rDNA和端粒重复序列鉴定马铃薯和茄子体细胞杂种染色体丢失和融合

植物体细胞杂交是植物种质资源创制的重要方法。体细胞杂种在原生质体再生的过程中染色体会产生非常多的遗传变异。研究体细胞杂种的染色体行为为马铃薯体细胞杂种的创制和利用提供理论基础。本研究采用rDNA和端粒重复序列作为探针进行原位杂交(fluorescence in situ hybridization),并结合基因组原位杂交(genomic in situ hybridization),对马铃薯和茄子体细胞杂种染色体组成和变异进行了分析。原位杂交结果表明,体细胞杂种中存在马铃薯和茄子融合的染色体和双着丝粒染色体,并发现部分融合染色体是由马铃薯和茄子2号染色体末端对末端融合得到的。重排的双着丝粒染色体的着丝粒一个来源于马铃薯,一个来源于茄子。此外,体细胞杂种中来源于茄子的5S rDNA在体细胞杂种再生及稳定的过程中全部丢失。研究结果表明马铃薯与茄子在进行体细胞杂交的过程中,染色体是不稳定的,容易造成融合后代出现双着丝粒和染色体重排等现象。体细胞杂种的染色体会通过染色体重排、双着丝粒、rDNA均一化等多种形式使其染色体趋于稳定。

Identification of chromosome loss and rearrangement in potato and eggplant somatic hybrids by rDNA and telomere repeats

Somatic hybridization is an important way to create new germplasm.Somatic hybrids produced plenty of genetic varia-tion during protoplast regeneration.In this study,to analyze the chromosome composition and variation of potato and eggplant somatic hybrids,rDNAs and telomeric repeats were used as probes for FISH(fluorescence in situ hybridization),combined with GISH(Genomic in situ hybridization).The results showed that rearranged chromosomes and dicentric chromosomes existed in somatic hybrids,and the parts of the rearranged chromosomes was derived from the end-to-end fusion of potato and eggplant chromosomes 2.One centromere of the rearranged dicentric chromosomes was derived from potato and the other was from egg-plant.Eggplant 5S rDNA sites were lost in somatic hybrids to homogenize the rDNA of somatic hybrids.The results of this study indicated that the chromosomes were unstable during the somatic hybridization of potato and eggplant,which can easily cause dicentric and chromosomal rearrangements in somatic hybrids.The chromosomes of somatic hybrids tended to be stable through various ways such as chromosome rearrangement,dicentric and rDNA homogenization.