Analysis Of Fhb1 Alleles And Resistance To Fusarium Head Blight In 3,177 Global Wheat Accessions

Fusarium head blight(FHB),elicited mainly by the fungal pathogen Fusarium graminearum(Fg),causes serious damages to global wheat production.Development of resistant cultivars is the most efficient measure for controlling FHB,which requires efficient identification and utilization of the wheat germplasm carrying FHB resistance genes.Because the recently cloned Fhb1 gene confers type II resistance to FHB,this project here analyzed Fhb1 alleles in 3177 global wheat accessions.By PCR screening with a functional molecular marker of Fhb1,the resistance-associated allele(Fhb1-R)was found in only 33 of the 3177 accessions,with the remaining materials carrying susceptibility-associated allele(Fhb1-S).Through two independent inoculation tests with Fg,eight Fhb1-R carrying lines were found to exhibit relatively high levels of type II resistance to FHB,seven of which were newly identified in this work.Remarkably,a substantial proportion of Fhb1-R carrying accessions were actually susceptible to Fg infection,highlighting an important influence of genetic background on Fhb1-R mediated FHB resistance.Further analysis of representative Fhb1-R carrying accessions indicated that this allele did not play a role in wheat defense to Fusarium crown rot(FCR),another serious disease caused mainly by Fusarium pseudograminearum(Fp).Nevertheless,this project discovered that one Fhb1-R carrying,but FHB susceptible,wheat accession was moderately resistant to FCR through three independent inoculation tests with Fp.This work provides valuable insight into Fhb1 alleles in a large set of global wheat germplasm and new genetic resources useful for improving wheat resistance to FHB,FCR or both in the future.