Abstract
BackgroundFusarium head blight (FHB) and Septoria tritici blotch (STB) severely impair wheat production. With the aim to further elucidate the genetic architecture underlying FHB and STB resistance, we phenotyped 1604 European wheat hybrids and their 135 parental lines for FHB and STB disease severities and determined genotypes at 17,372 single-nucleotide polymorphic loci.ResultsCross-validated association mapping revealed the absence of large effect QTL for both traits. Genomic selection showed a three times higher prediction accuracy for FHB than STB disease severity for test sets largely unrelated to the training sets.ConclusionsOur findings suggest that the genetic architecture is less complex and, hence, can be more properly tackled to perform accurate prediction for FHB than STB disease severity. Consequently, FHB disease severity is an interesting model trait to fine-tune genomic selection models exploiting beyond relatedness also knowledge of the genetic architecture.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1628-8) contains supplementary material, which is available to authorized users.
Highlights
Fusarium head blight (FHB) and Septoria tritici blotch (STB) severely impair wheat production
Extensive field evaluation resulted in high heritabilities of FHB and STB disease severities In the three environments Harzhof 2012, Harzhof 2013 and Rosenthal 2013 FHB and STB disease severities were scored on the same plots, but we observed no significant correlations between FHB and STB disease severity values for all three environments (Additional file 1: Figure S1) and : This finding is in accordance to a previous study in wheat investigating the potential to simultaneously test for FHB and STB resistance in the same plot [29], it is unlikely that the combined evaluation of both diseases impaired the quality of phenotypic data, representing an efficient phenotyping strategy
The Pearson moment correlations among phenotypic values of the 1604 hybrids and their 135 parental lines estimated for single environments were on average moderate (r = 0.31, P < 0.01 for FHB disease severity and r = 0.31, P < 0.01 for STB disease severity)
Summary
Fusarium head blight (FHB) and Septoria tritici blotch (STB) severely impair wheat production. In marker-assisted selection, a small number of predefined functional markers is used to predict the performance of genotyped material for a trait [5] This strategy is worthwhile if major quantitative trait loci (QTL) are present that contribute to a large proportion of the Fusarium head blight (FHB) caused by Fusarium graminearum, F. culmorum and other Fusarium species severely impacts wheat production worldwide [10]. Accurate knowledge of the genetic architecture of FHB and STB resistance is needed for a custom-tailored design of Mirdita et al BMC Genomics (2015) 16:430 genomics-based breeding strategies In this context, it is important to take into account that prediction accuracy of genomic selection is driven by the linkage disequilibrium between molecular markers and QTL, and exploits genetic relatedness between members of the training and the test population [12]. Genomic selection models are not necessarily stable across different cycles of selection
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