Ørgaard Marian, Linde-Laursen Ib
Botanical Group, Department of Ecology, Faculty of Life Sciences, University of Copenhagen, Denmark.
Hereditas. 2007 Sep;144(4):159-70. doi: 10.1111/j.2007.0018-0661.01987.x.
Seventeen Danish accessions of five taxa of Barbarea, i.e. B. stricta, B. verna, B. intermedia and B. vulgaris ssp. vulgaris and ssp. arcuata including the two morphologically and biochemically differentiated P(pubescent)- and G(glabrous)-types, and 4 P-xG-type hybrids were analysed cytologically using fluorescent in situ hybridization (FISH) and AgNO(3)-staining. The number of chromocentres varied among nuclei of somatic interphases (generally+/-2) centred around 18 in the P-type of B. vulgaris ssp. arcuata, and around 16 in the G-type, and in the other materials. The observations suggest preponderant chromosome numbers of 2n=18 and 2n=16 in root-tip cells. Chromosome numbers of metaphases supported the idea. In situ hybridization demonstrated the presence of a maximum of two rDNA sites in B. intermedia, four sites in B. stricta and B. vulgaris ssp. vulgaris, and six sites in a P-xG-type hybrid of ssp. arcuata and in B. verna. P- and G-types of B. vulgaris ssp. arcuata both had accessions with four and six rDNA sites revealing polymorphism for the character. The sites differed pairwise in size in the taxa except in the P-type. P-type nuclei had peak numbers of four rDNA sites. Nuclei of other taxa had peak numbers of 2. In nuclei with six sites, one very small pair showed no transcriptional activity. Major rDNA sites presented a low frequency of association. The number of stronger rDNA signals agreed with the observation of maximally 2 AgNO(3)-stained nucleoli in B. intermedia and 3 or 4 nucleoli in the other taxa indicating 2 and 4 nucleolus organizing chromosomes in the genomes, respectively.
对17份丹麦的山芥属5个分类群的材料进行了细胞学分析，这些材料包括硬毛山芥、春山芥、中间山芥、普通山芥普通亚种和弓叶山芥亚种，其中有形态学和生物化学上有差异的P（有毛）型和G（无毛）型，以及4个P-xG型杂种，分析方法为荧光原位杂交（FISH）和硝酸银染色。在体细胞间期核中，染色中心的数量各不相同（一般为±2个），在弓叶山芥普通亚种的P型中，染色中心数量一般以18个为中心，在G型以及其他材料中，染色中心数量一般以16个为中心。这些观察结果表明，根尖细胞中优势染色体数为2n = 18和2n = 16。中期染色体数支持了这一观点。原位杂交表明，中间山芥中最多有两个rDNA位点，硬毛山芥和普通山芥普通亚种中有四个位点，弓叶山芥亚种的一个P-xG型杂种和春山芥中有六个位点。弓叶山芥普通亚种的P型和G型都有四个和六个rDNA位点的材料，显示出该性状的多态性。除P型外，各分类群中这些位点的大小两两不同。P型核中rDNA位点的峰值数量为四个。其他分类群的核中rDNA位点的峰值数量为两个。在有六个位点的核中，有一对非常小的位点没有转录活性。主要rDNA位点的关联频率较低。较强rDNA信号的数量与以下观察结果一致：中间山芥中最多有2个硝酸银染色的核仁，其他分类群中有3或4个核仁，分别表明基因组中有2条和4条核仁组织染色体。
