‘红江橙’天然多倍体的45S rDNA荧光原位杂交分析

Studies on 45S rDNA-FISH of Natural Polyploids in Citrus sinensis Osbeck.‘Hongjiangcheng’

以实生筛选获得的红江橙三倍体和四倍体植株及其二倍体对照为试验材料,利用荧光原位杂交(fluorescence in situ hybridization,FISH)技术分析了不同倍性红江橙体细胞染色体上45S rDNA的分布。结果表明,红江橙二倍体体细胞中期染色体中存在3个45S rDNA杂交位点,分别位于第1对染色体的核仁组成区和第8号染色体的整个随体上;三倍体体细胞中期染色体中存在4个杂交位点,其中有3个与二倍体基本相同,另外1个位于第3号染色体的核仁组成区;四倍体体细胞中期染色体中存在6个杂交位点,分布的位置及区域和信号的强弱均与二倍体基本相同。供试材料体细胞间期核与中期染色体中的杂交信号数及强弱程度基本相似。通过分析,提出红江橙三倍体的形成与2n雌配子的形成有关,伴随有外源基因组的重组;四倍体可能产生于珠心系细胞的直接加倍,并且伴随有染色体的断裂和易位。

The materials of experiment were natural triploids, natural tetraploids selected in seeds and diploids of Citrus sinensis Osbeck. ‘ Hongjiangcheng＇. Making use of the technique of 45S rDNA-FISH, the FISH karyotypes of these materials were studied and the results were analysized. Three hybridized signals were detected on NORs （ nuclear organization region） on chromosomes number 1 and all regions of satellite of chromosome number 8 in the mitotic metaphase. Four hybridized signals located on the mitotic metaphase chromosomes of triploid. One signal was detected on NOR of chromosome number 3, and the other three were same as diploid. There were six hybridized signals on the mitotic metaphase chromosomes of tetraploid, and these signals were same as diploid. And same hybridized signals were detected on mitotic interphase. According to the results, the formation of triploids should be relative to 2n female gametes with recombination of foreign genes. Tetraploids should be relative to the chromosome doubling of nucellus cells, and a few chromosomes breakage and translocation were found.