Plant response to solar ultraviolet-B radiation in a southern South American Sphagnum peatland

1. Plant growth and pigmentation of the moss Sphagnum magellanicum and the vascular plants Empetrum rubrum, Nothofagus antarctica and Tetroncium magellanicum were measured under near-ambient (90% of ambient) and reduced (20%) ultraviolet-B (UV-B) radiation for three growing seasons in a Sphagnum peatland in Tierra del Fuego, Argentina (55°S). 2. Reduction of solar UV-B increased height growth but decreased volumetric density in S. magellanicum so that biomass production was not influenced during the 3 years. The morphology of vascular plants tended not to respond to UV-B reduction. 3. A 10-20% decrease in UV-B-absorbing compounds occurred in T. magellanicum under solar UV-B reduction. No effects were seen on chlorophyll or carotenoids in S. magellanicum, although, for UV-B-absorbing compounds, a significant interaction between UV-B and year suggests some response to solar UV-B reduction. 4. The climate-related growth of the dwarf shrub E. rubrum was assessed retrospectively by correlating an 8-year record of annual stem elongation with macroclimatic factors including solar UV-B and visible radiation, precipitation and temperature. 5. No significant negative correlations were found between annual E. rubrum stem elongation and ambient solar UV-B, the ratio of UV-B: visible radiation, or the 305-nm: 340-nm irradiance ratio for an 8-year record (1990-91 to 1997-98), nor was stem elongation affected by solar UV-B reduction in our experimental field plots after 3 years. 6. The role of solar UV-B radiation on plant growth in Sphagnum peatlands in Tierra del Fuego, Argentina, is likely to depend on the severity of stratospheric ozone depletion over the next several decades. The increases in ambient solar UV-B associated with ozone depletion over the last 20 years are less than the difference between our radiation treatments. Therefore, providing that the ozone layer substantially recovers by the middle of this century, only modest effects of increased solar UV-B on plant growth may be expected.Fil: Searles, Peter Stoughton. State University of Utah; Estados UnidosFil: Flint, Stephan D.. State University of Utah; Estados UnidosFil: Diaz, Susana Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Rousseaux, Maria Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Ballare, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Caldwell, Martyn M.. State University of Utah; Estados Unido

Linking phytochrome to plant immunity: low red : far-red ratios increase Arabidopsis susceptibility to Botrytis cinerea by reducing the biosynthesis of indolic glucosinolates and camalexin

Shade-intolerant plants respond to low red : far-red (R : FR) ratios, which signal the proximity of potential competitors, by down-regulating immune responses. Here we investigated the mechanisms underlying this immune suppression in Arabidopsis. We used genetic, transcriptomic and metabolomic approaches to examine the functional connections between R : FR ratio and Arabidopsis resistance to the fungus Botrytis cinerea. Low R : FR ratios reduced the concentration of indol-3-ylmethyl glucosinolate (I3M) (an indolic glucosinolate, iGS) and camalexin in plants inoculated with B. cinerea, and attenuated the I3M response triggered by jasmonate elicitation. These effects on metabolite abundance correlated with reduced expression of iGS and camalexin biosynthetic genes. Furthermore, the effect of low R : FR increasing Arabidopsis susceptibility to B. cinerea was not present in mutants deficient in the biosynthesis of camalexin (pad3) or metabolism of iGS (pen2). Finally, in a mutant deficient in the JASMONATE ZIM DOMAIN-10 (JAZ10) protein, which does not respond to low R : FR with increased susceptibility to B. cinerea, supplemental FR failed to down-regulate iGS production. These results indicate that suppression of Arabidopsis immunity against B. cinerea by low R : FR ratios is mediated by reduced levels of Trp-derived defenses, and provide further evidence for a functional role of JAZ10 in the link between phytochrome and jasmonate signaling.Fil: Cargnel, Miriam D.. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Demkura, Patricia Verónica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Ballare, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico La Plata. Instituto de Investigaciones Biotecnológicas - Instituto Tecnológico Chascomús. Instituto de Investigaciones Biotecnológicas (sede Chascomús); Argentin

The shade-avoidance syndrome: Multiple signals and ecological consequences

Plants use photoreceptor proteins to detect the proximity of other plants and to activate adaptive responses. Of these photoreceptors, phytochrome B (phyB), which is sensitive to changes in the red (R) to far-red (FR) ratio of sunlight, is the one that has been studied in greatest detail. The molecular connections between the proximity signal (low R:FR) and a model physiological response (increased elongation growth) have now been mapped in considerable detail in Arabidopsis seedlings. We briefly review our current understanding of these connections and discuss recent progress in establishing the roles of other photoreceptors in regulating growth-related pathways in response to competition cues. We also consider processes other than elongation that are controlled by photoreceptors and contribute to plant fitness under variable light conditions, including photoresponses that optimize the utilization of soil resources. In examining recent advances in the field, we highlight emerging roles of phyB as a major modulator of hormones related to plant immunity, in particular salicylic acid and jasmonic acid (JA). Recent attempts to manipulate connections between light signals and defence in Arabidopsis suggest that it might be possible to improve crop health at high planting densities by targeting links between phyB and JA signalling.Fil: Ballare, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Biotecnológicas. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas; ArgentinaFil: Pierik, Ronald. Utrecht University; Países Bajo

Control of Plant Growth and Defense by Photoreceptors: From Mechanisms to Opportunities in Agriculture

Plants detect and respond to the proximity of competitors using light signals perceived by photoreceptor proteins. A low ratio of red to far-red radiation (R:FR ratio) is a key signal of competition that is sensed by the photoreceptor phytochrome B (phyB). Low R:FR ratios increase the synthesis of growth-related hormones, including auxin and gibberellins, promoting stem elongation and other shade-avoidance responses. Other photoreceptors that help plants to optimize their developmental configuration and resource allocation patterns in the canopy include blue light photoreceptors, such as cryptochromes and phototropins, and UV receptors, such as UVR8. All photoreceptors act by directly or indirectly controlling the activity of two major regulatory nodes for growth and development: the COP1/SPA ubiquitin E3 ligase complex and the PIF transcription factors. phyB is also an important modulator of hormonal pathways that regulate plant defense against herbivores and pathogens, including the jasmonic acid signaling pathway. In this Perspective, we discuss recent advances on the studies of the mechanisms that link photoreceptors with growth and defense. Understanding these mechanisms is important to provide a functional platform for breeding programs aimed at improving plant productivity, stress tolerance, and crop health in species of agronomic interest, and to manipulate the light environments in protected agriculture.Fil: Pierik, Ronald. University of Utrecht; Países BajosFil: Ballare, Carlos Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Universidad Nacional de San Martín. Instituto de Investigaciones Biotecnológicas. - Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Biotecnológicas; Argentin

Analisi tecnico-economica e tecnica di gestione di hub energetici ibridi situati offshore

La tesi ha lo scopo di sviluppare software di supporto alla gestione di sistemi in isola e connessi alla rete che prevedono la produzione di energia elettrica da fonti rinnovabili. -Ottimizzazione del sistema in isola. -Ottimizzazione del sistema connesso alla rete. -Dimensionamento del sistema in isola. -Dimensionamento del sistema connesso alla rete

Plant photomorphogenesis and canopy growth

An important motivation for studying photomorphogenesis is to understand the relationships among plant photophysiology in canopies, canopy productivity, and agronomic yield. This understanding is essential to optimize lighting systems used for plant farming in controlled environments (CE) and for the design of genetically engineered crop strains with altered photoresponses. This article provides an overview of some basic principles of plant photomorphogenesis in canopies and discusses their implications for (1) scaling up information on plant photophysiology from individual plants in CE to whole canopies in the field, and (2) designing lighting conditions to increase plant productivity in CE used for agronomic purposes (e.g. space farming in CE Life Support Systems). We concentrate on the visible (lambda between 400 and 700 nm) and far-infrared (FR; lambda greater than 700 nm) spectral regions, since the ultraviolet (UV; 280 to 400 nm) is covered by other authors in this volume

The Gsα gene: Predominant maternal origin of transcription in human thyroid gland and gonads

Mutations in the guanine nucleotide binding α-subunit 1 gene (GNAS1) cause Albright's hereditary osteodistrophy, and the parent of transmission determines variable phenotypic expression of the disease. This has suggested that GNAS1 may be under tissue-specific imprinting control, although studies so far available have failed to clearly define the pattern of GNAS1 expression in humans. To establish if GNAS1 is imprinted in human endocrine tissues, we selected 14 thyroid, 10 granulosa cell, 13 pituitary (3 normal glands, 7 GH-secreting adenomas, and 3 nonfunctioning adenomas), 3 adrenal, and 11 lymphocyte samples shown to be heterozygous for a known polymorphism in exon 5. RNA from these tissues was analyzed by RT-PCR, and expression from both parental alleles was evaluated by enzymatic digestion and subsequent quantification of the resulting fragments. The parental origin of Gsα was assessed by evaluating neuroendocrine secretory protein 55 and extra large αs-like protein transcripts, which have been shown to be monoallelically and parent-specifically expressed from the maternal and paternal allele, respectively. By this approach, the great majority of thyroid (n = 12), ovarian (n = 7), and pituitary (n = 11) samples showed an almost exclusive or significantly predominant expression of the maternal allele over the paternal one, whereas in lymphocyte and adrenal samples both alleles were equally expressed. Our results provide evidence for a predominant maternal origin of GNAS1 transcripts in different human adult endocrine tissues, particularly thyroid, ovary, and pituitary, and strongly suggest that this mechanism may play a crucial role in the determination of the phenotypic expression of Albright's hereditary osteodistrophy

Auxin-mediated plant architectural changes in response to shade and high temperature.

The remarkable plasticity of their architecture allows plants to adjust growth to the environment and to overcome adverse conditions. Two examples of environmental stresses that drastically affect shoot development are imminent shade and high temperature. Plants in crowded environments and plants in elevated ambient temperature display very similar phenotypic adaptations of elongated hypocotyls in seedlings and elevated and elongated leaves at later developmental stages. The comparable growth responses to shade and high temperature are partly regulated through shared signaling pathways, of which the phytohormone auxin and the phytochrome interacting factors (PIFs) are important components. During both shade- and temperature-induced elongation growth auxin biosynthesis and signaling are upregulated in a PIF-dependent manner. In this review we will discuss recent progress in our understanding of how auxin mediates architectural adaptations to shade and high temperature

Progesterone Receptor induces bcl-x expression through intragenic binding sites favoring RNA Polymerase II elongation

Steroid receptors were classically described for regulating transcription by binding to target gene promoters. However, genome-wide studies reveal that steroid receptors-binding sites are mainly located at intragenic regions. To determine the role of these sites, we examined the effect of pro- gestins on the transcription of the bcl-x gene, where only intragenic progesterone receptor-binding sites (PRbs) were identified. We found that in response to hormone treatment, the PR is recruited to these sites along with two histone acetyltransferases CREB-binding protein (CBP) and GCN5, leading to an increase in histone H3 and H4 acetylation and to the binding of the SWI/SNF complex. Concomitant, a more relaxed chromatin was detected along bcl-x gene mainly in the regions sur- rounding the intragenic PRbs. PR also mediated the recruitment of the positive elongation factor pTEFb, favoring RNA polymerase II (Pol II) elongation activity. Together these events promoted the re-dis- tribution of the active Pol II toward the 30-end of the gene and a decrease in the ratio between proximal and distal transcription. These results suggest a novel mechanism by which PR regulates gene ex- pression by facilitating the proper passage of the polymerase along hormone-dependent genes.Fil: Bertucci, Paola Yanina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Nacht, Ana Silvina. Universitat Pompeu Fabra; España. Centro de Regulación Genómica; EspañaFil: Alló, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; ArgentinaFil: Rocha Viegas, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; ArgentinaFil: Ballaré, Cecilia. Universitat Pompeu Fabra; España. Centro de Regulación Genómica; EspañaFil: Soronellas, Daniel. Centro de Regulación Genómica; España. Universitat Pompeu Fabra; EspañaFil: Castellano, Giancarlo. Centro de Regulación Genómica; España. Universitat Pompeu Fabra; EspañaFil: Zaurin, Roser. Centro de Regulación Genómica; España. Universitat Pompeu Fabra; EspañaFil: Kornblihtt, Alberto Rodolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Fisiología, Biología Molecular y Celular; ArgentinaFil: Beato, Miguel. Centro de Regulación Genómica; España. Universitat Pompeu Fabra; EspañaFil: Vicent, Guillermo. Centro de Regulación Genómica; España. Universitat Pompeu Fabra; EspañaFil: Pecci, Adali. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Fisiología, Biología Molecular y Neurociencias; Argentin

Scale‐dependent effects of host patch traits on species composition in a stickleback parasite metacommunity

A core goal of ecology is to understand the abiotic and biotic variables that regulate species distributions and community composition. A major obstacle is that the rules governing species distributions can change with spatial scale. Here, we illustrate this point using data from a spatially nested metacommunity of parasites infecting a metapopulation of threespine stickleback fish from 34 lakes on Vancouver Island, British Columbia. Like most parasite metacommunities, the composition of stickleback parasites differs among host individuals within each host population, and differs between host populations. The distribution of each parasite taxon depends, to varying degrees, on individual host traits (e.g., mass, diet) and on host‐population characteristics (e.g., lake size, mean host mass, mean diet). However, in most cases in this data set, a given parasite was regulated by different factors at the host‐individual and host‐population scales, leading to scale‐dependent patterns of parasite‐species co‐occurrence