Maria Regina Torres Boeger

Comparação da morfologia foliar de espécies arbóreas de três estádios sucessionais distintos de floresta ombrófila densa (Floresta Atlântica) no Sul do Brasil

We investigated the leaf morphology of trees from three distinct successional stages (early, intermediate, late) of a lowland rain forest located near the coast of Parana State, Brazil. This forest grows on sandy soil with low nutrient content. Leaves from trees from the early successional stage present a higher degree of sclerophylly, having thicker leaves, smaller leaf area, higher stomata density, thicker palisade parenchyma, and higher prevalence of sclerenchyma than those of species from the intermediate and late successional stages. Variation of leaf morphology along the successional gradient is likely related to microclimatic changes and the interaction of plant-soil processes, which intensify in older successional stages.

Postglacial north–south expansion of populations of Rhizophora mangle (Rhizophoraceae) along the Brazilian coast revealed by microsatellite analysis

PREMISE OF THE STUDY Red mangrove (Rhizophora mangle) dominates tropical tidal areas along both sides of the Atlantic, yet little is known about its degree of population differentiation over large geographical scales. Information on the genetic variability of mangrove species along the Brazilian coast is important not only for understanding the recent gene flow dynamic between populations, but also to evaluate models of evolutionary diversification and develop effective strategies for conservation. We investigated the genetic variability of the red mangrove along the Brazilian coast. METHODS Eight microsatellite loci were used to genotype 145 individuals across 10 populations spanning more than 4500 km of coast line. We estimated the genetic variability and structure of the populations and the historical gene flow between them. KEY RESULTS The level of genetic variability was low, with only 27 different alleles being detected and allele richness between 1.25 and 2.75. On the other hand, there was substantial population differentiation (R(st) = 0.48; P < 0.001), especially between the northern and southern populations. The populations from Pará and Maranhão had significantly greater genetic variability than did the remaining locations. CONCLUSIONS This difference might reflect the older age of the northern mangroves, which likely remained stable during the Quaternary glaciations. The lowest variability observed in the southern populations of the red mangrove most likely reflects their recent age, associated with allelic reduction, resulting from the consecutive founder events that followed subsequent colonization of estuaries during the gradual warming by the end of the last glacial period.

Nutrientes foliares de espécies arbóreas de três estádios sucessionais de floresta ombrófila densa no sul do Brasil

We investigated the leaf nutrient content of trees species from three distinct successional stages (early, intermediate, late) of a lowland rain forest located near the coast of Parana State, Brazil. This forest grows on sandy soil with low nutrient content. We collected mature leaves from five different individuals of each sucessional stages of the most important tree species of each successional stage (four of the early; eight of the intermediate and 11 of the late stages) for chemical analysis of following elements: N, P, K, Ca, Mg, C, Zn, Fe, Cu e Mn. The species from early sucessional stage have lower contents of N, P, K, Zn, Fe, and higher contents of Mg. These concentrations are statistically different (p 25:1), despite of the tendency to decrease as succession advances. The increment of concentration of the most studied foliar nutrients along the successional gradient is probably related to the accumulation of litter above the soil that provides a more adequate environment for efficient nutrient cycling and higher nutrient concentration in the soil.

Heat stress causes alterations in the cell-wall polymers and anatomy of coffee leaves (Coffea arabica L.)

Coffee plants were subjected to heat stress (37 °C) and compared with control plants (24 °C). Cell wall polysaccharides were extracted using water (W), EDTA (E) and 4M NaOH (H30 and H70). In addition, monolignols were analyzed, and the leaves were observed by microscopy. Plants under heat stress accumulated higher contents of arabinose and galactose in fraction W. Xylose contents were observed to decrease in H30 fractions after the heat stress, whereas galactose and uronic acid increased. H70 fractions from plants exposed to heat stress showed increased xylose contents, whereas the contents of arabinose and glucose decreased. Differences in the molar-mass profiles of polysaccharides were also observed. The primary monolignol contents increased after the heat stress. Structural alterations in palisade cells and ultrastructural damage in chloroplasts were also observed. Our results demonstrate that the chemical profile of coffee cell-wall polymers and structural cell anatomy change under heat stress.

Leaf morphology of 89 tree species from a lowland tropical rain forest (Atlantic forest) in South Brazil

Este estudo examinou a morfologia e anatomia foliar de 89 especies arboreas de uma area de Floresta Atlântica Litorânea no Sul do Brasil. A maioria das especies (>75%) possuem folhas pequenas (notofilas e microfilas) elipticas e simples com margens inteiras. Essas folhas apresentam uma estrutura anatomica formada por epiderme uniseriada, parenquima palicadico composto por um unico estrato de celulas e o parenquima esponjoso composto por 5 to 8 estratos celulares. O tecido esclerenquimatico e limitado aos feixes vasculares. A maioria das especies arboreas (91%) possui folhas com caracteristicas mesomorficas Poucas especies (9%) sao xerofilas como era esperado em florestas que crescem sob solo arenoso oligotrofico. As caracteristicas mesomorficas parecem estar associadas a eficientes mecanismos de ciclagem de nutrientes que compensam o baixo conteudo de nutrientes do solo mineral.

Salt stress alters the cell wall polysaccharides and anatomy of coffee (Coffea arabica L.) leaf cells.

Coffea arabica is the most important agricultural commodity in the world, and salinity is a major threat to its sustainable irrigation. Coffee leaf polysaccharides from plants subjected to salt stress were extracted and the leaves visualized through optical and electron microscopy. Alterations were detected in the monosaccharide composition of the pectin and hemicelluloses, with increases in uronic acid in all fractions. Changes in the polysaccharides were confirmed by HPSEC and FTIR. Moreover, the monolignol content was increased in the final residue, which suggests increased lignin content. The cytoplasm was altered, and the chloroplasts appeared irregular in shape. The arrangement of the stroma lamellae was disordered, and no starch granules were present. It was concluded that leaves of C. arabica under salt stress showed alterations in cell wall polysaccharides, increased monolignol content and structural damage to the cells of the mesophyll.

Efeitos da radiação ultravioleta-B sobre a morfologia foliar de Arabidopsis thaliana (L.) Heynh. (Brassicaceae)

Reduction of the ozone layer results in the increase in ultraviolet radiation reaching the earths surface, especially the ultraviolet-B (UV-B). The increase of radiation may induce structural and physiological changes in plants, influencing their growth and development. This paper evaluates the effects of ambient UV-B radiation upon to the leaf morphology of Arabidopsis thaliana developed under controlled conditions. The seeds of A. thaliana grown in environmental chamber, with 300 µmol m-2s-1 de photosynthetically active radiation (PAR) with and without 6 kJ m-2 s-1 of radiation UV-Bbe (UV-Bbe; UV-B biologically effective). After 21 days, ten leaves of each treatment (with and without UV-B radiation) were collected to measure leaf area, fresh and dry mass, AEF, stomata and trichome densities of both leaf surfaces, leaf thickness and concentration of phenolic compounds and total chlorophyll, and chlorophyll a and b. Leaves treated with UV-B radiation presented smaller leaf area, fresh and dry weight, hair density, and stomata density on the adaxial epidermis. However, leaves treated with UV-B presented higher mean values for total thickness, mesophyll thickness, higher concentration of total chlorophyll, chlorophyll a and b, and phenolic compounds when compared to leaves without UV-B radiation. These significant morphological differences (p < 0.05) between leaves treated with and without UV-B radiation indicate that A. thaliana is not insensible to UV-B radiation and possess mechanisms that minimize the negative effects on leaf development and growth. Although, the plant responses to UV-B radiation involves several physiological mechanisms, that need more detailed investigation.

Capacidade da Typha dominguensis na fitorremediação de efluentes de tanques de piscicultura na Bacia do Iraí - Paraná

Eutrophication is characterized by a process in which a water body acquires high levels of nutrients, especially phosphates and nitrates, resulting in organic matter accumulation with further decomposition. One of the alternatives for environmental descontamination is the use of phytoremediation. The objective of this investigation was to test the capacity of Typha dominguensis in reducing eutrophication in fish pond effluents. An experiment was installed at Canguiri Research Station, at the Federal University of Parana, using water from fish ponds. Typha dominguensis, being the test plant, was grown under five levels of N and P in factorial combination with six repetitions in an aerated closed system. After 160 days of cultivation, the plants were collected and evaluated for biomass production and nutrient extraction capacity. Roots were not considered for the chemical analysis. In the best treatment, a depuration rate in water of 87% for N and 54% for P was observed. This indicated a very promising potential of the species for these purposes.

Physiological aspects of sun and shade leaves of Lithraea molleoides (Vell.) Engl. (Anacardiaceae)

O presente trabalho teve como objetivo avaliar de forma comparativa alguns parâmetros fisiologicos de folhas de sol e de sombra de um especime de L. molleoides. Esta especie e conhecida popularmente como aroeira-branca. As folhas da porcao superior periferica, denominadas folhas de sol, apresentaram igual taxa fotossintetica, menores teores de clorofilas (a, b e totais), mesma razao clorofila a/ clorofila b, menor taxa transpiratoria, mesma condutância estomatica e concentracao intercelular de CO2 em relacao as folhas da porcao inferior interna, denominadas folhas de sombra. A concentracao de nutrientes, excetuando Ca e Mg, foi igual em folhas de sol e de sombra. As respostas dos parâmetros fisiologicos avaliados indicam que as folhas de sombra, apesar de receberem menor intensidade luminosa, tem possibilidade de crescer e se desenvolver com a mesma capacidade das folhas de sol.

Riqueza, estrutura e interações edáficas em um gradiente de restinga do Parque Estadual do Acaraí, Estado de Santa Catarina, Brasil

The present work characterized the flora and phytocommunities of a restinga gradient on the coast plain of Santa Catarina State and correlated them to edaphic attributes. The floristic survey followed the wide patrolling method and the community structure was determined through the plot method. Soil samples of each physiognomy were collected for analysis of macronutrients, organic matter, moisture, and litter thickness. Flora comprises 319 species, 244 of which occur exclusively in formations of herbaceous restinga (63), shrub restinga (32), shrub-tree restinga (46), and transition forest (103). The structural pattern of each restinga physiognomy studied was influenced by edaphic factors as organic matter, potassium, and aluminum contents, cation exchange capacity, and litter thickness. These attributes are determinant for the flora characterizing each phytocommunity.