Two broad-spectrum blast resistance genes, Pi9(t) and Pi2(t), are physically linked on rice chromosome 6

G. Liu, G. Lu, L. Zeng, G.-L. Wang
Molecular Genetics and Genomics, 2002, 267(4): 472-480  DOI: 10.1007/s00438-002-0677-2     追溯原文......本站官方QQ群:62473826

To understand the molecular basis of broadspectrum resistance to rice blast, fine-scale mapping of the two blast resistance (R) genes, Pi9(t) and Pi2(t), was conducted. These two genes were introgressed from different resistance donors, previously reported to confer resistance to many blast isolates in the Philippines, and were mapped to an approximately 10-cM interval on chromosome 6. To further test their resistance spectrum, 43 blast isolates collected from 13 countries were used to inoculate the Pi2(t) and Pi9(t) plants. Pi9(t)-bearing lines were highly resistant to all isolates tested, and lines carrying Pi2(t) were resistant to 36 isolates, confirming the broad-spectrum resistance of these two genes to diverse blast isolates. Three RAPD markers tightly linked to Pi9(t) were identified using the bulk segregant analysis technique. Twelve positive bacterial artificial chromosome (BAC) clones were identified and a BAC contig covering about 100 kb was constructed when the Pi9(t) BAC library was screened withone of the markers. A high-resolution map of Pi9(t) was constructed using BAC ends. The Pi2(t) gene was tightly linked to all of the Pi9(t) markers in 450 F2 plants. These data suggest that Pi9(t) and Pi2(t) are either allelic or tightly linked in an approximately 100-kb region. The mapping results for Pi9(t) and Pi2(t) provide essential information for the positional cloning of these two important blast resistance genes in rice.


为了了解稻瘟病广谱抗性的分子机制,本研究对两个稻瘟病抗性基因Pi9(t)和Pi2(t)进行精细定位。这两个基因分别来自不同的抗源,之前有报道对许多菲律宾的稻瘟病菌株具有抗性,并定位到第6染色体上约10-cM的区间。为了进一步检测Pi9(t)和Pi2(t)的抗谱,用自13个国家收集的43株稻瘟病菌株进行接种鉴定。带有Pi9(t)的株系对所有菌株具有抗性,带有Pi2(t)的株系对其中36个菌株具有抗性,证明这两个基因对稻瘟病菌具有广谱抗性。通过批量分离分析技术找到3个与Pi9(t)紧密连锁的RAPD标记。通过其中一个标记筛选Pi9(t) BAC库并鉴定出12个阳性克隆,其中一个BAC重叠群覆盖了约100kb长度。利用BAC克隆末端构建了Pi9(t)的高分辨率图谱。Pi2(t)在所有450个F2植株上与Pi9(t)的标记连锁,这表明Pi9(t)和Pi2(t)为等位基因或者在约100-kb区段内紧密连锁。Pi9(t)和Pi2(t)的定位结果为进一步克隆这两个重要的水稻抗稻瘟病基因提供了必要的信息。

  稻瘟病抗性基因 Pi9; Pi2/Piz-5; Pi50; Piz; Pi