用Rim2超级家族分子指纹鉴别杂交水稻及预测杂种优势

Identification of Hybrid Rice and Prediction of Heterosis with Rim2 Superfamily Molecular Fingerprint

选用5对Rim2引物对21份籼稻和20份粳稻材料进行了DNA指纹扩增,共扩增出38条谱带,其中多态性谱带26条,多态性水平为69.64%;粳稻平均多态性水平为56.67%,明显高于籼稻。根据Nei’s遗传距离计算获得的聚类树状图表明,参试21份籼稻材料聚为6组,20份粳稻材料聚为7组。亲缘关系分析表明,Rim2分子指纹可以区分多数的籼稻或粳稻材料,且显示出材料的遗传特征。考察部分籼稻和粳稻杂交组合的产量对照优势与双亲间遗传距离的关系,发现杂交粳稻的遗传距离与杂交优势表现出相关性,而杂交籼稻无此相关性。

The rice Rim2 is a unique stress-induced transposon superfamily recently identified in Oryza genomes. The polymorphisms of Rim2 core region provide a novel technique to fingerprint rice genetic variation. In the past decade, DNA markers such as RAPD, AFLP, RFLP and SSR have been extensively used for fingerprinting and exploring the genetic diversity and evolutionary relation of rice genetic resources. In this paper, Rim2 elements were used as the DNA marker to fingerprint indica and japonica hybrid rice and to predict their heterosis according to the molecularly genetic distance. Five pairs of PCR primers based on the Rim2 sequences were selected to amplify cDNA of twenty-one indica and twenty japonica rice, including three sterile lines, nine restoring lines and nine hybrids in indica and three sterile lines, eight restoring lines and nine hybrids in japonica. A total of thirty-eight bands were obtained, of which twenty-six were polymorphie, accounting for 69.64% . The average polymorphism rate of japonica was 56.67%, which was apparently higher than that of indica. The dendrogram based on Nei＇s distance showed that twenty-one indiea rice and twenty japonica rice could be divided into six groups and seven groups respectively. The analysis of genetic relationship among materials showed that Rim2 molecular fingerprint could distinguish most of indica or japonica rice. Correlations were found in japonica flee between the genetic distance of parents and their hybrid heterosis, while not in indica rice. These findings demonstrate the potential of developing a more powerful molecular tool based on the tremendous variability of the Rim2 superfamily to explore on administration of seed production, variety licensing, marker-aid selection in breeding programs, such as RAPD, AFLP, RFLP and SSR have achieved.