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

Lemon maturation causes anatomical and biochemical changes at the flavedo tissue level

Plants mobilize the photosynthates by three transport pathways: apoplastic, symplastic through plasmodesmata (PD), and transcellular. In flavedo of postharvest mature lemons, a high activity of cell wall-bound invertase (WI), an enzyme associated with transcellular transport of monosaccharides, has been detected. In order to elucidate whether this high enzymatic activity is related to restricted transport in the symplastic pathway with fruit maturation, the aim of the present work was to compare anatomical and biochemical parameters in peel tissues of immature and mature lemons. Anatomical structure focusing on cell walls, callose deposition, WI activity, and sucrose content were analyzed in peel tissues of immature and mature lemons. The parenchyma of flavedo tissue of immature lemons presented an elevated number of primary pit fields (PPF). These PPF, associated to PD or cell wall interruptions, had the appearance of a string of beads. However, in mature lemons, the number of PPF was scarce due to callose deposition. WI activity and apoplastic sucrose content increased significantly in flavedo of mature lemons in comparison to immature lemons. Present findings lay structural and functional bases relevant to understand differences between immature and mature lemons, which would help to design agricultural practices in pre- and post-harvest management.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Lemon maturation causes anatomical and biochemical changes at the flavedo tissue level

Plants mobilize photosynthates by three transport pathways: apoplastic, symplastic through plasmodesmata (PD), and transcellular. In the flavedo of post-harvest mature lemons, a high level of activity of cell wall-bound invertase (WI), an enzyme associated with transcellular transport of monosaccharides, has been detected. To elucidate whether this high enzymatic activity is related to restricted transport in the symplastic pathway with fruit maturation, the aim of the present work was to compare anatomical and biochemical parameters in peel tissues of immature and mature lemons. Anatomical structure of cell walls, callose deposition, WI activity, and sucrose content were analyzed in peel tissues of immature and mature lemons. The parenchyma of the flavedo tissue of immature lemons presented an elevated number of primary pit fields (PPF). These PPF, associated with PD or cell wall interruptions, had the appearance of a string of beads; however, in mature lemons, the number of PPF was scarce due to callose deposition. WI activity and apoplastic sucrose content increased significantly in the flavedo of mature lemons compared to immature lemons. The present findings lay structural and functional bases relevant to understanding differences between immature and mature lemons, which would help to design agricultural practices in pre-and post-harvest management.Fil: Albornoz, Patricia Liliana. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Departamento de Biología. Cátedra de Anatomía Vegetal; Argentina. Instituto de Morfologia Vegetal ; Direccion de Botanica ; Fundacion Miguel Lillo;Fil: Interdonato, Osvaldo Roque. Universidad Nacional de Tucumán. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Cátedra de Fisiología Vegetal; ArgentinaFil: Hammann, Ariadna. Universidad Nacional de Catamarca. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Rosa, Mariana Daniela. Universidad Nacional de Tucumán. Instituto de Bioprospección y Fisiología Vegetal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Bioprospección y Fisiología Vegetal; ArgentinaFil: Prado, Fernando Eduardo. Universidad Nacional de Tucumán. Instituto de Bioprospección y Fisiología Vegetal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Bioprospección y Fisiología Vegetal; ArgentinaFil: Rapisarda, Viviana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentina. Universidad Nacional de Tucumán. Facultad de Bioquímica, Química y Farmacia. Instituto de Química Biológica; ArgentinaFil: Hilal, Mirna Beatriz. Universidad Nacional de Tucumán. Instituto de Bioprospección y Fisiología Vegetal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Noa Sur. Instituto de Bioprospección y Fisiología Vegetal; Argentina. Universidad Nacional de Catamarca. Facultad de Ciencias Exactas y Naturales; Argentin

Short-term UV-B exposure induces metabolic and anatomical changes in peel of harvested lemons contributing in fruit protection against green mold

UV-B radiation (UVBR) is a small fraction of the solar spectrum from 280 to 315 nm. UVBR produces photomorphogenic acclimation responses in plants, modulating their cellular structure and physiology. Here, changes in the peel of harvested lemons after short time exposure to UVBR were analyzed and its potential effects against fungal infection were studied. In the flavedo, UVBR treatment induced variations in the respiratory profiles and increased the phenolic compound contents. Final products of the flavonoid pathway (flavones, flavonols and anthocyanins) increased more markedly than their precursors (flavanones and dihydroflavonols). The increased accumulation of soluble phenolics in the flavedo of treated lemons is associated with the high antioxidant activity found in the flavedo of these samples. Supporting the biochemical determinations, anatomical observations showed abundant intravacuolar deposits of phenolic compounds and an increase in the cell wall thickness in UVBR-treated samples. Metabolic and anatomical modifications associated to UVBR improved natural defenses against Penicillium digitatum, the causal agent of green mold disease. Our results suggest that mature postharvest lemons exposed to the artificial radiation showed phenotypic plasticity, allowing an acclimation response to UVBR which confers fruit resistance to pathogens. Thus, combination of UVBR with other treatments could represent an important improvement to control postharvest diseases on citrus.Fil: Ruiz, Verónica Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Interdonato, Osvaldo Roque. Universidad Nacional de Tucumán. Facultad de Agronomía y Zootecnia; ArgentinaFil: Cerioni, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Albornoz, Patricia Liliana. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; ArgentinaFil: Ramallo, J.. Laboratorio de Desarrollo e Investigación; ArgentinaFil: Prado, Fernando Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; ArgentinaFil: Hilal, Mirna Beatriz. Universidad Nacional de Tucuman. Facultad de Ciencias Naturales e Instituto Miguel Lillo. Instituto Miguel Lillo; ArgentinaFil: Rapisarda, Viviana Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; Argentin