Co-application of Difenoconazole with Thymol Results in Suppression of a Parastagonospora Nodorum Mutant Strain Resistant to this Triazole

Results of in vitro study of thymol, a natural chemosensitizer, as a potential agent for overcoming of difenoconazole resistance of Parastagonospora nodorum causing glume and leaf blotch of wheat are first reported. The level of difenoconazole resistance of a natural mutant PNm1 strain with low sensitivity to the Dividend fungicide (a.i. difenoconazole) was determined by the cultivation of this isolate on potato dextrose agar in the presence of the fungicide at sub-lethal and lethal (in relation to the initial fungicide-sensitive strain) concentrations. A principal possibility of the thymol use to overcome resistance of P. nodorum to DMI (demethylation inhibitors) fungicides is shown. Co-application of this compound with Dividend SC, 3 % resulted in a significant reduction of resistance of the mutant strain and enhancement of its sensitivity to difenoconazole up to the level corresponding to the initial non-resistant isolate

Co-application of Difenoconazole with Thymol Results in Suppression of A Parastagonospora Nodorum Mutant Strain Resistant to This Triazole

Results of in vitro study of thymol, a natural chemosensitizer, as a potential agent for overcoming of difenoconazole resistance of Parastagonospora nodorum causing glume and leaf blotch of wheat are first reported. The level of difenoconazole resistance of a natural mutant PNm1 strain with low sensitivity to the Dividend fungicide (a.i. difenoconazole) was determined by the cultivation of this isolate on potato dextrose agar in the presence of the fungicide at sub-lethal and lethal (in relation to the initial fungicide-sensitive strain) concentrations. A principal possibility of the thymol use to overcome resistance of P. nodorum to DMI (demethylation inhibitors) fungicides is shown. Co-application of this compound with Dividend SC, 3 % resulted in a significant reduction of resistance of the mutant strain and enhancement of its sensitivity to difenoconazole up to the level corresponding to the initial non-resistant isolate

Effect of Various Compounds Blocking the Colony Pigmentation on the Aflatoxin B1 Production by Aspergillus flavus

Aflatoxins and melanins are the products of a polyketide biosynthesis. In this study, the search of potential inhibitors of the aflatoxin B1 (AFB1) biosynthesis was performed among compounds blocking the pigmentation in fungi. Four compounds—three natural (thymol, 3-hydroxybenzaldehyde, compactin) and one synthetic (fluconazole)—were examined for their ability to block the pigmentation and AFB1 production in Aspergillus flavus. All compounds inhibited the mycelium pigmentation of a fungus growing on solid medium. At the same time, thymol, fluconazole, and 3-hydroxybenzaldehyde stimulated AFB1 accumulation in culture broth of A. flavus under submerged fermentation, whereas the addition of 2.5 μg/mL of compactin resulted in a 50× reduction in AFB1 production. Moreover, compactin also suppressed the sporulation of A. flavus on solid medium. In vivo treatment of corn and wheat grain with compactin (50 μg/g of grain) reduced the level of AFB1 accumulation 14 and 15 times, respectively. Further prospects of the compactin study as potential AFB1 inhibitor are discussed

Evaluation of eliciting activity of peptidil prolyl cys/trans isomerase from <em>Pseudonomas fluorescens</em> encapsulated in sodium alginate regarding plant resistance to viral and fungal pahogens

Use of chemical pesticides poses a threat for environment and human health, so green technologies of crop protection are of high demand. Some microbial proteins able to activate plant defense mechanisms and prevent the development of resistance in plant pathogens, may be good alternative to chemicals, but practical use of such elicitors is limited due to need to protect them against adverse environment prior their delivery to target receptors of plant cells. In this study we examined a possibility to encapsulate heat resistant FKBP-type peptidyl prolyl cis-trans isomerase (PPIase) from Pseudomonas fluorescens, which possesses a significant eliciting activity in relation to a range of plant pathogens, in sodium alginate microparticles and evaluated the stability of resulted complex under long-term UV irradiation and in the presence of proteinase K, as well as its eliciting activity in three different “plant-pathogen” models comparing to that of free PPIase. The obtained PPIase-containing microparticles consisted of 70% of sodium alginate, 20% of bovine serum albumin, and 10% of PPIase. In contrast to free PPIase, which lost its eliciting properties after 8-h UV treatment, encapsulated PPIase kept its eliciting ability unchanged; after being exposed to proteinase K, its eliciting ability twice exceeded that of free PPIase. Using “tobacco-TMV”, “tobacco-Alternaria longipes”, and “wheat-Stagonospora nodorum” model systems, we showed that encapsulation process did not influence on the eliciting activity of PPIase. In the case of the “wheat-S. nodorum” model system, we also observed a significant eliciting activity of alginate-albumin complex and almost doubled activity of encapsulated PPIase as compared to the free PPIase. As far as we know, this is the first observation of a synergistic interaction between alginate and other compound possessing any bioactive properties. The results of the study show some prospects for a PPIase use in agriculture

Role of microbes in plant protection using intersection of nanotechnology and biology

Published online: 15 Aug 2018Plant pathogens are one of the dominating components which restrain crop productivity. Preliminary step headed for managing plant disease is to accurately recognize the pathogen under lab, glasshouse, and field conditions. Modern approach, such as culture-based, antibody-based rapid methods and quantitative polymerase chain reaction (Q-PCR), entrusts on multiple assays to precisely identify the specific plant pathogens which are further time-consuming and lack high sensitivity. Nanobiotechnology ameliorates crop productivity through transmission of genes to target sites for breeding of varieties resistant to different plant pathogens with focus on improving sensitivity. Intersection of nanotechnology and biology also improves specificity and agility of pathogen detection which further facilitates crop disease management. Bio-fabrication of nanoparticles like silver (Ag) and copper (Cu) is used as novel antimicrobials for the management of pathogenic microorganisms that inhibits fungal hyphae and conidial germination in agricultural crops. Biological agents reduce metal which leads to capping of nanoparticles through the secretion of various enzymes. A modern class of protein nanocompartments called as encapsulins that encapsulate cargo proteins are found in bacteria and archaea. Nanobiotechnology also reduces detection times of crop pathogens and cost by the development of biosensors and phage proteins. In this chapter we emphasize on microbial semblance in nanobiotechnology applications that precede to integrated disease management of agricultural crops including precise diagnostic layout of plant diseases and modification of crop environments to adversely affect crop pathogens