Seasonal circulation over the Catalan inner-shelf (northwest Mediterranean Sea)

This study characterizes the seasonal cycle of the Catalan inner-shelf circulation using observations and complementary numerical results. The relation between seasonal circulation and forcing mechanisms is explored through the depth-averaged momentum balance, for the period between May 2010 and April 2011, when velocity observations were partially available. The monthly-mean along-shelf flow is mainly controlled by the along-shelf pressure gradient and by surface and bottom stresses. During summer, fall, and winter, the along-shelf momentum balance is dominated by the barotropic pressure gradient and local winds. During spring, both wind stress and pressure gradient act in the same direction and are compensated by bottom stress. In the cross-shelf direction the dominant forces are in geostrophic balance, consistent with dynamic altimetry data. Key Points A hydrodynamic model is implemented for the first time in Catalan inner-shelf. Frictional and pressure gradient are revealed as the main forcing mechanisms A clear seasonal pattern is found in the current velocity.Peer ReviewedPostprint (published version

From perception to execution: Elucidation of signaling components that link initial MTI activation to local and systemic immunity in Arabidopsis

In order to resist pathogens plants have evolved so‐called pattern recognition receptors (PRR) for early detection of microbe‐associated molecular patterns (MAMPs). Binding of these molecules to their cognate PRR leads to the activation of plant immunity (MTI). Recently, it has been shown that accumulation and function of the PRR EFR that recognizes the bacterial elongation factor (EF)‐Tu epitope elf18, is dependent on functional endoplasmic reticulum (ER)‐resident glucosidase II (GII). A weakly dysfunctional gIIa allele, designated rsw3, is impaired in late and sustained activation of defense‐related genes, despite wild‐type like early defense activation upon elf18 treatment. Nevertheless, rsw3 plants exhibit a super‐susceptible phenotype towards Pseudomonas syringae pv. tomato and fail to induce EFR‐mediated resistance. Those findings indicate the significance of sustained MTI activation for robust defence execution. However, the mechanism linking initial MAMP detection to robust and sustained immune activation remains elusive. A whole genome transcript analysis revealed a group of genes which failed to be induced in rsw3 at 10 hours post treatment with elf18. In silico analysis provided evidence for those genes to be directly involved in defense execution in the presence of pathogens. Among those genes we identified PBS3. Analysis of pbs3 plants exhibited a similar phenotype as rsw3 plants showing impairment in sustained elf18‐triggered transcriptional reprogramming, pointing to an important role of the PBS3 enzyme and its catalysed products during EFR‐mediated immunity. In addition, EFR‐induced sustained PROPEP2 and PROPEP3 up‐regulation could not be maintained in rsw3 plants. Those genes encode for two putative precursor proteins of endogenous elicitor peptides in Arabidopsis. The Leu‐rich repeat receptor kinases PEPR1 and PEPR2 recognize the Pep‐epitopes, triggering immune outputs which are reminiscent of MAMP responses. Those findings suggest that the Pep/PEPR pathway acts as an amplifying machinery of MTI. In this respect, sustained induction of PROPEP2 and PROPEP3 upon elf18‐elicitation might represent a mechanism of linking initial MAMP signaling activation to robust immunity. Here we show that basal defense against hemibiotrophic pathogens as well as the generation of SAR is compromised in pepr1 pepr2 plants, providing evidence for a role of this signaling system in plant immunity. By analyzing genome‐wide transcriptional changes, we obtained commonalities and differences between EFR‐ and PEPR‐regulated genes and pathways. Our data indicate that Pep/PEPR signaling activation facilitates co‐activation of typically antagonizing salicylate and jasmonate pathways, consistent with a role of PEPRs for defenses against hemibiotrophic pathogens. Interestingly, the expression of PROPEP2 and PROPEP3 is predominantly detectable at local challenged sites during SAR, pointing to a role of the Pep/PEPR pathway in the generation of systemic immune signals. In sum, the data presented in this work uncover possible novel mechanism linking MTI activation to defense execution and reveal new insights into the function of the PEPR signaling pathway during basal defense and SAR

Genetic analysis of MAMP-triggered immunity in Arabidopsis

In their natural environment, plants live in a close association with a large variety of microorganisms. A number of these microorganisms can be detrimental to plants and are considered as potential pathogens. In order to ward off these pathogens, plants have developed a highly effective and dynamic immune system. As a first line of defense, plants recognize the presence of microbes through the perception of molecular structures typical of a microbial class, termed microbe-associated molecular patterns (MAMPs). In Arabidopsis, the Leu-rich repeat receptor-like kinases FLS2 and EFR recognize the bacterial MAMPs flagellin and EF-Tu (and their bioactive epitopes flg22 and elf18), respectively. Perception of these MAMPs triggers defense responses that restrict microbial invasion and growth. However, the molecular basis of MAMP-triggered immunity (MTI) is still largely unknown. As MTI functionally links to and provides an evolutionary basis for different branches of plant immunity, it is instrumental for the understanding of plant-microbe interactions. The work presented here aimed at the identification of molecular components of MTI. A forward-genetic screen revealed priority in sweet life (psl) mutants that show de-repressed anthocyanin accumulation in the presence of elf18 or flg22. PSL2 was identified as the single-copy Arabidopsis UDP-glucose:glycoprotein glucosyltranseferase (UGGT), whereas PSL25 most likely identifies the Arabidopsis endoplasmic reticulum (ER) Glucosidase I. These are components of an ER protein quality control (ERQC) pathway that ensures proper folding and maturation of membrane-resident and secreted proteins. These and other ERQC components are required for the generation of functional EFR. PSL36 was identified as a novel allele of EIN2 (ETHYLENE INSENSITIVE2), a central regulator of the ethylene(ET) pathway. Loss of EIN2 function results in pronounced defects in FLS2 and EFR signaling outputs. Whereas ET signaling is crucial for FLS2 expression, EFR steady-state levels are unaltered in ein2 plants. These data point to a role for ET in post-recognition signaling by EFR. The identification of a set of EFR-triggered genes that depend on ET-signaling for their full activation reveals possible mechanisms of signal integration during MTI

Possibility of achieving organic yields for medicinal and aromatic plants by biofertilization with azotobacter chroococcum

The aim of this study was to examine the effects of management practices and biofertilization on microbial activity in rhizosphere and yield of medicinal and aromatic plants. Field experiment was performed using four plant species: peppermint (Mentha x piperita L.), pot marigold (Calendula officinalis L.), sweet basil (Ocimum basilicum L.), and dill (Anethum graveolens L.). Treatments were arranged in a split-plot layout in four replicates using basic plots under conventional and organic management, and subplots with and without biofertilizer (Azotobacter chroococcum). Organic management positively affected the microbial number and activity. Biofertilization increased the total microbial number (13-21%), number of ammonifiers (13-60%), nitrogen-fixing bacteria (7-36%), actinomycetes (36-50%), fungi (60-100%), celluloly tic microorganisms (57-217%), dehydrogenase (28-52%) and beta-glucosidase activity (15-39%). The effects of management practices and biofertilization were highly significant for the yield of examined plants. The yields were higher on inoculated treatments both in conventional (5-26%) and organic (7-15%) growing system

The rissaga of 15 June 2006 in Ciutadella (Menorca), a meteorological tsunami

An extraordinary "rissaga" event (the local name for high-amplitude sea level oscillations) with 4–5 m of amplitude occurred on 15 June 2006 at Ciutadella (Menorca, Spain). In this paper we describe the rissaga event and propose that the meteorological mechanism responsible for it was an unusual pressure jump, associated with a convective squall line

Mikrobiološka aktivnost zemljišta u konvencionalnoj i organskoj proizvodnji pasulja i kukuruza

The objective of this study was to compare the effects of conventional and organic production system on microbial activity in the soil cultivated with bean and maize crops. The trial in Đurđevo was set up according to the conventional farming system, while organic farming system was used in Futog. Two maize hybrids and two bean cultivars were used in the trial. Soil samples were collected in two periods during 2014 (before sowing, at flowering stage of bean crops, and at 9-11 leaf stage of maize) at two depths, at both locations. The following microbiological parameters were tested: the total number of micro­organisms, number of ammonifiers, Azotobacter sp., free nitrogen fixing bacteria, fungi, actinomycetes, and activity of dehydrogenase enzyme. The results showed that the total number of microorganisms, number of free N-fixers and dehydrogenase activity were high­er within organic production, while Azotobacter sp. was more abundant in conventional production. Variations in the number of ammonifiers, fungi and actinomycetes in relation to the type of production were not obtained. Significant differences in microbial activity were also obtained between period and depths of sampling.Cilj ovih istraživanja bio je da se uporede efekti konvencionalnog i organskog sistema gajenja na mikrobiološku aktivnost u zemljištu koje je pod pasuljem i kukuruzom kao usevima. Ogled u Đurđevu postavljen je u sistemu konvencionalne poljoprivredne proizvodnje, a ogled u Futogu u sistemu organske proizvodnje. U ogledima su korišćena dva hibrida kukuruza i dve sorte pasulja Instituta za ratarstvo i povrtarstvo u Novom Sadu. Uzorci zemljišta za mikrobiološke analize uzeti su tokom 2014. godine (pre setve i u fazi cvetanja pasulja, kao i u fazi 9-11 listova kukuruza), sa dve dubine, na oba lokaliteta. Mikrobiološka aktivnost praćena je na osnovu zastupljenosti ukupnog broja mikroorganizama, amonifikatora, Azotobacter sp., slobodnih azotofiksatora, gljiva, aktinomiceta i aktivnosti enzima dehidrogenaze. Rezultati su pokazali da su ukupan broj mikroorganizama, broj slobodnih azotofiksatora i dehidrogenazna aktiv­nost bili veći u sistemu organske proizvodnje, dok su vrste iz roda Azotobacter sp. bile zastupljenije u sistemu konvencionalne proizvodnje. Nisu zabeležene razlike u brojnosti amonifikatora, gljiva i aktinomiceta u zavisnosti od sistema gajenja. Takođe, značajne razlike u mikrobiološkoj aktivnosti utvrđene su između perioda i dubine uzorkovanja