Construction of Mungbean Genetic Linkage Map

A high-density genetic linkage map with informative markers is essential for plant genome analyses, such as gene mapping, identification of quantitative trait loci, map-based cloning, and physical map construction. A genetic linkage map of mungbean (Vigna radiata, 2n = 2x = 22) was constructed using a recombinant inbred line (RIL) population derived from an inter-subspecific cross between Berken (a bruchid-susceptible cultivar) and ACC41 (a bruchid-resistant genotype belonging to V. radiata subsp. sublobata). For enhancing the density of the existing linkage map, 104 pairs of polymorphic simple sequence repeat (SSR) primer, were screened out. In combination with the data from other markers, a new genetic linkage map consisting of 179 markers was obtained. They included 97 SSR markers (91 of which were derived from mungbean close relatives), 76 RFLP markers, and 2 STS markers. These markers were assigned to 12 linkage groups with an average distance of 10.2 cM between markers. The transferability of the SSR markers from these relatives of mungbean, including azuki bean (V. angularis), black gram (V. mungo), common bean (Phaseolus vulgaris), and cowpea (V. unguiculata) was also evaluated. Approximately 65% of SSR markers form azuki bean, 72% from black gram, 42% from common bean, and 30% from cowpea could be effectively amplified in mungbean. These different ratios might reflect different levels of genomic homology between mungbean and the four close relatives. A total of 98 pairs of polymorphic SSR primers from these close relatives were effective in genetic analysis of mungbean. The new linkage map of mungbean was compared with a published linkage map of azuki bean based on 32 common SSR markers. The majority of these markers were mapped in similar orders between these 2 species and a few markers with different orders suggested relative rearrangements between the 2 genomes. As previously reported, a major locus resistant to bruchid was located on linkage group I (9). In this new map, the distances between the bruchid locus and its flanking markers were 8.0 cM (C78) and 2.7 cM (C220), respectively.

摘要利用绿豆及其近缘种的701对SSR引物, 对现有绿豆遗传连锁图谱进行补充, 结果在高感豆象绿豆栽培种Berken和高抗豆象绿豆野生种ACC41两亲本间筛选到多态性SSR引物104对。群体分析后, 结合其他分子数据, 使用作图软件Mapmaker/Exp 3.0b, 获得一张含有179个遗传标记和12个连锁群, 总长1 831.8 cM、平均图距10.2 cM的新遗传连锁图谱, 包括97个SSR标记, 91个来自绿豆近缘种; RFLP标记76个; RAPD标记4个; STS标记2个。对32个绿豆、小豆共用SSR标记在遗传连锁图谱的分布分析发现, 二个基因组间有一定程度的同源性, 共用标记在连锁群上的排列顺序基本上一致, 只有部分标记显示绿豆和小豆基因组在进化过程中发生了染色体重排; 利用新图谱对ACC41的抗绿豆象主效基因重新定位, 仍定位于I(9)连锁群, 与其相邻分子标记的距离均小于8 cM, 其中与右翼SSR标记C220的距离约2.7 cM。与原图谱比较, 新定位的抗性基因与其相邻标记的连锁更加紧密。