RESUMEN
Honey bee-associated bacteria are a source of natural compounds of interest for controlling hive decline which is threatening bee health globally. Genes involved in the biosynthesis of a series of extracellular compounds released by bacteria living on the external surface of honey bees were investigated. A biosynthetic gene-based approach was adopted by developing a battery of primers to target the genes involved in the biosynthesis of four groups of bioactive compounds (pyrrolizidine alkaloids, surfactin, 2-heptanone and helveticin J). The primers were tested on 51 bacterial isolates belonging to Bacillus thuringiensis, Acetobacteraceae bacterium, Bifidobacterium asteroides and Apilactobacillus kunkeei. The developed primers led to species-specific detection and characterization of the functional genes involved in the production of three out of four groups of compounds selected for this study. The findings suggest that microbial populations inhabiting apiaries harbor genes involved in the biosynthesis of metabolites linked to the reduction of important honey bee pathogens such as Varroa destructor, Paenibacillus larvae and Nosema ceranae. The gene-based approach adopted for evaluating the biosynthetic potential of bioactive compounds in hives is promising for investigating further compounds for low input control strategies of bee enemies.
Asunto(s)
Antiinfecciosos , Antiparasitarios , Bacterias , Abejas , Genes Bacterianos , Animales , Antiinfecciosos/metabolismo , Antiparasitarios/metabolismo , Bacterias/genética , Abejas/microbiología , Genes Bacterianos/genética , Biosíntesis de Proteínas/genéticaRESUMEN
Forecasting the severity of plant diseases is an emerging need for farmers and companies to optimize management actions and to predict crop yields. Process-based models are viable tools for this purpose, thanks to their capability to reproduce pathogen epidemiological processes as a function of the variability of agro-environmental conditions. We formalized the key phases of the life cycle of Puccinia kuenhii (W. Krüger) EJ Butler, the causal agent of orange rust on sugarcane, into a new simulation model, called ARISE (Orange Rust Intensity Index). ARISE is composed of generic models of epidemiological processes modulated by partial components of host resistance and was parameterized according to P. kuenhii hydro-thermal requirements. After calibration and evaluation with field data, ARISE was executed on sugarcane areas in Brazil, India and Australia to assess the pathogen suitability in different environments. ARISE performed well in calibration and evaluation, where it accurately matched observations of orange rust severity. It also reproduced a large spatial and temporal variability in simulated areas, confirming that the pathogen suitability is strictly dependent on warm temperatures and high relative air humidity. Further improvements will entail coupling ARISE with a sugarcane growth model to assess yield losses, while further testing the model with field data, using input weather data at a finer resolution to develop a decision support system for sugarcane growers.
Asunto(s)
Basidiomycota , Saccharum , Brasil , Enfermedades de las Plantas , Tiempo (Meteorología)RESUMEN
An investigation was carried out on rhizosphere bacteria to determine if they may be associated with perennial crops affected by nonspecific decline, a phenomenon that is difficult to diagnose and prevent. Esca disease of grapevine was chosen for this case study because of its easy foliar symptom identification. Ribosomal DNA fingerprint analysis by polymerase chain reaction - denaturing gradient gel electrophoresis (PCR-DGGE), quantitative PCR (qPCR), and rDNA amplicon sequencing by next-generation sequencing (NGS) were adopted to investigate the bacterial communities associated with grapevines, which were selected for the presence and absence of external foliar symptoms in 11 vineyards. According to PCR-DGGE and qPCR, bacterial communities differed in site of origin (vineyards), but not between symptomatic and asymptomatic plants, whereas qPCR gave a significantly higher presence of total bacteria and Pseudomonas spp. in asymptomatic plants. NGS confirmed no difference between symptomatic and asymptomatic plants, apart from a few minor genera (<0.5%) such as Salinibacterium, Flavobacterium, Nocardia, and Janthinobacterium, which were, in all cases, higher in asymptomatic plants and whose functional role should be the object of further investigation. The fact that total bacteria and Pseudomonas were more abundant in the rhizosphere of asymptomatic grapevines and that some bacterial genera were associated with the latter, represents a new element when investigating the multiple-origin phenomenon such as esca disease of grapevine.