海岛棉原位杂交及核型比较

采用Ａ染色体组（Ａ genome)棉种亚洲基因组ＤＮＡ（gDNA)为探针，对海岛棉体细胞染色体进行荧光原位杂交（ＦＩＳＨ），结果发现５２条染色体中有杂交信号与否的刚好各一半，从而直观地证实了海岛棉异源双二倍体起源的理论，但是，染色体的长度Ａ亚组的并非全部大于Ｄ亚组的。海岛棉基于ＦＩＳＨ图像的核型公式为：２n=4x=52=38m 14sm(sat)。３对随体染色体序号分别是Ａ亚组第１１、Ｄ亚组第２２和２５，均属于近中部着丝点（sm)类型，随体均在各自杂色体的短臂上，而且与所有染色体无关晨同一亚组起源。Ａ亚组第５、６和９对染色体长臂发生长了片段的易位，易位的片段较大，占所在染色体和蔗的百分率依次为１９．２１％、１７．６９％和１２．８８％，在Ｄ亚组１３对染色体中，最少５对的着丝点区域多或少地显示出与亚洲棉gDNA探针杂交的红色荧光信号，意味着有Ａ亚组染色体的交换。

Studies of FISH and Karyotype of Gossypium barbadense

Based on the fluorescent in situ hybridization (FISH) of somatic chromosome of Gossypium barbadense with the probe of genomic DNA (gDNA) of Gossypium arboreum, two sets of chromosomes were easily distingulshed by signals hybridized or not The FISH directly proved that G. barbadense originated from two different diploid species, but was not in concordance with the former point that every chromosome of A sub-genome of tetraploid species was bigger than that of othersub-genome (D genome). The karyotype formula of G. barbadense based on its FISH was 2n = 4x = 52 = 38m 14sm(6sat). There were three pairs of satellite chromosomes which were all sin types. Their satellites located in short arms but originated differently from their chromosomes of sub-genome. Fragment translocations occured in the long arms of homologous chromosomes of number 5, 6 and 9 of A sub-genome. It was suggested that the translated fragments come from D sub-genome. The fragments are fairly large with the relative lengths of 19.21%, 17.69% and 12.88% of their whole chromosomes, respectively. At least five pairs of chromosomes in D sub-genome show some hybridized signals of gDNA Probe of G. arboreum in their centromere regions, which indicated that there would be chromatin introgressions from A sub-genome.