Development, registration and commercialization of microbial pesticides for plant protection

Plant protection against pathogens, pests and weeds has been progressively reoriented from a therapeutic approach to a rational use of pesticide chemicals in which consumer health and environmental preservation prevail over any other productive or economic considerations. Microbial pesticides are being introduced in this new scenario of crop protection and currently several beneficial microorganisms are the active ingredients of a new generation of microbial pesticides or the basis for many natural products of microbial origin. The development of a microbial pesticide requires several steps addressed to its isolation in pure culture and screening by means of efficacy bioassays performed in vitro, ex vivo, in vivo, or in pilot trials under real conditions of application (field, greenhouse, post-harvest). For the commercial delivery of amicrobial pesticide, the biocontrol agent must be produced at an industrial scale (fermentation), preserved for storage and formulated by means of biocompatible additives to increase survival and to improve the application and stability of the final product. Despite the relative high number of patents for biopesticides, only a few of them have materialized in a register for agricultural use. The excessive specificity in most cases and biosafety or environmental concerns in others are major limiting factors. Non-target effects may be possible in particular cases, such as displacement of beneficial microorganisms, allergenicity, toxinogenicity (production of secondary metabolites toxic to plants, animals, or humans), pathogenicity (to plants or animals) by the agent itself or due to contaminants, or horizontal gene transfer of these characteristics to nontarget microorganisms. However, these non-target effects should not be evaluated in an absolute manner, but relative to chemical control or the absence of any control of the target disease (for example, toxins derived from the pathogen). Consumer concerns about live microbes due to emerging food-borne diseases and bioterrorism do not help to create a socially receptive environment to microbial pesticides. The future of microbial pesticides is not only in developing new active ingredients based on microorganisms beneficial to plants, but in producing self-protected plants (so-called plant-incorporated pesticides) by transforming agronomically high-value crop plants with genes from biological control agents

Mechanisms of antagonism of Pseudomonas fluorescens EPS62e against Erwinia amylovora, the causal agent of fire blight

Pseudomonas fluorescens EPS62e was selected during a screening procedure for its high efficacy in controlling infections by Erwinia amylovora, the causal agent of fire blight disease, on different plant materials. In field trials carried out in pear trees during bloom, EPS62e colonized flowers until the carrying capacity, providing a moderate efficacy of fire-blight control. The putative mechanisms of EPS62e antagonism against E. amylovora were studied. EPS62e did not produce antimicrobial compounds described in P. fluorescens species and only developed antagonism in King’s B medium, where it produced siderophores. Interaction experiments in culture plate wells including a membrane filter, which physically separated the cultures, confirmed that inhibition of E. amylovora requires cell-to-cell contact. The spectrum of nutrient assimilation indicated that EPS62e used significantly more or different carbon sources than the pathogen. The maximum growth rate and affinity for nutrients in immature fruit extract were higher in EPS62e than in E. amylovora, but the cell yield was similar. The fitness of EPS62e and E. amylovora was studied upon inoculation in immature pear fruit wounds and hypanthia of intact flowers under controlled-environment conditions. When inoculated separately, EPS62e grew faster in flowers, whereas E. amylovora grew faster in fruit wounds because of its rapid spread to adjacent tissues. However, in preventive inoculations of EPS62e, subsequent growth of EPS101 was significantly inhibited. It is concluded that cell-to-cell interference as well as differences in growth potential and the spectrum and efficiency of nutrient use are mechanisms of antagonism of EPS62e against E. amylovora. [Int Microbiol 2007; 10(2):123-132

Antimicrobial peptide genes in Bacillus strains from plant environments

The presence of the antimicrobial peptide (AMP) biosynthetic genes srfAA (surfactin), bacA (bacylisin), fenD (fengycin), bmyB (bacyllomicin), spaS (subtilin), and ituC (iturin) was examined in 184 isolates of Bacillus spp. obtained from plant environments (aerial, rhizosphere, soil) in the Mediterranean land area of Spain. Most strains had between two and four AMP genes whereas strains with five genes were seldom detected and none of the strains had six genes. The most frequent AMP gene markers were srfAA, bacA, bmyB, and fenD, and the most frequent genotypes srfAA-bacA-bmyB and srfAAbacA-bmyB-fenD. The dominance of these particular genes in Bacillus strains associated with plants reinforces the competitive role of surfactin, bacyllomicin, fengycin, and bacilysin in the fitness of strains in natural environments. The use of these AMP gene markers may assist in the selection of putative biological control agents of plant pathogens

Production of BP178, a derivative of the synthetic antibacterial peptide BP100, in the rice seed endosperm

Background: BP178 peptide is a synthetic BP100-magainin derivative possessing strong inhibitory activity against plant pathogenic bacteria, offering a great potential for future applications in plant protection and other fields. Here we report the production and recovery of a bioactive BP178 peptide using rice seeds as biofactories. - Results: a synthetic gene encoding the BP178 peptide was prepared and introduced in rice plants. The gene was efficiently expressed in transgenic rice under the control of an endosperm-specific promoter. Among the three endosperm-specific rice promoters (Glutelin B1, Glutelin B4 or Globulin 1), best results were obtained when using the Globulin 1 promoter. The BP178 peptide accumulated in the seed endosperm and was easily recovered from rice seeds using a simple procedure with a yield of 21 μg/g. The transgene was stably inherited for at least three generations, and peptide accumulation remained stable during long term storage of transgenic seeds. The purified peptide showed in vitro activity against the bacterial plant pathogen Dickeya sp., the causal agent of the dark brown sheath rot of rice. Seedlings of transgenic events showed enhanced resistance to the fungal pathogen Fusarium verticillioides, supporting that the in planta produced peptide was biologically active. -Conclusions: the strategy developed in this work for the sustainable production of BP178 peptide using rice seeds as biofactories represents a promising system for future production of peptides for plant protection and possibly in other fields

Lactic acid bacteria from fresh fruit and vegetables as biocontrol agents of phytopathogenic bacteria and fungi

The aim of the study was to evaluate the efficacy of lactic acid bacteria isolated from fresh fruits and vegetables as biocontrol agents against the phytopathogenic and spoilage bacteria and fungi, Xanthomonas campestris, Erwinia carotovora, Penicillium expansum, Monilinia laxa, and Botrytis cinerea. The antagonistic activity of 496 lactic acid bacteria strains was tested in vitro, and all tested microorganisms except P. expansum were inhibited by at least one isolate. The 496 isolates were also tested for inhibition of infection of P. expansum in wounds of Golden Delicious apples. Four strains TC97, AC318, TM319 and FF441 reduced the fungal rot diameter of apples by 20%, and only, Weissella cibaria strain TM128 decreased infection levels by 50%. Cell-free supernatants of selected antagonistic bacteria were studied to determine the nature of the antimicrobial compounds produced. Organic acids were the preferred inhibition mechanism but hydrogen peroxide was also detected when strains BC48, TM128, PM141 and FF441 were tested against Erwinia carotovora. These results support the potentiality of lactic acid bacteria as biocontrol agents against postharvest rot. Previous works reporting of antifungal activity by lactic acid bacteria are scarce

Construction of the Poincare sheaf for higher genus curves

Let $X$ be a smooth projective curve of genus $g$ and $L$ be a degree $l$ line bundle on $X$ with $l\geq 2g-1$. Denote the stack of rank two Higgs bundles on $X$ with value in $L$ by $\mathcal{H}iggs$ and the semistable part by $\mathcal{H}iggs_{ss}$. Let $H$ be the Hitchin base. In this paper we will construct the Poincare sheaf $\mathcal{P}$ on $\mathcal{H}iggs\times_{H}\mathcal{H}iggs_{ss}$ which is a maximal Cohen-Macaulay sheaf and flat over $\mathcal{H}iggs_{ss}$. In particular this includes the locus of nonreduced spectral curves.Comment: arXiv admin note: text overlap with arXiv:1709.0529

Políticas públicas en el trabajo remoto de los servidores de un programa de gobierno regional del Perú, 2022

El presente trabajo de investigación tuvo por objetivo general revelar si hay vinculación entre las políticas públicas y el trabajo remoto en un programa de gobierno regional del Perú, para lo cual se utilizó la técnica investigación por entrevistas semiestructuradas a los servidores de las diferentes Subgerencias Regionales del Programa de gobierno regional. A través de los resultados de los coeficientes de concurrencias se concluyó que no había vinculación entre las políticas públicas y el trabajo remoto, posiblemente porque el trabajo remoto es una política pública de emergencia obligatoria no planificada, pero si reactiva ante la presencia de la pandemia del Covid 19. Pero si se encontró concurrencias entre los códigos de la categoría políticas públicas con coeficiente más relevante de 0.28 y en los códigos de la categoría con coeficiente de 0.13 trabajo remoto estableciéndose sus redes semánticas de asociación. Por lo que la caracterización de las políticas públicas en el PGR, permitirá la atención de las necesidades de la población de manera más eficaz y eficiente. Asimismo, el proceso de implementación del trabajo remoto se establece a partir del compromiso de los servidores del PGR la consistencia de los TIC y los equipos que tienen para el buen desarrollo del mismo y para la final atención a sus administrado

Phenotypic comparison of clinical and plant-beneficial strains of Pantoea agglomerans

Certain strains of Pantoea are used as biocontrol agents for the suppression of plant diseases. However, their commercial registration is hampered in some countries because of biosafety concerns. This study compares clinical and plant-beneficial strains of P. agglomerans and related species using a phenotypic analysis approach in which plant-beneficial effects, adverse effects in nematode models, and toxicity were evaluated. Plant-beneficial effects were determined as the inhibition of apple fruit infection by Penicillium expansum and apple flower infection by Erwinia amylovora. Clinical strains had no general inhibitory activity against infection by the fungal or bacterial plant pathogens, as only one clinical strain inhibited P. expansum and three inhibited E. amylovora. By contrast, all biocontrol strains showed activity against at least one of the phytopathogens, and three strains were active against both. The adverse effects in animals were evaluated in the plant-parasitic nematode Meloidogyne javanica and the bacterial-feeding nematode Caenorhabditis elegans. Both models indicated adverse effects of the two clinical strains but not of any of the plant-beneficial strains. Toxicity was evaluated by means of hemolytic activity in blood, and genotoxicity with the Ames test. None of the strains, whether clinical or plant-beneficial, showed any evidence of toxicity