Quantitative trait loci mapping of resistance to sugarcane mosaic virus inmaize

Sugarcane mosaic virus (SCMV) is an important virus disease of maize (Zea m ays) in Europe. In this study, we mapped and characterized quantitative tra it loci (QTL) affecting resistance to SCMV in a maize population consisting of 219 F-3 or immortalized F-2 families from the cross of two European mai ze inbreds, D32 (resistant) x D145 (susceptible). Resistance was evaluated in replicated field trials across two environments under artificial inocula tion. The method of composite interval mapping was employed for QTL detecti on with a linkage map based on 87 restriction fragment length polymorphism and 7 mapped microsatellite markers. Genotypic and genotype x environment i nteraction variances for SCMV resistance were highly significant in the pop ulation. Heritabilities ranged from 0.77 to 0.94 for disease scores recorde d on seven consecutive dates. Five QTL for SCMV resistance were identified on chromosomes 1, 3, 5, 6, and 10 in the joint analyses. Two major QTL on c hromosomes 3 and 6 were detected consistently in both environments. Signifi cant epistatic effects were found among some of these QTL. A simultaneous f it with all QTL in the joint analyses explained between 70 and 77% of the p henotypic variance observed at various stages of plant development. Resista nce to SCMV was correlated with plant height and days to anthesis.