Genetic Improvement Of Thousand-seed Weight And Tribenuron-methyl-resistance For Core Parent 624R In Brassica Napus L.

624R is an elite restorer of polima cytoplasmic male sterility and has been used as the father lines for a few hybrid cuitivars with excellent agronomic traits,but it has the defects in the traits of thousand-seed weight(about 2.5 g)and herbicide resistance.We used 624 R as recurrent parent,ZY50 with large seed(thousand seed weight about 4.3 g)and 7-5RS with tribenuron-methyl-resistance as donor parent to improve thousand-seed weight and tribenuron-methyl resistance of 624 R by combining backcrossing with marker-assisted selection and microspore culture technology.The main results of this study are as follows:1.The development of a DH population with the genetic improvement of thousand-seed weight of 624 R.Thirty-five plants with heterozygous genotype at the four QTLs(These four QTLs consisted of QSWA3-1,QSWA3-2,QSWA3-3 and QSWA9 locus which could explain 5%,10%,10% and 30% of the phenotypic variation of thousand-seed weight,respectively)that control thousand-seed weight were obtained in the BC3F1 generation by combining backcrossing with marker-assisted selection.These plants were then used for microspore culture,and a DH population consisted of 606 plants were developed.2.The genotypes of the DH population were analyzed with markers that were closely linked to the four QTLs that control thousand-seed weight.The result indicated that 81 individuals had the same genotype as the recurrent parent at the four loci,and 109 individuals were improved at one locus,107 at two loci,56 at three loci and 23 at all four loci.3.The genetic background of the DH population were analyzed with 37 pairs of SSR markers that evenly distributed on the chromosomes of Brassica napus.It was found that recovery rate of 36.27% of the DH individuals were between 85.00% and 90.00%,43.73% of the DH individuals was above 90.00%,and the highest was up to100.00%.4.The phenotype of main yield-related traits that included thousand-seed weight,seeds per silique and silique length of the DH population were analyzed.The QSWA3-1 locus may has the greatest effect on thousand-seed weight improvement,while the combination of QSWA3-2,QSWA3-3 with QSWA9 may have the most obvious effect on improving the thousand-seed weight.Considering the effect on seeds per sillique and sillique length,it may has the the greatest effect on thousand-seed weight improvement when combing QSWA3-2?QSWA3-3 with QSWA9.5.The development of a DH population with the genetic improvement of tribenuron-methyl-resistance of 624 R.Twenty-six plants with heterozygous gene of tribenuron-methyl resistance were obtained in the BC3F1 generation by combining backcrossing with marker-assisted selection and phenotype selection of tribenuron-methyl resistance.These plants were then used for microspore culture later,and a DH population consisted of 188 plants were obtained.6.The foreground selection of the DH population were made by Scahas3-2 maker,and 71 plants with the anti-tribenuron-methyl gene were obtained.We further validated tribenuron-methyl resistance of these plants by spraying of tribenuron-methyl to lateral branch.7.The background of the DH population was analyzed with 49 pairs of SSR markers that were evenly distributed on the chromosomes of Brassica napus.It was found that recovery rate of 30.99% of the DH individuals was between 85.00% and 90.00%,38.03% individuals above 90.00%,and the highest recovery rate was up to 95.91%.