Evaluation of wheat stem sawfly‐resistant solid stem Qss.msub‐3BL alleles in hard red winter wheat

Abstract

Host plant resistance provided by solid stems has been the most effective means for mitigating wheat stem sawfly (WSS) (Cephus cinctus Norton) damage in spring and winter wheat (Triticum aestivum L.). The solid stem trait originates from the spring wheat cultivar “Rescue” and is associated with a quantitative trait locus allele Qss.msub‐3BL.b that explains the majority of the variation for stem solidness. Recently, a new Qss.msub‐3BL solid stem allele, designated Qss.msub‐3BL.c, was identified in the spring wheat cultivar “Conan”. It produces a solid stem phenotype early in plant development but dissipates during plant growth. The Qss.msub‐3BL.c allele provides effective WSS resistance in spring wheat but has not been tested in winter wheat. To examine if the Qss.msub‐3BL.c allele provides adequate WSS resistance in winter wheat, near‐isogenic lines (NILs) were developed using marker‐assisted backcrossing. This enabled comparisons between the hollow stem Qss.msub‐3BL.a, solid stem Qss.msub‐3BL.b and solid stem Qss.msub‐3BL.c alleles for stem solidness, WSS resistance, and agronomic traits in Montana growing environments. Compared to the hollow stem allele, the NILs with the Qss.msub‐3BL.c allele increased stem solidness and reduced WSS stem cutting. However, the Qss.msub‐3BL.c allele resulted in lower solid stem scores and greater WSS stem cutting compared to the Qss.msub‐3BL.b allele. Overall, these findings indicate that the Qss.msub‐3BL.c allele failed to provide sufficient WSS resistance in the winter wheat backgrounds tested in this study.

A “solid” solution for wheat stem sawfly (Hymenoptera: Cephidae) resistance: Genetics, breeding and development of solid stem wheat

“…In winter wheat, the WSS emergence not only coincides with duration between stem elongation and anthesis but also the post‐anthesis period. High WSS infestation was observed in winter wheat after the degradation of pith produced by Conan‐derived allele (Wong et al., 2023). It will be interesting to fine map and identify the genes associated with ESS and SS phenotypes.…”

Untargeted metabolomics profiling of oat (Avena sativa L.) and wheat (Triticum aestivum L.) infested with wheat stem sawfly (Cephus cinctus Norton) reveals differences associated with plant defense and insect nutrition

“…The stem solidness trait is highly heritable and is associated with the quantitative trait locus (QTL) Qss.msub-3BL ( Cook et al., 2004 ). This QTL has been well studied, and several alleles conferring differing levels of stem solidness have been identified at this locus ( Varella et al., 2017 ; Cook et al., 2019 ; Wong et al., 2022 ). The allele Qss.msub-3BL.a is associated with the hollow stemmed phenotype, while the allele Qss.msub-3BL.b confers stem solidness throughout plant development.…”