QTL Analysis For Brace Root Traits Using Recombinant Inbred Lines Of Maize

Maize is the food crop which has the largest planting area and the most output of the production in the world.Maize is the main food crop,the important feed and the industrail material in our country.The brace root was born in the air on the portion of the stem base.The brace root can resistance lodging through its support and absorption.Meanwhile, increasing planting density can improve the toughness and strength of brace root so as to achieve better support and lodging resistance effect.The most important is to enhance the intensity of brace root and reduce the rate of lodging to improve the yield of maize greatly in the time of mechanical harvesting applying in the field on harvest time.Therefore,studying on the morphogenesis and adapting to mechanized harvesting of maize is closely related. However,so far,there was few research about the genetic structure and regulatory genes underlying brace root of maize morphogenesis.In this study,we use inbred lines BYK and BYD which selected from Agricultural University of China National Maize Improvement Center.The inbred lines as materials for construct RIL groups identify brace root traits and apply gene chip technology to analysis linkage groups genome group genotype.Combined with linkage groups form index and genotype data analysis linkage of controlling root phenotype gene locus by composite interval mapping method.Investigating the genetic basis of brace root development and the locus controlling three traits that tier number of brace root,brace root number of first tier and radius of brace root striking into the soil are mapped by quantitative trait loci(QTL) analysis.The major results were introduced as follows:1.Analysising the BYK RIL brace root traits data of Beijing,Shenyang and Inner Mongolia of 2015,treated by Best Linear Unbiased Prediction and analysised linear mixed model by Windows QTL Carographer 2.5 software.3 QTL of tier number of brace root were detected after 1000 analoged in the level of P=0.05.The QTL are respectively localing on 1,2 and 9 chromosomes and their LOD value are 4.21,3.96 and 4.24.The phenotypic variance are 7.42%,7.46%and 7.56%and additive effect are-0.11,0.11 and-0.11,so the additive effects of alleles of tier number of brace root are respectively from K22,BY815 and K22.3 QTL of brace root number of first tier were detected which are respectively localing on 2,9 and 10 chromosomes and their LOD value are 4.51,6.22 and 4.43.The phenotypic variance are 7.82%,10.99%and 7.54%and additive effect are 0.51,0.59 and 0.48,so the additive effects of alleles of brace root number of first tier are from BY815.2 QTL of radius of brace root striking into the soil were detected which are respectively localing on 2 and 10 chromosomes and their LOD value are 3.93 and 5.34.The phenotypic variance are 6.75%and 9.37%and additive effect are-1.01 and 1.14,so the additive effects of alleles of radius of brace striking into the soil are from K22 and BY815.2. Analysising the BYD RIL brace root traits data of Beijing of 2015,treated by Best Linear Unbiased Prediction and analysised linear mixed model by Windows QTL Carographer 2.5 software.After 1000 analoged 4 QTL of tier number of brace root were detected in the level of P=0.05.The QTL are respectively localing on 1 and 2 chromosomes and their LOD value are 3.85,4.03,4.07 and 3.26.The phenotypic variance are 6.61%,7.02%,7.09%and 5.76%and additive effect are-0.06,so the additive effects of allelesof tier number of brace root are respectively from DE3. 2 QTL of brace rootnumber of first tier were detected which are respectively localing on 2 and 9 chromosomes and their LOD value are 5.42,3.56 and 4.11.The phenotypic variance are 9.66%,6.37%and7.30%and additive effect are 0.52,0.42 and 0.44,so the additive effects of alleles of brace root number of first tier are from BY815.We d etected 3 QTL of radius of brace root striking into the soil which were respectively local on 3 and 5 chromosomes and their LOD value are 3.36,5.26 and 3.35.The phenotypic variance are 6.11%,9.39%and 5.84%and additive effect are 0.49,0.63 and0.39,so theadditive effects of alleles of radius of brace striking into the soil are from BY815.