Anatomical and histochemical evidence of leaf salt glands in Jacquinia armillaris Jacq. (Primulaceae)

Abstract

Salt glands, which exclude salt solution to avoid tissue toxicity, have been reported for halophytes species of Primulaceae. Jacquinia armillaris is a species of Primulaceae that occurs in saline coastal environments in the Neotropics and possesses peltate trichomes sunken in leaf surface. The present study investigated these trichomes to describe their structure and check if they are true salt glands. Anatomical and histochemical investigation of the secretory trichomes of the leaves of J. armillaris revealed that they comprise a collecting cell and a single stalk cell with multiple secretory cells located on the top. A collecting chamber originates from the distension and release of the cuticle of the secretory cells. A crystalline substance, which tested positive for sodium, was observed in the collecting chamber. This crystalline salt substance is exuded and deposited on leaf surface. Current results demonstrate that the glandular trichomes of J. armillaris are true salt glands, and thus represent a new record of salt glands for the tribe Theophrasteae of Primulaceae s.l.