The evolution of toxic phenolic compounds in a group of Anacardiaceae genera

Anacardiaceae are largely tropical trees, shrubs and lianas of the order Sapindales, characterized by production of three types of toxic phenols: biflavonoids, alkylcatechols and alkylresorcinols. Anatomical, morphological and rbcL sequence data were used to reconstruct the phylogeny of a group of Anacardiaceae and address questions about the origin and evolution of these toxic phenolic compounds. Their evolutionary patterns are discussed in relation to the group of Hemipteran insects that feed on Anacardiaceae. Our study included 22 taxa of Anacardiaceae and the results support previous phylogenetic studies in that two clades are detected: a basal clade, with Spondias and related genera that do not produce toxic phenolic compounds, and a second clade with the remaining genera, i.e., those that produce biflavonoids, as do species of Burseraceae. The evolutionary patterns of alkylcatechols and alkylresorcinols are not straightforward; these substances are produced in unrelated groups of genera. We suggest, however, that Hemipteran insects do not feed on taxa of Anacardiaceae that produce alkylcatechols.