Identification of QTLs associated with Fusarium head blight resistance in Zhedar 2 barley

Abstract

Fusarium head blight (FHB) in barley and wheat, caused by Fusarium graminearum, is a continual problem worldwide. Primarily, FHB reduces yield and quality, and results in the production of the toxin deoxynivalenol (DON), which can affect food safety. Identification of QTLs for FHB severity, DON level and related traits heading-date (HD) and plant-height (HT) with consistent effects across a set of environments, would provide the basis for marker-assisted selection (MAS) and potentially increase the efficiency of selection for resistance. A segregating population of 75 double-haploid lines, developed from the three-way cross Zhedar 2/ND9712//Foster, was used for genome mapping and FHB severity evaluation. A linkage map of 214 RFLP, SSR and AFLP markers was constructed. Phenotypic data were collected in replicated field trials from five environments in two growing seasons. The data were analyzed using MQTL software to detect quantitative trait locus (QTL) x environment (E) interactions. Because of the presence of QTL x E, the MQM procedure in MAPQTL was applied to identify QTLs in single environments. We identified nine QTLs for FHB severity and five for low DON. Many of the disease-related QTLs identified were coincident with FHB QTLs identified in previous studies. Only two of the QTLs identified in this study were consistent across all five environments, and both were Zhedar 2 specific. Five of the FHB QTLs were associated with HD, and two were associated with HT. Regions that appear to be promising candidates for MAS and further genetic analysis include the two FHB QTLs on chromosome 2H and one on 6H, which were also associated with low DON and later heading-date in multiple environments. This study provides a starting point for manipulating Zhedar 2-derived resistance by MAS in barley to develop cultivars that will show effective resistance under disease pressure.

QTL Analysis of Fusarium Head Blight Severity in Recombinant Inbred Population Derived from a Cross between Two-rowed Barley Varieties

“…2). Ma et al (2000), Mesfin et al (2003) and Dahleen et al (2003) reported the presence of QTLs for FHB on chromosome 6H. Some of the reported QTLs may correspond to the QTL detected in the present study.…”

“…2). Mesfin et al (2003) and Dahleen et al (2003) also reported the presence of QTLs for FHB severity in the vicinity of the vrs1 locus on chromosome 2H in two-rowed × six-rowed populations. Thus, the vrs1 locus might exert a pleiotropic effect conferring FHB resistance, but may not be the major factor for FHB resistance.…”

“…Since several RI lines with open flowering showed a high level of FHB resistance, while several RI lines with closed flowering showed a low level of FHB resistance, the possibility of linkage cannot be ruled out. Moreover, multiple QTLs for FHB severity were reported in this chromosomal region in several previous studies (de la Pena et al 1999, Zhu et al 1999, Ma et al 2000, Dahleen et al 2003. Further studies using largescale populations or near-isogenic lines should be carried out to determine whether the resistance is derived from the linkage effect of the cly1/Cly2 locus.…”

“…QTL analyses associated with FHB severity and deoxynivalenol (DON) accumulation have been conducted in barley to select resistant genotypes, and identify the responsible genetic factors (de la Pena et al 1999, Zhu et al 1999, Ma et al 2000, Dahleen et al 2003. In previous studies, some associations between FHB resistance and certain morphological traits had also been reported.…”

“…For example, several extensive germplasm screening studies indicated that two-rowed varieties (Vrs1) showed a higher FHB resistance than six-rowed (vrs1) varieties (Takeda and Heta 1989, Zhou et al 1991, Steffenson et al 1996. Mesfin et al (2003) and Dahleen et al (2003) reported the presences of a QTL near the vrs1 locus on chromosome 2H using populations derived from two-rowed × six-rowed crosses. They could not determine whether the QTL effect was caused by the pleiotropic effect of the vrs1 locus or the linkage between the QTL and the vrs1 locus.…”