广谱稻瘟病抗性基因Pigm和Pi2的抗谱差异及与Pi1的互作效应

Resistance Spectrum Difference between Two Broad-Spectrum Blast Resistance Genes,Pigm and Pi2,and Their Interaction Effect on Pi1

Pigm是Pi2基因簇的等位或紧密连锁基因。本研究构建了4个不同遗传背景下Pigm和Pi2的系列近等基因系，204个菌株苗期接种结果显示其抗性频率均超过70％，但Pigm和Pi2的抗谱重叠度仅为54．4％~65．7％，聚合Pi1／Pigm和Pi1/Pi2以杂种的抗性频率均超过90％。穗瘟人工接种及病圃自然诱发鉴定表现与苗期接种一致的发病趋势。农艺性状调查结果显示获得的近等基因系与其轮回亲本基本相似，存在较少的累赘连锁。表明Pigm是一个与Pi2抗谱差异明显的广谱抗性基因，对稻瘟病抗性育种具有重要应用价值。

Pigm, an R gene to rice blast disease, is either allelic or tightly linked to Pi2. In this study, a series of near-isogenic lines （NILs） containing Pigm and Pi2 under four genetic backgrounds of rice cultivars were established, respectively. The results from inoculating with 204 representative races at seedling stage showed that the resistance frequency of NILs carrying Pigm and Pi2 all reached more than 70%, but the overlapping degree of resistance spectrum between them was only 54.4% to 65.7%, and the resistance frequency of hybrids pyramiding Pil/Pigm and Pil/Pi2 was more than 90%. Disease development from artificial inoculation at heading stage and natural induction in disease nursery showed consistent trend with that from inoculation at seedling stage. Agronomic traits of most NILs were similar to those of recurrent parent, indicating that the target region contains few linkage drags. In conclusion, Pigm is a broad-spectrum blast resistance gene possessing significant resistance spectrum difference from Pi2, and holds important value for rice blast breeding.