Parenchyma Cells

Se realizó la caracterización anatómica de la pared de los culmos de Guadua aculeata Rupr., los especímenes fueron colectados en el predio “Las Margaritas” ubicado en el municipio de Hueytamalco, Puebla, México. El objetivo fue conocer la proporción de las estructuras anatómicas que componen el culmo y las dimensiones de las fibras, para contribuir al conocimiento de la especie. Se estudió la composición anatómica del culmo y se hizo la caracterización estructural de las fibras; en ambos casos se utilizaron cuatro culmos. Para la medición de las fibras, cada culmo se seccionó en tres partes de su longitud (inferior, medio y superior), de estas secciones se cortaron rodajas del entrenudo y cercanas al nudo. Se hicieron tres divisiones del interior al exterior de la pared del culmo en las rodajas (interna, media y externa). En la composición anatómica, la metodología fue similar a la caracterización de fibras hasta el corte de las rodajas del nudo y entrenudo. De estas se hicieron cor...

To examine anatomical adaptations in a potential forage grass, Imperata cylindrica (L.) Raeuschel, a population was collected from the natural salt-affected soils of the Salt Range, Pakistan. Using a hydroponic system, the degree of salt tolerance in terms of structural modifications in the Salt Range ecotype was compared with that in an ecotype collected from a normal non-saline habitat of the Faisalabad region. The Salt Range ecotype was superior to the Faisalabad ecotype in biomass production under saline conditions. High salt tolerance of the Salt Range ecotype was associated with increased succulence in root and leaf (mainly midrib), formation of aerenchyma in leaf sheath, increased vascular bundle area, metaxylem area and phloem area, highly developed bulliform cells on leaves and increased sclerification in root and leaf. Furthermore, both stomatal density and stomatal area were considerably reduced under high salinities in the Salt Range ecotype.

Under optimal growth conditions (120 µmol photons m−2 sec−1 photosynthetically active radiation (PAR), 16-h photoperiod), the recessive ozone-sensitive Arabidopsis thaliana L. Heynh. mutant lcd1-1 exhibits a pale phenotype compared to the wild type. Confocal and multiphoton microscopy revealed that the paleness of lcd1-1 is because of a lower cell density in the leaf palisade parenchyma, resulting in decreased chlorophyll content. When exposed to ozone, lcd1-1 leaves become paler and contain an increased amount of the lipid peroxidation product malondialdehyde compared to the wild type, suggesting that lcd1-1 suffers from elevated levels of reactive oxygen species (ROS) generated in the apoplast. Infection of leaves with virulent Pseudomonas syringae reveals higher bacterial growth as well as lower pathogenesis-related protein 1 (PR-1) and PR-5 expression in lcd1-1 than in the wild type. When the wild type and lcd1-1 are exposed to short-term high-light stress, leaves do not bleach in lcd1-1 and potential activities of photosystems I (PSI) and II (PSII) decrease to a similar extent in both the genotypes, indicating that the photosynthetic apparatus is not affected by lcd1-1 mutation. The LCD1 gene, found to contain a nonsense mutation in the mutant, has been identified. It is located at the bottom of chromosome 2 of the Arabidopsis genome. However, the function of the protein encoded by LCD1 is not yet known. We hypothesize that LCD1 plays a role in normal leaf development, and that the increased sensitivity to ozone and virulent P. syringae is a secondary effect that presumably results from the lower-cell-density phenotype in lcd1-1.

A study on the comparison of morpho-anatomical structure and DNA extract of sun and shade leaves of jute (Corchorus capsularis L.) was done. Morphological structure of exposed the Corchorus capsularis are taller, leaves are lighter, thicker, bigger and broader than shaded. Anatomical form of exposed jute have many stomata on the leaf, two layered palisade and compact spongy layer of leaf lamina, compact cells of the mesophyll of midrib, compact parenchyma cells of the cortex of the stem, and larger vacuole in the pith of the stem. While shaded jute has less stomata on the leaf, one layered palisade and loosely arranged cells in the spongy layer of leaf lamina, loosely arranged cells of the mesophyll of midrib, loosely arranged parenchyma cells of the cortex of the stem, and small vacuole in the pith of the stem. In terms of DNA extract, exposed leaves of jute (Corchorus capsularis L.) has more DNA extract than that of the shaded leaves. Thus, morpho-anatomical structure and DNA extract of exposed and shaded jute (Corchorus capsularis L.) differ.

Laguncularia racemosa wood is commonly used in north-western Mexico and harvested without the knowledge of whether environmental conditions affect wood quality. Laguncularia racemosa anatomy variation was evaluated to identify which cell features, mainly fibre features, are related to an environmental gradient and how this variation affects wood quality. Trees were sampled in six sites along the river where different flooding periods and levels occur. Analyses revealed that in sites with high salinity and flooding levels, there are more abundant vessels and axial parenchyma although the fibres and vessel elements are shorter, suggesting a water stress effect. Correlation analysis confirmed that the higher the percentage of gelatinous fibres, the longer the fibres. This occurred in L. racemosa trees growing in those sites with a high sand particle percentage and a lower flooding level. Anova (analysis of variance) revealed non-significant differences among sites for flexibility, rigidity and Peteri coefficients as well as for Runkel ratio, however the rigidity coefficient is affected by occurrence of gelatinous fibres. L. racemosa wood harvesting should avoid those sites with high flooding level, high sand particle percentage and high salinity that may modify wood quality.

Cinnamyl alcohol dehydrogenase (CAD) which catalyses the synthesis of the cinnamyl alcohols, the immediate precursors of lignins, from the corresponding cinnamaldehydes is considered to be a highly specific marker for lignification We have isolated and characterized a CAD genomic clone from eucalyptus, a woody species of economic importance. The full-length promoter (EuCAD, 2.5 kb) and a series of 5′ deletions were fused to the β-glucuronidase (GUS) reporter gene. These constructs were tested in a homologous transient expression system of eucalyptus protoplasts which enabled the identification of several regions involved in transcriptional control. In order to study the spatial and developmental regulation of the CAD gene, the chimeric gene fusion (EuCAD-GUS) was then transferred via Agrobacterium tumefaciens-mediated transformation into poplar, an easily transformable woody angiosperm. Quantitative fluorometric assays conducted on eight independent in vitro transformants showed that GUS activity was highest in roots followed thereafter by stems and leaves. Histochemical staining for GUS activity on both in vitro primary transformants and more mature greenhouse-grown plants indicated a specific expression in the vascular tissues of stems, roots, petioles and leaves. At the onset of xylem differentiation, GUS activity was detected in parenchyma cells differentiating between the xylem-conducting elements. After secondary growth has occurred, GUS activity was localized in xylem ray cells and parenchyma cells surrounding the lignified phloem and sclerenchyma fibers. This first characterization of a woody angiosperm CAD promoter provides functional evidence for the role of CAD in lignification and suggests that parenchyma cells expressing CAD may provide lignin precursors to the adjacent lignified elements (vessels and fibres).

Aquilaria produces fragrant wood known as ‘gaharu’ in its stem and branches, often in mature and damaged trees. In this study, anatomical characteristics in juvenile and mature trees were investigated by comparing their anatomical structures after various staining methods and direct observations under a light microscope. Juvenile and mature wood share similar anatomical structures. No major differences were observed other than the percentage of area covered by included phloem in juvenile was 2.16 times more than that of the mature wood. Microscopic observation revealed that in mature resinous wood, brownish bodies were found in ray and axial parenchyma, included phloem, xylem vessels and fibres, and this finding indicates that these are important elements for ‘gaharu’ depositing. Thus, it was concluded that juvenile tree possess the anatomical features of that of mature wood in producing ‘gaharu’.

The olive tree (Olea europaea L.), like many other woody plants, has a long juvenile period in which the plant is not able to produce flowers. Knowledge of the moment when the plant is capable of flowering is important for breeding programs and also for determining the physiological basis for sexual reproductive behavior, but currently the only indicator of that

Isoprene synthase (ISPS) catalyzes the formation of isoprene, an important volatile terpenoid with strong effects on global atmospheric chemistry and protective physiological functions in plant leaves. Many terpene synthase genes including isoprene synthase, a member of the TPS-b cluster of this numerous gene family, were already functionally analysed but much less is known about regulation of their promoters. To study regulation of the PcISPS gene in detail we developed transgenic Grey poplar (Populus × canescens) and Arabidopsis thaliana plants in which the PcISPS promoter is fused to enhanced green fluorescent protein (E-GFP) and β-glucuronidase (GUS) reporter genes. We analysed these reporters during plant development, for organ specificity and in plants subjected to different light and temperature regimes. We observed low promoter activity in non-isoprene emitting tissue like roots where ISPS gene is transcribed but no active enzyme is detectable. In leaves we demonstrate that light and temperature directly modulate ISPS promoter activity. Moreover, with confocal laser scanning microscopy we show a cell specific gradient of ISPS promoter activity within the leaf parenchyma depending on light direction. Our results indicate that ISPS promoter activity, which correlates with basal isoprene emission capacity, is not uniformly distributed within leaf tissue and that it can adapt rapidly towards internal as well as external environmental stimuli.