The Location Of Flowering Time QTLs And The Development Of Linkage Markers On A Genome In The Brassica Napus L.

Flowering time is an indication of traits during ripening,flowering early means ripening early.At present,the localization of QTL(Quantitative trait locus)for flowering time is still in a rough position,so that the distance between the QTL of flowering time and the marker is large,and there is a bias in marker-assisted breeding.Based on the previous study,this study was to separate and sequence the SSR markers linked to the flowering time QTL located on the A chromosome to determine the chromosome of the flowering time QTL.Based on the reference genome of the chromosome in which it is located,the homologous series method was used to develop the marker which linked to the flowering time QTL.Encrypting the QTL section and selecting the marker closely linked to the flowering time QTL by using BSA method.The candidate genes in the segment where the QTL is located were analysised in the DNA leval and RNA level.All of these are the basis for further marker-assisted breeding.The main findings of the paper are as follows:(1)Screening the 85 SSR markers linked to flowering time QTL on established maps by BSA method.It was found that there are 6 pairs of primers that can amplify 9 specific bands in the parental and extreme gene pools.After labeling and sequencing,the QTL FQ10 and FQ12 of flowering time were initially determined to be in the range of 4785 Kb-11400 Kb on the A3 chromosome.(2)Designing a pair of primers every 100 Kb with Primer 5 according to the sequence of candidate intervals and the total number of of primers are 166.The designed primers were screened by primer polymorphism in the parental and extreme gene pools,and a total of 8 markers with polymorphism in the parental and gene pools were screened.The polymorphic markers were isolated and sequenced,and the sequence alignment revealed that 7 of them were labeled on the A3 chromosome.The sequence and position of these markers are consistent with the predicted sequence and position.(3)Based on the A3 chromosome alignment with Arabidopsis flowering time-related gene sequences,it was found that there are 25 homologous sequences on the A3 chromosome associated with flowering time-related genes.Screening the 63 pairs of specific primers designed according to 25 candidate genes in the parental and gene pools.Separating,sequencing and sequence alignment of specific markers found that the four flowering time-related genes,FT,FY,FLC,and HSCP,are differerent in DNA levels in the parental and gene pools.(4)Primers designed with the coding sequence of the differential gene were used to perform full-length cDNA cloning in the cDNA of the early and late flowering parents.It was found that HSCP,FT and FLD are different between parents.(5)QTL IciMapping was used to locate the flowering time QTL.The physical position of the QTL site was determined according to the physical location of each marker.The physical position of the two QTLs was 8764 Kb-9600 Kb and 9800 Kb-11399 Kb.