Search for new QTL of resistance to powdery mildew (Blumeria graminis f.sp. hordei) in a Spanish barley landrace
2008
Dhif, H.
The aim of this study was to investigate the location and effect of quantitative trait loci for resistance against powdery mildew (caused by Blumeria graminis f.sp. hordei) in a Spanish barley line derived from a landrace, CNE97. For this purpose, a RIL population of 262 lines was constructed (CNE97 x French cultivar Plaisant), susceptible to most races of powdery mildew. Phenotyping was carried out at a collaborating laboratory (IRRST-JKI), with artificial inoculations at seedling stage. Genotyping was carried out with a total of 111 markers, comprising mostly microsatellites and some resistance gene analogs (RGA), in a sequential manner: First, 75 lines at the F6 stage were assayed with all the markers. Then, only 20 markers were assayed in the rest of the population, focusing on regions most likely to carry QTL, according to the analysis of the F6. Two QTL of large effect were both localized on chromosome 7H at both steps of the process. Between both, they explain 34 to 45 per cent of the phenotypic variance for resistance. One locus was localized on chromosome arm 7HS, in the region flanked by the RGA S9020 and the microsatellite GBM1060, which is consistent with the mapped mlt gene, which confers resistance to powdery mildew. The second QTL was in tight linkage with the microsatellite EBmac0755, on chromosome arm 7HL. Due to this location, it is possible that it co-locates with another powdery mildew resistance gene, Mlf. Resistance alleles for these putative genes have been found only in H. vulgare ssp. spontaneum accessions. This is the first report of the existence of both QTL at the same time in cultivated barley, which offers great advantages for their use in barley breeding
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