Impact of the galling Dasineura sp. on the structural and chemical profile of Peumus boldus stems

Key message Dasineura sp. galls develop in the vascular system of Peumus boldus stems, inhibiting phloem and fiber formation and alkaloid and fatty acid synthesis, and fostering compound synthesis towards alkanes. Abstract Peumus boldus is a native Chilean tree with recognized biological activity, mainly medicinal, insecticidal, and herbicidal, whose stems house the galling insect Dasineura sp. Galling insects have the ability to manipulate host tissues for food and shelter. With this in mind, it would be expected that the phytophagous action of Dasineura sp. could impact the structural and chemical composition of P. boldus stems. To prove this hypothesis, a comparative study of P. boldus stem and gall anatomy and chemical composition was performed. The galling Dasineura sp. induces structural alterations in the vascular cylinder of P. boldus stems, where it establishes itself. The differentiation of phloem tissue and perivascular fibers is also inhibited, forming homogeneous parenchymal tissue in the outer gall tissue. The vascular cambium assumes new functions, forming two new cell types, the parenchymatic and the nutritive cells around the larval chamber on which the larvae feed. Dasineura sp. also induces alterations in P. boldus stem chemical composition, redirecting compound synthesis towards alkane production and inhibiting the synthesis of one alkaloid and fatty acid, two sesquiterpenes, and three sterols in the non-galled stems. The redistribution of the accumulation sites of proteins, lipids, and reducing sugars towards the gall nutritive cells, guarantee the Dasineura sp. nutrition.