Differential gene expression in near isogenic lines of solid-stem spring wheat associated with wheat stem sawfly (Cephus cinctus) resistance

Wheat stem sawfly (WSS), Hymenoptera Cephus cinctus Norton, is a major pest of spring wheat, Triticum aestivum L., in the Great Plains region of North America. In early summer, adult WSS oviposit inside the stem. Stem boring activity of the larvae has negative effects on photosynthetic activity and movement of assimilates which leads to yield loss. At the end of the growing season, larvae cut a ring around the inside of the stem at the base of the plant which causes further yield loss due to lodging. Stem solidness traits provides tolerance to WSS and is associated with the QTL Qss.msub-3BL. In near isogenic lines (NILs) of spring wheat, the 3BLc allele is responsible for early stem solidness that offers the plant some resistance to infestation. When compared with the 3BLb allele, 3BLc is also associated with a decreased number of ovipositor insertions and number of eggs laid. Our study uses transcriptomics to identify genomic differences between NILs containing the 3BLb and 3BLc alleles. A greenhouse study was conducted using six plants from each line at Zadok’s stage 32 and Zadok’s stage 49. In these lines, several gene transcripts were differentially expressed at both growth stages. These differences may determine host plant attractiveness and influence the behavior of female sawflies.