Genetic Diversity Of Rice Varieties Resistant To Rice Blast And Molecular Marker Of The Resistance Genes

38 primers synthesized according to resistance gene conserved domains were made up 28 primer pairs. These primer pairs were used to amplify LTH NILs in China. The results showed that the amplified band types in same NILs varied with primer pairs used. The primer pair LM637/LM638 could amplify 40 bands from the varieties, which was the most among 3 primer pairs. Only 1 to 2 bands were amplified by Ptokin1N/Ptokin2N while no band appeared in the amplification of Ptokin2-invl/Ptokin2-inv2. In addition, the bands amplified by the primer pair S1/AS3 were significantly different in two NILs (LTH and Co39).3 primer pairs including XLRRfor/XLRRrev, Ptokin1/Ptokin2 and S1/AS3 were selected to amplified 27 rice cultivars from Jiangsu Province. These primer pairs were designed according to different resistance gene conserved domains and had high ability of the amplification. 127 bands were amplified from 27 rice cultivars by 3 primer pairs, in which 101 bands were polymorphic, with the polymorphic band frequency of 79.53%. The frequency of polymorphic bands amplified by XLRRfor/XLRRrev was the highest among 3 primer pairs, with the sum of 47 bands and the polymorphic band frequency of 85.11%. Furthermore, there were no differences in the molecular weight of polymorphic bands amplified by 3 primer pairs.RGA-PCR maps of rice cultivars amplified by 3 primer pairs or primer pair combinations could be grouped by cluster analysis. There were no completely corresponding relations between these RGA-PCR map groups and resistance phenotypes of rice cultivars. But RGA-PCR maps amplified by XLRRfor/XLRRrev or its combinations had same relations with the resistance phenotypes, which might be because the primer pair came from rice.28 primer pairs were used to amplify LTH NILs varieties. There were 11 primer pairs by which special bands could be amplified. 33 special bands were retrieved and re-amplified, and 11 simple bands were acquired. Two fragments (HS-1 and HS-19) with the size from 480bp to 490bp were selected to sign as probes. There were samesignals in all rice varieties by dot hybridization, which indicated that all rice varieties tested could have same or partial RGA.The results of electrophoresis and southern hybridization showed that HS-1 fragment could detect special signals in rice varieties with resistance gene Pi-ta2, which revealed that this sequence could link with Pi-ta2 gene or be a part of the gene.34 rice varieties had the special band of 480bp among 202 rice varieties amplified with XLRRfor/XLRRrev. By comparison, it was found that although rice varieties had the same special band, their resistance phenotypes could be different, which maybe related to genetic complexity of resistance phenotypes.HS-1 fragment has been cloned and sequenced, and was 478bp. It was 95% identical with RGA29 which was a resistance gene analog cloned from rice by Mago(1999).