Genetic Analysis Of The Plant Architecture Related Traits And Candidate Gene Analysis Of Short Internode In Maize

In this study,the design a 6×6 Diallel hybrid population was used to verify the feasibility of using internode traits to create dwarf resources,and analyze the plant architecture related traits combining ability of each inbred line.It provides a research basis for QTL analysis and candidate gene mining.Then,using SLAF-seq technique,Chang 7-2and PHB1M and 138 F_2:3 families were sequenced by high-throughput sequencing based on the reference genomic information of HZS,and the genetic map of high-density SNP was constructed.QTL mapping was conducted by combining the phenotypic data of six plant architecture related traits and 10 different internode lengths under two density treatments.Finally,QTL mapping,BSA-seq and RNA-seq strategy were used to rapidly detect candidate genes controlling short internodes of Chang 7-2.It provides theoretical support for fine mapping of plant architecture related traits and molecular assisted breeding,and explores a new way for rapid creation of low stalk,low ear inbred lines and dwarf breeding of maize.The main research results are as follows:1.Through Diallel cross analysis,the basic combining ability of five plant architecture related traits,nine different internode lengths and one yield trait of five backbone inbred lines and one self-breeding line 16C75 was obtained.16C75 mainly affected the plant height and ear height of the hybrid by reducing the number of internodes and different internode lengths of the hybrid.The direction of parental selection for the preparation of 16C75 hybrid was also clarified.The plant height and internode GCA effect values of Chang 7-2 and Zheng 58 were negative,which could be used as good parents for short internode selection and short internode donor resource.The yield of SCA in Chang7-2 was basically the same as that in PHB1M,and the difference of plant architecture related traits was significant,which was an excellent basis for mapping population.2.SLAF-seq technology was used to sequence Chang 7-2 and PHB1M and 138 F2:3populations based on the reference genomic information of HZS,and 4,220 high-quality SLAF tags（7,876 SNPs）were used as the markers to construct the linkage map with a total length of 1,354.81c M.The mean distance between each two markers was 0.32 c M.3.A total of 35 QTL loci were detected for 5 plant architecture related traits and 11different internode length traits using this map,of which 14 QTL’s PVE exceeded 10%.Total leaf number,ear height,number of internodes,number of leaves on the ear,the 7th and 10th internodes have the major effect QTLs.The reduced alleles for leaf number and number of internodes were derived from PHB1M,and the reduced alleles for ear height,7th and 10th internodes were derived from Chang 7-2.4.There is a common genetic mechanism between the total number of leaves and total number of internodes.q LC-2-lg8 overlapped with q IC-2-lg8,and SLFA7305498 and SLFA6717271 were common markers for the two QTL.5.The distribution of different internode QTL on different chromosomes was controlled,indicating that different internodes could be inherited independently.QTLs for the 7th,8th,9th and 10th internodes were found on Chr1,and the additive effect values were all negative.The reduced alleles were derived from Chang 7-2,where q Se I-1-LG1was neared to q Ei I-1-LG1,and q NI-2-LG1 was adjacent to q Te I-1-LG1.QTL of the 11th internode,12th internode and 13th internode was mapped on Chr2,and the additive effect value was positive.The synergistic allele was derived from PHB1M,and the QTL of the three internodes were overlaped.SLFA10998085 and SLFA 11357931 are common markers of qELI-2-lg2,qTWI-2-lg2 and qTHI-2-lg2.The QTL of the 7th and 9th internodes on Chr10 are overlapped,and SLFA14228348,SLFA14668204,SLFA15291633 and SLFA15234622 were the common markers of q SEI-1-lg10 and q NI-1-lg10.6.The co-mapped region of the main QTL qTEI-2-LG1 associated with BSA at the10th internode was on the Chr1 with a starting position of 278,315,944 bp and a terminating position of 281,916,798 bp,with a total region of 3.6Mb,and the additive effect value was-0.63.PVE value was 10.85%,and allelic variation was derived from Chang 7-2.the SNPs of 17 non-synonymous mutant genes were developed,and the existence of q TEI-2-LG1 was verified and was verified in 16C75,it played a role in controlling the length of the 10th internode.7.The Chr1＿pilon＿281798.1＿1560,Chr1＿pilon＿279637＿4440,Chr1＿pilon＿27868.9＿4803 and Chr1＿pilon＿278721.4＿15234 were the candidate genes in q Te I-2-LG1 region.The SNP site information corresponding to each gene was obtained.q RT-PCR was used to verify that the gene expression was consistent with that of RNA-seq.Wherein,protein annotation of Chr1＿pilon＿27868.9＿4803 is correlated with UDP-glucoronosyl and UDP-glucosyl transferase,Chr1＿pilon＿278721.4＿15234 is correlated with UDP-glucose/GDP-mannose dehydrogenase family,NAD binding domain,UDP-glucose/GDP-mannose dehydrogenase family,UDP binding domain,and UDP-glucose/GDP-mannose dehydrogenase family,central domain.