Identification And Molecular Polymerization Breeding Of Fusarium Head Blight(FHB) Resistance In Huang-Huai Wheat Region

Fusarium Head Blight(FHB)is an explosive grain disease.The main pathogens are Fusarium graminearum,Fusarium asiatica and other Fusarium oxysporum,which not only seriously affect the yield and quality of wheat,but also pose a serious threat to human and animal health.In recent years,the epidemic area of FHB has been expanding,especially in Huang-Huai wheat area.The southern part of Huang-Huai wheat region is the most important wheat producing area in China,and the wheat yield and quality in this area play an important role in national food security.The cultivation and utilization of resistant varieties is the most simple,effective and environmentally friendly way to control FHB.However,most of the wheat varieties popularized in Huang-Huai wheat region are susceptible to FHB,which is affected by tedious resistance identification,excellent resistance sources and lack of molecular markers.The progress of wheat breeding for resistance to scab in Huang-Huai wheat region is slow.In this study,based on Huang-Huai wheat region,the identification method of FHB resistance was optimized,and 104 wheat FHB-resistant cultivars resources collected and created were identified,and the effects of 6 resistance genes(Fhb1,Fhb2,Fhb4,Fhb5,Fhb7,Qfh.wh1)on FHB resistance were analyzed.At the same time,a multiplex PCR system for FHB resistance gene detection was established.The identification method of resistance to wheat scab at seedling stage was explored.The main contents and results are as follows:1.Optimization of FHB resistance identification conditions in Huang-Huai wheat region: two wheat varieties with resistance and two susceptible wheat varieties were selected for identification of FHB resistance by single flower drip,and the effects of different moisturizing time on the results of resistance identification were analyzed.The results showed that the infection of FHB was caused by bagging for 1 to 7 days,and the severity of the disease increased significantly with the extension of bagging time.There was no significant difference in the severity of the same resistant and susceptible varieties under bagging for 4 to 7 days.The severity of susceptible varieties in 4 ~ 7 days was significantly higher than that in 1 ~ 3 days(P < 0.05),and the evaluation of resistance was also different from that in 1 ~ 3 days,which indicated that bagging and moisturizing for 4 days was suitable for the identification of FHB resistance in Huang-Huai wheat area.2.Identification of excellent FHB resistance cultivars resources: using the optimized inoculation identification method,104 wheat cultivars at home and abroad were identified by using the dominant pathogens of FHB in Henan and Jiangsu provinces as pathogens.the main agronomic characters such as plant height,number of spikes and 1000-grain weight were investigated.The results showed that there were significant differences in FHB resistance of the tested cultivars.In the past 3 years,19(18.3%)and 12(11.5%)strains were resistant to Henan and Jiangsu respectively,and85(81.7%)and 92(88.5%)were susceptible respectively.Among them,12 cultivars,such as Sumai 3,Wangshuibai,Xumai 021,Yunong 903 and Yunong 901,were resistant to two kinds of pathogenic bacteria for 3 consecutive years.3.Establishment of multiplex PCR detection system for disease resistance genes:a multiplex PCR system of 6 FHB resistance genes from 21 wheat gcultivars with known genotypes was selected.After optimization,2(Fhb2+Fhb5)or 3(Fhb1+Fhb7+Qfh.wh1)resistance genes could be completed by one multiple PCR,and 6 resistance genes could be detected by 3 PCR reactions,which increased the detection efficiency by 50%.4.Using the multiple PCR system established in this study,the genotypes of FHB resistance genes were analyzed by closely linked molecular markers,and the effects of different genotype composition on FHB resistance were analyzed.The results showed that:(1)there were 4,4,4,8,1 and 6 germplasms carrying only one resistance gene Fhb1,Fhb2,Fhb4,Fhb5,Fhb7 and Qfh.wh1,respectively.The average severity of Fhb1 and Qfh.wh1 was lower(2.2 and 2.8,respectively),while that of Fhb2 and Fhb7 was higher(3.6,respectively).The number of cultivars carrying two resistance genes Fhb1+Fhb4,Fhb1+Fhb7,Fhb2+Fhb5,Fhb2+Fhb7 and Fhb4+Fhb5 was 1,1,2,3 and 2,respectively,in which the severity of Fhb1+Fhb4genotype was the lowest(2.2),the result of identification was moderately resistant,the severity of Fhb1+Fhb7 was lower(3.0),the result of identification was inconsistent between years,and the severity of Fhb4+Fhb5 genotype was the highest(3.6).Five cultivars carrying 3 or 4 resistance genes(Wangshuibai,Sumai 3,Ning10161,Shengxuan 6 and Shengxuan 5)were all less than 2.5.the results were moderately resistant and above,and Wangshuibai carried 4 resistance genes(Fhb1+Fhb2+Fhb4+Fhb5).According to the analysis of the results of the tested cultivars,Fhb1 and Qfh.wh1 genes had better resistance to FHB,and there were disease-resistant cultivars in the materials which existed alone or polymerized with other genes.5.The laboratory rapid identification technique of wheat FHB resistance was established 16 cultivars with stable results of single flower drip identification for 3consecutive years from 2018 to 2020 were selected,including 4 wheat FHB resistance to(R),4 moderately resistant(MR),4 moderately susceptible(MS)and 4 susceptible(S).The results showed that:(1)there was a certain positive correlation between the disease index of stem base rot at seedling stage and the resistance to spikelet rate of scab at adult stage(r = 0.627 0).723),which laid a good foundation for the rapid identification of stem rot at seedling stage and the prediction of FHB resistance.In this study,the identification method of wheat scab resistance in Huang-Huai wheat region was optimized,and then the resistance identification of wheat cultivars and molecular detection of 6 resistance genes were carried out by using the optimized method.The multiple PCR detection system of 6 genes was established,and the molecular detection efficiency was increased by 50%.Efficient molecular detection methods were used to determine the effects of different genotypes on FHB resistance.In addition,the method of predicting FHB resistance by indoor resistance to stem rot at seedling stage was explored.The results provide excellent aggregation information of disease resistance cultivars and resistance genes for FHB breeding,and provide an efficient detection method for molecular marker-assisted selection,as well as an important basis for predicting FHB resistance through stem base rot resistance at seedling stage,which is of great significance to promote the breeding process of FHB resistance in China.