QTL Mapping And Candidate Gene Ananlysis Of Maize Plant Architecture Related Traits By Using Two F2:3 Families

Maize plant architecture related traits are important in affecting maize yield,including plant height,spike height,tassel spindle length,tassel branch number and leaf number beyond ear.It is very important to study the genetic mechanism of maize plant architecture related traits such as plant height,spike length,spike spindle length and so on.In this study,two F2:3 families by crossing with maize inbred lines of Mo17,Qi319 one parental lines and Huangzao4 as the common parental line,were used as materials,and lots of QTLs controlling maize plant architecture related traits were identified on by combining the genotype and phenotype identification results of high-density SNP markers.The main research results were listed as follows:1.For the F2:3 families of Mo17 ×Huangzao4 and Qi319 × Huangzao4:phenotypic identification results showed that plant height was positively correlated with spike length,spike spindle length and spike branch number,and spike length was positively correlated with spike branch number.The traits related to plant architecture showed an obvious trend of normal distribution,which was consistent with quantitative traits.2.QTLs of two F2:3 families were mapped by complete interval mapping.For F2:3 families of Mo17 ×Huangzao4: a total of 26 QTLs of plant architecture related traits such as plant height,ear height and spike branch number were located,wherein5 QTLs were detected in plant height.Seventeen QTLs were detected at ear height.Two QTLs were detected in the spike branch number.Two QTLs were detected for leaves number beyond ear.These QTLs were distributed on 9 other chromosomes besides chromosome 5,and 4 QTLs were detected on chromosome 1.Four QTLs were detected on the second chromosome.Three QTLs were detected on the third chromosome.Three QTLs were detected on the fourth chromosome.Six QTLs were detected on chromosome 6.One QTL was detected on chromosome 7.Two QTLs were detected on chromosome 8.One QTL was detected on chromosome 9.TwoQTLs were detected on chromosome 10 with single QTL can explain 2.66% ～19.17% phenotypic variation.Among them,the phenotypic contribution rate of four QTLs were more than 10%,which were QPH 1:1(13.60%),q PH8(19.17%),q TTL6(13.35%)and q EN10(10.88).For Qi319 × Huangzao4 F2:3 families: a total of 23 QTLs of plant height,ear height,tassel spindle length and other plant architecture related traits were located,wherein 2 QTLs were detected in plant height.Six QTLs were detected at ear height.Two QTLs were detected in the tassel length.The first branch number of tassel was 1,and the number of leaves on tassel was 12 QTLs.These QTLs were located on 9 chromosomes besides chromosome 7,and 4 QTLs were detected on chromosome 1.Two QTLs were detected on the second chromosome.Four QTLs were detected on the third chromosome.Four QTLs were detected on the fourth chromosome.Two QTLs were detected on chromosome 5.One QTL was detected on chromosome 6.Three QTLs were detected on chromosome 8.One QTL was detected on chromosome 9.Two QTLs were detected on chromosome10,with single QTL can explain 2.03% ～ 16.60% phenotypic variation.The phenotypic contribution rate of 5 QTLs was more than 10%,which were q PH3(11.01%),q PH9(15.60%),qeh1-3(16.60%),q TTL3(13.67%)and q TTL3(14.10%).There was a QTL in the region s＿129036404-s＿129060152 labeled on chromosome 8 that controlled both the spindle length of the tassel and the number of leaves on the tassel,which could explain the variation in the spindle length of the tassel of 11.25% and the phenotype variation in the number of leaves on the tassel of6.91%,respectively,showing the phenomenon of one-factor multiplicity.3.For HM and HQ families,through further research and analysis of 49 QTLs which had been located for 5 traits related to plant architecture,such as plant height,ear height and leaves numbers beyond ear,9 "consistent QTLs" were obtained.They were distributed on chromosome 1,2,4,6,8 and 10,including 1 "consistent QTLs" controlling ear height on chromosome 1.There were one "consistent QTLs" on chromosome 2 that controlled the ear height and leaves numbers beyond ear.There were 3 "consistent QTLs" on chromosome 4 to control ear height and tassel length.There were 1 "consistent QTLs" on chromosome 6 that controlled ear heightand leaves numbers beyond ear.There were 2 "consistent QTLs" on chromosome 8 that controlled leaves numbers beyond ear.There are 1 "consistent QTLs" on chromosome10 that control ear.4.According to the 49 QTLs identified in this study,combined with the public database of maize,rice and sorghum,In the 49 QTLS detected,47 genes were detected,and linear comparison showed that 32 of them had clear functional annotations.There are seven suspected candidate genes,and 3 of them had homologous genes in rice and sorghum at the same time,which had functions involved in cell growth and development.I.e.GRMZM2G145905 is located in the QTL(s96825065-s97203803)region on chromosome 8,which has the function of encoding plant proteins.There is an oxidoretase gene GRMZM2G068328 in the region of QTL(s239978231-s240218640)on chromosome 1,and a proteolytic enzyme gene GRMZM2G162800 in the region of QTL(s14752449-s15129113)of chromosome1.These three genes can be used as the suspected key genes to control the variation of plant type traits,which can provide new research targets for the subsequent cloning of candidate genes and the study of gene function.These results would provide further proof for the molecular genetic mechanism of maize plant architecture related traits variation.It provides theoretical support for the improvement of ideal maize plant architecture and the breeding of new maize varieties in the future.