QTL Analysis Of Plant Type And Yield Related Traits In Maize

High yield is the primary goal in maize breeding,and the yield is the ultimate appearance determined by many factors.The ear number per acre,ear row number,kernels per row and 100 grain weight are the main components of maize yield.Previous evidence indicated that plant-type traits is closely related with the ear number of acre,and ear length affect kernels per row and yield.Therefore,genetic dissection of plan-type traits and ear length and identification of corresponding QTLs will provide a theoretical basis for breeding new maize varieties with lodging resistance,high yield,density tolerance In this study,284 maize inbred lines were used to carry out genetic analysis of plant typetraits,and 17 QTL related to plant type related traits were obtained.Additionally,QTL analysis of ear length was performed with 150 single segment substitution lines constructed with two elite inbred lines,Zong 3and Xu 178,and a major QTL(q EL3)was identified.The detailed results are as follows:1?Whole genome association analysis of plant type related traits.(1)The variation coefficient,range and variance of six characters in different locations were compared(plant height,ear height,the ratio of plant height and ear height,total leaf number,leaf number above the ear,the ratio of total leaf number and leaf number above the ear).In two environments of Zhengzhou and Xunxian County,all these traits showed typical normal distribution of quantitative characters,and most of them had highly positive or negative correlation.The analysis of variance showed that the genotype,environment,and genotype x environment of the six traits reached a significant level.(2)The GWAS results of three models of Q,K and Q+K showed that the K model could better evaluate the plant type related traits.56 SNPs significantly associated with plant height,ear height,the ratio of plant height and ear height,total leaf number and leaf number above the ear were detected in this two environments.(P = 3.99 * 10-6).The 17 interval of QTL including 56 SNPs were distributed on chromosome 1,3,5?6,7,8,9 and 10.A single QTL could explain the phenotypic variation of 7.97-10.56%.4 of the 17 QTL can be detected in 2 environments,which are the major QTLs of plant type related traits.Gene including significantly associated SNP or neighboring gene located on flanking region of significantly associated SNP was consideredas a candidate gene for QTL,fourcandidate genes were identified and are GRMZM5G897342,GRMZM2G542272,GRMZM2G440125 GRMZM2G074689 ?GRMZM5G897342 is a candidate gene encoding thioredoxin(Trx)in the chloroplasts and participates in the regulation of photosynthesis;candidate gene,GRMZM2G440125,encoding a RING domain of finger zinc finger protein,involved in physiological and biochemical processes in plant cells through the ubiquitin pathway?Candidate gene,GRMZM2G074689,encodes a calmodulin protein(Ca M)with EF-hand domain.Ca M is the most typical Ca2+ sensing protein,which participates in cell physiological activities combined with downstream Ca M binding protein.QTL analysis of ear length: we previously constructed a set of single segment substitution lines with two elite inbred lines Xu 178 and Zong 3 and detected a major QTL of ear length and yield through multi-plot demonstration for several years.To further clone this QTL,BC1 populations was generated with a single segment substitution line,SSSL3.09 and Xu 178 Subsequently,through the overlapping group mapping method,we mapped the QTL to a 4.5Mb region between markers chr3.09-14 and chr3.09-176 on chromosome 3,which build the foundation for the fine mapping and gene cloning of the target gene.