Equation 3 assumes that plant hydraulic capacitance from the point where Js was measured to the leaves is negligible, leaf boundary layer conductance is large compared with stomatal conductance and VPD is uniform in the canopy Oren et al. The sensitivity of gc to VPD was assessed using the approach described by Oren et al. In this approach, we fitted a linear regression between gc and ln VPD. However, Oren et al. As we intended to use the gc data to make inferences about D.
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Abstract Background Drimys brasiliensis Miers is native to Brazil, where it is mainly found in montane forests and flooded areas in the South and Southeast regions of the country. The objectives of the present study were to compare the leaf anatomy and the chemical constitution of the essential oils from D.
Fifty-nine constituents have been identified in the oils, with the predominance of sesquiterpenes. Two trends could be inferred for the species in relation to its secondary metabolism and the altitude. Conclusions D. Its essential oils presented promising compounds for the future evaluation of biological potentialities. Background The Mantiqueira Mountains are a part of the Atlantic Forest domain in Brazil, in which altitudinal forests are located, and can be classified as Cloud Forests, since they are practically covered by fog during most of the year.
These forests represent biodiverse and endemic unique ecosystems, which are generally fragmented and threatened, and present a vegetation which is not well studied yet Aldrich et al.
Studies conducted by Bertoncello et al. In addition, studies by Meireles et al. The species has a peculiar anatomic structure among the angiosperms of the Brazilian flora, as it does not present vessel elements on the xylem, and the stomatal pores are clogged with plugs, comprised of cutin and wax Feild et al.
The essential oils from D. The production of essential oils in plants and other secondary metabolites is constantly influenced by environmental factors Gobbo-Neto and Lopes [ ] , which also cause modifications in the leaf anatomic structures of the plants Kofidis et al. Evaluations of leaf anatomy, such as analyses of stomatal density and index, are essential for the comprehension of the gas exchange between the plants and the atmosphere.
They become relevant mainly if the new scenarios of climatic changes for the future are considered Zhou et al. The leaves and branches were collected in adult plants, in the east face of the crown. The average temperature of the warmest month is less than The predominant soil is cambisol Pane and Pereira [ ]. Fully expanded leaves were selected, free of pathogens, from 4 individuals of D.
The paradermal sections were carried out on both leaf surfaces adaxial and abaxial , manually, with the help of a steel blade. For the detection of total lipids, the reagent Sudan IV was used; for the detection of the essential oils, the reagent NADI was used, and for the verification of the phenolic compounds, ferric chloride was used.
Scanning electron microscopy In order to observe the surfaces of D. Leaf gas exchange measurements Leaf gas exchange characteristics from 4 individuals of D. Stomatal conductance gs , leaf transpiration rate E and internal carbon rate Ci were evaluated in the leaves. The extractions of the oils were carried out from fresh leaves, fresh branches and dry leaves from 4 individuals of D.
The whole plant material was cleaned with tissue paper. The leaves and the branches were placed in the glass flask and covered with water. The oil was withdrawn with the help of a Pasteur pipette, placed in a dark glass flask wrapped with aluminum foil and stored under refrigeration.
In parallel with the extractions, a humidity test was carried out, according to Pimentel et al. The injected sample volume was 0. The identification of the constituents was carried out based on the comparison of its retention indexes with the ones in the literature Adams [ ].
For the calculation of the retention index, the Dool and Kratz equation [ ] was used in relation to homologous series of n-alkanes nC9-nC Two equipment libraries have also been used NIST and NIST21 , which allow the comparison of the obtained spectrum data with those existing in the libraries. Statistical analyses The data related to D. Due to the big quantity of chemical compounds present in the essential oils from D. For this analysis, the means of the proportions of the chemical constituents of the oils from 4 individuals of D.
Results and discussion Morpho-anatomical properties of D. In both altitude levels, the stomata found were of the paracitic type and were present only on the abaxial surface of D. Metcalfe and Chalk [ ] report the presence of such sclereids in the representatives of the Winteraceae family. Sclereids were present in a higher amount in D. The central vein of D. These structures were found in both altitude levels. The presence of secretory cells has already been reported for the species of the Winteraceae family Metcalfe and Chalk [ ]; West [ ]; Esau [ ]; Read and Menary [ ].
The histochemical tests also identified phenolic compounds in the mesophyll of D. The abaxial surface of D. Smith [ ] , Metcalfe and Chalk [ ] , Ehrendorfer et al. Vieira and Gomes [ ] attributed the function to converge light stimuli for the mesophyll to the papillae of the abaxial epidermis from Psychotria leiocarpa Cham.
Rubiaceae leaves, for the performance of photosynthesis, since the studied leaves developed under reduced luminosity. Full size image Recent studies conducted by Eller et al. The authors suggested that the water absorption in D. Feild et al. Gray, evidenced that the plugs of the stomata constituted of cuticle material present on the abaxial surface of Drimys leaves, are responsible for the protection of the leaves against excessive soaking caused by the recurring fog in cloud forests.
The authors discuss that the plugs, together with the papillae and epicuticular waxes, due to their high hydrophobicity, comprise a structure which is able to prevent the constant formation of water films on the leaves, that would make gas exchange difficult. The authors also clarify that the diffusion of CO2 in water is much slower than in the air about times , so a water film on the leaves would reduce gas exchange, because it would create a barrier for the entrance of CO2 in the leaves.
Based on the presented evidences, it can be inferred that the occurrence of papillae in D. The papillae present on the abaxial surface of the leaves would favor the absorption of CO2 through the same process described for D. Complementing these data, the leaf transpiration of D. Our results confirm the proposal of Feild et al.
This article has been cited by other articles in PMC. Abstract This paper evaluates CHCl3 and CH3OH extracts of the stem bark, branches and leaves of Drimys brasiliensis and drimane sesquiterpenes isolated from the stem bark against strains of Leishmania amazonensis and Leishmania braziliensis promastigotes and Plasmodium falciparum trophozoites. All of the extracts and compounds were tested in cell lines in comparison with reference standards and cell viability was determined by the XTT method. Therefore, the results suggest that D. Keywords: leishmaniasis, malaria, Drimys, drimane sesquiterpenes Neglected tropical diseases, including leishmaniasis, are among the most common causes of illness among the poorest populations living in developing countries.