Effects of light intensity on the anatomical structure, secretory structures, histochemistry and essential oil composition of Aeollanthus suaveolens Mart. ex Spreng. (Lamiaceae)

Abstract

Aeollanthus suaveolens Mart. ex Spreng belongs to Lamiaceae family, and in the Amazon this species is cultivated by natives’ people, this medicinal plant is popularly known as Catinga-de-mulata, being used by the population for general pain treatment. The present study analyzed the effects of light intensity on the anatomy, secretory structures, histochemistry and composition of essential oil of leaf and stem of A. suaveolens. The anatomical structure were observed in response to two light intensities, namely 50% (half shade, HS) and 100% (full sun, FS) light. Histochemical analyses were performed to detect lipids, essential oils, alkaloids, phenolic compounds, sesquiterpene lactones, mucilage, and tannins. Secretory structures were observed under a scanning electron microscope. The results obtained in the present work indicate that the light intensity can affect the histo chemistry and structures of A. suaveolens. Cross sections of the leaves and stem revealed glandular trichomes on both leaf surfaces as well as the stem surface. Essential oil was detected by histochemical analyses in all types of secretory trichomes. These anatomical and histochemical responses suggest modifications to protect the photosynthetic apparatus from excess light, in addition we note that in the chemical composition of the essential oil the class of hydrocarbons sesquiterpene prevailed.