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Rice progenies used for the construction of genetic maps permit exhaustive identification and characterization of resistance genes present in their parental cultivars. We inoculated a rice progeny derived from the cross IR64 × Azucena with different Magnaporthe grisea isolates that showed differential responses on the parental cultivars. By QTL mapping, nine unlinked loci conferring resistance to each isolate were identified and named Pi-24(t) to Pi-32(t). They could correspond to nine specific resistance genes. Five of these resistance loci (RLs) were mapped at chromosomal locations where no resistance gene was previously reported, defining new resistance genes. Using degenerate primers of the NBS (nucleotide binding site) motif found in many resistance genes, two resistance gene analogues (RGAs) IR86 and IR14 were identified and mapped closely to two blast RLs (resistance identified in this study, i.e. Pi-29(t) and Pi-30(t) respectively). These two RLs may correspond to the Pi-11 and Pi-a blast resistance genes previously identified. Moreover, the ir86 and ir14 genes have been identified "in silico" on the indica rice cultivar 93-11, recently sequenced by Chinese researchers. Both genes encodes NBS-LRR-like proteins that are characteristics of plant-disease resistance genes. [ABSTRACT FROM AUTHOR]

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We developed sequence characterized amplified region (SCAR) markers to monitor recombination and migration within Magnaporthe grisea populations. Twenty-two primer pairs were designed from random amplified polymorphic DNA (RAPD) markers or available gene sequences. Sixteen of these SCARs were polymorphic in M. grisea when tested on 232 isolates collected from worldwide origins. [ABSTRACT FROM AUTHOR]

Presents a correction to the article "Identification of Five New Blast Resistance Genes in the Highly Blast-Resistant Rice Variety IR64 Using a QTL Mapping Strategy," published in the April 30, 2003 issue of the journal "Theoretical and Applied Genetics."