analysis. In general, the patterns of distribution of DAPI banding were consistent with C-banding for M. coerulea. The possible origination of tetraploid alfalfa was discussed based on DAPI banding patterns and FISH analysis for ribosomal genes.