芸薹属多倍体植物基因组进化的RAPD分析

RAPD analysis on the genome evolution of polyploids in Brassica

多倍化是促进高等植物发生进化的重要力量。为了更清楚地了解多倍体在形成之后其基因组是如何进化的 ,利用 38个随机引物对芸薹属BrassicaL .禹氏三角 (U’Triangle)中的多倍体物种及其祖先二倍体物种进行了研究。根据扩增出的 2 73条带计算了遗传距离 ,并用UPGMA法进行了聚类分析。结果发现 ,二倍体物种B .campestris (AA)与B .oleracea (CC)的亲缘关系比与B .nigra (BB)的要近 ;异源多倍体B .napus (AACC)比起其二倍体祖先之一B .campestris(AA)与另一个祖先种B .oleracea(CC)的关系更近 ,异源多倍体B .juncea (AABB)和B .carinata(BBCC)都只与其二倍体祖先种之一B .nigra (BB)的关系更为接近。结合统计分析的结果表明 ,比较而言 ,异源多倍体B .napus (AACC)形成后其祖先基因组A和C变化不大 ;B .juncea(AABB)和B .carinata (BBCC)形成后各自都是其一个祖先基因组 ,即B基因组变化较小 。

Polyploidy has played an important role in the evolution of higher plants. In order to understand how polyploid genomes evolve after their formation, the Brassica triangle was used to study genomic evolution after the formation of polyploids. Random amplified polymorphic DNA (RAPD) analysis was performed on the diploids and allopolyploids in Brassica triangle with 38 random 10-base primers. A total of 273 bands were detected, among which 264 bands were polymorphic. Based on the RAPD data, genetic distances among the samples were calculated and two dendrograms were constructed by using UPGMA method. The results have revealed that (1) B. campestris (AA) was more closely related to B. oleracea (CC) than to B. nigra (BB), (2) B. napus (AACC) nested with its diploid progenitors, B. campestris (AA) and B. oleracea (CC), in one cluster, and (3) the allopolyploids carrying B genome nested with B. nigra (BB) in other cluster. The results suggest that both genome A and genome C are not much modified after the formation of B. napus (AACC) and that genome B is modified less than genome A or C after B and A, or B and C merge into a common nucleus.