Evaluación de parámetros morfoanatómicos foliares para la identificación de Rubus imperialis Cham. & Schltdl. (Rosaceae) en la Selva Montana de Tucumán, Argentina

Podazza, G. & M. G. Gallardo. 2007. “Evaluación de parámetros morfoanatómicos foliares para la identificación de Rubus imperialis Cham. & Schltdl. (Rosaceae) en la Selva Montana de Tucumán, Argentina”. Lilloa 44 (1-2). En la Selva Montana de Yungas del noroeste argentino (NOA), las especies silvestres Rubus boliviensis y R. imperialis, son citadas indistintamente, sugiriendo su coexistencia. Sería valioso contar con caracteres morfoanatómicos de la lámina foliar que permitan complementar las descripciones de la especie e identificar aquellos caracteres que presentan variaciones. En este trabajo se analizaron parámetros morfoanatómicos del tercio medio superior de láminas foliares pertenecientes a individuos provenientes de sitios ubicados a 700 y 1.100 msnm (Tucumán, Argentina). Dichos parámetros son: el espesor de tejidos y densidad y clasificación de tricomas y estomas, y la inversa del AFE (1/AFE, masa foliar específica en g.cm-2) La especie que se encuentra presente en Tucumán corresponde a R. imperialis y posee características anatómicas foliares específicas como presencia de cámara subestomática y vaina parenquimática alrededor del nervio medio. En los caracteres analizados a nivel foliar fue evidente que un incremento en altitud se manifiesta en un incremento en las superficies de asimilación fotosintética

Efectos de metales bivalentes en la germinación y desarrollo radicular de Chenopodium quinoa (Willd.)

Podazza, G., J. A. González y F. E. Prado. 2005. Efectos de metales bivalentes en la germinación y desarrollo radicular de Chenopodium quinoa (Willd.). Lilloa 42 (1-2). Se estudió el efecto de contaminantes metálicos bivalentes (Cu2+, Mn2+, Sr2+ y Co2+) sobre la germinación y elongación radicular en Chenopodium quinoa Willd., en concentraciones de 25, 50, 75, 100 ,150 y 200 mM. El análisis se realizó en las primeras 12 horas de germinación, tiempo en el cual la especie utilizada alcanza el máximo de germinación. Se observó que todos los iones ensayados reducen la germinación y elongación de la radícula dependiendo los resultados de la concentración y tipo de ión utilizado. El análisis estadístico detectó una correlación inversa negativa entre concentración y germinación/elongación para todos los contaminantes

Early interconnectivity between metabolic and defense events against oxidative stress induced by cadmium in roots of four citrus rootstocks

The effect of cadmium on roots of four citrus rootstocks was studied to assess the relationships between oxidative stress, carbohydrates, phenolics and antioxidant responses. Swingle citrumelo (SC), Rangpur lime (RL), Troyer citrange (TC) and Volkamer lemon (VL) genotypes were exposed to 0, 5 and 10μM Cd over 7 days, after which Cd accumulation was markedly higher in roots compared with stems and leaves. Malondialdehyde (MDA) and lipoxygenase (LOX) activity increased in Cd-treated SC and RL roots, suggesting that a lipid peroxidation is the main driver of plasma membrane damage. In contrast, in TC and VL genotypes, LOX-mediated lipid peroxidation does not appear to play a key role in Cd-induced lipid peroxidation, but H2O2 accumulation seems to be responsible of less plasma membrane damage. Catalase (CAT), superoxide dismutase (SOD) and guaiacol and syringaldazine peroxidases (G-POD and S-POD respectively) were differentially affected by Cd. Lipid profile and ATPase-dependant proton extrusion indicated higher disfunctionalities of root plasma membrane in SC and RL genotypes than in TC and VL genotypes. Differences in carbohydrates and phenolic compounds were also observed. Histochemical analysis of G-POD activity and lignin and suberin deposition revealed differences among genotypes. A model to explain the relationships among carbohydrates, soluble phenolics, lipid peroxidation and H2O2 accumulation in Cd-exposed roots was proposed.Fil: Podazza, Griselda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Ecología Vegetal; ArgentinaFil: Arias, Marta. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Biología. Cátedra de Anatomía Vegetal; ArgentinaFil: Prado, Fernando Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Biología. Cátedra de Anatomía Vegetal; Argentin

Soluble sugars—Metabolism, sensing and abiotic stress: A complex network in the life of plants

Plants are autotrophic and photosynthetic organisms that both produce and consume sugars. Soluble sugars are highly sensitive to environmental stresses, which act on the supply of carbohydrates from source organs to sink ones. Sucrose and hexoses both play dual functions in gene regulation as exemplified by the upregulation of growth-related genes and downregulation of stress-related genes. Although coordinately regulated by sugars, these growth- and stress-related genes are upregulated or downregulated through HXK-dependent and/or HXK-independent pathways. Sucrose-non-fermenting-1- (SNF1-) related protein pathway, analogue to the protein kinase (SNF-) yeast-signalling pathway, seems also involved in sugar sensing and transduction in plants. However, even if plants share with yeast some elements involved in sugar sensing, several aspects of sugar perception are likely to be peculiar to higher plants. In this paper, we have reviewed recent evidences how plants sense and respond to environmental factors through sugar-sensing mechanisms. However, we think that forward and reverse genetic analysis in combination with expression profiling must be continued to uncover many signalling components, and a full biochemical characterization of the signalling complexes will be required to determine specificity and cross-talk in abiotic stress signalling pathways

Cadmium induces changes in sucrose partitioning, invertase activities, and membrane functionality in roots of Rangpur Lime (Citrus limonia L. Osbeck)

Cadmium (Cd) uptake effects on sucrose content, invertase activities, and plasma membrane functionality were investigated in Rangpur lime roots (Citrus limonia L. Osbeck). Cadmium accumulation was significant in roots but not in shoots and leaves. Cadmium produced significant reduction in roots DW and increment in WC. Leaves and shoots did not show significant differences on both parameters. Sucrose content was higher in control roots than in Cd-exposed ones. Apoplastic sucrose content was much higher in Cd-exposed roots than in control ones. Cd-exposed roots showed a significant decrease in both cell wall-bound and cytoplasmic (neutral) invertase activities; while the vacuolar isoform did not show any change. Alterations in lipid composition and membrane fluidity of Cd-exposed roots were also observed. In Cd-exposed roots phospholipid and glycolipid contents decreased about 50%, while sterols content was reduced about 22%. Proton extrusion was inhibited by Cd. Lipid peroxidation and proton extrusion inhibition were also detected by histochemical analysis. This work findings demonstrate that Cd affects sucrose partitioning and invertase activities in apoplastic and symplastic regions in Rangpur lime roots as well as the plasma membrane functionality and H+-ATPase activity.Fil: Podazza, Griselda. Fundación Miguel Lillo. Dirección de Botánica. Instituto de Ecología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: Rosa, Mariana Daniela. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Cátedra de Fisiología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; ArgentinaFil: González, Juan Antonio. Fundación Miguel Lillo; ArgentinaFil: Hilal, Mirna Beatriz. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Cátedra de Fisiología Vegetal; ArgentinaFil: Prado, Fernando Eduardo. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Cátedra de Fisiología Vegetal; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin