利用原位杂交及CAPS标记分析芸薹属A、B和C基因组间的关系

以来源于Brassica rapa基因组(AA)的重复序列(151 bp)为探针, 分别同二倍体白菜型油菜(AA, 2n=20)、甘蓝(CC, 2n=18)和异源四倍体芥菜型油菜(AABB, 2n=36)的中期染色体杂交, 白菜型油菜和甘蓝的所有染色体上都有杂交信号, 芥菜型油菜的染色体上显示出20个明显的信号, 其余染色体上信号很弱或无, 可以区分出A和B基因组。对来源于油菜3个基本种与3个复合种FAE1基因进行CAPS分析表明, 3个基本种表现出不同的酶切式样, 用Mbo I和Msp I酶切表现出多态性, 基因组A和C非常相似, 而基因组B与A、C关系较远, 同时3个复合种也并不是2个基本种的简单相加, 表明异源四倍体在长期进化过程中可能发生了重排和重组。

Relationships among Genome A, B, and C Revealed by FISH and CAPS

Physical localization of repetitive DNA sequence from genome A (151 bp) was carried out on the chromosomes of the selected Brassica species by FISH (fluorescence in situ hybridization). The signals distributed on all the chromosomes of A (Brassica rapa, 2n=20) or C genome (B. oleracea, 2n=18). For B. juncea (AABB, 2n=36), the signals were found on all the chromosomes of genome A and the strength of signal varied among different chromosomes, while the chromosomes of genome B showed weak or no signals. FAE1 gene is a rate-limiting gene for erucic acid synthesis in Brassica. The genes from six Brassica species of U-triangule were cloned by PCR. These PCR products were digested with different restriction endonucleases. Mbo I and Msp I were found to produce informative CAPS patterns of FAE1 gene. Three diploids displayed different patterns, the patterns of genome A was very similar to that of genome C, while the patterns of genome B was the most diverged out of the patterns of the A and C genomes. Three amphidiploids generally exhibited additive patterns of the progenitors, but not strictly in all cases, indicating that rearrangements and recombinations did occur in the formation and evolution of amphidiploids. Genetic relation-ships among Brassica species could be demonstrated through CAPS analysis of FAE1 gene and FISH method when repetitive DNA sequence (not ribosomal RNA genes) was used as a probe.