豆科三属八种植物的核型及rDNA定位研究

Karyotype Analysis and Physical Mapping of 45S rDNA in Eight Species of Sophora,Robinia and Amorpha

对豆科槐属的国槐(SophorajaponicaL.)、五叶槐(S.japonicaL.f.oligophyllaFranch.)、龙爪槐(S.japonicaL.f·pendulaLoud.)、黄金槐(S.xanthanthaC.Y.Ma.)(以上均为四倍体,2n=4x=28)、红花槐(S.rubrifloraTsoong.,2n=3x=21),刺槐属的刺槐(Robiniapseudoa-caciaL.,2n=2x=22)、毛洋槐(R.hispidaL.,2n=2x=30)和紫穗槐属的紫穗槐(AmorphafruticosaL.,2n=2x=40)核型进行了分析,并应用荧光原位杂交技术进行了45SrDNA的染色体定位。槐属4个四倍体种各具4个45SrDNA位点,位于两对染色体的着丝粒周围;红花槐,3个45SrDNA位点位于第5组染色体随体区域。刺槐,4个rDNA位点位于两对随体染色体端部;毛洋槐,8个rDNA位点,4个位于两对染色体的随体及次缢痕,另4个位于两对染色体着丝粒周围。紫穗槐,6个45SrDNA位点,分别位于3对染色体的着丝粒和随体。本文对rDNA作为染色体标记在核型分析中的应用及在基因组中的分布特点进行了讨论。

The karyotype analysis and physical locations of 45S rDNA were carried out by means of fluorescence in situ hybridization in three species and two forms of Sophora ,two species of Robina and one species of Amorpha.S.japonica L., S.japonica L.f. oligophylla Franch., S.japonica L.f. pendula Loud.,and S.xanthantha C.Y.Ma.are all tetraploids with 2n=28.There were four 45S rDNA sites in pericentromeric regions of two pairs of chromosomes in each of them. S.rubriflora Tsoong.is a triploid with 2n=21 and 3 sites were located on each satellite of group 5 chromosomes.In R.pseudoacacia L. (2n=2x=22),we examined four intensive signals in telomeric regions of two pairs of satellite chromosomes.While in R.hispida L. (2n=2x=30),there were another four signals in centromeric regions besides those like in R.pseudoacacia.Amorpha fruticosa L.has the most chromosomes (2n=40) among the eight materials,however,there were only six 45S rDNA loci and they lay in centromeric regions,and satellites of three paris of chromosomes.45S rDNA is a valuable chromosomal landmark in karyotype analysis.The distribution and genomic organization of rDNA in the three genera were also discussed.