Fine Mapping Of Multilocular Gene Bjln1in Brassica Juncea L.

Siliques play an important role of source and sink in the process of rapeseedyield formation, seed number per silique is also a crucial yield component. Normalrapeseed has bilocular silique. Silique of multilocular rapeseed has3rooms at least,even5rooms. Former research on yield of multilocular rape indicates thatmultilocular rape has a higher yield than bilocular rape with the same geneticbackground, which is caused by the increase of seed number per silique. Thus, it’s aresultful way to improve rapeseed yield by breeding multilocular rapeseed, and it’smeaningful to research on multilocular trait. Our research consists of morphologicalcharacter of multilocular silique, genetic analysis of multilocular trait and mappingof multilocular gene on Qinghai multilocular rapeseed(B. juncea) Duoshi. Mainresults are as follows:1. Anatomical Structure: External form of multilocular silique appearedshorter and coarser than bilocular silique. Observed internal form of multilocularsilique through dissection, which had four seedcases developed from4carpels, therewere2parallel replum dividing the ovary into3rooms, the middle room is largerthan2flanking rooms. The structure of Duoshi silique was similar to trilocularrapeseed(B. juncea) from Gansu, and was different from multilocular silique of B.rapa and B. napus. In addition, seeds in multilocular silique was significantly morethan bilocular silique.2. Genetic analysis: Qinghai Duoshi(multilocular, B. juncea) andXinjie(bilocular, B. juncea), Tayou2(bilocular, B. juncea) were used as parents forthe research. F1, RF1, BC1, RBC1and F2populations were obtained by crossing.Individuals of F1and RF1population were all bilocular plants, which indicated thatmultilocular trait in Duoshi was recessive character without effects of cytoplasmicgenetic material. Segregation ratio of BC1, RBC1and F2were3:1and15:1 respectively, which explained that multilocular trait in Duoshi was determined bytwo genes free to genetic, named Bjln1and Bjln2.3. Gene Location: Backcross with Duoshi repeatedly, BC3population wasobtained for location of multilocular gene Bjln1, which contained685multilocularplants and640bilocular plants. AFLP and BSA were combined to screen markerstightly linked with Bjln1in BC3population,2AFLP markers(A1, A2) were detectedand were located on Scaffold000019of A7in B. rapa and on Chr1in A. thalianaafter BLASTn analysis.SSR and SCAR markers were developed by sequences onScaffold000019related to Bjln1for screening.7new SSR markers(S1～S7) and1existing SCAR marker(MK014) tightly linked with Bjln1were obtained. A linkagemap for Bjln1were constructed, which contained10markers(A1, A2, S1～S7,MK014), S6(952Kb) was demonstrated to be co-separate with Bjln1, Bjln1waslocated between S5(2cM,787Kb)and S7(0.4cM,995Kb), which covered208Kbon Scaffold000019. Furthermore,3co-dominant markers (S3, S5, MK014) for Bjln1were determined by BC3F2and BC3F2:3populations.