Leaf architecture and symmetry of understory tree species of anAraucaria forest / Arquitetura foliar e simetria de espécies do sub-bosque da floresta com Araucária

Shade plants of ombrophilous forests are subjected to light-limiting conditions and need toinvest in architectural structures associated with leaf symmetry to increase light capture. This study investigated the leaf architecture of six Araucaria forest tree species with distinct symmetry: Cupania vernalis, Casearia sylvestris, Schinus terebinthifolius, Piper gaudichaudianum, Roupala brasiliensis and Cedrela fissilis. We hypothesized that symmetry, associated with other traits, minimizes self-shading. Asymmetry index, petiole length, total leaf area, leaf angle, internode length and stem diameter were measured. The asymmetry index did not indicate a clear distinction between asymmetric and symmetric leaves. Leaves classified as asymmetric had higher values for the asymmetry index in the median and basal regions of the leaf, while symmetrical leaves had higher values in the apical region. The results also indicated an adjustment among structural leaf traits that facilitated a three-dimensional organization that produced an advantageous arrangement for light capture, which seems to be a response to selective pressure by the heterogeneous light conditions of the ombrophilous forest understory.

Nas florestas ombrófilas, as plantas de sombra estão sujeitas a condições limitantes de luz enecessitam investir em atributos estruturais associados à simetria foliar para maximizar a captura da luz. Esse estudo investigou a arquitetura foliar de seis espécies arbóreas (Cupania vernalis, Casearia sylvestris, Schinus terebinthifolius, Piper gaudichaudianum, Roupala brasiliensis e Cedrela fissilis) da Floresta com Araucária. Nossa hipótese é que a simetria foliar, associada a outros atributos foliares, minimiza o autosombreamento. Foram mensurados o índice de assimetria, o comprimento do pecíolo, a área foliar total, ângulo foliar, o comprimento do internó e o diâmetro do caule. O índice de assimetria não indicou uma distinção clara entre folhas assimétricas e simétricas. Folhas classificadas como assimétricas apresentaram maior índice na região mediana e basal da folha, enquanto as folhas simétricas apresentaram maior índice na região apical. Os resultados também indicaram um ajuste entre os atributos estruturais que permitiram um arranjo tridimensional das folhas vantajoso para a captura de luz, o que parece ser uma resposta à pressão seletiva pelas condições heterogêneas de luz do sub-bosque de floresta ombrófila.

Anthocyanin, bisabolol and phenylammonialyase activity in cell cultures of Populus deltoides.

Phenolics, anthocyanin and alpha-bisabolol production from poplar (Populus delotides) in tissue culture was determined. A number of phenolic acids were identified by HPLC. PAL activity in response to phytohormones, cells growth and anthocyanin production showed a positive correlation. A component, alpha-bisabolol, was identified using gas chromatography and UV spectroscopy. In vitro production of said metabolites was influenced by phytohormones.

Physiological variability arising from in vitro propagation of Nothofagus obliqua

As with cuttings, the microcuttings produced from in vitro generated shoots could be affected by topophysis. Very little research has been done about such in vitro effect. This paper reports the influence of the topophysis on the regeneration response (shoot multiplication, microcutting rooting and plantlet acclimation) of explants on the in vitro culture of juvenile N. obliqua trees. The results showed that the main responsible of the physiological variability arising from all the in vitro propagation stages is topophysis. This influence was found in the first culture and can be extended to the next subculture (multiplication stage). Growth of the obtained plants was also affected (rooting of microcuttings and plantlet acclimation). The multiplication rate was lower in apical portion (1:3.66) than basal portion (1:5.8) while rooting was 48.6 and 27.0 respectively. By the way, length of acclimated explants was 52.4 mm in the apical rooted explants and 28.7 mm in the basal ones at the 30th day. In order to reduce such variability, it is necessary to take into account the initial position of the explants during the establishment and multiplication stages of micropropagation of forest trees