Effect and QTL analysis of nutrient traits of maize kernel under N-input and No N-input conditions

n this investigation, two sets of F2:4 and F2:5 families deriving from an elite maize hybrid Nongda108 were used to analyze genetic effects of nutrient components under nitrogen plus (+N) and no-nitrogen plus (-N) conditions in 2004 and 2005. A genetic linkage map was constructed including 199 SSR markers covered 2101.1cM on 10 chromosomes of maize, with an average interval length of 10.6cM. Four nutrient components including protein, starch, oil and lysine in kernel of F2:4 and F2:5 families were measured using near infrared reflectance spectroscopy (NIRS) method. The results show that the contents of protein, oil and lysine in kernel are decreased, while starch content is increased under -N condition, and the changing ranges are dependent on different materials. A total of 24 QTLs（13 for +N and 11 for -N treatment）, including 21 different loci, associated with nutrient components of kernel are detected using composite interval mapping method (CIM), locating on chromosome 1, 2, 3, 4, 7 and 9, mainly concentrated on chromosome 3 and 9. The contribution of single QTL to phenotypic variation varies from 8.05% to 34.31%, among them, qPro1a is the main contribution to protein content, accounting for 34.31% and qOil3b is the main contribution to oil content, ccounting for 17.66% under -N condertion. Out of 21 QTLs, nine QTLs appear additive effect, and eight QTLs express partially dominant effect.