QTL Mapping for Downy Mildew Resistance in Pearl Millet [Pennisetum glaucum (L.) R. Br.]

Pearl millet [Pennisetum glaucum (L.) R. Br.] is a multipurpose cereal grown for grain, stover and green fodder. Relative to other cereal species, it ranks fifth in annual world production. Use of molecular marker technology for pearl millet genetic improvement has been limited because of an insufficiently developed linkage map. The majority of the pearl millet molecular markers (RFLP and SSR) mapped to date are clustered around the seven pearl millet chromosome centromeres and only a few marker loci are mapped to more distal regions. There is a need for more evenly distributed markers throughout the genome linkage and greater marker coverage of the gaps in earlier established maps. The objective of this research was to develop a PCR-based molecular marker linkage map of downy mildew concened molecular markers of pearl millet on the basis of a segregating F-2 population resulting from a cross between J-2480 (Resistant) and J-2372 (Susceptible). This mapping effort involved 125 F2 populations and 24 polymorphic PCR-based SSR. The average genetic distance between markers was 10 cM, varying from 4.9 to 21.2 cM. The number of markers in each linkage group (LG) ranged from 2 to 7. The resulting map consisted of seven linkage groups that spanned about 240.8 cM. The majority of the markers used in this study to construct the genetic linkage map were randomly distributed in each LG which makes it useful in pearl millet mapping and breeding.