Analysis of Fhb1 gene and resistance to Fusarium head blight in 3,177 diverse wheat accessions

Abstract

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 Fhb1 gene recently cloned from the wheat cultivars Sumai 3 and Wangshuibai, designated here as Fhb1-R, confers type II resistance to FHB, we investigated the presence of Fhb1-R in 3,177 wheat accessions from different countries of the world. By PCR screening with a functional molecular marker amplifying a part of Fhb1 genomic sequence, Fhb1-R was detected in 33 of the 3,177 accessions. Through two independent inoculation tests with Fg under greenhouse conditions, 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 the fact that the presence of Fhb1-R is not always associated with type II FHB resistance. Further analysis of representative Fhb1-R carrying accessions led to the finding of one Fhb1-R carrying, but FHB susceptible, wheat accession showing moderate resistance to Fusarium crown rot (FCR), another serious disease caused mainly by Fusarium pseudograminearum (Fp). Our work provides insight into the presence of Fhb1-R in a large set of diverse wheat germplasm lines and new genetic resources likely useful for improving wheat resistance to FHB or FCR in the future.