Factors Structuring the Epiphytic Archaeal and Fungal Communities in a Semi-arid Mediterranean Ecosystem

The phyllosphere microbiome exerts a strong effect on plants’ productivity, and its composition is determined by various factors. To date, most phyllosphere studies have focused on bacteria, while fungi and especially archaea have been overlooked. We studied the effects of plant host and season on the abundance and diversity of the epiphytic archaeal and fungal communities in a typical semi-arid Mediterranean ecosystem. We collected leaves in two largely contrasting seasons (summer and winter) from eight perennial species of varying attributes which could be grouped into the following: (i) high-canopy, evergreen sclerophyllοus shrubs with leathery leaves, and low-canopy, either semi-deciduous shrubs or non-woody perennials with non-leathery leaves, and (ii) aromatic and non-aromatic plants. We determined the abundance of epiphytic Crenarchaea, total fungi, Alternaria and Cladosporium (main airborne fungi) via q-PCR and the structure of the epiphytic archaeal and fungal communities via amplicon sequencing. We observed a strong seasonal effect with all microbial groups examined showing higher abundance in summer. Plant host and season were equally important determinants of the composition of the fungal community consisted mostly of Ascomycota, with Hypocreales dominating in winter and Capnodiales and Pleosporales in summer. In contrast, the archaeal community showed plant host driven patterns dominated by the Soil Crenarchaeotic Group (SCG) and Aenigmarchaeota. Plant habit and aromatic nature exhibited filtering effects only on the epiphytic fungal communities. Our study provides a first in-depth analysis of the key determinants shaping the phyllosphere archaeal and fungal communities of a semi-arid Mediterranean ecosystem. © 2021, The Author(s), under exclusive licence to Springer Science+Business Media, LLC part of Springer Nature

Sweet cherry fruit cracking: follow-up testing methods and cultivar-metabolic screening

Background Rain-induced fruit cracking is a major physiological problem in most sweet cherry cultivars. For an in vivo cracking assay, the ‘Christensen method’ (cracking evaluation following fruit immersion in water) is commonly used; however, this test does not adequately simulate environmental conditions. Herein, we have designed and evaluated a cracking protocol, named ‘Waterfall method’, in which fruits are continuously wetted under controlled conditions. Results The application of this method alone, or in combination with ‘Christensen method, was shown to be a reliable approach to characterize sweet cherry cracking behavior. Seventeen cherry cultivars were tested for their cracking behavior using both protocols, and primary as well as secondary metabolites identification was performed in skin tissue using a combined GC–MS and UPLC-MS/MS platform. Significant variations of some of the detected metabolites were discovered and important cracking index–metabolite correlations were identified. Conclusions We have established an alternative/complementary method of cherry cracking characterization alongside to Christiansen assay

Organizational Behavior, Decision Making and Virtual Simulations in Military Personnel

The aim of this study is to make a brief review of the research on Human Behavior Models (HBMs) in military simulations. The need to represent the behavior of individual combatants as well as teams and larger organizations is expanding as a result of increasing use of simulations for training, systems analysis, mission rehearsal, systems acquisition, joint force analysis and command decision aiding. Both for training and command decision aiding, the behaviors that are important to represent realistically are those that can be observed by the other participants in the simulation, including physical movement, detection and identification of enemy forces, as well as the aspects of behavior influenced by the cultural background, such as Beliefs, Desires and Intents. Innovative technologies provide opportunities to train the required skills in an interactive and realistic setting, for this reason are needed adequate models that generate the behavior of virtual players. Areas of modelling human behaviors are combat field situations and situations of high risk decision making, teamwork, culturally and emotionally affected behavior. In this paper we provide an overview of current research on human behavior models in military simulation, in order to be used to train military forces, develop force structures and design weapon systems. Implications for further research are made

Underexpression of apoplastic polyamine oxidase improves thermotolerance in Nicotiana tabacum

Polyamines (PAs) and hydrogen peroxide (H2O2), the product of PA oxidation by polyamine oxidase (PAO), are potential players affecting plant growth, development and responses to abiotic/biotic stresses. Genetically modified Nicotiana tabacum plants with altered PA/H2O2 homeostasis due to over/underexpression of the ZmPAO gene (S-ZmPAO/AS-ZmPAO, respectively) were assessed under heat stress (HS). Underexpression of ZmPAO correlates with increased thermotolerance of the photosynthetic machinery and improved biomass accumulation, accompanied by enhanced levels of the enzymatic and non-enzymatic antioxidants, whereas ZmPAO overexpressors exhibit significant impairment of thermotolerance. These data provide important clues on PA catabolism/H2O2/thermotolerance, which merit further exploitation. © 201

The relationship between the chemical composition of three essential oils and their insecticidal activity against Acanthoscelides obtectus (Say)

The chemical composition of the essential oils isolated from various parts of three Greek aromatic plants (Lavandula hybrida Rev, Rosmarinus officinalis L and Eucalyptus globulus Labill) collected at different seasons was determined by GC/MS analysis. The insecticidal action of these oils and of their main constituents on Acanthoscelides obtectus (Say) adults was evaluated and their LC50 values were estimated. All essential oils tested exhibited strong activity against A obtectus adults, with varying LC50 values depending on insect sex and the composition of the essential oils. A correlation between total oxygenated monoterpenoid content and activity was observed, with oxygenated compounds exhibiting higher activity than hydrocarbons. Among the main constituents, only linalyl and terpinyl acetate were not active against A obtectus, while all the others exhibited insecticidal activity against both male and female adults, with LC50 values ranging from 0.8 to 47.1 mg litre(-1) air. An attempt to correlate the insecticidal activity to the monoterpenoid's structure is presented, and the difference in sensitivity between male and female individuals is also explored. (C) 2004 Society of Chemical Industr

Deregulation of apoplastic polyamine oxidase affects development and salt response of tobacco plants

Polyamine (PA) homeostasis is associated with plant development, growth and responses to biotic/abiotic stresses. Apoplastic PA oxidase (PAO) catalyzes the oxidation of PAs contributing to cellular homeostasis of reactive oxygen species (ROS) and PAs. In tobacco, PAs decrease with plant age, while apoplastic PAO activity increases. Our previous results with young transgenic tobacco plants with enhanced/reduced apoplastic PAO activity (S-ZmPAO/AS-ZmPAO, respectively) established the importance of apoplastic PAO in controlling tolerance to short-term salt stress. However, it remains unclear if the apoplastic PAO pathway is important for salt tolerance at later stages of plant development. In this work, we examined whether apoplastic PAO controls also plant development and tolerance of adult plants during long-term salt stress. The AS-ZmPAO plants contained higher Ca2+ during salt stress, showing also reduced chlorophyll content index (CCI), leaf area and biomass but taller phenotype compared to the wild-type plants during salt. On the contrary, the S-ZmPAO had more leaves with slightly greater size compared to the AS-ZmPAO and higher antioxidant genes/enzyme activities. Accumulation of proline in the roots was evident at prolonged stress and correlated negatively with PAO deregulation as did the transcripts of genes mediating ethylene biosynthesis. In contrast to the strong effect of apoplastic PAO to salt tolerance in young plants described previously, the effect it exerts at later stages of development is rather moderate. However, the different phenotypes observed in plants deregulating PAO reinforce the view that apoplastic PAO exerts multifaceted roles on plant growth and stress responses. Our data suggest that deregulation of the apoplastic PAO can be further examined as a potential approach to breed plants with enhanced/reduced tolerance to abiotic stress with minimal associated trade-offs. © 2017 Elsevier Gmb

Coated Cu-doped ZnO and Cu nanoparticles as control agents against plant pathogenic fungi and nematodes

In the current study, coated copper nanoparticles with polyethylene glycol 8000 (Cu@PEG NPs) and copper-doped zinc oxide nanoparticles with diethylene glycol (Cu-doped ZnO@DEG NPs) have been synthesized via solvothermal and microwave-assisted process, physicochemical characterized, and studied as nano-fungicides and nano-nematicides. Spheroidal Cu-doped ZnO@DEG NPs and urchin-like Cu@PEG NPs have been isolated with average crystallite sizes of 12 and 21 nm, respectively. The Cu doping (11.3 wt%) in ZnO lattice (88.7 wt%) was investigated by Rietveld refinement analysis and confirmed by X-ray Diffraction (XRD) and X-ray Photoelectron Spectroscopy (XPS). The Cu-doped ZnO@DEG and Cu@PEG NPs revealed a growth inhibition of fungi Botrytis cinerea (B. cinerea) and Sclerotinia sclerotiorum (S. sclerotiorum) and nematode paralysis of Meloidogyne javanica in a dose-dependent manner. Cu-doped ZnO@DEG NPs were more effective against M. javanica (EC50 = 2.60 μg/mL) than the Cu@PEG NPs (EC50 = 25 μg/mL). In contrast, the antifungal activity was approximately similar for both NPs, with EC50 values at 310 and 327 μg/mL against B. cinerea, respectively, and 260 and 278 μg/mL against S. sclerotiorum, respectively. Lettuce (Lactuca sativa) plants were inoculated with S. sclerotiorum or M. javanica and sprayed with either Cu-doped ZnO@DEG NPs or Cu@PEG NPs. The antifungal effect was evaluated based on a disease index (DI), and nematicidal activity was assessed based on the total number of galls and nematode females per root gram. NPs successfully inhibited the growth of both pathogens without causing phytotoxicity on lettuce. The DI were significantly decreased as compared to the positive control (DI = 5.2), estimated equal to 1.7, 2.9 and 2.5 for Cu@PEG NPs, Cu-doped ZnO@DEG NPs and the chemical control (KOCIDE 2000), respectively. The reduction in galling and population of M. javanica ranged from 39.32% to 32.29%, statistically like chemical control. The treatment of lettuce plants with Cu-doped ZnO@DEG NPs increased the leaf net photosynthetic value at 4.60 and 6.66 μmol CO2−2 s−1 in plants inoculated with S. sclerotiorum and M. javanica, respectively, as compared to the control (3.00 μmol CO2−2 s−1). The antioxidant capacity of NPs treated lettuce plants was evaluated as 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity in leaf extracts. Plants inoculated with S. sclerotiorum and sprayed with Cu-doped ZnO@DEG and Cu@PEG NPs, exhibited a 34.22% and 32.70% increase in antioxidant capacity, respectively, higher than the control. Similarly, an increase in antioxidant capacity was measured (39.49 and 37.36%) in lettuce inoculated with M. javanica and treated with Cu-doped ZnO@DEG and Cu@PEG NPs, respectively. Moreover, an increase of phenolic compounds in lettuce leaf tissue treated with NPs was measured as compared to the control. Overall, foliar applied Cu and Cu-doped ZnO NPs could be a promising tool to control phytopathogenic fungi and nematodes contributing to sustainability of agri-food sector

Proteomic and metabolic analysis reveals novel sweet cherry fruit development regulatory points influenced by girdling

Despite the application of girdling technique for several centuries, its impact on the metabolic shifts that underly fruit biology remains fragmentary. To characterize the influence of girdling on sweet cherry (Prunus avium L.) fruit development and ripening, second-year-old shoots of the cultivars ‘Lapins’ and ‘Skeena’ were girdled before full blossom. Fruit characteristics were evaluated across six developmental stages (S), from green-small fruit (stage S1) to full ripe stage (stage S6). In both cultivars, girdling significantly altered the fruit ripening physiognomy. Time course fruit metabolomic along with proteomic approaches unraveled common and cultivar-specific responses to girdling. Notably, several primary and secondary metabolites, such as soluble sugars (glucose, trehalose), alcohol (mannitol), phenolic compounds (rutin, naringenin-7-O-glucoside), including anthocyanins (cyanidin-3-O-rutinoside, cyanidin-3-O-galactoside, cyanidin-3.5-O-diglucoside) were accumulated by girdling, while various amino acids (glycine, threonine, asparagine) were decreased in both cultivars. Proteins predominantly associated with ribosome, DNA repair and recombination, chromosome, membrane trafficking, RNA transport, oxidative phosphorylation, and redox homeostasis were depressed in fruits of both girdled cultivars. This study provides the first system-wide datasets concerning metabolomic and proteomic changes in girdled fruits, which reveal that shoot girdling may induce long-term changes in sweet cherry metabolis

Metabolic mechanisms underpinning vegetative bud dormancy release and shoot development in sweet cherry

Few studies have focused on the metabolic characterization of bud dormancy and shoot growth in temperate fruit species, although this is an intresting framework to anticipate adaptation in global climate changes. To examine this issue, two experimental approaches were applied, using sweet cherry (Prunus avium L. cv ‘Grace Star’) bud and shoot tissues. Initially, annual shoots containing vegetative buds that collected at endodormancy and ecodormancy stages were used to compare changes in shoots- and buds-specific metabolic profiles under chamber-controlled conditions. Detailed analysis suggested that primary metabolites, such as arabitol, fucitol and tryptophan were modified in buds from endo- to eco-dormancy. Differences between buds and shoots metabolic fingerprints were also found in various secondary metabolites, including quercetin, glucosides and osmotic-associated metabolites. In order to investigate the mechanism underlying shoot developmental during bud dormancy break, metabolic analysis was also conducted in annual shoots, that were sampled at five distinct bud-related vegetative stages from ecodormancy to fully developed leaf stage under natural orchard conditions. Several amino acids (ornithine, alanine, isoleucine, GABA, asparagine and tryptophan) and classes of secondary metabolites, including anthocyanidins (peonidin-3-O-galactoside), flavonoids (apigenin, isorhamnetin, chrysin and trilobatin) and lignin-related compounds (sinapyl and coniferyl alcohols) were altered across developmental stages. Additionally, nutrient homeostasis was altered during shoot development, as N, P, Ca, Mg, B steady-state level as well as Ca/Mg + K and N/P stoichiometry were significantly changed. This study provides a bud- and shoot-based metabolic framework at different conditions and dormancy stages, thereby helps to understand dormancy release and bud-break in temperate fruit trees. © 2018 Elsevier B.V