| Wheat stripe rust is one of the most serious diseases that endanger the yield and quality of wheat.Breeding resistant cultivars is currently the most economical,safe and effective way to control wheat stripe rust.We found that Guixie 3 showed near-immunity or high resistance to CYR34 race during several years of disease resistance evaluation at multi-site.In order to accurately map gene for stripe rust resistance in Guixie 3,a recombinant inbred line(RIL)population was constructed by crossing Avocet S(AVS)and Guixie 3.Resistant gene for stripe rust was mapped by BSR-seq and55 K SNP array.The main results are as follows:1.In this study,the RIL population constructed by Guixie 3 and AVS was identified for resistance to stripe rust at the adult stage in three environments for two years.The results showed that the number of susceptible strains in RIL population under GY19 and CD20 was more than that under GY20.The phenotypic data of stripe rust in RIL population showed continuous distribution,and the ratio of the number of resistant and susceptible strains in GY19 and CD20 was close to 1∶1.2.BSR-Seq analysis showed a total of 277 high-confidence differential SNPs or Indels were associated with stripe rust resistance in the RIL population,and 93.14% of those SNPs were located on the 2AS chromosome.It is speculated that the gene for stripe rust resistance carried in GX3 is located near the end of the 2AS chromosome at 12～59 Mb.3.The RIL population was genotyped using 55 K SNP array,and 6,364high-quality SNP markers were obtained to construct a genetic map.The total length of the map is 4363.9 c M,and the marker density is 1.5markers/c M.Among them,chromosome 3A has the longest length(333.0c M),and chromosome 2A has the largest number and density of markers(828,3.2 markers/c M).4.According to genotyping data and disease resistance evaluation,a total of 7 QTLs for stripe rust resistance were located on chromosomes 1B(1),2A(2),2D(1),5A(2)and 6B(1).In all three environments,a major QTL(Qyr.gaas.2AS)was detected at the end of the 2AS chromosome(2.5c M),which was consistent with BSR-seq results.Its confidence interval was AX-108900782～AX-111675237(0-2.5c M),and the corresponding physical interval is 15.8-31.9 Mb(16.1 Mb),it can explain 17.07-34.59%of the phenotypic variation.5.According to the results of BSR-seq and QTL mapping,we designed 103 pairs of SSR primers in the target segment of the 2AS chromosome(15.8-31.9 Mb),and selected 22 pairs of reported SSR markers.Those SSR markers were screened and verified in the two parents,resistance pools and RIL populations.Finally,Qyr.gaas.2AS was accurately mapped to the end of the 2AS chromosome with six polymorphic markers(Xcfd36,Xwmc382,hls-2A-04,hls-2A-17,hls-2A-18 and hls-2A-103),and namly Yr GX3.6.Using BLAST analysis,13 candidate genes were predicted in the target interval.Of which a gene(Traes CS2A02G042400.1)is related to the resistance protein(NBS-LRR),another Glycosyltransferases gene(Traes CS2A02G040300.1)and one Glutathione S-transferase T3(Traes CS2A02G041200.1)gene have also been reported to be related to plant resistance,so we speculated that these three genes are most likely to be the target gene of Yr GX3.We will perform functional verification in the next study. |
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