Development Of Two Triticum Aestivum-Dasypyrum Villosum T2DS.2VL Translocation Lines And Their Genetic Effections On Wheat Disease Reactions And Major Agronomic Traits

Triticum aestivum L.（2n=6x=42,AABBDD）is the third food crop in China and its genetic improvement has made great achievements during the past 70 years.The same polyploidization process combined with the domestication bottleneck induced severe diversity reduction in the ancestral population of bread wheat,which was likely impeding its range expansion.Many studies showed that introgression benefit genes from wild species into wheat could increase the diversity of bread wheat.Nowadays wheat sharp eyespot and powdery mildew have become the epidemic diseases in the Huanghuai and Yangtze River major wheat productions.Utilization of the cultivars with sufficient levels of wheat sharp eyespot and powdery mildew resistance is the most practical and cost-effective means to control these diseases.Searching for the resistant sources from wild relatives of wheat is one of the important ways to utilize the novel resistance genes.D.villosum（2n=2x=14,VV）,a wild relative of wheat,has excellent traits such as resistance to various wheat diseases.It is an important tertiary gene pool for wheat genetic improvement.Previously,a serts of wheat–D.villosum introgression lines were used to evaluate their reactions to several wheat diseases,results showed that different 2V（2D）disomic substitution lines had excellent resistance to wheat sharp eyespot or powdery mildew.However,the T2DL.2VS translocation line was susceptible to these diseases,indicating that these resistance gene（s）may be located on the long arm of the 2V chromosome.Therefore,the purposes of this study were to develop wheat–D.villosum T2DS.2VL translocation lines derived from different D.villosum accessions,evaluate their resistance to wheat sharp eyespot and powdery mildew,and analyze the main agronomy traits.The result will provide new germplasm for wheat breeding improvement in wheat sharp eyespot and powdery mildew resistance.The main research contents are as follows:1.The development and genetic analysis of the wheat–D.villosum T2DS.2VL#4translocation line introgressed from D.villosum accession 91C43The TW.2VL#4 translocation line NAU1821 selected from DS2V#4（2D）×CS F₁generation was characterized by the combination methods of genomic in situ hybridization,fluorescent in situ hybridization,and 2V-specific molecular markers analysis.Finally cleared the identification of the translocated chromosome in NAU1821 was T2DS.2VL#4.After that,this translocated chromosome was respectively introgressed to the Aikang58 and NAU0686 backgrounds through backcrossing 3-4 times.The transmission frequency of T2DS.2VL#4 translocated chromosome in the backcrossing progenies indicated that T2DS.2VL#4 translocated chromosome transmitted to its offsprings normally.Moveover,wheat sharp eyespot evaluation showed that the disease indexes of the T2DS.2VL#4translocated chromosome homozygous lines were significantly reduced by more 30%than that of the non-T2DS.2VL#4 lines in Aikang58 background.It could be concluded that the2VL#4 chromosome arm carries wheat sharp eyespot resistance gene（s）.However,powdery mildew evaluation revealed that the T2DS.2VL#4 homozygous plants were susceptible at the adult stage（IT=9）,and there was no significant difference with the non-alien plants（IT=9）,indicatging that none powdery mildew resistance was present in T2DS.2VL#4translocation line.As well as,the investigation of agronomic traits showed that there were significant differences in the main stem spike length and grains per spike between the homozygous plants with T2DS.2VL#4 translocated chromosome and the non-alien plants in Aikang 58 and NAU0686 background,respectively.But there were no significant differences in the growth period,maximum tiller number and plant height.The results above showed that with the exception of wheat sharp eyespot resistance,T2DS.2VL#4translocated chromosome might have a positive effect on the increasing of spike length and grain number per spike.The genetic efection of the T2DS.2VL#4 recombinant chromosome on yield-related characters will be further evaluted in muti varieties background.2.The development and genetic analysis of the wheat–D.villosum T2DS.2VL#5translocation line introgressed from D.villosum accession 01I40A total of 137 selfing seeds derived from the crossing between the wheat-D.villosum2V（2D）disomic substitution line NAU18213 and NAU0686 were identified by the combination methods of genomic in situ hybridization,fluorescent in situ hybridization and2V-specific markers.As a result,three T2DS.2VL#5 translocation lines were developed,and the translocated frequency is 2.19%.The evaluation of powdery mildew reaction showed that the powdery mildew resistant gene was co-segregated with the 2VL#5chromosome arm.Although there are differences in plant height and heading date among populations,the dwarf and heading-late characters were not related to the alien chromatin.It could be concluded that the dwarf and heading-late traits could be caused by background factors or wheat chromosomal structure variation.Among the three T2DS.2VL#5translocation lines,212V-97 has better agronomic traits than the other two plants.In the up planting season,T2DS.2VL#5 translocated chromosome homozygous lines and the non-T2DS.2VL#5 lines will be selected from 212V-97 selfed progeny for fuether genetic analysis the effectios of T2DS.2VL#5 translocated chromosome on disease resistance and yield-related traits.3.Screening the polymorphism molecular markers of D.villosum 2VL chromosome armThe two wheat-D.villosum T2DS.2VL translocation lines developed in the present study provided special materials for mapping the excellent genes located on the 2VL chromosome.To further clarify the polymorphisms between different 2VL chromosome arms at the molecular level,118 pairs of 2VL specific molecular markers were screened.Of which 14 pairs had polymorphisms between 2VL#4 and 2VL#5 chromosome.Among them,4 pairs were dominant,and 10 pairs were co-dominant.These 14 pairs markers sequences were analyzed with the homologous sequences on Chinese Spring 2DL chromosome arm,which will be used to genetic map genes in the up research program.