| Fusarium head blight(FHB)is an important worldwide disease caused by many Fusarium species.In recent years,with the global climate change,wheat-maize double cropping a year,straw returning to the field and lack of disease-resistant cultivars,FHB has become the main disease in the main wheat producing areas of China-Huanghuai wheat region,which poses a serious threat to the sustained and stable yield increase of wheat.FHB not only causes yield reduction,but also accumulates carcinogenic and teratogenic mycotoxins such as deoxynivalenol(DON)in grains,which seriously threatens national food security and human health.Planting resistant cultivars is the most economical and effective means to control wheat head blight.At present,most wheat cultivars in Huanghuai wheat region are susceptible to FHB.Improving resistance to FHB has become one of the main goals of breeding in this region.However,the lack of germplasm resources for resistance to FHB and the difficulty in identification of resistance,especially the lack of germplasm with superior resistance to DON accumulation and the high cost of DON content determination,have largely restricted the development of wheat cultivars resistant to DON accumulation.In this study,using isolate F0609 of F.asiaticum as pathogen,39 wheat germplasm resources with different FHB resistance collected at home and abroad were were identified by single flower drip inoculation.Meanwhile,DON content detected by enzyme-linked immunosorbent assay(ELISA)kit,agronomic traits such as plant height and grain weight plant investigated and main quality traits including protein content and hardness index detected.The correlation between disease-related indexs such as percentage of diseased spikelets(PDS)and percentage of scabbed kernels(PSK)and DON content was analyzed,and molecular markers linked to FHB resistance genes / QTL Fhb1,Fhb2,Fhb4,Fhb5 and Fhb7 were used for molecular detection,so as to screen out excellent germplasm resources resistant to DON accumulation and good agronomic traits,to establish a method to predict DON content by easy observation index,and to analyze DON content of different resistance to FHB gene aggregation germplasm.On this basis,178 new wheat lines of double haploid(DH)resistant to FHB were identified,agronomic traits investigatedand,quality traits determined and genotype detected,and excellent combinations and excellent lines were screened.The main results are as follows:1.Among the 39 collected wheat germplasm,two germplasm(accounting for5.1%)are resistant,five germplasm(12.8%)are moderately resistant,eight germplasm(20.5%)are moderately susceptible,and 24 germplasm(61.5%)are susceptible.There are 17 germplasm(43.6%),including Sumai 3,Ningmai 9,Wangshuibai,Zhoumai 27,with DON content(27)1.0000 mg/kg,and especially the DON content of Sumai 3,Ningmai 9 and Wangshuibai was lower than 0.5000 mg/kg,which was significantly different from other 36 germplasm.Most of the resistant germplasm with DON content less than 1.0000 mg/kg had poor agronomic traits.For example,the average plant height of the 4 resistant germplasm with DON content less than 1.0000 mg/kg was 122.3 cm,1 000-kernel wight was only 33.7 g,single panicle weight and grain weight plant were 1.4 g and 18.5 g,respectively.The DON content of Ningmai 9 and Yangmai 158 was lower than 1.0000 mg/kg,and their agronomic and quality traits were good.The quality index of Ningmai 9 was close to weak gluten,while that of Yangmai 158 was medium strong gluten,which could be used as improved parents for FHB resistance.Susceptible cultivars Zhoumai 27 and 04 Zhong36 belonged to dwarf,large spike and resistance to DON accumulation,which could be used as improved resistance to DON accumulation parents in Huanghuai wheat region.Compared with other genotypes,the germplasm resistance of aggregated Fhb1 and Fhb2、Fhb4、Fhb5、Fhb7 reached the level of moderate resistance and above,and the average DON content was lower and less than 1.0000 mg/kg.2.Correlation analysis between DON content and FHB disease index: DON content was significantly positively correlated with PSK,PDS,severity and disease index(DI)(r = 0.954,r = 0.404,r = 0.371,r = 0.371),and the correlation coefficient between DON content and PSK was the highest;The regression equation of PSK and DON content was y = 0.2539 x-0.0556(R2 = 0.9101,x: was PSK and y: DON content).When the PSK was less than 4.0%,DON content was less than 1.0000mg/kg(the upper limit of DON content stipulated in mycotoxin limit GB 2761-2017 of National Food Safety Standard).Therefore,the PSK was less than 4.0%,which could be used as the upper limit standard for selection of new wheat lines resistant to DON accumulation in Huanghuai wheat region.The correlation coefficient between DON content of 178 DH lines predicted by PSK and that measured in practice reached 0.834.Therefore,in the process of breeding new wheat cultivars resistant to DON accumulation,directly observed PSK can be used to predict DON content,quickly screen lines with low DON content and reduce breeding costs.3.Identification and detection of DH lines for FHB resistance breeding: Among the 178 new DH lines for resistance to FHB,138 new wheat lines(accounting for77.5%)are resistant,13 new wheat lines(7.3%)are moderately resistant,ten new wheat lines(5.6%)are moderately susceptible,and 17 new wheat lines(9.6%)are susceptible.The offspring of combinations for FHB resistance ‘Zhou 06047-9-1 /Shengxuan 6 // Zheng 7698’ were resistant lines,and the proportion of resistant lines in the offspring of ‘Zhou 06045-9-2 / Shengxuan 6 // Zhou 08044’,‘Zhou 22 //Ningmai 9 //Zhou 22’,‘Yangmai 21 / 2 * Zhoumai 32’ was 75%,80.4 % and 60%,respectively.The average DON content was less than 1.0000 mg/kg in the breeding combinations of wheat resistant to FHB including ‘Zhou 06047-9-1 / Shengxuan 6 //Zheng 7698’ and ‘Zhou 06045-9-2 / Shengxuan 6 // Zhou 08044’.‘Zhou22 / Ningmai9 // zhou22’(average plant height 84 cm,1000-kernel wight 42.4 g,average yield7141.5 kg/hm2)and ‘Yangmai 21 / 2 * Zhoumai 32’(plant height 77.7 cm,1000-kernel wight 45.6g,average yield 7540.5 kg/hm2)with better comprehensive traits were screened by combining agronomic and quality traits,which could be used as improved parents of weak gluten and medium gluten in wheat breeding for resistance to DON accumulation,and 27 excellent new DH lines could be used as improved parents of high quality weak gluten and medium gluten in wheat breeding for resistance to DON accumulation.Compared with other genotypes,the germplasm resistance of aggregated Fhb1 and Fhb2、Fhb4、Fhb5 reached resistant level,and the average DON content was lower and less than 1.0000 mgIn this study,excellent germplasm was identified for the cultivation of new wheat cultivars resistant to DON accumulation in Huanghuai wheat region,and the PSK of FHB could be used as the initial screening index for the cultivation of new wheat cultivars resistant to DON accumulation.151 wheat DH lines resistant to FHB were identified,and molecular marker-assisted selection gene aggregation information was provided,which is helpful to promote the process of breeding new wheat cultivars with resistance to DON accumulation. |
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