Conifer defense against insects: proteome analysis of Sitka spruce (Picea sitchensis) bark induced by mechanical wounding or feeding by white pine weevils (Pissodes strobi).

Feeding insects can have major ecological and economic impacts on both natural and planted forests. Understanding the molecular and biochemical mechanisms by which conifers defend themselves from insect pests is a major goal of ongoing research in forest health genomics. In previous work, we demonstrated a complex system of anatomical, chemical, and transcriptome responses in Sitka spruce (Picea sitchensis) upon feeding by the economically significant insect pest, the white pine weevil (Pissodes strobi). In this study, changes to the proteome of Sitka spruce bark tissue were examined subsequent to feeding by white pine weevils or mechanical wounding. 2-D PAGE and high-throughput MS/MS were used to examine induced changes in protein abundance and protein modification. Significant changes were observed as early as 2 h following the onset of insect feeding. Among the insect-induced proteins are a series of related small heat shock proteins, other stress response proteins, proteins involved in secondary metabolism, oxidoreductases, and a novel spruce protein. Comparison of protein expression and cDNA microarray profiles of induced spruce stem tissues reveals the complementary nature of transcriptome and proteome analyses and the need to apply a multifaceted approach to the large-scale analysis of plant defense systems.