| Maize dwarf mosaic disease caused by sugarcane mosaic virus (SCMV) is a worldwide disease and is also one of the most important diseases in the China corn belt. Developing disease-resistant varieties is the most economic and efficient approach to control the disease. To explore SCMV-resistant genes and the linked markers in Chinese maize germplasm by moleculer marker technology will offer useful information for setting strategy to facilitate disease-resistant breeding efforts efficiently. In this study, F2 and F3 populations derived from the cross (X178 X B73), were used for linkage map construction by molecular markers SSR and AFLP and evaluation of disease resistance, respectively. In spring and summer crops, the 216 F3 families were evaluated for SCMV resistance at seedling, elongation, anthesis and adult stages under artificial inoculation, respectively. The QTL relevant to disease resistance and effects were analyzed with composite interval mapping. The main results were summarized as follows:(1) A genetic linkage map was constructed with 134 SSR markers and 119 AFLP markers based on an F2 segregation population (234 individuals ) derived from (XI78 X B73), with a total length of 1659.3 cM and average distance between markers of 6.58 cM. The proportion less than 20 cM between markers accounted for 88.9%.(2) Based on molecular quantitative genetic analysis, the heritabilities of resistance to SCMV in maize were high in different developmental stages, ranged from 69.2% to 80.0%, which indicates that the resistance to diseases was controlled by multi-genes. Moreover, the correlation analysis presented that disease incidence and index of SCMV at different stages were highly positive correlated; and values became declined with the plant development.(3) Two hundred and sixteen F3 family lines were sown in Beijing for SCMV evaluation at two periods of spring and summer crops. Using composite interval mapping, 5 QTL were detected across seedling, elongation, anthesis and adult stages in spring crop, located on chromosomes 3, 4, 5, 6 and 8, respectively, expressing 4.5% to 32.6% of phenotypic variance. Five QTL were detected across four stages in summer crop, located on chromosomes 2, 3, 5, 6 and 9, respectively, expressing 4.3~40.5% of phenotypic variance.(4 ) The QTL mapping results for resistance to SCMV were related with developmental stages, and the number and location of QTL varied with different stages. For spring crop, 3 QTL of seedling stage were found on chromosomes 3, 6 and 8; 3 QTL on chromosomes 3, 5 and 6 at elongation stage; One more QTL was found on chromosome 8 at anthesis stage than elongation stage; 4 QTL were found on chromosomes 3, 4, 5 and 6 at adult stage. For summer crop, at seedling stage (1 and 2), 4 QTL were found on chromosomes 3, 5, 6 and 9; at elongation stage 1, 2 QTL were found on chromosomes 3 and 6; at elongation stage 2 and anthesis stage, 3 QTL were found on chromosomes 3, 6 and 9, respectively; at adult stage, 4 QTL were found on chromosomes 3, 5, 6 and 9.
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