Anatomy, histochemistry, and comparative analysis of hydroxycinnamic derivatives in healthy leaves and galls induced by Baccharopelma spp. (Hemiptera: Psyllidae) in Baccharis spicata (Lam) Baill (Asteraceae)

Abstract

Baccharis spicata is a plant native to the south of South America And is infected by psyllids of the Baccharopelma genus, which induce a fold gall in its leaves. This infection induces a series of anatomical and phytochemical variations compared to the healthy leaf: the content of total phenolic compounds and total hidroxycinnamic derivatives is lower, though the chlorogenic acid measured by HPLC remains the same and the 4,5 dichlorogenic acid content is near the half of the one observed in the one in the healthy leaf. Regarding to its anatomy, the gall has an homogeneous mesophyll and flavonoids in its outer epidermis compared to an isobilateral mesophyll and epidermal flavonoidic idioblasts observed in the leaf. The increase in the expression of waxes suggests it is a protective function against the desiccation by preventing water evaporation in the structure. The results here exposed suggest that the psyllid manipulates plant tissues, inducing hyperplasia and hypertrophy in the tissues, differentiating them from healthy structures and inducing changes in the biosynthesis of secondary polyphenolic metabolites that act like intermediary between the gall and the environment.