Using ⁶⁰Co-γ Radiation Mutagenesis Technology To Create New Trititrigia Germplasm

Thinopyrum intermedium（2n=6x=42）is a perennial species belonging to Elytrigia with many excellent characters,such as high resistance to abiotic and biotic stress.It has become one of the wild parents commonly used in the genetic improvement of wheat.Previously,we obtained the wheat-Th.intermedium alien addition lines SN6306（2n=44）by hybridizing wheat cultivar Yannong 15 and Th.intermedium.In order to obtain the excellent wheat-Th.intermedium translocation line,⁶⁰Co-γradiation treating SN6306 was performed to create wheat-Th.intermedium translocation lines.M₁seeds were obtained after self-inbred.In this study,we screened out 20 excellent mutants by analyzing the agronomic traits of the M₁mutation populations,and the 20 mutants screened out 13 mutants by identified grain quality and cytological.Finally,we screened out 4 excellent mutants,which provided a reference for further screening and identification of these mutant materials.The main results are as follows.1.Statistical analysis of agronomic traits of M₁generation mutantsIn the M₁generations,statistics on agronomic traits of 220 mutants which developed normally were analyzed.According to the statistics,the mutant traits are mainly involved in six aspects:stem,ear,plant type,grain,leaf type and fertility.The mutation rate related to yield was more than 5%,such as more tiller,which is beneficial to wheat breeding.the mutation traits with mutation rate above 5%were ranked as follows:more tiller>long awn>dwarf>no awn>square>club shape>medium plant type>dense spike.Meanwhile,the statistics were analyzed with SPSS to reveal the relationship between valid tiller number and YPP（yield per plant）,spikelet number and YPP,spike length and YPP,respectively.The results show that the valid tiller number and spikelet number are major factors affecting yield per plant.In subsequent breeding,we can focus on observing the mutants with more valid tiller numbers and spikelet numbers.2.Cytological detection and grain quality of the M₂generation mutantAccording to the survey results of M₁generation,20 excellent mutants were performed cytological detection and near-infrared spectrum.There are 13 mutants identified by cytological methods whose root tip cell chromosome number was 42.And the grain qualities of 12 mutants were better than that of the parent SN6306.3.13 M₂generation mutants’agronomic character,molecular marker and powdery mildew resistance identificationStatistical analysis of agronomic traits of mutants in the greenhouse.The results showed that the spike length and spikelet numbers per spike of 13 mutant’s whole were higher than those of the parent SN6306,and had the potential to increase yield.Using the designed primers specific to Th.intermedia to identify 13 mutants,and 10 pairs of primers could amplify bands consistent with Th.intermedia in the 4 mutants（A005,A008,A011 and A078）,these mutants also presented as high resistance to almost immune in powdery mildew resistance experiment.Novel germplasm materials obtained in our study provide a reference for wheat breeding.We designed 10 pairs of primers that can be as specific molecular markers for identification of the chromosome fragments of Th.intermedia.In addition,there are many types of mutations created by radiation mutagenesis,which may provide new recourse for further selecting.