Abstract
A large environmental influence on phenotypic estimates of disease resistance and the complex polygenic nature of Fusarium head blight (FHB) resistance in wheat (Triticum aestivum) are impediments to developing resistant cultivars. The objective of this research was to investigate the utility of a detached leaf assay, inoculated using inoculum from isolates of Microdochium nivale var. majus, to identify components of FHB resistance among 30 entries of U.S. soft red winter wheat in the 2002 Uniform Southern FHB Nursery (USFHBN). Whole plant FHB resistance of the USFHBN entries was evaluated in replicated, mist-irrigated field trials at 10 locations in eight states during the 2001-2002 season. Incubation period (days from inoculation to the first appearance of a dull gray-green water-soaked lesion) was the only detached leaf variable significantly correlated across all FHB resistance parameters accounting for 45% of the variation in FHB incidence, 27% of FHB severity, 30% of Fusarium damaged kernels, and 26% of the variation in grain deoxynivalenol (DON) concentration. The results for incubation period contrasted with previous studies of moderately resistant European cultivars, in that longer incubation period was correlated with greater FHB susceptibility, but agreed with previous findings for the Chinese cultivar Sumai 3 and CIMMYT germ plasm containing diverse sources of FHB resistance. The results support the view that the detached leaf assay method has potential for use to distinguish between specific sources of FHB resistance when combined with data on FHB reaction and pedigree information. For example, entry 28, a di-haploid line from the cross between the moderately resistant U.S. cultivar Roane and the resistant Chinese line W14, exhibited detached leaf parameters that suggested a combination of both sources of FHB resistance. The USFHBN represents the combination of adapted and exotic germ plasm, but four moderately resistant U.S. commercial cultivars (Roane, McCormick, NC-Neuse, and Pat) had long incubation and latent periods and short lesion lengths in the detached leaf assay as observed in moderately FHB resistant European cultivars. The dichotomy in the relationship between incubation period and FHB resistance indicates that this may need to be considered to effectively combine exotic and existing/adapted sources of FHB resistance.
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Claims 10
Claim · model-written summary
Incubation period was the only leaf variable correlated with all FHB resistance parameters.
Not reportedTaxon
Verbatim
e0“Incubation period (days from inoculation to the first appearance of a dull gray-green water-soaked lesion) was the only detached leaf variable significantly correlated across all FHB resistance parameters”
Claim · model-written summary
Incubation period accounted for 45% of FHB incidence variation.
Not reportedTaxonOrgan / stageDirection
Verbatim
e0“accounting for 45% of the variation in FHB incidence”
Claim · model-written summary
Incubation period accounted for 27% of FHB severity variation.
Not reportedTaxonOrgan / stageDirection
Verbatim
e0“27% of FHB severity”
Claim · model-written summary
Incubation period accounted for 30% of damaged kernel variation.
Not reportedTaxonOrgan / stageDirection
Verbatim
e0“30% of Fusarium damaged kernels”
Claim · model-written summary
Incubation period accounted for 26% of grain DON concentration variation.
Not reportedTaxonOrgan / stageDirection
Verbatim
e0“26% of the variation in grain deoxynivalenol (DON) concentration.”
Claim · model-written summary
Longer incubation period correlated with greater FHB susceptibility in this germplasm.
Not reportedTaxonOrgan / stage
Verbatim
e0“longer incubation period was correlated with greater FHB susceptibility”
Claim · model-written summary
Entry 28 leaf parameters suggested both parental FHB resistance sources.
Verbatim
e0“entry 28, a di-haploid line from the cross between the moderately resistant U.S. cultivar Roane and the resistant Chinese line W14, exhibited detached leaf parameters that suggested a combination of both sources of FHB resistance.”
Claim · model-written summary
Four moderately resistant US cultivars had long incubation and latent periods and short lesion lengths.
- Material
- Roane, McCormick, NC-Neuse, and Pate0
- Outcome
- incubation and latent periods and short lesion lengthse0
Not reportedTaxon
Verbatim
e0“four moderately resistant U.S. commercial cultivars (Roane, McCormick, NC-Neuse, and Pat) had long incubation and latent periods and short lesion lengths in the detached leaf assay”
Claim · model-written summary
The detached leaf assay may distinguish specific FHB resistance sources when combined with FHB reaction and pedigree information.
- Outcome
- distinguish between specific sources of FHB resistancee0
Not reportedComparator
Verbatim
e0“detached leaf assay method has potential for use to distinguish between specific sources of FHB resistance when combined with data on FHB reaction and pedigree information.”
Claim · model-written summary
The authors advise considering the incubation-period resistance relationship when combining exotic and adapted resistance.
- Outcome
- combine exotic and existing/adapted sources of FHB resistancee0
Not reportedTaxon
Verbatim
e0“this may need to be considered to effectively combine exotic and existing/adapted sources of FHB resistance.”