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【目的】研究二倍体野生棉与四倍体栽培棉间的遗传亲缘关系,进一步探索各棉种间的起源与进化。【方法】以5个二倍体基因组的代表种B1(异常棉)、C1(斯特提棉)、E2(索马里棉)、F1(长萼棉)以及G1(比克氏棉)的基因组DNA(gDNA)为探针,以2个四倍体栽培种(陆地棉中棉所16、海岛棉新海7号)有丝分裂中期染色体为靶DNA,进行了基因组原位杂交(Genomic in situ hybridization,GISH)分析。【结果】以B1、E2和F1gDNA为探针时,杂交信号主要分布在2个栽培种较长的13对A亚组染色体上;各产生3对较强的GISH-NOR信号,其中1对分布在较长的A亚组上,2对分布在较短的D亚组上,其GISH-NOR信号强度与分布情况与以D基因组棉种为探针时相似。说明二倍体B、E、F基因组与四倍体棉A亚基因组具有较高的同源性,亲缘关系更近。这一点与它们的地理分布情况相符;而它们基因组中的45S rDNA重复序列与二倍体D基因组的45S rDNA重复序列同源性较高。C1和G1中以gDNA为探针时,杂交信号分布在2个栽培种全部26对染色体上,无法区分开A或D亚组染色体,都有3对较强的GISH-NOR信号。这一现象与D基因组拟似棉(D6)gDNA为探针的GISH相似,表明二倍体C和G基因组与四倍体棉的A和D亚基因组均具有较高的同源性,或者C和G基因组同时含有A基因组(或其他非洲棉基因组)和D基因组成分,进一步证实了其基因组成分的杂合性;而它们基因组中的45S rDNA重复序列同属D基因组类型。【结论】这些发现可为棉花杂交育种和棉属起源与演化研究提供有用信息。
【Objective】 The genetic relationship between diploid wild cotton and tetraploid cotton was studied, and the origin and evolution of cotton genotypes were further explored. 【Method】 The genomic DNAs of B1 (anomalous cotton), C1 (sterilized cotton), E2 (Somali cotton), F1 (calyx cotton) and G1 (bixon cotton) of 5 diploid genomes (gDNA) was used as the probe. Genome in situ hybridization (GISH) was performed with two tetraploid cultivars (cotton Gossypium hirsutum 16 and sea island cotton Xinhai 7) as mitotic metaphase chromosomes. analysis. 【Result】 When B1, E2 and F1gDNA were used as probes, the hybridization signals were mainly distributed on 13 pairs of A subgroups of chromosomes with longer length of two cultivars. Three pairs of GISH-NOR signals were generated, of which one pair distributed In longer A subgroups, 2 pairs were distributed in shorter D subgroups, and their GISH-NOR signal intensity and distribution were similar to that of the D genome cotton probe. The results showed that the diploid B, E, F genomes have higher homology with the tetraploid cotton A subgenome, and have a closer genetic relationship. This is consistent with their geographical distribution; however, the 45S rDNA repeats in their genome are highly homologous to the 45S rDNA repeats of the diploid D genome. When gDNA was used as the probe in C1 and G1, the hybridization signal was distributed on all 26 chromosomes of two cultivars. There were 3 pairs of strong GISH-NOR signals that could not be distinguished from A or D subgroups. This phenomenon is similar to the GISH probe of the D genome gDNA (D6), indicating that the diploid C and G genomes have high homology to the A and D subgenomes of tetraploid cotton, or C And the G genome contain both the A genome (or other African cotton genome) and the D genome further confirming the heterozygosity of their genome components; whereas the 45S rDNA repeats in their genome belong to the same genomic D genome. 【Conclusion】 These findings may provide useful information for cotton cross breeding and the study on the origin and evolution of cotton genus.