Identification And Excavation Of Resistance Loci Of Brassica To Clubroot

Cruciferous clubroot is a soil-borne disease caused by Plasmodiophora brassicae（P.brassicae）.Its global spread has caused huge harm and loss to the growth and production of cruciferous crops,and has seriously threatened the safety of rapeseed production in my country.Breeding of rapeseed for resistance is considered to be the most effective,economical and environmentally friendly control method.Due to the variety of physiological races of P.brassicae,the resistance of varieties with a single resistant locus is easily broken.Therefore,the discovery of new resistance sources and the transformation of resistant loci provide important support for the cultivation of excellent resistant varieties..In this study,a number of germplasm resources for clubroot resistance were obtained through field and indoor resistance identification in a variety of cruciferous plants with resistance.Combined with the analysis method of molecular marker-assisted selection,new resistance germplasm resources of disease loci.The transgenic progeny of different generations are then obtained by crossing with the superior Brassica napus parent.The main results of this study are as follows:1.Identification of new disease resistance loci in Brassica plantsIn this study,through molecular marker-assisted selection analysis,the known resistant loci PbBa8.1 and CRb were excluded from the two resistant parent materials（Brassica juncea WJ and Brassica napus WK）to obtain new resistant germplasm resources.Through the field test and the identification of inoculation in the greenhouse,it is known from the 3:1 inoculation ratio of the WJ self-bred progeny F₁ and the 1:1inoculation ratio of the WK and the susceptible material Mendel-5 cross progeny F₁ that the above new resistant materials are all It is a heterozygous resistant material and is controlled by a dominant gene.Using the self-crossing of the above materials or crossing with the superior rapeseed parents,the transgenic disease-resistant progeny were obtained.2.Creation of ECD04 progeny populations resistant to P.brassicae in Xinmin areaIt is known from previous studies that European Brassica rapa ECD04 is resistant to the physiological race of P.brassicae in Xinmin area.In this study,an F₁ population resistant to Xinmin pathogen was created by crossing the excellent rape variety ZS11with European Brassica rapa ECD04,and the new population was harvested in the greenhouse.Bacterial identification found that F₁ had the isolation of resistance and infection,and the analysis showed that the hybrid parent ECD04 was a genotype heterozygous resistance gene.This work created a resistant progeny population of ECD04,and in the later stage,the genetic proportion of ZS11 in the resistant progeny was continuously increased through multiple backcrosses.3.The resistance performance of Brassica napus WK and Brassica juncea WJ to P.brassicae in different regionsIn this study,two different resistant materials WJ,WK P.brassicae and two resistant varieties 409R,H5R were connected with from Tengchong,Jixi,Dingmiaocun and Jishou,respectively.409R only showed partial susceptibility to Tengchong physiological race,and was fully resistant to other regions;H5R showed better performance to Jixi physiological race;WK and WJ were not resistant to Tengchong bacteria at all,and were isolated from other regions.Compared with H5R,WK had similar resistance to Jixi bacteria,but the resistance to Jishou and Dingmiao village was stronger than that of H5R;WJ’s resistance to the P.brassicae of Dingmiao Village,Jishou and Jixiwas weaker than that of the other three resistant materials 409R,H5R and WK.The utilization value of WJ is to provide new resistant germplasm resources for resistant breeding,and to provide new resistant loci for future resistant aggregation breeding.For future resistant breeding work,different resistant countermeasures should be formulated according to the conditions of different disease areas,so as to promote the progress of my country’s rape planting industry.In summary,this study aims to discover new clubroot resistance loci in cruciferous plants,and identify resistant populations by inoculating P.brassicae in diseased areas and greenhouses.By initial location and fine-mapping,the new resistant locus were identified and finally introduced into excellent Brassica napus,providing new resources for the resistant breeding of Brassica napus.