Fine Mapping And Cloning Of The Stem Development Regulation Gene Qd1 In Wheat

As an important grain crop in China,wheat is of great significance for ensuring national food security.In the previous work of our lab,a stalk stage quick development mutant?qd?was obtained from the winter wheat variety Lunxuan 987?WT?by using ⁷Li ion beam mutagenesis,and its stem development regulation gene qd1 was initially located to 26.80 Mb?31.88 Mb.In this study,whole genome resequencing technology was used to develop molecular markers to fine mapping and clone the stem development regulation gene qd1 in wheat.Main results for this study are as follows:1.Identification of plant height phenotypes of WT and qd.From the mid-late jointing stage to booting stage,a large amount of dry matter produced by qd photosynthesis accumulates in the stem parts,accelerating the elongation rate of the internodes cell of the second and third stem internodes,leading to the development of qd's stem growth rate is faster than WT,and the two plants have extremely significant differences at the booting stage.The height of qd is about 10 cm higher than WT.2.Fine Mapping of the stem development regulation gene qd1 in wheat.Using whole genome resequencing technology,4481 SNP sites were developed in the initial location interval,of which 25sites could be used for genetically isolating populations.Through genotyping of 2338 recombined individual strains in F_2:3 population and 4123 recombined individual strains in F_2:4 population,182recombined individual strains in 6 recombined lines were screened out.The stem development regulation gene qd1 was mapped to the KASP marker WGR02?WGR22,within the range of 28.86Mb?30.19 Mb?total 1.33 Mb?on chromosome 4B,and its genetic distance was 0.29 cM.3.Analysis of candidate genes within the fine mapping interval.According to genome annotation information,four candidate genes were searched in this interval,namely TraesCS4B02G04230,TraesCS4B02G042400,TraesCS4B02G042500 and TraesCS4B02G042600.4.Candidate gene sequencing and expression analysis.By analyzing the sequencing results of candidate genes,it was found that there were no insertion,deletion or termination mutations of large fragments in the four genes,there were six missense mutations in TraesCS4B02G042300 and TraesCS4B02G042400,respectively.Only one synonymous mutation in TraesCS4B02G042500 and TraesCS4B02G042600,respectively.Through the analysis of the expression of candidate genes,it was found that the expression of gene TraesCS4B02G042300 in the stem of parent material was similar to its growth and development stage,and the expression of the other three genes was not significantly related to parents'growth and development stage,so it was speculated that the candidate gene TraesCS4B02G042300 was the stem development regulation gene qd1 in wheat.5.Cloning of gene TraesCS4B02G042300.The cloning sequencing results of gene TraesCS4B02G042300 showed that there are 23 point mutations in this gene,of which only 3 point mutations were missense mutations and their amino acids changes were Val to Ile,Asn to Ser,Glu to Lys.Phylogenetic tree was constructed for the gene TraesCS4B02G042300 gene sequence and amino acid sequence found that the insertion of 3 missense mutations in the gene TraesCS4B02G042300resulted in the coding oxysterol-binding protein transform into a PH domain-containing protein or uncharacterized protein.