Improvement Of Clubroot And Herbicide Resistances Of Ogu-cms Restorers In Brassica Napus

Canola is an important oil crop in China with obvious heterosis.The radish male sterile cytoplasm（Ogura CMS）have shown the complete pollen abortion in almost all environmental conditions,which is one of the most promising systems for heterosis utilization in rapeseed.However,the restorer genes of Ogura CMS exist in radish,a large number of adverse traits can appear in the process of creating Brassica napus restorer lines by fragment introduction,so it is an important issue to select and breed Ogura CMS restorer line materials with excellent characters for using this system in production.In recent years,the development of the rape industry has been seriously affected and the reasons are as follows:first,the clubroot has been widely prevalent in many major rape producing areas;second,the reduction of rural labor input has brought about a very serious weed problem in rape fields.In this study,two resistant sources,Bing409R（CRb resistance locus）and Huashuang 5R（Pb Ba8.1 resistance locus）,have used as the clubroot resistance donors,and two resistant sources,H56（H56ALS resistance locus）and5N（5NALS resistance locus）,have been used as the sulfonylureas herbicide resistance donors.Through the rapid breeding and marker-assisted selection techniques,the loci of clubroot and herbicide resistances have been successfully directed into 7 different restorer lines after 5 generations of gene polymerization breeding,so as to select elite Ogura CMS restorer lines with double resistance to clubroot and sulfonylurea herbicides.This study can provide excellent parental resources for later practice production and utilization,and has certain guiding significance for the improvement and application of rapeseed varieties in China.The main results are as follows:1.Improvement for the restorer line R2163:In the foreground selection,the clubroot Pb Ba8.1 resistance locus and the H56ALS herbicide resistance loci have been successfully polymerized into the restorer line R2163 using the MAS and Hi-Tom sequencing respectively to identify and screen the resistance loci.In the foreground selection,AFLP technology has been used to detect the background recovery rate,and an individual plant with a background recovery rate of 98.81%has been obtained in BC₃generation for self-cross.The progeny of restorer line R2163R with homozygous clubroot resistance and heterozygous herbicide resistance has been obtained in BC₃F₂ generation.2.Improvement of the restorer lines R3819,R2589 and RBGS201:Through the foreground selecting,the clubroot CRb resistance locus and the H56ALS herbicide resistance loci have been successfully polymerized into the restorer line R3819,R2589and RBGS201,respectively.AFLP technology has been used to detect the background recovery rate in the foreground selection,and the restorer lines R3819,R2589 and RBGS201 with background recovery rates of 95.16%,95.61%and 96.15%were obtained in the BC₂,BC₃F₁ and BC₁ generations,respectively.These individual plants were selected to self-cross,and finally obtain the restorer line material that is homozygous for clubroot disease resistance and heterozygous for herbicide resistance.3.Improvement of the restorer lines R9538,R5001,R3810,RBGS201,and R2589:Through the foreground selecting,the clubroot CRb resistance locus and the 5NALS herbicide resistance loci have been successfully polymerized into the restorer line R9538,R5001,R3810,RBGS201,and R2589,respectively.The restorer line R9538（background recovery rate of 96.67%）,R5001（background recovery rate of 96.43%）and R3810（background recovery rate of 95.83%）were obtained by using AFLP technology in the foreground selection,and R2589 with a background recovery rate of 95.83%was obtained in the BC₂generation.These individual plants were selected to self-cross,and finally obtain the restorer line material that is homozygous for clubroot disease resistance and heterozygous for herbicide resistance.However,the background recovery rate of restorer line RBGS201 was only 92.19%,and backcrossing was continued in the next generation to increase the background recovery rate to more than 95%.