Identification of Novel QTL for Sawfly Resistance in Wheat

Abstract

The wheat stem sawfly (WSS) (Cephus cinctus Nort.) is an important pest of wheat (Triticum aestivum L. em. Thell.) in the Northern Great Plains. This paper reports the genetic analysis of antixenosis for egg‐laying WSS females in recombinant inbred lines (RIL) of hard red spring wheat. Female WSS preferentially choose certain wheat genotypes for egg‐laying, with the cultivar Reeder being preferred and Conan being less preferred. We measured percent stem infestation and percent stem cutting for 91 RIL from a Reeder–Conan cross in four sawfly‐infested locations in Montana. Heritability based on means over environments was h2 = 0.86 for infestation and h2 = 0.75 for cutting. Percent infestation was negatively correlated with heading date (r = −0.57, P < 0.001) and degree of stem solidness (r = −0.31, P < 0.01). A molecular map was created with 431 markers. Quantitative trait loci (QTL) for infestation and cutting were identified as cosegregating with QTL for heading date (controlled by Ppd‐D1 on chromosome 2D) and stem solidness (controlled by Qss.msub.3BL). Additionally, significant QTL for infestation and cutting on chromosomes 2D and 4A were present in several environments, and did not cosegregate with heading date, plant height, or solid stems. These QTL may complement the use of solid stems for host plant resistance by developing wheat lines that vary for attractiveness to the wheat stem sawfly.

Association Analysis of Stem Solidness and Wheat Stem Sawfly Resistance in a Panel of North American Spring Wheat Germplasm

“…In other studies, the solid-stem QTL on 3B was associated with reduced stem cutting (Beres et al, 2011b;Cook et al, 2004;Sherman et al, 2010). In other studies, the solid-stem QTL on 3B was associated with reduced stem cutting (Beres et al, 2011b;Cook et al, 2004;Sherman et al, 2010).…”

“…The use of an elite panel limited the array of allelic variation assessed in this study and, as expected, failed to detect a few QTLs that have been previously shown to be associated with WSS resistance (Sherman et al, 2010;Joukhadar et al, 2013). Nevertheless, the use of this panel allowed us to determine the genetic basis of WSS resistance available within North American breeding programs.…”

“…Panel lines were genotyped using the wheat 90K iSelect single nucleotide polymorphism (SNP) assay (Wang et al, 2014) and 25,728 polymorphic markers were detected. To give a final score of late stem solidness, the ratings of the five internodes were summed to provide scores between 5 (hollow) and 25 (solid) for each stem (Sherman et al, 2010). The estimated chromosomal positions of 2753 markers were based on the consensus WSNP map developed by Cavanagh et al (2013).…”

Mapping and Quantitative Trait Loci Analysis of Drought Tolerance in a Spring Wheat Population Using Amplified Fragment Length Polymorphism and Diversity Array Technology Markers

“…If verified, this result would mean this QTL is a good candidate for use in areas with chronic drought but may not be suitable for environments where high yield can be achieved on a somewhat regular basis, XgwmIóO and Xu'Pt-4487 are likely detecting the same chromosomal region, which is relatively narrow. Using a 'Conan' X 'Reeder' population, XwPt-4487 cosegregated with Xivmc313 on chromosome 4A (Sherman et al, 2010). According to the consensus map (Somers et al,, 2004), Xwmc313 and XgwmíóO are approximately 4 cM apart on chromosome 4A.…”

Host selection by the wheat stem sawfly in winter wheat and the role of semiochemicals mediating oviposition preference

“…Several host plant volatiles with behavioral activity have been identified in spring wheat: the green leaf volatiles (Z)-3-hexenyl acetate and (Z)-3-hexenol, the terpene b-ocimene, and 6-methyl-5-hepten-2-one (Piesik et al, 2008). Quantitative trait loci for WSS oviposition preference have been identified (Sherman et al, 2010). Oviposition preference in WSS is also influenced by height, developmental stage, and stem diameter.…”