Scion-rootstock interaction and drought systemic effect modulate the organ-specific terpene profiles in grafted Pinus pinaster Ait

•Organs show different terpene profiles as a long-term optimized resources allocation.•Provenance environment selectively affects diterpene biosynthesis in needles.•Scion-conferred terpene phenotypes were observed, highlighting isoabienol content.•Drought triggers a needle/root resin acid relocation linked to real drought endured.•Changes in terpene levels rely on drought tolerance of scion-rootstock combination.