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).
利用廣譜抗性基因是控制稻瘟病最有效和經(jīng)濟的手段。水稻品種二八占（EBZ）在華南被廣泛用作抗稻瘟病的供體親本，并由它衍生出許多對稻瘟病具有廣譜抗性的品種。用EBZ和高感病品種麗江新團(tuán)黑谷（LTH）培育的重組自交系進(jìn)行定位，在EBZ的第1染色體(Pish)，第6染色體(Pi2/Pi9)和第12染色體(Pita/Pita-2) 均發(fā)現(xiàn)了抗性基因。Pi2/Pi9等位基因的種族特異性和抗譜均與其他已知的Pi2/Pi9攜帶體有所差異。通過對大量感病的EBZ × LTH F2株系和EBZ × LTH BC1F2分離群體進(jìn)行精細(xì)定位，將基因定至包括Pi2/Pi9在內(nèi)的53 kb區(qū)間。對Pi2/Pi9的四個功能NBS-LRR基因的LRR結(jié)構(gòu)域進(jìn)行序列比對，發(fā)現(xiàn)來自EBZ的等位基因與其他已知的Pi2/Pi9等位基因不同的，該基因被命名為Pi50(t)。