Improvement And Evaluation Of Clubroot Disease In Brassica Napus ‘W3’ And ‘Zhongshuang 11’

Brassica napus is the world’s second-largest oil crop,and the use of rapeseed oil accounts for 13-16% of China’s total edible oil.In addition,Brassica napus can be used for ornamental,vegetables,feed and green manure,and plays an important role in China’s economic growth.However,in recent years,clubroot disease has exploded in a large area in the main producing areas of Chinese cabbage.Clubroot spores can survive in the soil for decades,and physical control,chemical control,and biological control methods are difficult to effectively prevent clubroot disease.As a result,the production of rapeseed in China has been seriously reduced,causing economic losses of 130 million yuan each year.How to effectively reduce the harm of clubroot disease is an urgent problem that to be solved.Clubroot disease breeding is considered to be the most economical and effective way to solve this problem.At present,multiple disease resistance genes have been mapped in Chinese cabbage,turnip and other materials,and have been successfully applied to the breeding of Chinese cabbage.However,Brassica napus lacks disease resistance genes.Therefore,it is particularly important to rapidly introduce disease resistance genes and cultivate resistant varieties.In this experiment,the traditional breeding method combined with Marker-Assisted Selection（MAS）was used to transfer the dominant resistance gene CRd of Chinese cabbage inbred line ’85-74’ to Brassica napus variety ‘W3’ and ‘zhongshuang 11 with excellent traits.The results obtained are as follows:1.Using ‘85-74’ as the source of resistance and ‘W3’ and ‘Zhongshuang 11’ for the recurrent parents to construct BC₁,BC₂,BC₃ and other groups respectively.Using 3 pairs of CRd flanking markers and 70 pairs of background markers evenly distributed on the A genome,individual plants containing the CRd disease resistance gene with the highest recovery rate were screened in each generation.The highest recovery rate of BC₁ generation was 76.1%,78.3%,and BC₂ generation was 92.8%,93.8%,the BC₃ generation recovery rate was 98.8% and 97.8%.2.BC₃ generation materials were selected for disease resistance identification during the test.The identification results were ’W3’ varieties,121 resistant plants and 108 susceptible plants.The ratio of disease resistant to susceptible plants was 1:1;Among the Zhongshuang 11’ varieties,the identification results of the bacteria were 112 susceptible plants and 127 resistant plants.The ratio of disease resistance to susceptibility was 1:1,indicating that the CRd gene showed dominant resistance in Brassica napus.Sex.Some genotypes were selected for genotypic identification.Twelve single genotypes were heterozygous,indicating that some individuals still have CRd gene but the phenotype is susceptible.This may be due to the small physiology of the root edema.Caused by the differentiation.The BC₃F₂ generation line was identified for resistance to field tuberculosis.The results showed that there were 93 resistant plants in the ’W3’ population and 39 susceptible plants.After the chi-square test（X2W3=1.87≤X20.05=3.86,df=1）The ratio of disease to disease is consistent with 3:1 separation;84 of the disease-resistant plants in ’Zhongshuang 11’ and 34 susceptible plants,the chisquare test（X2zhognshuang 11=0.42≤X20.05=3.86,df=1）The ratio to the disease is in line with the 3:1 separation.Some susceptible individuals were selected for genotypic identification,and 5 genotypes were to be found heterozygous,which may be consistent with the above reasons.3.The six main agronomic traits of the improved lines were measured,and the improved ’W3-104’,’W3-28’ in plant height,number of effective pods per plant,number of pods,1000-grain weight,yield per plant were found.There was no significant difference with the recurrent parent ’W3’;among them,’W3-28’ and ’W3-104’ and ’W3’ had 1.32 and 2.12 respectively on the effective number of branches,but there was a significant difference,but ’W3-104 There is no significant difference between ’and ’W3’.The improved ’ZS-919’,’ZS-649’ had no significant difference in plant height,one effective branch number,1000-grain weight,yield per plant and recurrent parent ’double 11’;in the number of pods per fruit and per fruit In the number of ’ZS-649’,’ZS-919’ was 33.6,14.67,1.64,and 1.94 higher than ’Zhongshuang 11’,respectively,with significant differences.4.The BC₃F₂ generation plant line was selected for nutrient quality measurement during the experiment.The total oil content of the improved ’W3’ was 37.45%,and there was no significant difference with the recurrent parent ’W3’.Protein,erucic acid,glucosinolate,linolenic acid,linoleic acid,The contents of oleic acid,stearic acid and palmitic acid were also not significantly different,and the improved 20-enoic acid content in ’W3’ was significantly increased by 0.93%.The oil content of the modified ’Zhongshuang 11’ was 48.46%,and its recurrent parent ’Zhongshuang 11’ increased significantly;the content of linolenic acid and 20-carbonic acid in unsaturated fatty acids increased by 4.62% and 3.23%,respectively.Sexual differences,linoleic acid and oleic acid had no significant difference;there was a significant difference in the content of stearic acid in saturated fatty acids of 0.53%,and there was no significant difference in palmitic acid.In the nutritional quality of rapeseed meal,the soluble sugar content in the improved ’W3’ was 16.47 mg/g,which was not significantly different from the cabbage,and the content in the red cabbage was significantly increased;the soluble sugar of ’Zhongshuang 11’ was improved.It was 15.13 mg/g,which was not significantly different from the cabbage,and the content in the red cabbage was significantly increased.The content of Ca in the modified ’W3’ was 817.3 mg/kg,and the content of Fe was 25.39 mg/kg.There was no significant difference with the cabbage,the content of Mg was 285.47 mg/kg,and the content of Zn was 5.63 mg/kg.Cabbage was significantly decreased;the content of Ca in the modified ’Zhongshuang 11’ was 1466.16 mg/kg,and the content of Fe was 31.69 mg/kg.There was no significant difference with the cabbage,and the content of Mg was 319.13 mg/kg.It was 6.31 mg/kg,which was significantly decreased in Chinese cabbage.