摘要
By using genome in situ hybridization(GISH)on root somatic chromosomes of allotetraploid derived from the cross Gossypium arboreum×G.bickii with genomic DNA(gDNA)of G.bickii as a probe,two sets of chromosomes,consisting of 26chromosomes each,were easily distinguished from each other by their distinctive hybridization signals.GISH analysis directly proved that the hybrid G.arboreum×G.bickii is an allotetraploid amphiploid.The karyotype formula of the species was 2n=4x=52=46m(4sat)+6sm(4sat).We identified four pairs of satellites with two pairs in each sub-genome.FISH analysis using 45S rDNA as a probe showed that the cross G.arboreum×G.bickii contained 14 NORs.At least five pairs of chromosomes in the G sub-genome showed double hybridization(red and blue)in their long arms,which indicates that chromatin introgression from the A sub-genome had occurred.
亚比棉异源四倍体是山西农业大学棉花育种组于上个世纪80年代用A染色体组亚洲棉(Gossypium.arboreum)(迁西小黑籽)与G染色体组野生棉比克氏棉(G.bickii)杂交成异源二倍体后,又经过加倍而获得的。亚比棉异源四倍体不仅育性得到恢复、结铃正常,而且成功地将比克氏棉的优异性状--种子腺体延缓形成转育到亚比棉中。这为实现棉花综合利用和提高抗虫性创育了新的育种材料。在随后的多年中,山西农业大学棉花育种组对亚比棉异源四倍体进行了广泛的细胞形态学研究,对其核型做了分析。然而,仅依据形态学和普通的核型图像,还不能确定该异源四倍体棉种中比克氏棉G染色体(亚)组在核型中的表现。该文以比克氏棉gDNA为探针,亚比棉异源四倍体根尖体细胞染色体为靶细胞染色体,封阻材料为亚洲棉(迁西小黑籽),进行亚比棉基因组原位杂交(Genomeinsituhybridization,GISH)及核型分析。从获得的图像中可以清晰地发现有52条染色体,其中有/无杂交信号的各一半,这直观地证实了人工复合亚比棉杂交种确为异源四倍体,而且是双二倍体。A亚组与G亚组染色体长度存在交替排列。亚比棉异源四倍体基于GISH图像的核型公式为:2n=4x=52=46m(4sat)+6sm(4sat)。A亚组和G亚组染色体上各有2对随体。G亚组染色体中至少有5对双重显色明显的染色体,意味着可能有A亚组染色体的交换,而A亚组染色体中只观察到或多或少的探针红色荧光信号,由于分辨率不够而难于定量分析。进一步以45SrDNA为探针,以鲑鱼精DNA作为封阻DNA,对亚比棉异源四倍体进行45SrDNA-FISH,实验表明,亚比棉异源四倍体有14个NOR(核仁组织区)信号,说明亚比棉异源四倍体有14个随体,即7对随体。比克氏棉对亚洲棉的GISH结果显示,在有亚洲棉DNA封阻的条件下,亚洲棉靶细胞染色体无任何杂交信号,说明比克氏棉与亚洲棉染色体之间不存在较大的同源或相似序列。
基金
This work was supported by the 10th Five Years Key Programs for Science and Technology Development of China(No.2004BA525B05-1)
the National Natural Science Foundation of China(No.30170501).
