A Study Of Blue Mould Of Tobacco Caused By Peronospora Hyoscyami Fsp Tabacina

Temperature, humidity, carbon dioxide and light play a key role in the viability of conidia of Peronospora hyoscyami f.sp. tabacina.;Conidia lodge in the depressions between the epidermal cells above the anticlinal walls, and commence to produce short germ tubes. An appressorium forms immediately at the top of the germ tube above or near an anticlinal wall.;A spherical vesicle about 12 um in diameter, forms inside the epidermal cell. An electron-transparent plug is formed in the inner end of the penetration tube.;Once the intracellular hypha leaves the epidermal cell, it develops in the intercellular spaces of the host tissue. The intercellular hyphae grow between the host cells, follow their contour and send haustoria of various shapes and sizes into adjoining cells. Between 5 and 6 days after inoculation, knots of intercellular hypha occupy the stomatal chamber. Juvenile conidiophores are evident emerging from the hyphal knots. Five to 6 dichotomies occur prior to the initiation of conidial formation.;Haustorial formation in P. hyoscyami f.sp. tabacina passes through three stages, bulb, cane and coil. After host wall penetration, the haustorium becomes bulb-shaped and grows into a straight hypha about 7-10 um in length that bends at its tip to produce a cane-like handle. The tip of the handle grows into a torulose coiled structure up to 50 um in length. A papilla or collar is never formed. The young haustorium is surrounded by extrahaustorial matrix composed of a thin inner electron-opaque layer on the haustorial wall and a much thicker electron-transparent layer, which extends to the extrahaustorial membrane. Haustoria occur in the mesophyll, palisade, lower and upper epidermis.;Starch accumulation / formation in infected tissue is different than in the healthy controls. Starch degradation was retarded as early as 2 h after infection and this retardation continued throughout the latent and sporulation period. Starch formation in infected tissue was retarded 31 h after inoculation and thereafter

Canadian biopesticides and bioherbicides

Non-Peer ReviewedBiopesticide technology is emerging as a viable and environmentally-friendly pest management tool in agriculture. Although the current global biopesticide market is small in comparison to the synthetic pesticide market, biopesticides are expected to exceed $1 billion in annual sales. The Canadian public's demand for safer foods and concern for the environment have encouraged initiatives to develop alternatives to conventional pesticides. Biopesticides are classed by Health Canada as reduced risk products that are less hazardous to human health and the environment and they represent the next generation of pest control products with novel modes of action. Agriculture and Agri-Food Canada (AAFC) has invested in a strategic priority to promote the development and commercialization of this technology. This paper presents a summary of new and emerging Canadian biopesticides and bioherbicides being developed by AAFC researchers

Anti-Virulence Potential and In Vivo Toxicity of Persicaria maculosa and Bistorta officinalis Extracts

Many traditional remedies represent potential candidates for integration with modern medical practice, but credible data on their activities are often scarce. For the first time, the anti-virulence potential and the safety for human use of the ethanol extracts of two medicinal plants, Persicaria maculosa (PEM) and Bistorta officinalis (BIO), have been addressed. Ethanol extracts of both plants exhibited anti-virulence activity against the medically important opportunistic pathogen Pseudomonas aeruginosa. At the subinhibitory concentration of 50 mu g/mL, the extracts demonstrated a maximal inhibitory effect (approx. 50%) against biofilm formation, the highest reduction of pyocyanin production (47% for PEM and 59% for BIO) and completely halted the swarming motility of P. aeruginosa. Both extracts demonstrated better anti-quorum sensing and antibiofilm activities, and a better ability to interfere with LasR receptor, than the tested dominant extracts' constituents. The bioactive concentrations of the extracts were not toxic in the zebrafish model system. This study represents an initial step towards the integration of P. maculosa and B. officinalis for use in the treatment of Pseudomonas infections

Differential regulation of four members of the ACC synthase gene family in plum

The regulation of ACC synthase (ACS) genes was studied in early (‘Early Golden’) and late (‘Shiro’) Japanese plum cultivars (Prunus salicina L.) in order to determine the role of this gene family in fruit ripening. Of the four Ps-ACS cDNAs isolated, two (Ps-ACS1 and -3) showed differential expression between the two cultivars. Ps-ACS1 accumulated during fruit ripening of ‘Early Golden’ (‘EG’) and ‘Shiro’ (‘SH’) in ethylene-dependent and -independent manners, respectively. Ps-ACS3a transcripts accumulated throughout fruit development and during ‘EG’ fruit ripening. Ps-ACS3b was detected only during ripening of ‘SH’ fruit. Furthermore, Ps-ACS3a transcript accumulation was negatively regulated by ethylene, whereas Ps-ACS3b was positively induced by the hormone. In both cultivars, the expression of Ps-ACS4 and -5 is under positive and negative feedback control by ethylene, respectively. Genetic analyses of ‘EG’ and ‘SH’ cultivars demonstrated that ‘EG’ is homozygous for Ps-ACS3a whereas ‘SH’ is heterozygous for Ps-ACS3 (a/b). The role of ethylene-overproducer 1-like in delaying fruit ripening by interacting with Ps-ACS proteins was also studied. The effect of the plant hormones, auxin, gibberellin, and cytokinin, in regulating ethylene production by promoting the induction of the different Ps-ACS mRNAs in plum was investigated. A model is presented in which differences in Ps-ACS alleles and gene expression between early and late plums are critical in determining the ripening behaviour of the cultivars

Design, synthesis, and biological evaluation of thiazole bioisosteres of goniofufurone through in vitro antiproliferative activity and in vivo toxicity (vol 121, 105691, 2022)

The contribution corrects an equation from the paper: Delasoie, J., Radakovic, N., Pavic, A., & Zobi, F. (2020). Neovascularization Effects of Carbon Monoxide Releasing Drugs Chemisorbed on Coscinodiscus Diatoms Carriers Characterized by Spectromicroscopy Imaging. Applied Sciences, 10(20), 7380. [https://doi.org/10.3390/app10207380

Complete Genome of the Xanthomonas euvesicatoria Specific Bacteriophage K Phi 1, Its Survival and Potential in Control of Pepper Bacterial Spot

Xanthomonas euvesicatoria phage K Phi 1, a member of Myoviridae family, was isolated from the rhizosphere of pepper plants showing symptoms of bacterial spot. The phage strain expressed antibacterial activity to all X. euvesicatoria strains tested and did not lyse other Xanthomonas spp., nor other less related bacterial species. The genome of K Phi D1 is double-stranded DNA of 46.077 bp including 66 open reading frames and an average GC content of 62.9%, representing the first complete genome sequence published for a phage infecting xanthomonads associated with pepper or tomato. The highest genome similarity was observed between phage K Phi 1 and the Xanthomonas oryzae pv. oryzae specific phage OP2. On the other hand, when compared with other members of the genus Bcep78virus, the genome similarity was lower. Forty-four (67%) predicted K Phi 1 proteins shared homology with Xanthomonas phage OP2, while 20 genes (30%) were unique to K Phi 1. Phage K Phi 1, which is chloroform resistant and stable in different media and in the pH range 5-11, showed a high titer storage ability for at least 2 years at +4 degrees C. Copper-hydroxide and copper-oxychloride reduced phage activity proportionally to the used concentrations and the exposure time. UV light was detrimental to the phage strain, but skim milk plus sucrose formulation extended its survival in vitro. The phages survived for at least 7 days on the surface of pepper leaves in the greenhouse, showing the ability to persist on the plant tissue without the presence of the host bacterium. Results of three repeated experiments showed that foliar applications of the unformulated K Phi 1 phage suspension effectively controlled pepper bacterial spot compared to the standard treatment and the untreated control. The integration of the phage K Phi 1 and copper-hydroxide treatments resulted in an increased efficacy compared to the copper-hydroxide alone

Identification and genetic characterization of a gibberellin 2-oxidase gene that controls tree stature and reproductive growth in plum

Several dwarf plum genotypes (Prunus salicina L.), due to deficiency of unknown gibberellin (GA) signalling, were identified. A cDNA encoding GA 2-oxidase (PslGA2ox), the major gibberellin catabolic enzyme in plants, was cloned and used to screen the GA-deficient hybrids. This resulted in the identification of a dwarf plum hybrid, designated as DGO24, that exhibits a markedly elevated PslGA2ox signal. Grafting ‘Early Golden’ (EG), a commercial plum cultivar, on DGO24 (EG/D) enhanced PslGA2ox accumulation in the scion part and generated trees of compact stature. Assessment of active GAs in such trees revealed that DGO24 and EG/D accumulated relatively much lower quantities of main bioactive GAs (GA1 and GA4) than control trees (EG/M). Moreover, the physiological function of PslGA2ox was studied by determining the molecular and developmental consequences due to ectopic expression in Arabidopsis. Among several lines, two groups of homozygous transgenics that exhibited contrasting phenotypes were identified. Group-1 displayed a dwarf growth pattern typical of mutants with a GA deficiency including smaller leaves, shorter stems, and delay in the development of reproductive events. In contrast, Group-2 exhibited a ‘GA overdose’ phenotype as all the plants showed elongated growth, a typical response to GA application, even under limited GA conditions, potentially due to co-suppression of closely related Arabidopsis homologous. The studies reveal the possibility of utilizing PslGA2ox as a marker for developing size-controlling rootstocks in Prunus

Molecular Mechanisms of Microcystin Toxicity in Animal Cells

Microcystins (MC) are potent hepatotoxins produced by the cyanobacteria of the genera Planktothrix, Microcystis, Aphanizomenon, Nostoc and Anabaena. These cyclic heptapeptides have strong affinity to serine/threonine protein phosphatases (PPs) thereby acting as an inhibitor of this group of enzymes. Through this interaction a cascade of events responsible for the MC cytotoxic and genotoxic effects in animal cells may take place. Moreover MC induces oxidative stress in animal cells and together with the inhibition of PPs, this pathway is considered to be one of the main mechanisms of MC toxicity. In recent years new insights on the key enzymes involved in the signal-transduction and toxicity have been reported demonstrating the complexity of the interaction of these toxins with animal cells. Key proteins involved in MC up-take, biotransformation and excretion have been identified, demonstrating the ability of aquatic animals to metabolize and excrete the toxin. MC have shown to interact with the mitochondria. The consequences are the dysfunction of the organelle, induction of reactive oxygen species (ROS) and cell apoptosis. MC activity leads to the differential expression/activity of transcriptional factors and protein kinases involved in the pathways of cellular differentiation, proliferation and tumor promotion activity. This activity may result from the direct inhibition of the protein phosphatases PP1 and PP2A. This review aims to summarize the increasing data regarding the molecular mechanisms of MC toxicity in animal systems, reporting for direct MC interacting proteins and key enzymes in the process of toxicity biotransformation/excretion of these cyclic peptides

Bumble bee parasite strains vary in resistance to phytochemicals

Nectar and pollen contain diverse phytochemicals that can reduce disease in pollinators. However, prior studies showed variable effects of nectar chemicals on infection, which could reflect variable phytochemical resistance among parasite strains. Inter-strain variation in resistance could influence evolutionary interactions between plants, pollinators, and pollinator disease, but testing direct effects of phytochemicals on parasites requires elimination of variation between bees. Using cell cultures of the bumble bee parasite Crithidia bombi, we determined (1) growth-inhibiting effects of nine floral phytochemicals and (2) variation in phytochemical resistance among four parasite strains. C. bombi growth was unaffected by naturally occurring concentrations of the known antitrypanosomal phenolics gallic acid, caffeic acid, and chlorogenic acid. However, C. bombi growth was inhibited by anabasine, eugenol, and thymol. Strains varied >3-fold in phytochemical resistance, suggesting that selection for phytochemical resistance could drive parasite evolution. Inhibitory concentrations of thymol (4.53-22.2 ppm) were similar to concentrations in Thymus vulgaris nectar (mean 5.2 ppm). Exposure of C. bombi to naturally occurring levels of phytochemicals—either within bees or during parasite transmission via flowers—could influence infection in nature. Flowers that produce antiparasitic phytochemical, including thymol, could potentially reduce infection in Bombus populations, thereby counteracting a possible contributor to pollinator decline