Mapping QTLs For Bolting-related Traits In Brassica Rapa In Different Populations Using CIM And ICIM Methods

Bolting is an important agronomic trait in Brassica rapa crops due to its effect on yield and quality. Bolting is a complicated trait regulated by multiple genes that is highly influenced by the environment. It is necessary to exploit bolting-related traits using different mapping methods in different groups. In this study, An F2:3 populations including 186 F3 lines, an RIL (F2:6) groups including 124 lines, an CSSLs including 132 lines derived from the Chinese cabbage type rape inbred line ’RcBr’ and Chinese cabbage inbred line ’08A061’.This three groups were used to investigate the phenotypic traits, respectively. QTL mapping of bolting-related traits using two method of CIM and ICIM in this three populations. The results are as follows:1. Based on genetic linkage map of Brassica rapa previous constructed, the CIM method was used to investigating QTL of the bolting-related traits in F2:3 population, RIL and CSSL population. A total of 40 QTLs loci controlling 3 bolting-related traits were detected in three groups, including 13 for bolting index,14 for days to 5cm elongated stalk,13 for flower time. Among them,21 QTLs were detected in F2:3 group,8 QTLs were detected in RILs, and 11 QTLs were detected in CSSLs.These locis were distributed on 8 chromosomes except A04, A05. Single QTL explain the phenotypic variation in the rate between 0.09%～36.61%.4 of 40 QTLs can explain more than 20%.2. Based on ICIM method of QTL Icimapping 3.0 was used to investigating QTL of the bolting-related traits in F2:3 population, RIL and CSSL population. A total of 52 QTLs loci controlling 3 bolting-related traits were detected in three groups, including 22 for bolting index,15 for days to 5cm elongated stalk,15 for flower time. Among them,24 QTLs were detected in F2:3 group,18 QTLs were detected in RILs, and 10 QTLs were detected in CSSLs. These locis were distributed on 10 chromosomes.Single QTL locus explain the phenotypic variation in the rate between 2.63%～33.39%.8 of 52 QTLs can explain more than 20%.3. In this experiment,92 QTLs were detected by two methods. The genetic contribution rate of each QTLs was different, and the phenotypic variation rate ranged from 0.09% to 36.61%. One QTL (qFT2.1) was detected on the top of A02, which explained 36.61% of the phenotypic variation.In our study,39 QTL locis were all detected by two methods, These locis were distributed on A01, A02, A06, A07 and A10 linkage groups. In additon, there are seven regions of co-localised M-QTL were detected.