Genetic Analysis Of The Wheat Stripe Rust Resistance Gene Yr10 In Common Wheat

Wheat stripe rust,caused by Puccinia striiformis f.sp.tritici?Pst?,is one of the most damaging diseases of wheat production in China.Compared with traditional chemical control,mining and utilization of stripe rust resistance gene is the most economical and effective approach for controlling the rust disease.Yr10 is one of the all-stage resistance gene?ASR?.It is an effective resistance gene for wheat breeding program which confers high levels of resistance to the predominant Pst races in China.Here,we testified the Yr10 candidate gene Yr10_CG?AF149112?and performed re-mapping of the Yr10 gene.From the results,we found that Yr10_CG locus is not true Yr10 gene,and there are 1.2 cM between these two genes.The main results are as follow:1.Yr10 gene confers relatively stable resistance to wheat stripe rust.Based on experiments of several consecutive years,plant materials carrying Yr10 gene showed high levels of resistance to the wheat stripe rust in Huanghuai wheat production area.And the Yr10single gene resistance phenotype is different from the Yr10 donor wheat line Moro.Moro displayed immune response,and Yr10 single gene displayed necrotic and chlorotic blotches or stripes on leaf tissue with no sporulation?IT=1-3?.This kind of infection type is Yr10 gene classical phenotype.2.Yr10_CG does not cosegregate with stripe rust resistance in common wheat.We used Yr10_CG specific primers to screen wheat cultivars and identified their phenotype.We characterized the stripe rust responses for 62 Yr10_CG-positive wheat cultivars,and different levels of stripe rust responses were found among these cultivars.Of them,11 cultivars are susceptible?IT=7-8?,and 4 cultivars are highly susceptible?IT=9?.Then,we prepared two constructs to conduct genetic complementation in wheat‘Bobwhite',which promoted by maize Ubiquitin promoter and wheat WKS1 promoter.The T₁ progenies were tested for their response to the Pst race CYR29,Apparently,the cDNA copy of Yr10_CG did not confer stripe rust resistance in Bobwhite.3.Yr10 is 1.2 cM distal to the Yr10_CG gene on the 1BS chromosome.We remapped Yr10beginning with a cross between Moro?two known stripe rust resistance loci,Yr10 and YrMor?and susceptible wheat Huixianhong.Then,we focused on two F_2:3 families?pop8 and pop10?that segregated for the Yr10 gene alone to map the Yr10 gene.To validate the linkage map,we made a large mapping population?pop11?including 1726 susceptible seedlings.Unexpectedly,Yr10_CG did not represent the Yr10 locus,and Yr10_CG was 1.2 cM proximal to the Yr10 locus.And we successfully developed a PCR marker Xsdauw79,which cosegregates with Yr10.4.Efficient mapping populations of Yr10 gene established by synthetic wheat.The low genetic polymorphism between common wheats made further mapping Yr10 difficult.So,F₃resistant recombinants?F₃RR?that are homozygous on the Yr10 locus have been selected from pop8 and pop10,and have been crossed with 6 Pst-susceptible synthetic wheat lines to develop new F₂ populations.After phenotype identification and statistical analysis,4 newly developed F₂ populations segregated for the Yr10 gene and had be used to precisely map the Yr10 gene.New markers were developed according to the reference genome sequence of wheat‘Chinese Spring'.However,most of these new markers were dominant markers,which only worked on the synthetic wheat lines.So,we guessed that the 1BS distal region may be associated with substantial chromosome variations.5.There are prominent chromosome variations in Yr10 region.We compared the 2.5 Mb sequences at the end of chromosome 1BS between the hexaploid wheat‘Chinese Spring'and the tetraploid wheat‘Zavitan'.From our results,we found that the 1BS distal region may be associated with substantial chromosome variations.11 genes from hexaploid wheat 1BS distal1.5 Mb region did not find homologous genes in tetraploid wheat.In addition,the 1BS chromosome is associated with a Mb-scale inversion between these two materials.Yr10 gene is located within this inversion region.6.Development of Yr10 gene mutant population.To isolate Yr10 gene and study gene function,we developed an EMS-based mutant population on the Yr10 single gene wheat material,which are homozygous on the Yr10 locus.After pre-experiment,we choosed 1.00%and 1.05%concentration to treat the seeds.Totally,we got 2100 M₁ generation plants.After phenotype identification and marker assisted selection,we screened M₂ generation population,and found 8 independent mutant lines which were highly susceptible to stripe rust.These mutants can be used for Yr10 gene isolation and functional identification.Our study identified the Yr10 candidate gene(Yr10_CG,GenBank ID AF149112)and remaped Yr10 gene on genetic mapping.We found that the Yr10_CG locus was not the Yr10gene,which was 1.2 cM distal to the Yr10 gene on the 1BS chromosome.We further developed a PCR marker Xsdauw79,which cosegregates with Yr10.The Yr10 confers all stage resistance to stripe rust.The accurate mapping of Yr10 provides a fine groundwork for wheat resistance breeding and map-based cloning of the rust resistance locus.