El género fúngico Alternaria contienez especies tanto saprofitas como patógenas. Como patógenos d... more El género fúngico Alternaria contienez especies tanto saprofitas como patógenas. Como patógenos de las plantas, causan serios problemas en la agricultura, reduciendo el rendimiento del cultivo y deteriorando frutos en el almacenamiento. Las especies de este género también pueden ser micotoxicogénicas, capaces de colonizar los cultivos y acumular en los productos infectados, metabolitos secundarios que pueden afectar la salud humana y/o animal. En el presente trabajo, se muestrearon frutos de manzano (Malus domestica) y pera (Pyrus comunnis) en tres localidades del Alto Valle del río Negro (Cipolletti, General Roca y Villa Regina), a fin de determinar la presencia de especies del género Alternaria asociadas a estos cultivos en la región. Se obtuvieron un total de 267 aislamientos pertenecientes al género Alternaria. Los mismos fueron identificados por sus características morfológicas (Simmons, 2007) como iguales o similares a Alternaria tenuissima, en mayor proporción (85 %). También...
Bacterial Spot of Almond is a pathology caused by Xanthomonas arboricola pv. pruni responsible fo... more Bacterial Spot of Almond is a pathology caused by Xanthomonas arboricola pv. pruni responsible for significant yield losses. During 2017, young symptomatic almond fruits were observed in orchards of Northern Patagonia, in Argentina. Symptoms consisted of small watery circular lesions, from which an amber gummy substance emerged. The objective of this work was to determine the etiology of this pathology considering the fact that the symptoms were coincident with those previously described for the bacterial spot with gum production caused by Xanthomonas arboricola pv. pruni on almond fruits in other parts of the world. The presence of Xanthomonas arboricola in damaged fruits was determined confirming their identity by molecular analysis. Symptomatology and gum production were demonstrated performing pathogenicity tests. As a result, Bacterial Spot with gum production is reported for the first time on almond fruits in Argentina.
Apple is a major crop in Argentina where 50% of the production is derived to by-products. Industr... more Apple is a major crop in Argentina where 50% of the production is derived to by-products. Industries process either recently harvested apples or fruit stored for up to 9 months. This crop is susceptible to fungal diseases both external and internal, such as mouldy core (MC). The incidence of fungal pathogens changes during storage, as well as the risk associated with their presence since some contaminants belong to mycotoxigenic genera. The objective of this study was to characterize the fungal contaminants of Red Delicious apple fruit in Argentina evaluating their evolvement from field to process, with main interest on MC causal agents and mycotoxigenic species. A total of 240 apples were analysed; 140, recently harvested and intended for fresh consumption (C), and 100 stored for 9 months in a refrigerated chamber (0-3 °C) and destined to industrialization (I). The 86% of fresh consumption apples showed external fungal lesions, and only 14% were undamaged; MC incidence was 34%. High biodiversity was observed; Penicillium was the predominant genus (54%), followed by Alternaria spp. (41%). Only 3% of industrialization fruit were undamaged, 48% had external lesions and 51% MC. However, biodiversity was lower in these apples. Alternaria spp. was recovered from 60% of apples, mainly causing MC, while Penicillium spp. took second place (34%). All the Alternaria isolates belonged to Section Alternaria with A. tenuissima as the predominant species-group. Alternariol was synthesised by 75% of the isolates, while both alternariol monomethyl-ether and tenuazonic acid by 76%. From the 100 I apples, 93 were contaminated with at least one of these mycotoxins. Alternaria was the main causal agent of MC in Argentinean Red Delicious apples, and fruit affected by this disease might be incorporated into the process line, with a consequent risk of mycotoxin contamination in apple by-products.
The characteristics and quality of home-made dry cured sausages can be recognized and associated ... more The characteristics and quality of home-made dry cured sausages can be recognized and associated with the region of origin. The characteristics of this type of sausages result from the superficial mycobiota that spontaneously colonizes the products. The aim of this study was to identify the house mycobiota associated with home-made dry cured sausages from different localities of Argentina and characterize the populations of Penicillium nalgiovense present by morphological and biochemical markers. To this end, 79 samples were collected from 10 localities of three main producing regions (Buenos Aires, Córdoba and La Pampa provinces). A total of 196 isolates belonging to six genera and 17 species were obtained. The predominant genus was Penicillium (134 of the isolates) and the predominant species was P. nalgiovense (108 isolates). The isoenzyme patterns of α-esterase (α-EST; EC 3.1.1.1) and Malate dehydrogenase NADP+(MDHP; EC 1.1.1.40) were characterized in 48 of these isolates (ten from Colonia Caroya, ten from Oncativo, ten from Tandil, nine from Mercedes and nine from La Pampa). A total of 26 bands were observed: 17 for α-EST and 9 for MDHP. α-EST was the most polymorphic isoenzyme, whereas MDPH presented no polymorphism. The results were subjected to numerical analysis. Cluster analysis revealed the formation of two groups: Group I formed by 24 isolates from Córdoba and Buenos Aires provinces and Group II with 24 isolates from La Pampa and Buenos Aires province. These data suggest the existence of morphological and biochemical variations among P. nalgiovense populations with different geographical origin.
Fungal spores are normal components of external environments. They have been reported to be assoc... more Fungal spores are normal components of external environments. They have been reported to be associated with human, animal and plant diseases causing primary and opportunistic infections. Cladosporium is commonly the most frequently isolated genus from air samples, and its species are considered mainly saprophytic, but there is a wide variety of taxa that can cause adverse effects on human and animal health and also on plants. In this work, we aimed to record Cladosporium spores frequency of isolation in northern Argentinean Patagonia and to perform a molecular characterization based on actin gene complemented with EF1α and ITS genes. The ability of the pathogens to cause disease in pip fruits of Packham’s Triumph and Abate Fetel pears and red delicious apples was determined. Results confirmed Cladosporium spores as the main genera isolated from air samples, and the molecular characterization revealed the existence of 11 species in this region grouped in C. cladosporioides and C. herbarum complexes. Pathogenicity tests revealed that Cladosporium sp. cause disease on fruit. Abate Fetel was the most susceptible to infection. These results compose the first study in Argentina in respect of identification at species level of airborne Cladosporium spores, and furthermore, it is the first report in northern Patagonia and the high valley of Río Negro productive region. This knowledge can help farmers to take preventive measures in order to avoid biological damage.
This work describes a longitudinal study of three consecutive years carried out in the air of agr... more This work describes a longitudinal study of three consecutive years carried out in the air of agricultural environments located in Northern Patagonia with cold dry desert climate (Köppen: Bwk). This study area comprises a rural valley with unique geographical and climatological conditions. Therefore, the aim of this work is to quantify and determine its fungal diversity, so this knowledge will contribute to detect potential pathogenic and toxic fungi that has been adapted to this type of environment and may overcome the incipient climate change. Samplings were conducted in two geographical zones of the study area and a microflow air sampler was used to isolate fungal taxa. The annual mean fungal counts were found in the order of E+03 CFU/m3 of air. The aerial mycoflora revealed a wide biodiversity of at least 28 genera and 50 fungal species. Cladosporium was the most abundant genus (76.97%), followed by Alternaria (12.48%), Epicoccum (4.41%) and Botrytis (1.81%). The rest of the genera were found in relative densities lower than 1%. In terms of species, C. cladosporioides (34.82%), C. limoniforme (21.72%), A. tenuissima (10.94%) and C. asperulatum predominated (9.01%). This is the first report of the air mycoflora of rural environments with cold dry desert climate which provides useful information to take preventive measures to avoid biological damage.
Xerophilic fungi represent a serious problem due to their ability to grow at low water activities... more Xerophilic fungi represent a serious problem due to their ability to grow at low water activities causing the spoiling of low and intermediate moisture foods, stored goods and animal feeds, with the consequent economic losses. The combined effect of water activity and temperature of four Eurotium species isolated from animal feeds was investigated. Eurotium amstelodami, Eurotium chevalieri, Eurotium repens and Eurotium rubrum were grown at 5, 15, 25, 37 and 45°C on malt extract agar adjusted with glycerol in the range 0.710-0.993 of water activities. The cardinal model proposed by Rosso and Robinson (2001) was applied to fit growth data, with the variable water activity at fixed temperatures, obtaining three cardinal water activities (a, a, a) and the specific growth rate at the optimum a (μ). A probabilistic model was also applied to define the interface between growth and no-growth. The cardinal model provided an adequate estimation of the optimal a to grow and the maximum growth ...
'Moldy heart' caused by Alternaria spp has been previously reported in apples in Argentin... more 'Moldy heart' caused by Alternaria spp has been previously reported in apples in Argentina. However, according to our knowledge this is the first report of Alternaria spp in 'moldy heart' affected peaches in this country. Direct isolation of the pathogen was performed on Dichloran-Chloramphenicol-Malt Extract-Agar. Seven strains were isolated and identified as A. alternata and one as A. tenuissima. Their toxicogenic potential (alternariol (AOH), alternariol methyl ether (AME) and tenuazonic acid (TA) production) was determined. The toxins were extracted with chloroform and determined by TLC. All strains produced AOH and AME while six of them were TA producers. The fungicides tested on agar were captan and mancozeb. At 2.5g/L (commercial concentration) both fungicides inhibited the germination of spores. Captan completely inhibited mycelial growth. The effect of the fungicide on toxin production was variable according to fungicide type, doses, strains and toxins considered.
Fusarium Head Blight (FHB) is an important disease affecting the production of wheat worldwide. F... more Fusarium Head Blight (FHB) is an important disease affecting the production of wheat worldwide. Fusarium species are causal agents of Fusarium Head Blight (FHB) in cereals and Fusarium graminearum (Schwabe) (teleomorph Gibberella zeae (Schwein.)) is considered the main cause of the disease. FHB incidence reduces grain yields and also produces fungal toxins, primarily trichothecenes, that contaminate grains used for human and animal consumption. The most common trichothecenes produced by F. graminearum are Deoxynivalenol (DON), its acetyl derivatives 3- acetyl-deoxynivalenol (3ADON) and 15-acetyldeoxynivalenol (15ADON), nivalenol (NIV), and its acetylated derivative 4-acetyl-nivalenol (4ANIV or fusarenone X). Another point of remarkable interest is the increase in the presence of other casual agents of FHB as F. poae, a relatively weak pathogen compared with F. graminearum, but capable of produce a large number of mycotoxins, including trichothecenes of type A and B, beauvericin and enniatins. Several toxins were identified in wheat in years of epidemic FHB development. All reports showed the preponderance of DON. Surveys on Fusarium mycotoxins in small-grain cereals and their by-products are frequently conducted in the major production regions of the world such as North America and Europe, but information in South America is scarce and previous evidence has placed DON as the main Fusarium toxin detected in wheat and by-products in Argentina, Brazil and Uruguay.
El género fúngico Alternaria contienez especies tanto saprofitas como patógenas. Como patógenos d... more El género fúngico Alternaria contienez especies tanto saprofitas como patógenas. Como patógenos de las plantas, causan serios problemas en la agricultura, reduciendo el rendimiento del cultivo y deteriorando frutos en el almacenamiento. Las especies de este género también pueden ser micotoxicogénicas, capaces de colonizar los cultivos y acumular en los productos infectados, metabolitos secundarios que pueden afectar la salud humana y/o animal. En el presente trabajo, se muestrearon frutos de manzano (Malus domestica) y pera (Pyrus comunnis) en tres localidades del Alto Valle del río Negro (Cipolletti, General Roca y Villa Regina), a fin de determinar la presencia de especies del género Alternaria asociadas a estos cultivos en la región. Se obtuvieron un total de 267 aislamientos pertenecientes al género Alternaria. Los mismos fueron identificados por sus características morfológicas (Simmons, 2007) como iguales o similares a Alternaria tenuissima, en mayor proporción (85 %). También...
Bacterial Spot of Almond is a pathology caused by Xanthomonas arboricola pv. pruni responsible fo... more Bacterial Spot of Almond is a pathology caused by Xanthomonas arboricola pv. pruni responsible for significant yield losses. During 2017, young symptomatic almond fruits were observed in orchards of Northern Patagonia, in Argentina. Symptoms consisted of small watery circular lesions, from which an amber gummy substance emerged. The objective of this work was to determine the etiology of this pathology considering the fact that the symptoms were coincident with those previously described for the bacterial spot with gum production caused by Xanthomonas arboricola pv. pruni on almond fruits in other parts of the world. The presence of Xanthomonas arboricola in damaged fruits was determined confirming their identity by molecular analysis. Symptomatology and gum production were demonstrated performing pathogenicity tests. As a result, Bacterial Spot with gum production is reported for the first time on almond fruits in Argentina.
Apple is a major crop in Argentina where 50% of the production is derived to by-products. Industr... more Apple is a major crop in Argentina where 50% of the production is derived to by-products. Industries process either recently harvested apples or fruit stored for up to 9 months. This crop is susceptible to fungal diseases both external and internal, such as mouldy core (MC). The incidence of fungal pathogens changes during storage, as well as the risk associated with their presence since some contaminants belong to mycotoxigenic genera. The objective of this study was to characterize the fungal contaminants of Red Delicious apple fruit in Argentina evaluating their evolvement from field to process, with main interest on MC causal agents and mycotoxigenic species. A total of 240 apples were analysed; 140, recently harvested and intended for fresh consumption (C), and 100 stored for 9 months in a refrigerated chamber (0-3 °C) and destined to industrialization (I). The 86% of fresh consumption apples showed external fungal lesions, and only 14% were undamaged; MC incidence was 34%. High biodiversity was observed; Penicillium was the predominant genus (54%), followed by Alternaria spp. (41%). Only 3% of industrialization fruit were undamaged, 48% had external lesions and 51% MC. However, biodiversity was lower in these apples. Alternaria spp. was recovered from 60% of apples, mainly causing MC, while Penicillium spp. took second place (34%). All the Alternaria isolates belonged to Section Alternaria with A. tenuissima as the predominant species-group. Alternariol was synthesised by 75% of the isolates, while both alternariol monomethyl-ether and tenuazonic acid by 76%. From the 100 I apples, 93 were contaminated with at least one of these mycotoxins. Alternaria was the main causal agent of MC in Argentinean Red Delicious apples, and fruit affected by this disease might be incorporated into the process line, with a consequent risk of mycotoxin contamination in apple by-products.
The characteristics and quality of home-made dry cured sausages can be recognized and associated ... more The characteristics and quality of home-made dry cured sausages can be recognized and associated with the region of origin. The characteristics of this type of sausages result from the superficial mycobiota that spontaneously colonizes the products. The aim of this study was to identify the house mycobiota associated with home-made dry cured sausages from different localities of Argentina and characterize the populations of Penicillium nalgiovense present by morphological and biochemical markers. To this end, 79 samples were collected from 10 localities of three main producing regions (Buenos Aires, Córdoba and La Pampa provinces). A total of 196 isolates belonging to six genera and 17 species were obtained. The predominant genus was Penicillium (134 of the isolates) and the predominant species was P. nalgiovense (108 isolates). The isoenzyme patterns of α-esterase (α-EST; EC 3.1.1.1) and Malate dehydrogenase NADP+(MDHP; EC 1.1.1.40) were characterized in 48 of these isolates (ten from Colonia Caroya, ten from Oncativo, ten from Tandil, nine from Mercedes and nine from La Pampa). A total of 26 bands were observed: 17 for α-EST and 9 for MDHP. α-EST was the most polymorphic isoenzyme, whereas MDPH presented no polymorphism. The results were subjected to numerical analysis. Cluster analysis revealed the formation of two groups: Group I formed by 24 isolates from Córdoba and Buenos Aires provinces and Group II with 24 isolates from La Pampa and Buenos Aires province. These data suggest the existence of morphological and biochemical variations among P. nalgiovense populations with different geographical origin.
Fungal spores are normal components of external environments. They have been reported to be assoc... more Fungal spores are normal components of external environments. They have been reported to be associated with human, animal and plant diseases causing primary and opportunistic infections. Cladosporium is commonly the most frequently isolated genus from air samples, and its species are considered mainly saprophytic, but there is a wide variety of taxa that can cause adverse effects on human and animal health and also on plants. In this work, we aimed to record Cladosporium spores frequency of isolation in northern Argentinean Patagonia and to perform a molecular characterization based on actin gene complemented with EF1α and ITS genes. The ability of the pathogens to cause disease in pip fruits of Packham’s Triumph and Abate Fetel pears and red delicious apples was determined. Results confirmed Cladosporium spores as the main genera isolated from air samples, and the molecular characterization revealed the existence of 11 species in this region grouped in C. cladosporioides and C. herbarum complexes. Pathogenicity tests revealed that Cladosporium sp. cause disease on fruit. Abate Fetel was the most susceptible to infection. These results compose the first study in Argentina in respect of identification at species level of airborne Cladosporium spores, and furthermore, it is the first report in northern Patagonia and the high valley of Río Negro productive region. This knowledge can help farmers to take preventive measures in order to avoid biological damage.
This work describes a longitudinal study of three consecutive years carried out in the air of agr... more This work describes a longitudinal study of three consecutive years carried out in the air of agricultural environments located in Northern Patagonia with cold dry desert climate (Köppen: Bwk). This study area comprises a rural valley with unique geographical and climatological conditions. Therefore, the aim of this work is to quantify and determine its fungal diversity, so this knowledge will contribute to detect potential pathogenic and toxic fungi that has been adapted to this type of environment and may overcome the incipient climate change. Samplings were conducted in two geographical zones of the study area and a microflow air sampler was used to isolate fungal taxa. The annual mean fungal counts were found in the order of E+03 CFU/m3 of air. The aerial mycoflora revealed a wide biodiversity of at least 28 genera and 50 fungal species. Cladosporium was the most abundant genus (76.97%), followed by Alternaria (12.48%), Epicoccum (4.41%) and Botrytis (1.81%). The rest of the genera were found in relative densities lower than 1%. In terms of species, C. cladosporioides (34.82%), C. limoniforme (21.72%), A. tenuissima (10.94%) and C. asperulatum predominated (9.01%). This is the first report of the air mycoflora of rural environments with cold dry desert climate which provides useful information to take preventive measures to avoid biological damage.
Xerophilic fungi represent a serious problem due to their ability to grow at low water activities... more Xerophilic fungi represent a serious problem due to their ability to grow at low water activities causing the spoiling of low and intermediate moisture foods, stored goods and animal feeds, with the consequent economic losses. The combined effect of water activity and temperature of four Eurotium species isolated from animal feeds was investigated. Eurotium amstelodami, Eurotium chevalieri, Eurotium repens and Eurotium rubrum were grown at 5, 15, 25, 37 and 45°C on malt extract agar adjusted with glycerol in the range 0.710-0.993 of water activities. The cardinal model proposed by Rosso and Robinson (2001) was applied to fit growth data, with the variable water activity at fixed temperatures, obtaining three cardinal water activities (a, a, a) and the specific growth rate at the optimum a (μ). A probabilistic model was also applied to define the interface between growth and no-growth. The cardinal model provided an adequate estimation of the optimal a to grow and the maximum growth ...
'Moldy heart' caused by Alternaria spp has been previously reported in apples in Argentin... more 'Moldy heart' caused by Alternaria spp has been previously reported in apples in Argentina. However, according to our knowledge this is the first report of Alternaria spp in 'moldy heart' affected peaches in this country. Direct isolation of the pathogen was performed on Dichloran-Chloramphenicol-Malt Extract-Agar. Seven strains were isolated and identified as A. alternata and one as A. tenuissima. Their toxicogenic potential (alternariol (AOH), alternariol methyl ether (AME) and tenuazonic acid (TA) production) was determined. The toxins were extracted with chloroform and determined by TLC. All strains produced AOH and AME while six of them were TA producers. The fungicides tested on agar were captan and mancozeb. At 2.5g/L (commercial concentration) both fungicides inhibited the germination of spores. Captan completely inhibited mycelial growth. The effect of the fungicide on toxin production was variable according to fungicide type, doses, strains and toxins considered.
Fusarium Head Blight (FHB) is an important disease affecting the production of wheat worldwide. F... more Fusarium Head Blight (FHB) is an important disease affecting the production of wheat worldwide. Fusarium species are causal agents of Fusarium Head Blight (FHB) in cereals and Fusarium graminearum (Schwabe) (teleomorph Gibberella zeae (Schwein.)) is considered the main cause of the disease. FHB incidence reduces grain yields and also produces fungal toxins, primarily trichothecenes, that contaminate grains used for human and animal consumption. The most common trichothecenes produced by F. graminearum are Deoxynivalenol (DON), its acetyl derivatives 3- acetyl-deoxynivalenol (3ADON) and 15-acetyldeoxynivalenol (15ADON), nivalenol (NIV), and its acetylated derivative 4-acetyl-nivalenol (4ANIV or fusarenone X). Another point of remarkable interest is the increase in the presence of other casual agents of FHB as F. poae, a relatively weak pathogen compared with F. graminearum, but capable of produce a large number of mycotoxins, including trichothecenes of type A and B, beauvericin and enniatins. Several toxins were identified in wheat in years of epidemic FHB development. All reports showed the preponderance of DON. Surveys on Fusarium mycotoxins in small-grain cereals and their by-products are frequently conducted in the major production regions of the world such as North America and Europe, but information in South America is scarce and previous evidence has placed DON as the main Fusarium toxin detected in wheat and by-products in Argentina, Brazil and Uruguay.
Uploads
Papers by Graciela Pose