RESUMO
Abstract Baccharis species belonging to sect. Caulopterae are difficult to identify. Most countries are controlling the quality of herbal medicines destined for the internal market or export. "Carquejas" are used arbitrarily for the same medicinal purposes and only three species of sect. Caulopterae are official herbal medicines. In the present study, a morpho-anatomical and statistical analysis was performed with nine species of sect. Caulopterae: Baccharis articulata, B. crispa, B. gaudichaudiana, B. microcephala, B. penningtonii, B. phyteumoides, B. sagittalis, B. triangularis and B. trimera, emphasizing the importance of anatomy as a taxonomic tool. A total of 114 populations of these nine species were examined. The first three principal components of morphoanatomical data provided relevant information to classify the species (75.04% of the total variability). The most discriminatory variable in this issue was the stomatal index (1.0530). We determined the qualitative and quantitative variables in order to differentiate the species by using principal components analysis and ANOVA tests. Stomata type, uniseriate trichome type and presence/absence of collenchyma in the wing margin are the qualitative variables that should be analyzed. Regarding quantitative variables, the epidermal ones in superficial view are more important and discriminatory than those of alate stem cross section and they must be considered for proper quality control of the species of this work.
RESUMO
Crop yield reduction due to salinity is a growing agronomical concern in many regions. Increased production of reactive oxygen species (ROS) in plant cells accompanies many abiotic stresses including salinity, acting as toxic and signaling molecules during plant stress responses. While ROS are generated in various cellular compartments, chloroplasts represent a main source in the light, and plastid ROS synthesis and/or elimination have been manipulated to improve stress tolerance. Transgenic tobacco plants expressing a plastid-targeted cyanobacterial flavodoxin, a flavoprotein that prevents ROS accumulation specifically in chloroplasts, displayed increased tolerance to many environmental stresses, including drought, excess irradiation, extreme temperatures and iron starvation. Surprisingly, flavodoxin expression failed to protect transgenic plants against NaCl toxicity. However, when high salt was directly applied to leaf discs, flavodoxin did increase tolerance, as reflected by preservation of chlorophylls, carotenoids and photosynthetic activities. Flavodoxin decreased salt-dependent ROS accumulation in leaf tissue from discs and whole plants, but this decline did not improve tolerance at the whole plant level. NaCl accumulation in roots, as well as increased osmotic pressure and salt-induced root damage, were not prevented by flavodoxin expression. The results indicate that ROS formed in chloroplasts have a marginal effect on plant responses during salt stress, and that sensitive targets are present in roots which are not protected by flavodoxin.
Assuntos
Cloroplastos/metabolismo , Nicotiana/crescimento & desenvolvimento , Folhas de Planta/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Cloreto de Sódio/toxicidade , Estresse Fisiológico/efeitos dos fármacos , Adaptação Fisiológica/efeitos dos fármacos , Cloroplastos/efeitos dos fármacos , Flavodoxina/metabolismo , Íons , Peróxidos Lipídicos/metabolismo , Osmose/efeitos dos fármacos , Folhas de Planta/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/metabolismo , Plantas Geneticamente Modificadas , Plastídeos/efeitos dos fármacos , Plastídeos/metabolismo , Salinidade , Nicotiana/efeitos dos fármacosRESUMO
Tagetes lucida Cav. (Asteraceae) es una especie nativa de América tropical, comúnmente usada en medicina vernácula y también como medicamento fitoterápico. La infusión se emplea como tónico para combatir la tos, dolores de cabeza, fiebre, cólicos, dolores abdominales, enfermedades gastrointestinales, dolor corporal y como emenagoga. Los extractos etanólicos de hojas de T. lucida presentan actividad bactericida. El objetivo de este trabajo fue realizar la micrográfica analítica de las partes usadas de esta especie a los fines de la estandarización de la droga cruda. Para ello, se estudió la morfología foliar, la epidermis de la hoja, los estomas, la arquitectura foliar, la estructura interna de hojas, tallos, inflorescencias y flores. En los tallos se han determinado dos tipos de estructuras secretoras coexistentes, conductos y cavidades secretoras de origen esquizógeno; mientras que en las hojas y brácteas involucrales solo encontramos cavidades. Los conductos secretores se caracterizan por presentar escaso diámetro, epitelio secretor uniestratificado y vaina parenquimática. En tanto, las cavidades secretoras son de diámetro conspicuo y epitelio secretor pluriestratificado sin la vaina parenquimática. Esta información es requerida no solo para los procedimientos de identificación que garanticen la utilización de la droga vegetal, sino para el control de calidad exigido en la producción de medicamentos fitoterápicos. (AU)