Comparação da anatomia foliar e dos óleos essenciais de Drimys brasiliensis Miers (Winteraceae) em uma Floresta Ombrófila Densa Altomontana

Abstract

Drimys brasiliensis Miers is native to Brazil, where it is mainly found in montane forests and wetlands of the south and southeast regions of the country. The objective of the present work was to compare the leaf anatomy and the chemical constitution of the essential oils of D. brasiliensis present in two altitude levels (1900 and 2100 m), in a Montane Cloud Forest, in Itamonte, MG. The plant material was collected from four individuals/altitude level. The characterization of the leaf anatomy was carried out by obtaining paradermal and cross sections to perform the stomatal analysis and to measure the thickness of the leaf tissues. The data were submitted to a variance analysis and to the Scott-Knott test. Histochemical tests have also been carried out, as well as scanning electron microscopy. The essential oils extractions have been carried out by hydrodistillation and the identification and the quantification of the constituents by gas chromatography. In order to check the similarity among the oils regarding the proportion of their constituents, principal component analysis has been used. Higher number of sclereids was noted in the mesophyll of the leaves at 1900 m altitude. At 2100 m, the formation of papillae was noted on the abaxial surface of the leaves, as well as an increase in the stomatal density and index, the reduction of the leaf tissues thickness and an increase in the intercellular spaces of the mesophyll. It seems that these characteristics optimize the CO2 absorption at 2100 m, where there is a reduction in the partial pressure of this atmospheric gas. Fifty-nine constituents have been identified in the species oils, with the predominance of sesquiterpenes. The biosyntheses of sesquiterpene alcohols at 1900 m, and phenylpropanoids and epi-cyclocolorenone at 2100 m, were favored.