Hydroxyacetophenone defenses in white spruce against spruce budworm

We review a recently discovered white spruce (Picea glauca) chemical defense against spruce budworm (Choristoneura fumiferana) involving hydroxyacetophenones. These defense metabolites detected in the foliage accumulate variably as the aglycons, piceol and pungenol, or the corresponding glucosides, picein and pungenin. We summarize current knowledge of the genomic, molecular and biochemical as well as genetic underpinnings of this defense and its effects on C. fumiferana. We present an update with new results on the ontogenic variation and the phenological window of this defense, including analysis of transcript responses in P. glauca to C. fumiferana herbivory. We also discuss this chemical defense from an evolutionary and a breeding context. Methods Gene counts and metadata for each library results presented in the "Induction of hydroxyacetophenone defense in the current year foliage of mature grafts of Picea glauca" section of the article. Files are in DESeq2 format. More details are provided in the method section within the article and the supplementary material. For more information, please contact [e-mail].