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Molecular Genetics and Genomics

, Volume 267, Issue 4, pp 472–480 | Cite as

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
Original Paper

Abstract.

To understand the molecular basis of broad-spectrum 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 with one 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.

Oryza sativa Magnaporthe grisea Resistance gene cluster High-resolution mapping 

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Copyright information

© Springer-Verlag 2002

Authors and Affiliations

  •  G. Liu
    • 1
  •  G. Lu
    • 1
  •  L. Zeng
    • 1
  •  G.-L. Wang
    • 1
  1. 1.Department of Plant Pathology, The Ohio State University, 201 Kottman Hall, 2021 Coffey Road, Columbus, OH 43210, USA

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