A major QTL for resistance of rice to the parasitic plant Striga hermonthica is not dependent on genetic background

BACKGROUND: The use of Striga-resistant germplasm is likely to be a cost-effective control strategy for preventing loss of yield owing to Striga. Previously, the authors identified quantitative trait loci (QTL) for resistance in rice to Striga hermonthica (Del.) Benth. in backcross inbred lines (BILs) derived from a cross between two cultivars Nipponbare and Kasalath. It is essential to validate QTL in different environments and/or genetic backgrounds to develop molecular markers linked to resistance QTL for use in marker-assisted selection (MAS) programmes. This study aimed to establish whether a large-effect Kasalath-derived resistance QTL allele on chromosome 4 of rice also conferred resistance in a different mapping population derived from a cross between Koshihikari and Kasalath, and to identify any further Striga resistance QTL. RESULTS: Three Striga resistance QTL were detected in Koshihikari-Kasalath BILs, two of which were derived from the Kasalath allele and one from the Koshihkari allele. The largest QTL (Kasalath allele) explained 16% of the variation in the mapping population and was located on chromosome 4. Comparison between these data and those of the authors' previous analysis revealed that the confidence intervals of the chromosome-4 QTL in the Nipponbare-Kasalath cross and the Kasalath-Koshihikari cross overlapped between 6.5 Mbp and 8 Mbp on the physical rice genome assembly. CONCLUSION: This study has both verified and narrowed down the position of a Striga resistance QTL of major effect, and demonstrated that it may be a tractable target for MAS. (C) 2009 Society of Chemical Industry