Pioneer bark beetle attacks orchestrate multifaceted localized defense responses in Norway spruce

Conifer forests around the globe are increasingly threatened by climate change. In addition to abiotic disturbances such as storm-throw, bark beetles are the most widespread cause of forest dieback, and yet, tree defense reactions and underlying molecular pathways have not been fully characterized. To investigate tree responses and molecular defense mechanisms under natural conditions, we used controlled beetle attacks and multi-omics approaches on 35-year-old clonal Norway spruce trees. Attacks by 3–6 individuals of the spruce bark beetle Ips typographus induced coordinated shifts in phytohormones, differential gene and protein expression, and an accumulation of key secondary compounds at the attack site during seven days of exposure. Differential gene expression of up to 1,900 genes from multiple defense-related pathways, together with increased levels of compounds involved in deterring bark beetle attacks, demonstrates how Norway spruce mounts a complex and multifaceted defense response to beetle attack. The comprehensive atlas of expression patterns enables a better understanding of how trees respond at the onset of bark beetle infestation and establishes a basis for future genome-assisted breeding.Please confirm if the author names are presented accurately and in the correct sequence. Author 14 Given name: [Maria Ángeles] Family name [Martínez-Godoy]. Also, kindly confirm the details in the metadata are correctDetails are correct, email for author 14 has been added