QTL Mapping For Nutritional Quality Traits In Maize

Starch,protein and oil are main nutritional content in normal maize.In this paper,F₂ individuals derived from the cross between maize(Zea mays L·) inbreds Huang C and 178 were used for the mapping population.A maize genetic linkage map with simple sequence repeat(SSR) markers had been established to detect and map QTLs affecting nutritional quality.The main results were as follows:1.Nutritional quality performances of mapping population:Parents,F₂,F_2:3 and F_2:4The quality traits under the three environmental conditions(2007 in Chongqing,2007 in Hainan and 2008 in Chongqing) were detected.Starch concentration of Huang C was 72.3835%,74.0141%, 73.5645%,while 178 is 74.2520%,74.2329%,73.9470%respectively.The protein and oil content of Huang C were better than that of 178 obviously.For the F₂,F_2:3 and F_2:4 population,Starch,protein and oil concentrations showed ultra-parent separation.The nutritional quality traits showed continuous separation under those enviromental conditions, and these results suggested that the nutrition-related traits were controlled by multiple genes.The correlation analysis of the quality traits indicated that the oil concentration of the F₂,F_2:3 and F_2:4 populations were positively significantly or highly significnatly correlated with their protein,while the oil concentration and the protein concentration were negatively highly significantly correlated with the starch concentration respectively.The analysis of variance for the quality traits of F2 population(2007 in Chongqing),F_2:3 population(2007 in Hainan) and F_2:4 population(2008 in Chongqing) indicated that there existed highly significant difference for oil,protein and starch concentration of different genotypes and different environment,suggesting that these quality traits were affected both by genotypes and environmental conditions.2.The construction of genetic linkage map507 pairs of maize SSR primers were used to detect the polymorphism in parents Huang C and 178,of which 91pairs of primers were obtained.The genetic linkage map of Huang C×178 with 15 linkage groups had been established,in which the markers on the 1^st,2^nd,4^th,7^th and the 8^th chromosome had been divided into two linkage groups.The 15 linkage groups covered 85 loci and spanned maize genome about 769.4cM,with an average interval is 9.05cM.3.QTL of the quality traitsBased on the linkage map and and nutritional quality detected,34 QTLs controlling nutritional quality traits were identified by using QTL cartographer.We mapped 12 QTL associated with oil,explaining phenotypic variation for 5.3%～17.7%;6 QTL associated with protein,explaining phenotypic variation for 5.3%～14.7%;and 7 QTL associated with starch concentratios,explaining phenotypic variation for 5.0%～10.4%.