Yield reduction historically associated with the Aegilops ventricosa 7DV introgression is genetically and physically distinct from the eyespot resistance gene Pch1

Abstract

Key message Yield 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. Abstract 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 7D V 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 7D v 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.Publisher's Note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

The Haplotype-Based Analysis of Aegilops tauschii Introgression Into Hard Red Winter Wheat and Its Impact on Productivity Traits

“…Wild relatives of wheat are a rich source of novel underutilized allelic diversity with a great potential to improve cultivated wheat through introgression (Placido et al, 2013;Zhang et al, 2017;Hao et al, 2020). The introgression from wild relatives into elite wheat cultivars was reported to increase pest and disease resistance (Periyannan et al, 2013;Saintenac et al, 2013), improve resilience toward environmental stress (Peleg et al, 2005;Placido et al, 2013), and increase yield (Pasquariello et al, 2020). The success of introgression breeding, however, could be affected by the negative epistasis between multiple alleles of wild and cultivated wheat (Nyine et al, 2020), especially in the low recombination regions of chromosomes, where the linkage with the negatively selected alleles could reduce the efficiency of selection for beneficial variants (Hill and Robertson, 1966).…”

“…Introgression could exhibit pleotropic effects, affecting multiple, often unrelated traits not directly targeted by selection. For example, the introgression from Aegilops ventricosa into the chromosome 7D of wheat was associated with an increase in grain protein content and resistance to eyespot at the expense of reduced yield (Pasquariello et al, 2020). In durum wheat, the introgression of the GNI-A1 gene from wild emmer increased grain weight by suppressing the fertility of distal florets, resulting in a negative correlation between grain number (GN) and grain weight (Golan et al, 2019).…”