Submitted to: Temperate Rice Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: March 1, 1999
Publication Date: N/A
A set of recombinant inbred lines (RILs) was developed from a cross between 'Lemont', a tropical japonica variety grown widely in the southern US and throughout the world, and 'Teqing', a very high yielding Chinese indica. A framework RFLP map containing 175 loci was developed from analysis of DNA extracted from 284 F10 progeny. Ancestral F8 plants were spray inoculated and evaluated for complete resistance to five individual races of the blast pathogen. Linkage analysis identified four major resistance genes located on chromosomes 2, 6, 11 and 12. The gene on chromosome 6 appears to be a new gene while the other three genes may be allelic to previously reported major genes. F8 plants were also grown in field plots that were naturally inoculated by a mixture of races and evaluated for quantitative measures of disease reaction. Interval analysis identified nine putative quantitative trait loci (QTLs) associated with one eor more of the field-resistance ratings. Three of four major gene loci mapped using qualitative single-race response data were also identified as QTLs. Four of the QTLs mapped here coincided with the locations of genes/QTLs identified elsewhere in other studies, suggesting that they may be more widely useful in providing varietal resistance. Both the durable resistance exhibited by Lemont and the complete and broad spectrum resistance exhibited by Teqing in the U.S. were attributed to a combination of major genes capable of inducing hypersensitive reactions and minor genes causing less distinctive phenotypic differences. This supports the strategy of pyramiding major genes and QTLs to develop varieties with improved resistance to the blast fungus. Seed and molecular data from this self-replicating population are being shared upon request.