São Paulo, diferem quanto à estrutura foliar, de exemplares encontrados em área rural, isenta de poluentes aéreos urbanos. Foram avaliadas, comparativamente, as dimensões da folha e, em microscopia de luz, a espessura dos tecidos foliares, a densidade de estômatos e de cristais da espécie, coletada em área rural e em dois pontos da cidade de São Paulo: canteiro central da Avenida dos Bandeirantes, com tráfego veicular intenso, portanto com alta carga de poluentes primários, e no Parque Estadual das Fontes do Ipiranga (PEFI) submetido a altas concentrações de poluentes secundários. Buscaram-se variações que possam ser decorrentes da poluição urbana. As folhas coletadas no meio urbano mostraram menores dimensões, menor espessura do mesofilo, maior densidade estomática e maior quantidade de cristais. A espessura do parênquima lacunoso sofreu redução, quando se comparam as plantas do ambiente rural e urbano; observou-se a menor espessura nas folhas submetidas a poluentes secundários. Não foram observadas variações qualitativas entre as folhas dos três locais avaliados. Considerando que folhas coletadas no meio urbano variaram menos entre si, quando comparadas àquelas de área rural, acredita-se que a poluição aérea da cidade possa ser responsável, pelo menos em parte, pelas variações observadas. Exposições padronizadas, em ambiente monitorado, devem ser realizadas para comprovar tal hipótese.Palavras-chave: anatomia foliar, Eugenia uniflora, poluição aérea, ambiente urbano, pitanga ABSTRACT -(Leaf anatomy of Eugenia uniflora L. (Myrtaceae) in urban and rural environments, São Paulo State, Brazil). The aim of this study was to compare leaves of Eugenia uniflora from the city of São Paulo with leaves of plants from a rural site. Leaf size, tissue thickness, and stomatal and crystal density of E. uniflora growing at two sites in the city of São Paulo were investigated by light microscopy and compared with samples from a rural area. The level and types of air pollutants varied at the urban sites. Primary pollutants were present on Bandeirantes Avenue and secondary ones in the park (Parque Estadual das Fontes do Ipiranga -PEFI). Urban leaves were smaller, thinner and with higher stomatal and crystal density. We observed greater spongy parenchyma thickness in leaves from the avenue when compared to those from the park. No qualitative differences were observed between urban and rural leaves. Leaves from the two urban sites showed similarities, but were different from rural leaves, so we believe that the differences observed may be attributed to the polluted environment of São Paulo. In order to confirm this hypothesis, control experiments should be done.Key words: leaf anatomy, Eugenia uniflora, air pollution, urban environment, "pitanga" IntroduçãoAs plantas que vivem no meio urbano, numa grande metrópole como São Paulo, sofrem os efeitos da poluição do ar oriunda, principalmente, da grande frota automotiva, que produz uma carga elevada de poluentes gasosos e particulados (CETESB 2004). A observação de troncos de árvores q...

This study aims to investigate colleters' secretory function, on cellular level, in Rubiaceae species from contrasting environments looking to explore the association between secretion and environment. We collected samples from eight species of Rubiaceae growing in forest and savanna having standard-type colleters with diverse histochemistry (hydrophilic, lipophilic and mixed secretions) and processed for both conventional and cytochemical study under transmission electron microscopy (TEM). The standard colleters, although similar in morphology and anatomy, exhibited marked differences on cellular level, especially in the abundance and topology of Golgi bodies, endoplasmic reticulum and plastids when comparing forest and savanna species. These differences were clearly aligned with the chemical nature of the secretions they produce, with predominance of hydrophilic secretions in forest species and lipophilic or mixed secretions in savanna species. The combination of methods in electron microscopy revealed the sites of synthesis and intracellular compartmentation of substances, the mechanisms of their secretion from the protoplast and confirmed the involvement of the outer walls of the epithelial cells in the elimination of exudates to the gland surface. Our study suggests a potential environment-associated plasticity of the secretory cells of standard-type colleters in modulating their secretory function performance.

Colleters are secretory structures that produce and release mucilage or a mucilage-resin mixture protecting meristems and young structures against desiccation, herbivores, and pathogens. The secretions may vary in colleters of same or different types, indicating that the functionality of colleters may be more specific than previously thought. In this study, we compared 17 Rubiaceae species from savanna and forest environment focusing on colleter secretions and its ecological role. First, we evaluated the morphology, distribution, and histochemistry of stipular colleters using light and scanning electron microscopy. Additionally, we investigated the phenology, microclimate, and the proportion of damaged apices in the savanna and forest species. We recorded standard-type colleters, variable in distribution and size, in 14 of the 17 studied species. The secretion varied from predominantly hydrophilic, mixed to predominantly lipophilic. During the budding period, secretion covered the vegetative apices. Savanna species had a prevalence of lipid secretion in habitats with higher luminosity, which had a lower proportion of damaged apices. In contrast, forest species occurred in habitats with lower luminosity and had a higher proportion of damaged apices, in general with the absence of lipids in the colleters. These results highlight that colleters with similar morphology clearly differed in secretions among species, especially between species from savanna and forest, in which the colleters appear potentially associated with protection against irradiation in savanna, but not in the forest environment.

The aim of this study was to evaluate the growth and development of Aechmea blanchetiana Baker L.B. Sm. in vitro on medium with 0.0, 0.145, 1.45 and 14.5 µM Cu and 0.0, 2.75, 27.5 and 275 µM Zn. Significant accumulation of Cu and Zn occurred at 14.5 µM Cu and 27.5 and 275 µM Zn, respectively, and there were no significant changes in contents of the other macro-and micronutrients. Superoxide dismutase (SOD) activity significantly changed in the presence of both metals. Spermine content increased as Zn concentration increased and decreased with increasing concentrations of Cu. There was an accumulation of H 2 O 2 in the leaf tissue of plants grown in 1.45 and 14.5 µM Cu and 27.5 and 275 µM Zn. A. blanchetiana was found tolerant to the Cu and Zn in concentrations used in this study and displays the capacity to accumulate these metals.

The aim of this study was to evaluate the growth and development of Aechmea blanchetiana Baker L.B. Sm. in vitro on medium with 0.0, 0.145, 1.45 and 14.5 µM Cu and 0.0, 2.75, 27.5 and 275 µM Zn. Significant accumulation of Cu and Zn occurred at 14.5 µM Cu and 27.5 and 275 µM Zn, respectively, and there were no significant changes in contents of the other macro-and micronutrients. Superoxide dismutase (SOD) activity significantly changed in the presence of both metals. Spermine content increased as Zn concentration increased and decreased with increasing concentrations of Cu. There was an accumulation of H 2 O 2 in the leaf tissue of plants grown in 1.45 and 14.5 µM Cu and 27.5 and 275 µM Zn.A. blanchetiana was found tolerant to the Cu and Zn in concentrations used in this study and displays the capacity to accumulate these metals.Additional key words: ascorbate peroxidase, ascorbic acid, Bromeliaceae, heavy metals, hydrogen peroxide, polyamines, superoxide dismutase. ⎯⎯⎯⎯

No abstract

Ozone (O 3) is an oxidative pollutant that causes visible foliar symptoms in sensitive plants. Importantly, cellular markers induced by physiological alterations, including oxidative burst (OB), hypersensitive response-like (HR-like) reactions, and accelerated cell senescence (ACS), precede these symptoms. Because little is known about the effects of ozone in tropical environments, we aimed to identify these cellular markers in Nicotiana tabacum, Ipomoea nil and Psidium guajava growing in an urban area of tropical Sao Paulo, Brazil, and describe the specific physiological alterations that trigger the development of visible symptoms. Cell wall wart-like protrusions, an OB cellular marker, and swelling of thylakoids and mitochondrial membranes, as well as accumulation of plastoglobuli, all markers of ACS, were cell markers common to all species studied. Cellular markers indicating HR-like reaction, as observed in the asymptomatic leaves of N. tabacum and I. nil, are precursors of future development of necrotic areas, featuring the visible symptoms. On the other hand, the main cause of visible symptoms in P. guajava appeared to be the accumulation of phenolic compounds in the mesophyll tissue, an ACS marker. Based on this line of evidence, these bioindicator plants growing in a tropical environment show the damaging effects of O 3 pollution, even before visible symptoms develop. Moreover, this damage can be detected through a distinct group of cellular markers.

Structural changes in ABSTRACT(Structural changes in Psidium guajava 'Paluma' leaves exposed to tropospheric ozone). Psidium guajava 'Paluma' has being tested as an ozone (O 3 ) bioindicator and responds with pigmentation between the veins on the adaxial surface, due to the accumulation of phenolic compounds. Th ese compounds act as non-enzymatic antioxidants that neutralize reactive oxygen species (ROS), formed from O 3 . Th is study aimed to evaluate the leaf structure of plants with and without visible symptoms and to establish these symptoms at the cellular level. Beside this we also aimed to detect structural changes that can minimize the eff ects of the O 3 on the plant. Th e accumulation of phenolic substances, stomatal density and structural changes in P. guajava 'Paluma' leaf tissues exposed during the four seasons of the year were evaluated. Th e study was conducted at the Parque Estadual das Fontes do Ipiranga ( PEFI), which is a park in the city of São Paulo that has high levels of O 3 . Leaves with symptoms showed, on the adaxial surface, anthocyanin accumulation in the vacuoles of epidermal cells and hypodermis. When the symptoms were more intense this accumulation was observed even in the fi rst three layers of palisade parenchyma. Comparing symptomatic and asymptomatic leaves, there was higher accumulation of phenolic compounds in the symptomatic leaves. Some parenchyma cells adjacent to substomatal chambers showed intrusive growth towards the stomatal pore, promoting its occlusion, which could reduce the entry of O 3 in the leaf. Th e accumulation of anthocyanins and other phenolic compounds, in addition to the occlusion of the chamber, protect the plant against O 3 eff ects. Th ese features and the compact arrangement of the mesophyll contribute to why Psidium guajava 'Paluma' does not present cell death, a symptom usually observed in species sensitive to O 3 .