Monitoring of indoor bioaerosol for the detection of SARS-CoV-2 in different hospital settings.

Background: Spore Trap is an environmental detection technology, already used in the field of allergology to monitor the presence and composition of potentially inspirable airborne micronic bioparticulate. This device is potentially suitable for environmental monitoring of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) in hospital, as well as in other high-risk closed environments. The aim of the present study is to investigate the accuracy of the Spore Trap system in detecting SARS-CoV-2 in indoor bioaerosol of hospital rooms.

Exposure to different light intensities affects emission of volatiles and accumulations of both pigments and phenolics in Azolla filiculoides.

Many agronomic trials demonstrated the nitrogen-fixing ability of the ferns Azolla spp. and its obligate cyanobiont Trichormus azollae. In this study, we have screened the emission of volatile organic compounds (VOCs) and analyzed pigments (chlorophylls, carotenoids) as well as phenolic compounds in Azolla filiculoides-T.

Light and Temperature Shape the Phenylpropanoid Profile of Fronds.

is a genus of floating freshwater ferns. By their high growth and N fixation rates, species have been exploited for centuries by populations of South-east Asia as biofertilizers in rice paddies. The use of species as a sustainable plant material for diverse applications, such as feeding, biofuel production, and bioremediation, has encountered a growing interest over the last few years.

Salicylic acid induced by herbivore feeding antagonizes jasmonic acid mediated plant defenses against insect attack.

We recently reported the transcriptomic signature of salicylic acid (SA) and jasmonic acid (JA) biosynthetic and responsive genes in plants infested with the herbivore . We demonstrated that insect feeding causes induction of both SA- and JA-mediated signaling pathways. Using transgenic SA-deficient plants, we also showed antagonistic cross-talk between these two phytohormones.

Role of chemical cues in cabbage stink bug host plant selection.

The cabbage stink bugs of the genus Eurydema, encompassing several oligophagous species, such as Eurydema oleracea (L.), are known to be important pests of cabbage, broccoli, and other cole crops in Europe. Despite their economic importance, the knowledge regarding the role of chemical cues in host plant selection of these species is very limited.

Drought stress induces a biphasic NO accumulation in Arabidopsis thaliana.

We have recently reported the proteomic signature of the early (≤30 min) drought stress responses in Arabidopsis thaliana suspension cells challenged with PEG. We found an over-representation in the gene ontology categories "Ribosome" and "Oxidative stress along with an increased abundance of late embryogenesis abundant (LEA) and early response to dehydration (ERD) proteins. Since nitric oxide (NO) plays a pivotal role in plant responses to drought stress and induces LEA and DREB proteins, here we monitored the levels of NO in Arabidopsis cell suspensions and leaf disks challenged with PEG, and performed comparative analyses of the proteomics and transcriptomics data in public domain to search for a common set of early drought and NO responsive proteins.

An Arabidopsis thaliana leucine-rich repeat protein harbors an adenylyl cyclase catalytic center and affects responses to pathogens.

Adenylyl cyclases (ACs) catalyze the formation of the second messenger cAMP from ATP. Here we report the characterization of an Arabidopsis thaliana leucine-rich repeat (LRR) protein (At3g14460; AtLRRAC1) as an adenylyl cyclase. Using an AC-specific search motif supported by computational assessments of protein models we identify an AC catalytic center within the N-terminus and demonstrate that AtLRRAC1 can generate cAMP in vitro.

Jasmonate-mediated defence responses, unlike salicylate-mediated responses, are involved in the recovery of grapevine from bois noir disease.

Background: Bois noir is an important disease of grapevine (Vitis vinifera L.), caused by phytoplasmas. An interesting, yet elusive aspect of the bois noir disease is "recovery", i.

Infestation of Broad Bean () by the Green Stink Bug () Decreases Shoot Abscisic Acid Contents under Well-Watered and Drought Conditions.

The response of broad bean () plants to water stress alone and in combination with green stink bug () infestation was investigated through measurement of: (1) leaf gas exchange; (2) plant hormone titres of abscisic acid (ABA) and its metabolites, and of salicylic acid (SA); and (3) hydrogen peroxide (HO) content. Furthermore, we evaluated the effects of experimentally water-stressed broad-bean plants on performance in terms of adult host-plant preference, and nymph growth and survival. Water stress significantly reduced both photosynthesis () and stomatal conductance ( ), while infestation by the green stink bug had no effects on photosynthesis but significantly altered partitioning of ABA between roots and shoots.

Arabidopsis flower specific defense gene expression patterns affect resistance to pathogens.

We investigated whether the Arabidopsis flower evolved protective measures to increase reproductive success. Firstly, analyses of available transcriptome data show that the most highly expressed transcripts in the closed sepal (stage 12) are enriched in genes with roles in responses to chemical stimuli and cellular metabolic processes. At stage 15, there is enrichment in transcripts with a role in responses to biotic stimuli.

Cyclic mononucleotides modulate potassium and calcium flux responses to H2O2 in Arabidopsis roots.

Cyclic mononucleotides are messengers in plant stress responses. Here we show that hydrogen peroxide (H2O2) induces rapid net K(+)-efflux and Ca(2+)-influx in Arabidopsis roots. Pre-treatment with either 10μM cAMP or cGMP for 1 or 24h does significantly reduce net K(+)-leakage and Ca(2+)-influx, and in the case of the K(+)-fluxes, the cell permeant cyclic mononucleotides are more effective.

Proteomic signatures implicate cAMP in light and temperature responses in Arabidopsis thaliana.

Unlabelled: The second messenger 3'-5'-cyclic adenosine monophosphate (cAMP) and adenylyl cyclases (ACs), enzymes that catalyse the formation of cAMP from ATP, are increasingly recognized as important signaling molecules in a number of physiological responses in higher plants. Here we used proteomics to identify cAMP-dependent protein signatures in Arabidopsis thaliana and identify a number of differentially expressed proteins with a role in light- and temperature-dependent responses, notably photosystem II subunit P-1, plasma membrane associated cation-binding protein and chaperonin 60 β. Based on these proteomics results we conclude that, much like in cyanobacteria, algae and fungi, cAMP may have a role in light signaling and the regulation of photosynthesis as well as responses to temperature and we speculate that ACs could act as light and/or temperature sensors in higher plants.

The Arabidopsis thaliana cysteine-rich receptor-like kinase CRK20 modulates host responses to Pseudomonas syringae pv. tomato DC3000 infection.

In plants, the cysteine-rich repeat kinases (CRKs) are a sub-family of receptor-like protein kinases that contain the DUF26 motif in their extracellular domains. It has been shown that in Arabidopsis thaliana, CRK20 is transcriptionally induced by pathogens, salicylic acid and ozone (O(3)). However, its role in responses to biotic and abiotic stress remains to be elucidated.

Ozone affects pollen viability and NAD(P)H oxidase release from Ambrosia artemisiifolia pollen.

Air pollution is frequently proposed as a cause of the increased incidence of allergy in industrialised countries. We investigated the impact of ozone (O(3)) on reactive oxygen species (ROS) and allergen content of ragweed pollen (Ambrosia artemisiifolia). Pollen was exposed to acute O(3) fumigation, with analysis of pollen viability, ROS and nitric oxide (NO) content, activity of nicotinamide adenine dinucleotide phosphate (NAD[P]H) oxidase, and expression of major allergens.

Morphological and cytological development and starch accumulation in hermaphrodite and staminate flowers of olive (Olea europaea L.).

In olive (Olea europaea L.), the formation of functionally staminate flowers rather than fully functional hermaphrodites is one of the major factors limiting fruit set, as flowers with aborted pistils are incapable of producing fruit. Studies conducted on various angiosperm species have shown a correlation between flower abortion and starch content.

Deciphering cGMP signatures and cGMP-dependent pathways in plant defence.

The second messenger, 3′,5′-cyclic monophosphate (cGMP), is a critical component of many different processes in plants while guanylyl cyclases that catalyse the formation of cGMP from GTP have remained somewhat elusive in higher plants. Consequently, two major aims are the discovery of novel GCs and the identification of cGMP mediated processes. Recently, we have reported temporal signatures of ozone (O)-induced hydrogen peroxide (HO) and nitric oxide (NO) generation, their effect on cGMP generation, and consequent transcriptional changes of genes diagnostic for stress responses in tobacco.

Ozone and nitric oxide induce cGMP-dependent and -independent transcription of defence genes in tobacco.

Here, we analyse the temporal signatures of ozone (O3)-induced hydrogen peroxide(H2O2) and nitric oxide (NO) and the role of the second messenger guanosine3′,5′-cyclic monophosphate (cGMP) in transcriptional changes of genes diagnostic for biotic and abiotic stress responses. Within 90 min O3 induced H2O2 and NO peaks and we demonstrate that NO donors cause rapid H2O2 accumulation in tobacco (Nicotiana tabacum) leaf. Ozone also causes highly significant, late (> 2 h) and sustained cGMP increases, suggesting that the second messenger may not be required in all early (< 2 h) responses to O3,but is essential and sufficient for the induction of some O3-dependent pathways.

NO release by nitric oxide donors in vitro and in planta.

Artificial nitric oxide (NO) donors are widely used as tools to study the role of NO in plants. However, reliable and reproducible characterisation of metabolic responses induced by different NO donors is complicated by the variability of their NO release characteristics. The latter are affected by different physical and biological factors including temperature and light.

cGMP in ozone and NO dependent responses.

We have recently reported that ozone (O(3)) can inhibit mitochondrial respiration and induce activation of the alternative oxidase (AOX) pathway and in particular AOX1a in tobacco. While O(3) causes mitochondrial H(2)O(2), early leaf nitric oxide (NO) as well as transient ethylene (ET) accumulation, the levels of jasmonic acid and 12-oxo-phytodienoic acid remained unchanged. It was shown that both, NO and ET dependent pathways can induce AOX1a transcription by O(3).

The overexpression of an alternative oxidase gene triggers ozone sensitivity in tobacco plants.

The alternative oxidase (AOX) of plant mitochondria transfers electrons from the ubiquinione pool to oxygen without energy conservation and prevents the formation of reactive oxygen species (ROS) when the ubiquinone pool is over-reduced. Thus, AOX may be involved in plant acclimation to a number of oxidative stresses. To test this hypothesis, we exposed wild-type (WT) Xanthi tobacco plants as well as Xanthi plants transformed with the Bright Yellow tobacco AOX1a cDNA with enhanced (SN21 and SN29), and decreased (SN10) AOX capacity to an acute ozone (O3) fumigation.

The tomato ethylene receptor LE-ETR3 (NR) is not involved in mediating ozone sensitivity: causal relationships among ethylene emission, oxidative burst and tissue damage.

The causal relationships among ethylene emission, oxidative burst and tissue damage, and the temporal expression patterns of some ethylene biosynthetic and responsive genes, were examined in the Never ripe (Nr) tomato (Lycopersicon esculentum) mutant and its isogenic wild type (cv. Pearson), to investigate the role played by the ethylene receptor LE-ETR3 (NR) in mediating the plant response to ozone (O(3)). Tomato plants were used in a time-course experiment in which they were exposed to acute O(3) fumigation with 200 nl l(-1) O(3) for 4 h.

Interaction between nitric oxide and ethylene in the induction of alternative oxidase in ozone-treated tobacco plants.

The higher plant mitochondrial electron transport chain contains, in addition to the cytochrome chain, an alternative pathway that terminates with a single homodimeric protein, the alternative oxidase (AOX). We recorded temporary inhibition of cytochrome capacity respiration and activation of AOX pathway capacity in tobacco plants (Nicotiana tabacum L. cv BelW3) fumigated with ozone (O(3)).

Gene expression profiles of O3-treated Arabidopsis plants.

To analyse cellular response to O(3), the tolerant Arabidopsis thaliana genotype Col-0 was exposed to O(3) fumigation (300 ppb) for 6 h and the modulation of gene expression during the treatment (3 h after the beginning of the treatment, T3 h) and the recovery phase (6 h from the end of the treatment, T12 h) assessed by gene chip microarray and real-time reverse transcriptase (RT)-PCR analyses. The Arabidopsis transcriptional profile is complex, as new genes (i.e.

Isoprene decreases the concentration of nitric oxide in leaves exposed to elevated ozone.

Isoprene reduces visible damage (necrosis) of leaves caused by exposure to ozone but the mechanism is not known. Here we show that in Phragmites leaves isoprene emission was stimulated after a 3-h exposure to high ozone levels. The photosynthetic apparatus of leaves in which isoprene emission was inhibited by fosmidomycin became more susceptible to damage by ozone than in isoprene-emitting leaves.