Mapping QTLs For Bolting-related Traits In Brassica Rapa

Brassica rapa is an important specie of the Crucifer Brassica, originated from China, which includes a variety of vegetable and oilseed crops. It is difficult to improve some important agronomic traits as for its complex genetic basis. So it is necessary to exploit existing genetic variation to dissect agronomic and quantitative traits in Brassica rapa at molecular levels. In our study, based on the SSR and InDel markers, a genetic map was constructed for mapping the bolting-related traits. Marker analysis was performed on a F2population obtained from F1progeny of two parents. The main results of the present study were as follows:1. A genetic linkage map of Brassica rapa was constructed, which was based on a F2population with186inividuals.161markers including107SSR markers and54InDel markers were integrated into the resulted map using JoinMap v3.0. This map consisted of10linkage groups, covering941.1cM with a mean marker interval of5.85cM. Various linkage groups were featured by11-25markers,58.3-129cM length. The10linkage groups can correspond to chromosomes by the anchored SSR and InDel markers.2. Based on a linkage map with161markers, Windows QTL Cartographer v2.5was used to investigating QTL of the bolting-related traits, and the data was collected under4seasons in different years. QTL analysis was performed by4phenotypic evaluation based on the difference in F2/F2:3families.46QTLs loci controlling4bolting-related traits were mapped on8linkage groups. These QTLs included16for bolting index,13for flower time,10for days to5cm elongated stalk,7for vernalization requirement.3. The explained variances were different, ranged from0.11%to44.02%.18of46QTLs can explain more than10.00%, which were detected on A02, A06, A07linkage groups. One QTL (10auDEQTL01) was detected on the top of A02, which explained44.01%of the phenotypic variation, and closely linked with BrFLC2gene. In our study, the detection of colocalized M-QTL occurred in nine genomic regions, which were detected on A02, A03, A06, A07linkage groups.