Abstract
Key messageYield penalty and increased grain protein content traits associated with Aegilops ventricosa 7D introgression have been mapped for the first time, and they are physically distinct from the eyespot resistance locus Pch1.Wheat wild relatives represent an important source of genetic variation, but introgression of agronomically relevant genes, such as for disease resistance, may lead to the simultaneous introduction of genetically linked deleterious traits. Pch1 is a dominant gene, conferring resistance to eyespot and was introgressed to wheat from Aegilops ventricosa as part of a large segment of the 7DV chromosome. This introgression has been associated with a significant yield reduction and a concomitant increase in grain protein content. In this study, we evaluated both traits and their relationship to the location of the Pch1 gene. We found that both QTLs were clearly distinct from the Pch1 gene, being located on a different linkage group to Pch1. In addition, we found that the QTL for increased grain protein content was strong and consistent across field trials, whereas the yield penalty QTL was unstable and environmentally dependent. The yield and grain protein content QTLs were genetically linked and located in the same linkage group. This finding is due in part to the small size of the population, and to the restricted recombination between wheat 7D and Ae. ventricosa 7Dv chromosomes. Although recombination in this interval is rare, it does occur. A recombinant line containing Pch1 and 7D_KASP6, the marker associated with increase in grain protein content, but not Xwmc221, the marker associated with the yield penalty effect, was identified.
Highlights
One of the most effective, economic, environmentally friendly and sustainable strategies to control plant diseases is the development and use of genetically resistant cultivars (Mundt 2014)
A new set of 20 7D-specific KASP markers (7D_KASP1 to 7D_KASP20) were developed from the Axiom Wheat HD Genotyping Array (Winfield et al 2016). These markers are based on 7D-specific SNPs able to distinguish between the Hobbit ‘sib’ (HS) and HS/VPM7D parents, and they were chosen on the basis of their distribution across the 7D chromosome
Some studies have concluded that the presence of Pch1 is responsible for any negative impact on yield (Kwiatek et al 2016), while other studies noted that an effect only occurred in some instances (Koen et al 2002)
Summary
One of the most effective, economic, environmentally friendly and sustainable strategies to control plant diseases is the development and use of genetically resistant cultivars (Mundt 2014). Wild relatives represent an important source of genetic variation for disease resistance. Dough stickiness is present in wheat lines containing the 1BL–1RS wheat–rye (Secale cereale) chromosome translocation originally introduced to enhance rust resistance through the action of Yr9, Lr26 and Sr31 (Dhaliwal et al 1987; Hsam et al 2000). Another introgressed gene which has been reported to have a pleiotropic negative effect is the eyespot resistance gene Pch (Kwiatek et al 2016)
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