The deployment of broad-spectrum resistance genes is the most effective and economic means of controlling blast in rice. The cultivar Er-Ba-Zhan (EBZ) is a widely used donor of blast resistance in South China, with many cultivars derived from it displaying broad-spectrum resistance against blast. Mapping in a set of recombinant inbred lines bred from the cross between EBZ and the highly blast-susceptible cultivar Liangjiangxintuanheigu (LTH) identified in EBZ a blast resistance gene on each of chromosomes 1 (Pish), 6 (Pi2/Pi9) and 12 (Pita/Pita-2). The resistance spectrum and race specificity of the allele at Pi2/Pi9 were both different from those present in other known Pi2/Pi9 carriers. Fine-scale mapping based on a large number of susceptible EBZ × LTH F2 and EBZ × LTH BC1F2 segregants placed the gene within a 53-kb segment, which includes Pi2/Pi9. Sequence comparisons of the LRR motifs of the four functional NBS-LRR genes within Pi2/Pi9 revealed that the EBZ allele is distinct from other known Pi2/Pi9 alleles. As a result, the gene has been given the designation Pi50(t).
利用广谱抗性基因是控制稻瘟病最有效和经济的手段。水稻品种二八占（EBZ）在华南被广泛用作抗稻瘟病的供体亲本，并由它衍生出许多对稻瘟病具有广谱抗性的品种。用EBZ和高感病品种丽江新团黑谷（LTH）培育的重组自交系进行定位，在EBZ的第1染色体(Pish)，第6染色体(Pi2/Pi9)和第12染色体(Pita/Pita-2) 均发现了抗性基因。Pi2/Pi9等位基因的种族特异性和抗谱均与其他已知的Pi2/Pi9携带体有所差异。通过对大量感病的EBZ × LTH F2株系和EBZ × LTH BC1F2分离群体进行精细定位，将基因定至包括Pi2/Pi9在内的53 kb区间。对Pi2/Pi9的四个功能NBS-LRR基因的LRR结构域进行序列比对，发现来自EBZ的等位基因与其他已知的Pi2/Pi9等位基因不同的，该基因被命名为Pi50(t)。