| Cereal cyst nematode(CCN,Heterodera sp.)and wheat powdery mildew(caused by Blumeria graminis f.sp.tritici,Bgt)are major yield limiting factors that continuously threaten wheat production worldwide.The simultaneous occurrence of CCN and powdery mildew leads to greater damage and making it more difficult to control.In China,the shortage of effective resources for CCN resistance limited the development of breeding for CCN resistant wheat cultivars.Previous study identified that Madsen,an American wheat cultivar,was highly resistant to CCN but susceptible to powdery mildew.Besides,Madsen was late-maturing which made it difficult to directly use in breeding programs.Liangxing 99 and Jimai 22 are the leading wheat cultivars with superior agronomic traits and powdery mildew resistance,carrying Pm52 and PmJM22,respectively.In this study,a number of advanced lines were developed from the cross ‘Madsen/Liangxing 99//Jimai 22.Assessments for response of these lines to CCN and powdery mildew were carried out to identify lines that were resistant to both CCN and powdery mildew.The main results are described below.1.Field assessments against CCN showed that 52 lines were resistant or moderately resistant to both H.filipjevi pathotype Hfc-1 and H.avenae pathotype Ha43.In the inoculation test,21 lines exhibited a moderately resistant or a resistant phenotype.Results of field test inoculated with a mixture of Bgt isolates demonstrated that 45 lines showed adult plant resistance to powdery mildew,and 74 lines were resistant to Bgt isolate E09 at the seedling stage in the greenhouse tests.Five lines were identified as they were resistant to both CCN and powdery mildew.2.Forty Bgt isolates collected from wheat producing areas of Beijing,Hebei,Henan and Shandong provinces were used to test the reactions of these 5 lines and the parental lines against powdery mildew.The results showed that H192,H782,H783,H1501,and H1504 were resistant to 20(50%),23(57.5%),23(57.5%),33(82.5%),and 33(82.5%)Bgt isolates,respectively.Liangxing 99 and Jimai 22 exhibited a highly resistance to 32(80%)and 30(75%)Bgt isolates,respectively.3.The heading dates of these 5 lines ranged from April 26 to April 30,similar to Liangxing 99 and Jimai 22 but obviously earlier than that of Madsen.The resistance to both CCN and powdery mildew and promising agronomic performance made them useful under the situation that CCN resistant germplasm was extrimly short in China.4.A 259 bp fragment,same as Madsen,Aegilops ventricosa and VPM1,was detected in the 5 selected lines using primer pair VENTRIUP-LN2 specific for chromosome 2NS.The fragments were amplified with primers URIC–LN2 followed by Dpn II digestion.Result demonstrated that Madsen,Aegilops ventricosa and VPM1 were homozygous for the 2NS chromosome segment,but five selected lines were heterozygous for this chromosome segment.This chromosome segment was considered as the sourse of CCN-resistance.5.A total of 28131 SNPs were found by genome-wide scanning of H1501,H1504 and the parental cultivars using Affymetrix AxiomTMwheat 660 K 96-Array Plate.For H1501,1501(5%)SNPs were inherited from Madsen,22495(80%)SNPs came from Liangxing 99,3098(11%)SNPs were from Jimai 22,and 1073(4%)SNPs were unique to H1501.For H1504,2398(9%),24265(86%),841(3%)SNPs were from Madsen,Liangxing 99 and Jimai 22,respectively.The SNPs specific to H1504 were 627(2%).Most SNPs of H1501 and H1504 originated from Liangxing99,indicating that the powdery mildew resistance and excellent agronomic traits might originate from Liangxing 99.In summary,the newly developed wheat lines with resistance to both CCN and powdery mildew can be used as effective sources in resistance breeding programs. |
