Identification of quantitative trait loci for resistance to Curvularia leaf spot of maize

Resistance of maize to Curvularia leaf spot (CLS), a severe foliar disease in hot and humid maize growing areas, is quantitative in nature. The F-2:3 families derived from the cross between the resistant Shen137 and susceptible Huangzao4 inbred lines, were used to detect QTL conferring resistance to CLS. Four QTL were detected on chromosomes 1, 3, 8, and 10, and could totally explain 38.8% of the total phenotypic variation. Another F-2 population consisting of 63 highly resistant and 59 highly susceptible plants, selected from 822 F-2 plants, was also subjected to QTL analysis for CLS resistance. Four OTL were found on four chromosomes 1, 4, 9, and 10, which accounted for 45.7% of the total phenotypic variation. Interestingly, a major resistance OTL, gCLS10.4, on chromosomal bin10.04 was consistently detected in both populations. Apart from additive effect, dominant effect also exerted significant influence on resistance to CLS. Therefore, breeders should avoid an early generation selection of resistant individuals in breeding program.