| Maize is one of the most important crops which can be used as both foodand forage. It is of strategic importance to the development of agriculture andeven national economy. In recent years, a leaf spot disease caused byCut-vu/aria Iunata (Walk.) Boed. has spread widely in North China andNortheast China, which has resulted in great loss of grain yield of maize. Thedevelopment of varieties or hybrids resistant to this disease is one of effectiveapproaches to protecting wide extension and great occurrence of this quite newdisease in China. To completely understand the genetic basis of resistance toCut-vu/aria lunata, especially to map and localize the genes conferring theresistance using biotechno]ogies such as molecu]ar marker technology, cancontribute to providing theoretical guide to breeding for disease resistance andproviding the basis on which molecular marker-assisted selection can beimplemented.Therefore, molecular characterization and quantitative trait loci (QTL5)analysis for the resistance to Curvularia lunata and some important agronomictraits were carried out in this study, using AFLP and SSR markers and an F2:3population of "Dan 340 (susceptible parent) x Shen 135 (resistant parent)". Themajor results and conclusions are described as follows.1.The resistance to Cut-vu/aria Zunata in maize and the agronomic traits studiedi.e. tasseling, silking, plant height and ear height were controlled by multiplegenes.2.In the study of QTL analysis of the resistance to Cut-vu/aria lunata, it wasfound that composite interval mapping (CIM) was most effective after thecomparison of three QTL mapping methods including single marker mapping,simple interval mapping (SIM) and composite interval mapping.3.Through composite interval mapping, four putative QTLs were detected forresistance to Cut-vu/aria lunata phenotyped in 1999, which were localized onchromosome 6, 6, 8 and 10, respectively and totally accounted for 49.9% ofphenotypic variation; six putative QTLs were detected for resistance toCut-vu/aria lunata phenotyped in 2000, two of which were localized onchromosome 6, three on chromosome 7 and one on chromosome 10, andtotally accounted for 77.6% of phenotypic variation. The quantitative trait3locus on chromosome 10 which was derived from Shen 135 (resistant parent)was common in the two years.4.Through simple interval mapping, three putative QTLs were detected for thedays from seedling to tassel emergence (tassel), which could account for40.4% of phenotypic variation; three putative QTLs were detected for the daysfrom seedling to silking (silking), which could account for 42.0% ofphenotypic variation; five putative QTLs were detected for the days fromtassel emergence to silking (ASI), which could account for 73.0% ofphenotypic variation. One QTL near marker P2486309 on chromosome 1,which was derived from Dan 340, conditioned both tassel emergence andsilking.5.Three putative QTLs were detected for plant height measured in 1999(plthgt99), which could account for 36.4% of phenotypic variation; twoputative QTLs were detected for plant height measured in 2000 (plthgto0),which could account for 18.1% of phenotypic variation. Five putatitve QTLswere detected for ear height measured in 1999 (earhgt99), which couldaccount for 35.5% of phenotypic variation; five putative QTLs were detectedfor ear height measured in 2000 (earhgto0), which could account for 3 7.9% ofphenotypic variation. One QTL near marker dupssr34 on chromosome 4,which conditioned plant height, was common in two years, with the geneticeffect of partial dominance. One QTL near marker P2051206 on chromosome2, which conditioned ear height, was common in two years, with the geneticeffect of overdominance.6.For each putative...
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