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February 20, 2004
Plant
Disease March 2004
Volume 88, Number 3
The American Pathological
Society (APS)
Interpretive summary
Identification
of Magnaporthe oryzae Avirulence Genes to Three Rice
Blast Resistance Genes
C. X. Luo, Faculty of Agriculture, Saga University, Saga,
840-8502, Japan; Y. Fujita, National Agricultural Research
Center for Hokkaido Region, Sapporo, 062-8555, Japan; N. Yasuda,
National Agricultural Research Center, Tsukuba, 305-8666, Japan;
K. Hirayae, National Agricultural Research Center, Joetsu,
943-0193, Japan; T. Nakajima, National Agricultural Research
Center for Kyushu Okinawa Region, Kumamoto, 861-1192, Japan; N.
Hayashi, National Institute of Agrobiological Sciences, Tsukuba,
305-8602, Japan; and M. Kusaba and H. Yaegashi, Faculty of
Agriculture, Saga University, Saga, 840-8502, Japan. Plant Dis.
D-2003-1216-01R, 2004. Accepted for publication 9 October 2003.
Rice blast, caused by Magnaporthe oryzae, is the most
disastrous and widespread disease of rice. One of the most
effective means of controlling rice blast is through the use of
resistant rice cultivars, but newly developed resistant
cultivars often lose their resistance after a few years of
commercial production. The breakdown of resistance in rice
cultivars to blast is probably due to genetic instability of
avirulence (Avr) genes. To identify a genetic mechanism
that governs the instability of Avr genes corresponding
to the resistance (R) genes would be indispensable for
developing rice cultivars with lasting resistance. To identify
the Avr genes that correspond to the specific R
genes Pik, Piz, and Piz-t, we
determined the mode of inheritance of avirulence on three
race-differential rice cultivars through a genetic cross of rice
blast isolates and then identified the Avr genes based on
the reaction of F3 families of rice to both the parental
isolates and standard isolates harboring known Avr genes.
We also constructed a partial linkage map containing the Avr
genes by using random amplified polymorphic DNA (RAPD) analysis.
http://www.apsnet.org/pd/summaries/dma04sum.asp
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