Construction Of A Molecular Genetic Map And Mapping Of QTLs Related To Main Agronomic Traits In Cabbage (Brassica Oleracea Var.capitata)

Cabbage(Brassica oleracea var.capitata)originate in the regions from Mediterran-ean Sea to Northern Sea coast,is an important vegetable crop of cruciferous crops,which widely cultivated in the world.In recent years,Fusarium wilt caused byFusarium oxysporum f. sp. conglutinans,started to appear in the main producing areasthe northern of china,had been a great theat to the production of warm season-growncabbage.Additionally,bolting which makes it completely lose market value is also theimportant issue that to be solved especially in the spring cabbage production.Therefore,the tasks of fusarium wilt resistant molecular breeding and developingbolting-resistant varieties is imminent.High density molecular genetic linkage map isnot only the basis of molecular marker assisted selection (MAS) and mapping QTL,but also the key of map based gene cloning.In this research,a F2population consistedof142individual plants derived from a cross between fusarium wilt resistant cabbageand early bolting self line ‘R4-P1’and fusarium wilt susceptible and late bolting line‘R2-P2’ combining with AFLP,SSR and SRAP markers were applied to construct ahigh density genetic linkage map of Brassica oleracea,on this basis,we analyzed itsgenetics and mapped the fusarium wilt-resistant gene and QTLs related to boltingtime and flowering time in cabbage.The main results are as follows:1. Identification of fusarium wilt in seeding stage of cabbage and geneticanalysis.Inoculated of Fusarium oxysporum on both of parents (R4-P1and R2-P2),individuals of F1,142individuals of F2and lines of F3corresponding to the142F2segregation used to construct the map,the results of the index of incidence proved thatits genetic law in line with the Mendelian inheritance, it showed that the trait offusarium wilt resistance was controlled by a single dominant gene.2. Construction of a Genetic Linkage Map in Cabbage (Brassica oleracea var.capitata).Software JoinMap3.0was used for genetic linkage analyzing190AFLP markers,54SSR markers and36SRAP markers,in the condition of LOD≥4.0, a total of240markers(162AFLP markers,52SSR markers,26SRAP markers) were mapped into9linkage groups(LG1~LG9),the number of linkage groups was the same with thenumber of chromosome in B.oleraeea (2n=2x=18，CC). Eventually, got a moleculargenetic linkage map,covering864.4cM of genome with an average interval distanee of3.6cM between loci, the length of markers in every linkage group varied from58.1cM to142.8cM,and the number of markers in linkage group ranged from20to52.3. Preliminary mapping of the resistant gene named FOC-1in cabbage.On the basis of high-density molecular genetic linkage map which has beenconstructed in cabbage,according to the identification results of fusarium wiltresistance in F3families,inferred the sense of fusarium wilt in F2segregatingpopulation,FOC-1was located on the LG1,in connection with the recent SSR markerswere KBRS003010N1F/R,A10a/b, with the distance respectively was1.0cM,1.2cM.4. QTL mapping and analyzing of the traits of bolting and flowering time.Based on the Cabbage (Brassica oleracea var. capitata) genetic linkage mapwhich had been constructed previously, QTL mapping and analysis related to boltingand flowering time in the individuals of F2were conducted using MapQTL4.0. TwoQTL (qbt-3-2, qbt-9-1) located on LG3and LG9controlling the traits of bolting timeand one QTL(qft-9-1) located on LG9controlling the traits of flowering time incabbage were detected. The three QTLs are all the sites of additive effect,17.5%,22.7%of variation that can be explained respectively. Meanwhile, two Molecularmarkers (E46M52-5,me26-em13-1) corresponding with the QTLs could be used forMAS of breeding for bolting tolerance. It will provide the basis of theoretical for theresistant bolting varieties breeding.