An approach to cloning of Pi-b rice blast resistance gene |
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Authors: | Krystyna Rybka Masaru Miyamoto Shingo Nakamura Shinji Kawasaki |
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Affiliation: | (1) Plant Breeding and Acclimatization Institute-Radzików, POB 1019, 00-950 Warszawa;(2) Institute of Plant Biotechnology, Ibaraki, Ago, Iwama, 309-02 Ibaraki, Japan;(3) Research and Development Corporation of Japan (JRDC), Honcho, Kawaguchi, 332 Saitama, Japan;(4) National Institute of Agrobiological Resources, Ibaraki 305 Tsukuba, Japan |
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Abstract: | A contig of clones from BAC rice genomic library encompassing blast resistance gene Pi-b was constructed. On an average eight clones (8 ± 2.6) were picked up by each marker, which was expected basing on the BAC library size (Nakamura et al. 1997). The 2.4 cM distance between flanking RFLP markers G 1234 and RZ 213 (Miyamoto et al. 1996) was spanned with 4 steps of contig including 25 clones. The physical distance of 370 kb between flanking markers corresponds to a small ratio of physical and genetical distances (155 kb/cM) due to a probable structure of the gene locus near the telomeric end of the chromosome. Markers cosegregating with blast resistance against Magnoporthe grisea were localized in a 2 kb restriction fragment. A new border marker was found on the telomeric side of the Pi-b gene, less than 10 kb from cosegregating markers. No clear marker for the centromeric side of the gene was found but the position of Pi-b rice blast resistant gene was narrowed to within at least 50 kb, which is to our knowledge the most precised estimation of the position of this gene. |
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Keywords: | Magnoporthe grisea rice blast mapping resistance gene rice |
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