Identification Of Molecular Markers And Preliminary Mapping Of Fertility Restorer Gene (rfp) For The 'polima' Cms In Brassica Napus L.

Cytoplasmic male sterility(CMS) is an important way for heterosis breeding in Brassica napus L.Polima CMS(pol CMS),as a main pollination controlling system,has been used widely for three-line or two-line rapeseed hybrid breeding in rapeseed.At present,a large number of elite hybrids of pol CMS have been developed and applied in production.Previous studies have proved that pol CMS is a sporophytic male sterile type and its sterility is associated with expression of cytoplasmic gene atp6/orf224 and its nuclear fertility restoring gene(Rfp).Because the Rfp exerts an essential role in heterosis utilization by the three-lines or two-lines strategies,cloning the Rfp has great significance in both breeding applications and understanding of the mechanism of male sterility's restoraion.In order to mapping the Rfp for gene cloning,a near-isogenic lines containing the Rfp gene was established,and the main results of the present study are as follows:1.In order to map the Rfp,a fertile individual from a backcross population was crossed with the recurrent parent to construct a NILs population.There were 980 fertile and 1044 sterile plants in the population,and the ratio of fertility:sterility agreed with the expected 1:1.2.Bulked segregant analysis(BSA) was utilized to identify AFLP markers linked to the Rfp.DNA bands amplified from 3840 pairs of AFLP primer combinations were screened.As a result,31 AFLP markers were found linked to the Rfp locus,15 of which were located at the same side of the Rfp locus,and the distance between the nearest marker and the target locus was 0.65 cM.3.Four AFLP fragments were sequenced and converted to SCAR markers successfully.The SCAR markers were tested in Pol CMS restorer lines with different genetic backgrounds and three of them(SCCQ1,SCCQ3 and SCCQ4) were ensured to be used for hybrid purity test and marker assisted selection.4.The four SCAR markers were blasted against the Arabidopsis genome using the programme BLASTn,and the information of a SSR marker SSRkbr integrating in the TN linkage map proved that the Rfp located in the Arabidopsis chromosome I.