Environmental and phytohormone modulation of organ-specific specialized metabolite profiles in the dryland tree Erythrina velutina.

Erythrina velutina is a tree that thrives in the shallow rocky soils of the dry and hot Caatinga, a unique Brazilian biome. It is rich in specialized metabolites with medicinal properties. Indeed, alkaloids and flavonoids are phytochemical markers of the genus. Our previous studies identified key biochemical and molecular targets in biosynthesis of these metabolites in E. velutina, including phytohormone signalling pathways and responses to environmental stressors. However, the role of these signalling molecules and external factors in modulating the tree natural product (NP) profiles remains unexplored. In this study, seedlings of E. velutina were subjected to environmental stress (heat, ultraviolet radiation, drought, salinity, mechanical damage) and phytohormone exposure (methyl jasmonate, salicylic acid, nitric oxide, abscisic acid). Leaves and roots were collected after 2 and 4 days of treatment for HPLC-DAD and chemometric analyses. The most prominent factors that increased accumulation of major metabolites were nitric oxide, drought, heat, ultraviolet radiation, and methyl jasmonate. The analyses revealed both organ- and temporal-specific metabolite profiles, as well as some typically shared features. Both phytoanticipin and phytoalexin-like metabolite profiles were recorded, with prevalence of the former. The results shed light on how the above factors affect metabolic tuning in E. velutina. Moreover, the generated datasets will be useful in selecting individual compounds for detailed functional investigation, as well as for directing chemical profiles towards known and novel metabolites of interest in this species.