Phenological indicators of resources offered to leaf herbivores in restinga communities.

Premise: Plants can limit the leaf tissue consumed by insect herbivores through chemical, structural, and nutritional leaf defenses or by escaping in space and time. Escaping is related to the phenological patterns of plants, which in turn respond to climatic factors. This study evaluated leaf production in a coastal plant community in southern Brazil to test the following hypotheses: (1) Leaves are continuously produced in this ecosystem, and (2) synchrony acts as an escape strategy from herbivory.

Interspecific variation in leaf pigments and nutrients of five tree species from a subtropical forest in southern Brazil.

The purpose of this study was to analyze the seasonal variation in the nutrient and pigment content of leaves from five tree species - of which three are perennial (Cupania vernalis, Matayba elaeagnoides and Nectandra lanceolata) and two are deciduous (Cedrela fissilis and Jacaranda micrantha) - in an ecotone between a Deciduous Seasonal Forest and a Mixed Ombrophilous Forest in the state of Santa Catarina, Brazil. Leaf samples were collected in the four seasons of the year to determine the content of macronutrients (N, K, P, Mg, Ca, S) and photosynthetic pigments (Chla, Chlb, Chltot, Cartot, Chla:Chlb and Cartot:Chltot). The principal component analysis showed that leaf pigments contributed to the formation of the first axis, which explains most of the data variance for all species, while leaf nutrient contribution showed strong interspecific variation.

Leaf morphological strategies of seedlings and saplings of Rhizophora mangle (Rhizophoraceae), Laguncularia racemosa (Combretaceae) and Avicennia schaueriana (Acanthaceae) from Southern Brazil.

The initial phase of a plant life cycle is a short and critical period, when individuals are more vulnerable to environmental factors. The morphological and anatomical study of seedlings and saplings leaf type enables the understanding of species strategies of fundamental importance in their establishment and survival. The objective of this study was to analyze the structure of seedlings and saplings leaf types of three mangrove species, Avicennia schaueriana, Laguncularia racemosa, Rhizophora mangle, to understand their early life adaptive strategies to the environment.

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.

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.

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.

Response of photosynthesis to high light and drought for Arabidopsis thaliana grown under a UV-B enhanced light regime.

Arabidopsis thaliana grown in a light regime that included ultraviolet-B (UV-B) radiation (6 kJ m(-2) d(-1)) had similar light-saturated photosynthetic rates but up to 50% lower stomatal conductance rates, as compared to plants grown without UV-B radiation. Growth responses of Arabidopsis to UV-B radiation included lower leaf area (25%) and biomass (10%) and higher UV-B absorbing compounds (30%) and chlorophyll content (52%). Lower stomatal conductance rates for plants grown with UV-B radiation were, in part, due to lower stomatal density on the adaxial surface.