Genetic Analysis And QTL Mapping On Agriculturally Important Traits In Foxtail Millet

Foxtail millet（Setaria italica（L）P.Beauv.）,with drought resistance and impoverishment tolerance,is the key crop for the green development of the ecological agriculture in the dry farming.High yield is an crucial goal for foxtail millet breeding,to increase the yield,ideal agronomic traits are the key.In this study,a F₇recombinant inbred line population（YRRIL）derived from a cross between Yugu 18,a high quality foxtail millet variety,and Hongjiugu,were used to investigate the rule of the phenotypic variation of the agriculturally important traits in foxtail millet.The phenotypic values of the plant height,the panicle length,the panicle diameter,the internode length under the panicle,the spikelet number per panicle,the grain weight per panicle,the length of bristle hair and 4 hull color traits,the L^*,a^*,b^*and C^*values in the YRRIL population were genetically analyzed using the mixed inheritance model of major gene plus polygene.Based on simplified genome sequencing technology,the genotypes of each line were analyzed to construct a high-density genetic linkage map.QTL associated with agronomic traits in foxtail millet was mapped.And epistatic QTL and genotype and environment interaction effects for agronomic traits was analyzed.Candidate genes in the interval of the stably major QTL were predicted.The main research results are as follows:1.Major gene plus polygene mixed inheritance analysisThe best inheritance model for the plant height and the spikelet number per panicle were PG-A and PG-AI,respectively,which were polygene inheritance models with high polygene heritability.The best inheritance model for the panicle length was the MX2-AE-A,which was controlled by the major genes and polygenes.The best inheritance model for the internode length under panicle was the 3MG-CEA,and the heritability of the major genes was low.The best inheritance model for the panicle diameter,the grain weight per panicle and the length of bristle hair were the major gene models with high heritability.The best model for the hull color L^*value and b^*value were MX2-DE-A and MX2-ED-A,respectively.The heritability of major genes was higher than that of polygenes.The best model for the a^*value was 3MG-PEA,and the best model for the C^*value was 4MG-EEEA,and the heritability of major genes was high.2.Construction of the high-density genetic linkage map of foxtail milletIn this study,1,420 bin markers were located on 9 chromosomes,and a high-density genetic linkage map that spanned 1227.383 c M of the foxtail millet genome with an average bin interval of 0.879 c M was constructed.The longest linkage group is LG9,which covers179.635 c M and contains 180 bin markers.The shortest linkage group is LG8,which covers96.704 c M and contains 183 bin markers.3.QTL mapping for the agronomic traitsA total of 96 additive QTL and seven epistatic QTL interactions associated with agronomic traits were identified,distributed in different intervals of the nine chromosomes of the foxtail millet.Among them,13 QTL were associated with the plant height and explained 0.77%–11.00%of the phenotypic variance.8 QTL were associated with the panicle length and explained 5.40%–12.70%of the phenotypic variance.One epistatic QTL interaction associated with the panicle length explained 0.32%of the phenotypic variance.12 QTL were associated with the panicle diameter and explained 0.90%–19.70%of the phenotypic variance.7 QTL were associated with the internode length under panicle and explained 5.50%–9.80%of the phenotypic variance.Four QTL were associated with the spikelet number per panicle and explained 0.70%–12.00%of the phenotypic variance.Six QTL were associated with the grain weight per panicle and explained 0.74%–11.60%of the phenotypic variance.Three QTL were associated with the length of bristle hair and explained4.40%–34.90%of the phenotypic variance.15 QTL were associated with the hull color L^*value and explained 0.90%–45.70%of the phenotypic variance.Seven QTL were associated with the hull color a^*value,explaining 3.10%–49.20%of the phenotypic variation,One pair of major QTL with significant epistatic effect explained 2.76%of the phenotypic variance.14 QTL associated with the hull color b^*value explained 4.70%–25.10%of the phenotypic variation,and three pairs of QTL with significant epistatic effect explained 1.09%,0.01%,and 0.78%of the phenotypic variance,respectively.Seven QTL associated with the hull color C^*value explained 1.31%–21.50%of the phenotypic variation.Two epistatic QTL explained 1.24%and 0.01%of phenotypic variation,respectively.4.Prediction of candidate genesA total of 21 major QTL were identified,of which,11 were stably detected in multiple environments,showing stable genetic effects.The candidate genes for the stably major QTL were predicted.Three candidate genes were related to the panicle length,one related to the length of bristle hair,one related to the grain weight per panicle,and six candidate genes play an important role in the change of foxtail millet hull color by participating in the synthesis and transportation of plant pigments.