Screening And Identification Of Wheat-Thinopyrum Intermedium Germplasms With Stem Rust Resistance

Thinopyrum intermedium（2n=6x=42,JJJ^SJ^SSt St or E^eE^eE^bE^bSt St）is widely used in wheat genetic improvement and has good resistance to stem rust,stripe rust,leaf rust and other diseases.In this study,we used GISH,FISH,molecular markers,disease resistance assessment to analyze wheat-Th.intermedium derived line 224-1 and its F₂segregating population by crossing with common wheat Chinese Spring,confirm the chromosome composition of 224-1 and screen seven stem rust resistant wheat-Th.intermedium translocation lines,which provides new germplasm resources for wheat resistance breeding.The main results are as follows:1.Cytological identification,disease resistance identification and molecular marker identification of 224-1.The results showed that 224-1 was a wheat-Th.intermedium 6St-6J^S（6B）substitution line.Compared with the FISH karyotype of parent Jintai 170,224-1 had obvious structural variations on chromosomes 5A,2B,2D and 6D.After inoculating the pathotype RKQQ at the seedling stage,224-1 showed high resistance.Four PLUG markers（TNAC1674 and TNAC1711,etc）and 15 IT markers（CINAU1499,CINAU1500 and CINAU1503,etc）were obtained from the sixth homologous group.The specific bands of Th.intermedium were amplified in 224-1,indicating that the alien chromosomes belonged to the sixth homologous group.In total,nineteen molecular markers were established for detecting chromosome 6St-6J^S.2.GISH,FISH and molecular markers were used to analyze 170 F₂segregating population obtained from the cross of 224-1 and CS,seven wheat-Th.intermedium translocation lines were obtained,among which 224F-52 was a 7DS·6J^Stranslocation line,224F-118 and 224F-154 were 6BL·6St translocation lines,224F-126 and 224F-158 were6BS·6J^Stranslocation lines,224F-144 was a 2DS·6J^Stranslocation line,and 224F-148 was a Th-6BS·6BL translocation line（Th represents a small chromosomal fragment of Th.intermedium,and its genome has not been determined yet）,and the probability of obtaining translocation line is 4.1%.The results of disease resistance survey showed that all the seven translocation lines were nearly immune to a mixture of Pgt races 34MKGQM and21C3CTHSM.The results showed that 17,3,13,18,8,10 and 10 of 19 markers could be used to identify the above seven wheat-Th.intermedium translocation lines,respectively.3.In the process of analyzing 170 F₂segregating population,the chromosome numbers of 224F-136 and 224F-119 were both 43.The former was an aneuploid with a pair of chromosomes 6St-6J^Sand one chromosome 6B.The latter was a wheat-Th.intermedium 6St-6J^Smonosomic addition line.The chromosome number of 224F-66 was 42,indicating that it was a wheat-Th.intermedium 6St-6J^Smonosomic substitution line missing a pair of chromosomes 6B.Lines 224F-66,224F-119 and 224F-136 were inoculated with mixtures of Pgt races 34MKGQM and 21C3CTHSM prevalent in China to assess stem rust responses.The results showed that the three derived lines were nearly immune to stem rust.