Study of the role of the DOF transcription factor DAG1 in the control of seedling development in Arabidopsis thaliana

Seedling development relies on environmental conditions; indeed, once seeds have germinated, they undergo photomorphogenesis or skotomorphogenesis, depending on the presence or absence of light. Photomorphogenesis is a multi-traits process characterised by inhibition of hypocotyl elongation, open and expanded cotyledons, and chloroplast development, whereas skotomorphogenesis is characterised by long hypocotyls and small unfolded cotyledons. Hypocotyl elongation is influenced by both environmental and hormonal cues and it has been extensively studied as a model for cell expansion. Nevertheless, the molecular network underlying this process is not yet fully elucidated. The Arabidopsis Dof protein DAG1 (Dof Affecting Germination1) is a repressor of seed germination, and a key player of the seed-to seedling transition, a crucial developmental phase positively controlled by light, as well as by the phytohormones ABA (abscissic acid) and GA (gibberellins). Indeed, DAG1 controls the ratio of ABA and GA, which play opposite roles, as ABA represses germination whereas GAs promote it. We have previously shown that inactivation of DAG1 affects inhibition of hypocotyl elongation. Indeed, light-grown dag1 mutant seedlings show significant shorter hypocotyls compared to the wild-type, suggesting that DAG1 is a negative component of this light-mediated process. To gain some insight into the molecular network in which DAG1 is involved, we have analysed the transcriptome profile of both dag1 and wild-type hypocotyls and seedlings. We have identified more than 250 genes that are differentially expressed in dag1 hypocotyls, and the analysis of this data suggests that DAG1 is mainly involved in promoting hypocotyl elongation. In addition, a number of the DE genes identified are correlated to the response to ABA stimulus. ABA plays a role in inhibition of hypocotyl elongation, although the molecular mechanism remains unclear. Therefore, we investigated the effect of ABA on hypocotyl development, and our results showed that ABA negatively controls cell expansion in hypocotyls, by acting on GA metabolism, and repressing auxin biosynthesis. Consistently, addition of exogenous ABA can revert the hypocotyl phenotype of dag1 mutant seedlings. In conclusion, our results prove that DAG1 is likely to be an element of a molecular network which controls cell expansion by modulating hormonal response, namely auxin, ABA and GAs

Panoramica delle applicazioni GIS al CRS4

2006-11-22Sardegna Ricerche, Edificio 2, Località Piscinamanna 09010 Pula (CA) - ItaliaGis Day 2006: dal Gis al Geo-We

A user friendly multi-catchments tool for the SWAT model

A software system to manage SWAT results (bsb.dbf and rch.dbf) has been developed on a multi catchment scale. Regions such as Sardinia, Sicily, Portugal etc are, in fact, characterized by a large variety of ecosystems within complex catchments. The AVS2000 interface deals with one watershed at a time, but the aggregation of SWAT results about adjacent basins may be necessary for an integrated water resources management. To achieve this goal, an ArcView extension, called multi-catch.avx, has been developed. The extension allows the user to select the subbasins within the basins under investigation and obtain statistical reports of the model output, from the rch and bsb tables, in the form of charts, statistics and maps. The tool helps water managers in the demanding problem of water management by automating the post processing operation when dealing with many catchments within a region. Multi-catch.avx uses the bsb and rch files of all the projects and dynamically permits making time and spatial analysis at the widest scale and creating maps in the ArcView environment. A project view is created where all the watersheds under study are displayed along with their subbasins. The user can dynamically visualize and analyse the spatial distribution of a chosen model output for all the active subbasins within the given basin, at a monthly or yearly time resolution. Moreover the bsb file of each project is aggregated to represent the whole basin under study and statistical indicators such as mean, standard deviation etc. are calculated. The newly developed ArcView extension has been utilized to map, and analyze 15 Swat projects within the Sardinian Region.153-15

Host cell wall damage during pathogen infection: mechanisms of perception and role in plant-pathogen interactions

The plant cell wall (CW) is a complex structure that acts as a mechanical barrier, restricting the access to most microbes. Phytopathogenic microorganisms can deploy an arsenal of CWdegrading enzymes (CWDEs) that are required for virulence. In turn, plants have evolved proteins able to inhibit the activity of specific microbial CWDEs, reducing CW damage and favoring the accumulation of CW-derived fragments that act as damage-associated molecular patterns (DAMPs) and trigger an immune response in the host. CW-derived DAMPs might be a component of the complex system of surveillance of CW integrity (CWI), that plants have evolved to detect changes in CW properties. Microbial CWDEs can activate the plant CWI maintenance system and induce compensatory responses to reinforce CWs during infection. Recent evidence indicates that the CWI surveillance system interacts in a complex way with the innate immune system to fine-tune downstream responses and strike a balance between defense and growth

Sistema informativo per l'individuazione di zone a rischio ambientale in un'area a sud della Sardegna

Il presente studio si inquadra nel più vasto progetto europeo del CRS4 ADAPT VISION. Esso prevede la realizzazione di un prototipo di sistema informativo territoriale che consenta di verificare se l'azione antropica, nell'area scelta per lo studio, ha determinato una trasformazione dell'ambiente dal punto di vista idrogeologico e forestale. L'area oggetto di studio si trova a cavallo dei comuni di Pula e Domus De Maria in Provincia di Cagliari (sud Sardegna). Tale area è caratterizzata da 3 zone differenti dal punto di vista morfologico, idrogeologico e forestale ma da una situazione analoga dal punto di vista vincolistico. La zona costiera e’ caratterizzata da un’alta concentrazione di insediamenti turistici. Lo studio ambientale dell'area ha messo in evidenza che l'aspetto predominante è il rischio di erosione; è stato quindi inserito nel sistema un modello empirico di individuazione di zone a rischio. Nella zona costiera ci si è preoccupati di verificare la possibilità di intrusione salina nelle acque sotterranee attraverso la misura della conducibilità elettrica in alcuni pozzi opportunamente scelti. Per verificare lo stato di salute della vegetazione sono state effettuate, in ognuna delle tre zone, misure dendrometriche. Inoltre, per la zona residenziale è stata prodotta una mappa di rischio di evacuazione, ottenuta tenendo conto dello stato della viabilità e della distribuzione della popolazione.The present study is part of CRS4’s European Project “ADAPT VISION”, and its purpose is to develop a GIS-based prototype that allows the user to evaluate the consequences of human activities on the landscape. The study area is located in the South-Western coast of Sardinia and it consists of three zones that are characterizated by the same legislative restriction, but that differ in morphology, hydrography and land use. An empirical model has been applied to the whole area in order to define erosion risk zones; in situ conductivity measurements in coastal wells have been taken to check the presence of saltwater intrusion; a spatial evacuation model has been used to achieve an escape route vulnerability map for the edified zone

Variable sediment oxygen uptake in response to dynamic forcing

Seiche-induced turbulence and the vertical distribution of dissolved oxygen above and within the sediment were analyzed to evaluate the sediment oxygen uptake rate (JO2), diffusive boundary layer thickness (δDBL), and sediment oxic zone depth (zmax) in situ. High temporal-resolution microprofiles across the sediment-water interface and current velocity data within the bottom boundary layer in a medium-sized mesotrophic lake were obtained during a 12-h field study. We resolved the dynamic forcing of a full 8-h seiche cycle and evaluated JO2 from both sides of the sediment-water interface. Turbulence (characterized by the energy dissipation rate, ε), the vertical distribution of dissolved oxygen across the sediment-water interface (characterized by δDBL and zmax), JO2, and the sediment oxygen consumption rate (RO2) are all strongly correlated in our freshwater system. Seiche-induced turbulence shifted from relatively active (ε = 1.2 × 10-8 W kg-1) to inactive (ε = 7.8 × 10-12 W kg-1). In response to this dynamic forcing, δDBL increased from 1.0 mm to the point of becoming undefined, zmax decreased from 2.2 to 0.3 mm as oxygen was depleted from the sediment, and JO2 decreased from 7.0 to 1.1 mmol m-2 d-1 over a time span of hours. JO2 and oxygen consumption were found to be almost equivalent (within ~ 5% and thus close to steady state), with RO2 adjusting rapidly to changes in JO2. Our results reveal the transient nature of sediment oxygen uptake and the importance of accurately characterizing turbulence when estimating JO2

A Decision Support System based on the SWAT model for the Sardinian Water Authorities

Sardinian Regional Authorities, such as Assessorato della Difesa dell’Ambiente, have the demanding problem of water management and protection. Targeted to their specific needs they use alternative applications and models for their specific tasks. Black box models, in the past, have been the most commonly used approach to describe the hydrological cycle. Despite their wide use, these models have shown severe limitations to take into account land use and climate changes. Physically based models can make better prediction when different combination of soil and land use, within the basin, have a significant effect on the hydrological cycle. The variety and complexity of alternative environmental problems found in the island, which vary from the impact of the agro-zootechnical to the industrial compartment, have suggested that empirical models are less suitable to predict the environmental dynamics at the catchment’s scale. Regional Authorities enact Regional Directives to enforce different European Directives, and no absolute limits can be drawn to separate their alternative field of application. The Piano di Tutela delle Acque Regional Directives aim to enforce water policy in terms of definition on where and how water resources must be used and what water protection actions need to be taken to improve water quality of rivers, lagoons, groundwater, lakes etc.. In this context, the hydrological physically based SWAT model has been chosen and applied to estimate both the water balance of the main catchments of the island and the impact of land management practices on downstream water bodies. The performance of the model has been evaluated on several stream flow monitoring gages against registered data.The study has been partially funded by the Sardinian Regional Authorities.369-37

Studio di un S.I. per la gestione delle emergenze in seguito a eventi calamitosi in Sardegna

La simulazione di situazioni di rischio derivanti da eventi calamitosi estesi è necessaria al fine di individuare le più rapide vie di accesso all'area colpita da parte dei mezzi e delle squadre di soccorso a terra e di indicare alle autorità preposte le vie di fuga ed evacuazione rapida delle persone verso zone sicure. Vi sono però alcune tipologie di incidenti, come ad esempio gli incendi o le emissioni tossiche, per le quali risulta difficoltoso stabilire a priori strategie generali di intervento, a causa della dipendenza da una moltitudine di fattori determinabili solo al momento dell'evento. In questi casi, un importante contributo allo studio di scenari di rischio può essere dato dall'impiego di modelli di evacuazione che forniscano una base preliminare, svincolata da eventi specifici, tesa a evidenziare le zone più critiche in funzione della distribuzione della popolazione e delle caratteristiche delle infrastrutture. Viene presentato un caso di studio relativo all'area industriale di Predda Niedda (Sassari).The simulation of disasters arising from hazardous events is necessary in order to identify the fastest access routes to the affected zones and to provide indications on the possible safety routes. However, there are several types of accidents, such as firestorms or toxic spills, for which the a priori definition of general emergency strategies appears problematic, due to dependence on many factors which can be assessed only at the time of the event. In such cases, an important support in the analysis of accident scenarios can be given by the use of community evacuation models independent of any hazard or zone, which can be employed to identify the spatial variation in evacuation difficulty taking into account only the distribution of the population and the existing infrastructure. The model described has been applied to a case study for the industrial area of Predda Niedda (Sassari)