Impact of climate change environmental conditions on the resilience of different formulations of the biocontrol agent Candida sake CPA‐1 on grapes

Biocontrol agents have become componentsof integrated crop protection systemsfor controlling economically important fungal pathogens.Candida sakeCPA-1 is abiocontrol agent of fungal pathogens of fruits, both pre- and post-harvest. Whilethe efficacy of different formulations have been examined previously, few studieshave considered the resilience of different formulations under changing climaticconditions of elevated temperature, drought stress and increased atmospheric CO2.This study examined the effect of (a) temperature9RH9elevated CO2(400vs1000 ppm) on the temporal establishment and viability of two dry and one liquidC. sakeCPA-1 formulations on grape berry surfaces; (b) temperature stress (25vs35°C); and (c) elevated CO2levels. Results indicated that temperature, RH and CO2concentration influenced the establishment and viability of the formulations butthere was no significant difference between formulations. For the combined three-component factors, increased temperature (35°C) and lower RH (40%) reduced theviable populations on grapes. The interaction with elevated CO2improved theestablishment of viable populations of the formulations tested. Viable populationsgreater than Log 4 CFUs per g were recovered from the grape surfaces suggestingthat these had conserved resilience for control ofBotrytisrot in grapes.info:eu-repo/semantics/acceptedVersio

Predicted ecological niches and environmental resilience of different formulations of the biocontrol yeast Candida sake CPA-1 using the Bioscreen C

Environmental resilience of biocontrol microorganisms has been a major bottleneck in the development of effective formulations. Candida sake is an effective biocontrol agent (BCA) against Penicillium expansum, Botrytis cinerea or Rhizopus stolonifer, and different formulations of the BCA have been optimised recently. The objective of this study was to compare the relative tolerance of different dry and liquid formulations of the biocontrol yeast C. sake CPA-1 to interacting environmental conditions using the Bioscreen C. Initially, the use of this automated turbidimetric method was optimised for use with different formulations of the biocontrol yeast. The best growth curves were obtained for the C. sake CPA-1 strain when grown in a synthetic grape juice medium under continuous shaking and with an initial concentration of 105 CFUs ml−1. All the formulations showed a direct relationship between optical density values and yeast concentrations. Temperature (15–30 °C) and water activity (aw; 0.94–0.99) influenced the yeast resilience most profoundly, whereas the effect of pH (3–7) was minimal. In general, the liquid formulation grew faster in more interacting environmental conditions but only the yeast cells in the dry potato starch formulation could grow in some stress conditions. This rapid screening method can be used for effective identification of the resilience of different biocontrol formulations under interacting ecological abiotic conditions.info:eu-repo/semantics/acceptedVersio

Infection risk of Monilinia fructicola on stone fruit during cold storage and immersion in the dump tank

Monilinia spp. is the main pathogen responsible for postharvest losses of stone fruit. Several studies have examined the conditions for Monilinia spp. infection in the field, but very limited information is available about postharvest. Storing fruit for 1 day in the cold room or dumping fruit in a water tank are the most common handling operations during the postharvest of fruit. Then, the aim of this study was to investigate the risk of Monilinia fructicola infection for two peach and one nectarine cultivars during cold storage and water dump operations. A new methodology was performed using a dry inoculum of M. fructicola. A set of fruit was used as control to demonstrated that at 20 °C 60% relative humidity (RH) was not able to infect fruit, however, the disease was developed when was already infected. In addition, M. fructicola was able to infect and develop disease in fruit at 20 °C 100 RH. The storage of fruit with the presence of M. fructicola conidia on their surface for up to 30 days at 0 °C 100% RH or 4 °C 100% RH did not suppose an important risk of infection since only 3.3 and 3.8%, respectively of fruit were already infected. Overall, all treatments tested with the water dump operation gave optimal conditions to M. fructicola to infect fruit when it was superficially dry inoculated or it was immersed with water contaminated with conidia, increasing the need for water disinfection. In addition, when fruit was immersed in water free from M. fructicola conidia, the postharvest operation gave optimal conditions to develop infections already produced.info:eu-repo/semantics/acceptedVersio

Enhanced shelf-life of the formulated biocontrol agent Bacillus amyloliquefaciens CPA-8 combining diverse packaging strategies and storage conditions

Two effective biocontrol products (named as BA3 and BA4) based on Bacillus amyloliquefaciens CPA-8 have been reported as a potential alternative to chemical applications against brown rot caused by Monilinia spp. on stone fruit. To have practical use, this study aimed to describe the best packaging strategies (bags or flasks, atmosphere, and temperature of storage) to not only guarantee efficacy but also stability and ease of application of the products to be handled through the normal channels of distribution and storage. In terms of the viability neither the BA3 nor the BA4 product has been compromised after twelve months of storage. However, storage at 4 °C affected the stability and visual aspect of both CPA-8 formulations, mainly associated not only to the increase of RH but also aw. Moreover, it should be pointed out that flasks did not conserve refrigerated BA3 samples in a suitable way, since RH and aw increased noticeably making their visual properties unsightly after 10 months of cold storage. At that time, the BA4 products were better preserved at 4 °C when packaged in flasks. Finally, this study also demonstrated that the most suitable packaging conditions for long-term storability (stored at 22 °C) did not show any negative effect in the biocontrol efficacy of CPA-8 in nectarines artificially infected with M. fructicola and provide suitable product delivery and field application. In conclusion, these results contribute to the final stage of development of these two CPA-8 products, practically ready for registration, thus contributing to the environmental-friendly management of postharvest diseases in stone fruit.info:eu-repo/semantics/acceptedVersio

Effectiveness of a pomegranate peel extract (PGE) in reducing Listeria monocytogenes in vitro and on fresh-cut pear, apple and melon

Pomegranate peel extract (PGE) is a new promising natural alternative control substance with large spectrum of activity against wide range of pathogenic microorganisms. In the present study, PGE was firstly investigated as natural antimicrobial against Listeria monocytogenes both in vitro and on fresh-cut fruits. The in vitro results showed quick and strong bactericidal and bacteriostatic activity against five different strains which were almost completely inhibited by the extract. Furthermore, it significantly decreased growth rate and maximum growth of all tested strains. In vivo trials, confirmed a strong antibacterial activity of the extract that significantly reduced the bacterial load on fresh-cut apple, melon and pear and maintained the population at low levels throughout the storage period (7 days). PGE at 12 g/l reduced L. monocytogenes by 1.24, 1.89, and 0.91 log units soon after treatment and by 3.81, 1.53, and 2.99 log units, after 7 days of storage on apple, pear and melon, respectively. This high antibacterial activity could be mainly related to the high content of polyphenols (ellagitannins) in the extract. Overall, results of this study suggest a potential industrial application of PGE to reduce the growth of the pathogenic microorganisms in fresh-cut fruit and ensure a microbial safety in case of contamination.info:eu-repo/semantics/acceptedVersio

Predicted ecological niches and environmental resilience of different formulations of the biocontrol yeast Candida sake CPA-1 using the Bioscreen C

Environmental resilience of biocontrol microorganisms has been a major bottleneck in the development of effective formulations. Candida sake is an effective biocontrol agent (BCA) against Penicillium expansum, Botrytis cinerea or Rhizopus stolonifer, and different formulations of the BCA have been optimised recently. The objective of this study was to compare the relative tolerance of different dry and liquid formulations of the biocontrol yeast C. sake CPA-1 to interacting environmental conditions using the Bioscreen C. Initially, the use of this automated turbidimetric method was optimised for use with different formulations of the biocontrol yeast. The best growth curves were obtained for the C. sake CPA-1 strain when grown in a synthetic grape juice medium under continuous shaking and with an initial concentration of 105 CFUs ml−1. All the formulations showed a direct relationship between optical density values and yeast concentrations. Temperature (15–30 °C) and water activity (aw; 0.94–0.99) influenced the yeast resilience most profoundly, whereas the effect of pH (3–7) was minimal. In general, the liquid formulation grew faster in more interacting environmental conditions but only the yeast cells in the dry potato starch formulation could grow in some stress conditions. This rapid screening method can be used for effective identification of the resilience of different biocontrol formulations under interacting ecological abiotic conditions

Impact of climate change environmental conditions on the resilience of different formulations of the biocontrol agent Candida sake CPA‐1 on grapes

Biocontrol agents have become components of integrated crop protection systems for controlling economically important fungal pathogens. Candida sake CPA‐1 is a biocontrol agent of fungal pathogens of fruits, both pre‐ and post‐harvest. While the efficacy of different formulations have been examined previously, few studies have considered the resilience of different formulations under changing climatic conditions of elevated temperature, drought stress and increased atmospheric CO2. This study examined the effect of (a) temperature × RH × elevated CO2 (400 vs 1000 ppm) on the temporal establishment and viability of two dry and one liquid C. sake CPA‐1 formulations on grape berry surfaces; (b) temperature stress (25 vs 35°C); and (c) elevated CO2 levels. Results indicated that temperature, RH and CO2 concentration influenced the establishment and viability of the formulations but there was no significant difference between formulations. For the combined three‐component factors, increased temperature (35°C) and lower RH (40%) reduced the viable populations on grapes. The interaction with elevated CO2 improved the establishment of viable populations of the formulations tested. Viable populations greater than Log 4 CFUs per g were recovered from the grape surfaces suggesting that these had conserved resilience for control of Botrytis rot in grapes

Pectin methyl esterases and rhamnogalacturonan hydrolases: weapons for successful Monilinia laxa infection in stone fruit?

The secretion of cell wall‐degrading enzymes is one of the mechanisms used by necrotrophic fungi to colonize host tissues. However, information about virulence factors of Monilinia spp., the causal agents of brown rot in stone fruit, is scarce. Plant cell walls have three main components that are broken down by fungal enzymes: cellulose, hemicellulose and pectin. In order to identify Monilinia laxa candidate proteins involved in pectin hydrolysis, two in vitro approaches were conducted: (i) phenotypic and ecophysiological characterization of growth of the pathogen at different pHs, in glucose‐ and pectin‐containing solid media for 7 days' incubation; and (ii) expression analysis of genes encoding M. laxa pectin methyl esterases (MlPMEs) and rhamnogalacturonan hydrolases (MlRG‐HYDs) after incubation for 0.5, 2, 6, 24 and 48 h in glucose‐ and pectin‐containing liquid media. Phenotypic tests showed the role of carbon source on M. laxa growth rate and aggressiveness, and indicated that pectinases were greatly affected by pH. Gene expression analyses uncovered differences among members of each family of pectinases and between the two families, defining sets of genes expressed at earlier (0.5–6 h) and later (48 h) phases. Notably, the up‐ or down‐regulation of these target genes was carbon source‐dependent. Finally, an in vivo study confirmed the synergistic and complementary role that these genes play in the M. laxa–stone fruit pathosystem. Based on these results, it is hypothesized that MlPME2, MlRG‐HYD1 and MlRG‐HYD2 may be potential virulence factors of M. laxa in the process from infection to colonization.info:eu-repo/semantics/acceptedVersio

Benthic suspension feeders, key players in Antartic marine ecosystems?

Ja fa un cert temps que hom accepta, de manera general i a partir d'estudis de la columna d'aigua en mar obert, que en les comunitats marines de l'oceà Antàrtic hi ha un període prolongat d'activitat hivernal mínima que s'estén al llarg de sis mesos com a mínim, que és el temps que dura l'hivern austral. Tanmateix, investigacions recents en algunes espècies d'invertebrats suspensívors (filtradors) bentònics litorals han suggerit que el període d'inactivitat potser dura només unes poques setmanes. Això planteja una interessant qüestió: què és el que permet que aquests organismes antàrtics mengin, i per tant romanguin actius, durant períodes molt més llargs del que fins ara s'havia cregut? Hom ha suggerit adaptacions especials a menjar en concentracions molt baixes d'aliment, o bé a usar eficientment l'abundància ocasional d'aliment enmig de llargs períodes d'escassedat. Molts animals suspensívors podrien usar fonts alternatives al seu aliment usual, el fito- i el zooplàncton; per exemple, la ?fracció fina' de matèria orgànica, o microplàncton (bacteris, ciliats i flagel·lats, junt amb carboni inorgànic particulat d'orígens diversos), que hom ha demostrat recentment que té un paper molt més significatiu del que hom creia a l'hora de complementar la dieta i de subvenir a les demandes energètiques de moltes espècies de suspensívors. També s'ha esmentat el possible paper de la resuspensió de sediments i, atès l'elevat valor alimentari del component orgànic dels sediments antàrtics, àdhuc de fons pregons, serà interessant investigar més en aquesta línia. Observacions recents relacionades amb la dieta natural (captura de preses) d'algunes espècies d'aigües somes porten a suposar que alguns suspensívors antàrtics, si més no, tenen taxes de creixement i reproducció que són similars a les assenyalades per a espècies d'aigües temperades.For quite some time it was generally accepted, from water column and open sea studies, that in Antarctic marine communities there is a prolonged period of minimal winter activity which lasts for at least six months during the Southern winter. However, recent studies on certain littoral benthic suspension feeders have suggested that the period of inactivity may last only a few weeks. This raises the question of what allows these organisms to feed, and hence remain active, for considerably longer periods than previously thought. Special adaptations to feeding at low levels of food concentration, or to using occasional food abundance followed by long periods of starvation have been suggested. Many suspension feeders might use alternative food sources to phytoand zooplankton, e.g., the «fine fraction» of organic matter, or microplankton (bacteria, ciliates, and flagellates including POC of several origins), which has recently been shown to play a much more significant role than expected in complementing the diet and meeting energy demands in many species of suspension feeders. The possible role of sediment resuspension has also been reported, and given the high food value of the organic component of sediments even on deep bottoms further research would be of interest. Recent observations related to the natural diet (prey capture) of several shallow species lead to the assumption that part of Antarctic suspension feeders have similar growth and reproduction rates to those reported for temperate waters. Efficient food assimilation may contribute to our understanding of the continuous reproduction state observed in octocorals and, also, of the development of tridimensionally structured communities which are suspension-feeder dominated, highly diversified, and have a high biomass

Mechanisms of resistance in postharvest fruit-pathogen interaction

Abstract T he objective of this review was to bring together concepts related to studies aimed at elucidating defense mechanisms against disease-causing agents, mainly in postharvest. Like plants, fruits are exposed to attack by pathogens that cause rot during postharvest storage, resulting in considerable losses. To control these pathogens, synthetic chemicals are used; however, since they are toxic, genetic resistance is regarded as a viable alternative. Fruits can withstand pathogens by means of physical barriers (presence of thick cuticular or trichome layers) and chemical ones, or through induced defenses that are activated once the host detects the presence of the pathogen, triggering the oxidative burst during the early hours of interaction. This burst entails the generation of reactive oxygen species (ROS), such as superoxide (O 2ˉ) , hydroxyl radical (OHˉ) or hydrogen peroxide (H 2 O 2 ), and the activation of genes involved in several metabolic pathways. The study of such mechanisms may allow detecting disease-resistant genetic materials, thus reducing the use of toxic products. Resumen E l objetivo de esta revisión fue conjuntar conceptos relacionados con estudios dirigidos a elucidar los mecanismos de defensa contra agentes causantes de enfermedades, principalmente en poscosecha. Al igual que las plantas, los frutos se encuentran expuestos al ataque por patógenos que producen podredumbres durante su almacenamiento en poscosecha, causando considerables pérdidas. Para el control de dichos patógenos, se emplean productos químicos de síntesis que son tóxicos, y la resistencia genética se considera una alternativa viable. Los frutos pueden tolerar a los patógenos mediante barreras físicas (presencia de capas gruesas de cutícula o de tricomas) y químicas, o bien, a través de defensas inducidas que se activan una vez que el huésped detecta la presencia del patógeno, desencadenando la explosión oxidativa durante las primeras horas de la interacción. Esta explosión conlleva la generación de especies reactivas de oxígeno (ROS) como el superóxido (O 2ˉ) , el radical hidroxilo (OHˉ) o el peróxido de hidrógeno (H 2 O 2 ), y la activación de genes involucrados en diversas rutas metabólicas. El estudio de tales mecanismos puede permitir detectar materiales genéticos resistentes a enfermedades, reduciendo así el uso de productos tóxicos