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Title: Optimizing phenotypic and genotypic selection for Fusarium head blight resistance in wheat

Author
item AGOSTINELLI, ANDRES - Asociados Don Mario Sa
item CLARK, ANTHONY - University Of Kentucky
item Brown-Guedira, Gina
item VAN SANFORD, DAVID - University Of Kentucky

Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/20/2011
Publication Date: 11/1/2011
Citation: Agostinelli, A.M., Clark, A., Brown Guedira, G.L., Van Sanford, D. 2011. Optimizing phenotypic and genotypic selection for Fusarium head blight resistance in wheat. Euphytica. DOI: 10.1007/s10681-011-0499-6.

Interpretive Summary: Fusarium head blight (FHB), or head scab, is an economically important disease of wheat. In developing FHB-resistant soft winter wheat cultivars, breeders have relied on field-based selection, selection with DNA markers, or a combination of the two. In this study, we evaluated both selection methods using lines derived from the cross of KY93C-1238-17-2 (high yielding, susceptible) x VA01W-476 (resistant line with two Chinese-derived resistance genes) to determine the optimal selection procedure. Lines were grown under artificial inoculation in scab nurseries for two years and visual FHB symptoms, percentage Fusarium damaged kernels, and deoxynivalenol (DON) concentration were measured. VA01W-476 contributed two major resistance genes: Fhb1 and QFhs.nau-2DL. In this genetic background, the effect of QFhs.nau-2DL was more pronounced than that of Fhb1, resulting in 55 vs. 25% DON reduction and 40 vs. 32% FDK reduction. DNA marker selection based on both genes was equivalent to phenotypic selection of the most resistant 28% of the population for DON and the most resistant 24% of the population for FDK. We propose that an initial round of field based selection at moderate selection intensity will enrich the population with major resistance alleles while maintaining variation at minor scab resistance genes and for other traits in general. DNA markers can then be used to extract lines whose agronomic worth has been demonstrated and which have the resistance genes.

Technical Abstract: Fusarium head blight (FHB), or head scab, is an economically important disease of wheat (Triticum aestivum L.). In developing FHB-resistant soft winter wheat cultivars, breeders have relied on phenotypic selection, marker-assisted selection (MAS), or a combination of the two. The objectives of this study were to estimate heritability of resistance in a resistant x susceptible cross and to simulate selection in order to determine the optimal combination of phenotypic and genotypic selection. F2 derived lines from the cross of KY93C-1238-17-2 (high yielding, susceptible) x VA01W-476 (resistant line with two exotic quantitative trait loci (QTL) and additional resistance) were grown under artificial inoculation in scab nurseries at Lexington (2007 and 2008) and Princeton (2008), KY. Visual symptoms were estimated on a 1–3 scale; percentage Fusarium damaged kernels (FDK), and deoxynivalenol (DON) concentration were measured. VA01W-476 contributed resistance alleles at two major QTL: Fhb1 and a QTL on chromosome 2DL, QFhs.nau-2DL. In this genetic background, the effect of QFhs.nau-2DL was more pronounced than that of Fhb1: 55 vs. 25% DON reduction and 40 vs. 32% FDK reduction. Genotypic selection based on both QTL was equivalent to phenotypic selection of the most resistant 28% of the population for DON and the most resistant 24% of the population for FDK. We propose that an initial round of phenotypic selection at moderate selection intensity will enrich the population with major QTL resistance alleles while maintaining variation at minor scab resistance loci and for other traits in general. Genotyping can then be used to extract lines whose phenotypic worth has been demonstrated and which are homozygous for resistance alleles at the major QTL.