Molecular Cytogenetic Identification Of Wheat-Th.ponticum Translocation Lines Resistant To Yellow Rust

Wheat yellow rust,caused by Puccinia striiformis,is one of the most important diseases that threaten the safe production of wheat.Breeding and promoting disease-resistant varieties is the most economical,safe and effective way to controlling wheat yellow rust,which is based on gene mining,germplasm innovation and utilization.Thinopyrum ponticum(2n=10x=70,St St St St E~eE~eE~bE~bE~xE~x or JJJJJJJ~SJ~SJ~SJ~S)is immune or highly resistant to a variety of wheat diseases,such as wheat powdery mildew,stem rust,leaf rust,yellow rust,yellow dwarf.It is a valuable gene pool for wheat genetic improvement.Our laboratory has created a batch of Trititrigia translocation lines with outstanding resistance to yellow rust by crossing Th.ponticum with common wheat.In this study,based on the evaluation of disease resistance,the comprehensive identification of 9 translocation lines was carried out by means of morphology,cytogenetics and molecular biology,and the following main results were obtained:1.Six Trititrigia translocation lines B21168,B21169,B21170,B21171,B21172,and SN52684 were bred from the crosses and backcrosses of Th.ponticum and Yannong 15,which were resistant to yellow rust.(1)The identification of disease resistance at the adult plant stage showed that B21168,B21171,and B21172 were immune to yellow rust,B21170 was nearly immune,and B21169and SN52684 were highly resistant.Pedigree analysis showed that yellow rust resistance originated from Th.ponticum.GISH-FISH results showed that B21168,B21169,B21170,B21171,and B21172 were 3DL·3DS-Tp disomic translocation lines(Tp represents the chromosome fragment of Th.ponticum,the same below),and SN52684 was 1BS·1BL-Tp disomic Translocation lines;Compared with parental FISH bands,it was found that chromosomes 2A,5A,6A,1B,5B,6B,2D,and 3D of the above-mentioned translocation lines had different structural variations.(2)A total of 43 specific molecular markers of Th.ponticum were obtained in the Trititrigia translocation lines,among which 12 markers were derived from Thinopyrum bessarabicum.Thus,B21168,B21169,B21170,B21171,and B21172 were identified as 3DS·3DL-3E~bdisomic translocation lines,and SN52684 was 1BL·1BS-1E~b disomic translocation line.There were differences in the chromosome structure and specific molecular markers of the six Trititrigia translocation lines,so they were different disomic translocation lines.After B21171and B21172 were resequenced and compared with the Chinese spring sequences,a specific marker Node106-1 of Th.ponticum was developed,which enriched the specific marker resources of Th.ponticum.2.Three translocation lines B21150,B21151 and B21152 were developed from the hybrid progenies of octoploid Trititrigia SNTE20 and Jimai 22,which were resistant to yellow rust.(1)The identification of yellow rust resistance at the adult stage showed that B21150 was nearly immune to yellow rust,and B21151 and B21152 were highly resistant to yellow rust.Pedigree analysis showed that the resistance to stripe rust originated from Th.ponticum.GISH-FISH results showed that B21150 and B21152 were 3DS·3DL-Tp disomic translocation lines,B21151 was 3DS·3DL-Tp disomic translocation+7DS·7DL-Tp monosomic translocation line;compared with parental FISH bands,chromosomes 2A,3A,5A,6A,5B,6B,7B,3D,and 7D of the three translocation lines had different structural variations.(2)Molecular marker analysis showed that 6 pairs of IT primers of the homeologous group 3 could amplify specific bands of Th.ponticum–Th.bessarabicum in B21150 and B21152,which could be used as specific markers for alien fragments,so they were 3DL·3DS-3E~b disomic translocation lines;A total of 4 specific molecular markers(the third part of the homology group markers CINAU1156,CINAU1206,CINAU1222 and the seventh part of the homology group marker CINAU1568)of Th.ponticum–Th.bessarabicum were obtained in the B21151,so B21151 was 3DL·3DS-3E~b disomic translocation+7DL·7DS-7E~b monosomic translocation line.The three Trititrigia translocation lines mentioned abovewere different in chromosome structure and alien specific markers,so they were different translocation lines.3.Among the 9 Trititrigia translocation lines,B21152 was highly resistant to yellow rust at the adult stage,with the plant height was 81.5cm and the thousand-kernels’weight was 45.1g.It has excellent comprehensive traits and can be used in wheat genetic improvement.