<i>Colletotrichum acutatum</i> is major pathogen of fruit crops, causing economically... more <i>Colletotrichum acutatum</i> is major pathogen of fruit crops, causing economically important losses of temperate, subtropical and tropical fruits worldwide. However, few studies have been carried out on key aspects of its biology. This is mainly because traditionally isolates of <i>C. acutatum</i> were often wrongly identified as <i>C. gloeosporioides</i>. Effective separation of the two species was not possible until the introduction of molecular tools for taxonomy. The life cycle of <i>C. acutatum</i> comprises a sexual and an asexual stage and much remains to be resolved regarding the genetics of sexuality and the effects of the sexual stage on population structure. <i>Colletotrichum acutatum</i> exhibits both infection strategies described for <i>Colletotrichum</i> species, i.e. intracellular hemibiotrophy and subcuticular-intramural necrotrophy, and may also undergo a period of quiescence in order to overcome resistance mechanisms in immature fruit such as pre-formed toxic compounds and phytoalexins, or due to the unsuitability of unripe fruit to fulfill the nutritional and energy requirements of the pathogen. <i>Colletotrichum acutatum</i> may overwinter as mycelium and/or appressoria in or on different parts of the host. Conidia are water-born and spread by rain episodes so infections are usually highest during the wettest periods of the growing season. Current management strategies for this fungus comprise the exploitation of cultivar resistance, cultural, chemical, and biological control methods, and preventive strategies such as disease-forecasting models. This review focuses on the current knowledge of biological aspects of <i>C. acutatum</i> and related <i>Colletotrichum </i>species and includes a discussion of the progress towards their control.<br><br><i>Colletotrichum acutatum</i> es uno de los principales hongos patógenos en agricultura y responsable de importantes pérdidas económicas en frutales en áreas tanto de climas templados como subtropicales y tropicales. Sin embargo, existen pocos estu [...]
The fungal pathogens Fusarium falciforme and Fusarium keratoplasticum are responsible for the sea... more The fungal pathogens Fusarium falciforme and Fusarium keratoplasticum are responsible for the sea turtle egg fusariosis (STEF) throughout main nesting areas of the world. In this study, we investigated whether eggs of the invasive alien red-eared slider turtle, Trachemys scripta, can carry these fungal pathogens. Using multilocus sequence typing of four nuclear DNA regions, we found that eggs of T. scripta naturally can carry these two Fusarium pathogenic species, as well as other Fusarium species belonging to the Fusarium solani species complex. Physiological studies on F. falciforme and F. keratoplasticum isolates revealed that their optimal growth temperature coincided with the pivotal temperature for T. scripta embryos, ca 29.5 ± 0.5 °C, providing an evidence of a potential advantageous biological property for host colonization and virulence. A host-pathogen interaction network analysis of species of the FSSC and their hosts confirmed that F. falciforme and F. keratoplasticum are generalist pathogens in a wide range of animal hosts of worldwide geographical distribution. Finally, we show that nesting areas of this invasive turtle T. scripta in the Mediterranean freshwater marshes can act as chronic reservoirs of these STEF pathogens, and this invasive species can act as a potential vector for the spread of STEF among wild native species and even to humans.
Procambarus clarkii is a worldwide freshwater invasive crustacean from North America and was firs... more Procambarus clarkii is a worldwide freshwater invasive crustacean from North America and was first introduced into Europe the 1970s. Along with P. clarkii, another invasive alien species was also spreading: Aphanomyces astaci. This pathogen is listed among the 100 World’s worst invasive species and involved in the European native crayfish decline. Although both species live in freshwater ecosystems, P. clarkii can withstand brackish waters and inhabit estuarine habitats. However, the presence of A. astaci associated to North American crayfishes has never been described in brackish waters. In this study, we have investigated the presence of A. astaci in a P. clarkii population of a Mediterranean coastal lagoon in the Albufera Natural Park, Valencia, Spain introduced in 1976. Our study confirmed the presence of this pathogen, and suggests that A. astaci has been spreading for more than four decades in the mentioned estuarine environment. Mitochondrial ribosomal rnnS and rnnL indicated...
Global climate patterns are shifting due to anthropogenic causes, putting pressure on many specie... more Global climate patterns are shifting due to anthropogenic causes, putting pressure on many species that are unable to adapt to such rapid changes. Sea turtle clutches, for example, normally develop between 26 and 33°C, but tolerate higher temperatures at the end of development. High temperatures, protracted rainfall, and droughts have been linked to fewer hatchlings. Likewise, climatic conditions can affect the size of sea turtle hatchlings, which could affect their probability of survival. We analyzed the effects of a biotic factor (egg mass) and environmental factors (precipitation and incubation temperature) on East Pacific leatherback turtle Dermochelys coriacea hatchling sizes in Costa Rica. Hatchling size (mass, straight carapace length, straight carapace width, and head width) was affected by both biotic and environmental factors. While egg mass was the strongest predictor for hatchling mass, temperature was the strongest for carapace length and head width. Carapace width was...
Several European freshwater crayfish species are currently included in one of the IUCN Red list c... more Several European freshwater crayfish species are currently included in one of the IUCN Red list categories. In the Iberian Peninsula, the native Austropotamobius pallipes species complex (the white clawed crayfish, WCC) has experienced a drastic decline since 1973. Implementing conservation management strategies for this species requires a better understanding of the patterns and structure of its genetic diversity. In this study, we assessed the levels and patterns of genetic variation in 71 populations along the whole distributional range of the WCC in the Iberian Peninsula. The two mitochondrial markers analyzed (Cytochrome Oxidase subunit I and 16S rRNA genes) indicated high levels of genetic diversity, which are significantly geographically structured in three main genetic groups, two corresponding to Northern and one to Central-Eastern and the westernmost Iberian Peninsula. The diversity found included new private haplotypes, and revealed the potential effect of paleogeographic...
The causative agent of crayfish plague, Aphanomyces astaci (Saprolegniales, Oomycota), is one of ... more The causative agent of crayfish plague, Aphanomyces astaci (Saprolegniales, Oomycota), is one of the 100 world's worst invasive alien species and represents a major threat to freshwater crayfish species worldwide. A better understanding of the biology and epidemiology of A. astaci relies on the application of efficient tools to detect the pathogen and assess its genetic diversity. In this study, we validated the specificity of two recently developed PCR-based approaches used to detect A. astaci groups. The first relies on the analysis of mitochondrial ribosomal rnnS (small) and rnnL (large) subunit sequences and the second, of sequences obtained by using genotype-specific primers designed from A. astaci whole genome sequencing. For this purpose, we tested the specificity against 76 selected isolates, including other oomycete species and the recently described species Aphanomyces fennicus, which, when used in nrITS-based specific tests for A. astaci, is known to result in a false positive. Under both approaches, we were able to efficiently and accurately identify A. astaci and its genetic groups in both pure cultures and clinical samples. We report that sequence analysis of the rnnS region alone is sufficient for the identification of A. astaci and a partial characterization of haplogroups. In contrast, the rnnL region alone is not sufficiently informative for A. astaci identification as other oomycete species present sequences identical to those of A. astaci.
The initial penetration process of appressoria of Colletotrichum acutatum on almond leaves was st... more The initial penetration process of appressoria of Colletotrichum acutatum on almond leaves was studied using digital image analysis of light micrographs and scanning electron microscopy. For image analysis, a series of sequential, partially focused digital micrographs of appressoria was analyzed to generate a single, completely focused montage image with a continuous in-focus depth of field. In studies on the development of the internal light spot (ILS), we observed that 50.4% of the appressoria formed an ILS after leaves were inoculated and incubated for 12 h at 20 degrees C, and that this increased to 95.8% after 24 h. Comparative image analyses of appressoria with and without ILSs using depth relief mapping and line profile software options showed that the ILS had a depth relief that was below that of the leaf surface. Depth relief analysis in the ILS region during incubation revealed an increase in depth in this area of up to 1.8 mum in some of the appressoria. A comparative mor...
... Oomycete Genetics and Genomics: Diversity, Interactions, and Research Tools Edited by Kurt La... more ... Oomycete Genetics and Genomics: Diversity, Interactions, and Research Tools Edited by Kurt Lamour and Sophien Kamoun Copyright r 2009 John Wiley &amp;amp;amp;amp;amp;amp;amp; Sons, Inc. Emma Robertson and Vicky Anderson contributed equally to this work. 407 Page 2. ...
SUMMARYThe crayfish plague pathogen, Aphanomyces astaci, is one of the most serious threats to in... more SUMMARYThe crayfish plague pathogen, Aphanomyces astaci, is one of the most serious threats to indigenous European crayfish species. The North American invasive spiny-cheek crayfish, Orconectes limosus, is an important source of this pathogen in central and western Europe. We evaluated potential changes in A. astaci spore release rate from infected individuals of this species by experiments investigating the pathogen transmission to susceptible noble crayfish, Astacus astacus. We filtered defined volumes of water regularly to quantify spore concentration, and sampled crayfish tissues at the end of the experiment. The filters and tissues were then tested for the presence of A. astaci DNA by species-specific quantitative PCR. Additionally, we tested the efficiency of horizontal transmission to apparently uninfected O. limosus. The experiments confirmed that A. astaci can be transmitted to susceptible crayfish during intermoult periods, and that the pathogen was more frequently detecte...
<i>Colletotrichum acutatum</i> is major pathogen of fruit crops, causing economically... more <i>Colletotrichum acutatum</i> is major pathogen of fruit crops, causing economically important losses of temperate, subtropical and tropical fruits worldwide. However, few studies have been carried out on key aspects of its biology. This is mainly because traditionally isolates of <i>C. acutatum</i> were often wrongly identified as <i>C. gloeosporioides</i>. Effective separation of the two species was not possible until the introduction of molecular tools for taxonomy. The life cycle of <i>C. acutatum</i> comprises a sexual and an asexual stage and much remains to be resolved regarding the genetics of sexuality and the effects of the sexual stage on population structure. <i>Colletotrichum acutatum</i> exhibits both infection strategies described for <i>Colletotrichum</i> species, i.e. intracellular hemibiotrophy and subcuticular-intramural necrotrophy, and may also undergo a period of quiescence in order to overcome resistance mechanisms in immature fruit such as pre-formed toxic compounds and phytoalexins, or due to the unsuitability of unripe fruit to fulfill the nutritional and energy requirements of the pathogen. <i>Colletotrichum acutatum</i> may overwinter as mycelium and/or appressoria in or on different parts of the host. Conidia are water-born and spread by rain episodes so infections are usually highest during the wettest periods of the growing season. Current management strategies for this fungus comprise the exploitation of cultivar resistance, cultural, chemical, and biological control methods, and preventive strategies such as disease-forecasting models. This review focuses on the current knowledge of biological aspects of <i>C. acutatum</i> and related <i>Colletotrichum </i>species and includes a discussion of the progress towards their control.<br><br><i>Colletotrichum acutatum</i> es uno de los principales hongos patógenos en agricultura y responsable de importantes pérdidas económicas en frutales en áreas tanto de climas templados como subtropicales y tropicales. Sin embargo, existen pocos estu [...]
The fungal pathogens Fusarium falciforme and Fusarium keratoplasticum are responsible for the sea... more The fungal pathogens Fusarium falciforme and Fusarium keratoplasticum are responsible for the sea turtle egg fusariosis (STEF) throughout main nesting areas of the world. In this study, we investigated whether eggs of the invasive alien red-eared slider turtle, Trachemys scripta, can carry these fungal pathogens. Using multilocus sequence typing of four nuclear DNA regions, we found that eggs of T. scripta naturally can carry these two Fusarium pathogenic species, as well as other Fusarium species belonging to the Fusarium solani species complex. Physiological studies on F. falciforme and F. keratoplasticum isolates revealed that their optimal growth temperature coincided with the pivotal temperature for T. scripta embryos, ca 29.5 ± 0.5 °C, providing an evidence of a potential advantageous biological property for host colonization and virulence. A host-pathogen interaction network analysis of species of the FSSC and their hosts confirmed that F. falciforme and F. keratoplasticum are generalist pathogens in a wide range of animal hosts of worldwide geographical distribution. Finally, we show that nesting areas of this invasive turtle T. scripta in the Mediterranean freshwater marshes can act as chronic reservoirs of these STEF pathogens, and this invasive species can act as a potential vector for the spread of STEF among wild native species and even to humans.
Procambarus clarkii is a worldwide freshwater invasive crustacean from North America and was firs... more Procambarus clarkii is a worldwide freshwater invasive crustacean from North America and was first introduced into Europe the 1970s. Along with P. clarkii, another invasive alien species was also spreading: Aphanomyces astaci. This pathogen is listed among the 100 World’s worst invasive species and involved in the European native crayfish decline. Although both species live in freshwater ecosystems, P. clarkii can withstand brackish waters and inhabit estuarine habitats. However, the presence of A. astaci associated to North American crayfishes has never been described in brackish waters. In this study, we have investigated the presence of A. astaci in a P. clarkii population of a Mediterranean coastal lagoon in the Albufera Natural Park, Valencia, Spain introduced in 1976. Our study confirmed the presence of this pathogen, and suggests that A. astaci has been spreading for more than four decades in the mentioned estuarine environment. Mitochondrial ribosomal rnnS and rnnL indicated...
Global climate patterns are shifting due to anthropogenic causes, putting pressure on many specie... more Global climate patterns are shifting due to anthropogenic causes, putting pressure on many species that are unable to adapt to such rapid changes. Sea turtle clutches, for example, normally develop between 26 and 33°C, but tolerate higher temperatures at the end of development. High temperatures, protracted rainfall, and droughts have been linked to fewer hatchlings. Likewise, climatic conditions can affect the size of sea turtle hatchlings, which could affect their probability of survival. We analyzed the effects of a biotic factor (egg mass) and environmental factors (precipitation and incubation temperature) on East Pacific leatherback turtle Dermochelys coriacea hatchling sizes in Costa Rica. Hatchling size (mass, straight carapace length, straight carapace width, and head width) was affected by both biotic and environmental factors. While egg mass was the strongest predictor for hatchling mass, temperature was the strongest for carapace length and head width. Carapace width was...
Several European freshwater crayfish species are currently included in one of the IUCN Red list c... more Several European freshwater crayfish species are currently included in one of the IUCN Red list categories. In the Iberian Peninsula, the native Austropotamobius pallipes species complex (the white clawed crayfish, WCC) has experienced a drastic decline since 1973. Implementing conservation management strategies for this species requires a better understanding of the patterns and structure of its genetic diversity. In this study, we assessed the levels and patterns of genetic variation in 71 populations along the whole distributional range of the WCC in the Iberian Peninsula. The two mitochondrial markers analyzed (Cytochrome Oxidase subunit I and 16S rRNA genes) indicated high levels of genetic diversity, which are significantly geographically structured in three main genetic groups, two corresponding to Northern and one to Central-Eastern and the westernmost Iberian Peninsula. The diversity found included new private haplotypes, and revealed the potential effect of paleogeographic...
The causative agent of crayfish plague, Aphanomyces astaci (Saprolegniales, Oomycota), is one of ... more The causative agent of crayfish plague, Aphanomyces astaci (Saprolegniales, Oomycota), is one of the 100 world's worst invasive alien species and represents a major threat to freshwater crayfish species worldwide. A better understanding of the biology and epidemiology of A. astaci relies on the application of efficient tools to detect the pathogen and assess its genetic diversity. In this study, we validated the specificity of two recently developed PCR-based approaches used to detect A. astaci groups. The first relies on the analysis of mitochondrial ribosomal rnnS (small) and rnnL (large) subunit sequences and the second, of sequences obtained by using genotype-specific primers designed from A. astaci whole genome sequencing. For this purpose, we tested the specificity against 76 selected isolates, including other oomycete species and the recently described species Aphanomyces fennicus, which, when used in nrITS-based specific tests for A. astaci, is known to result in a false positive. Under both approaches, we were able to efficiently and accurately identify A. astaci and its genetic groups in both pure cultures and clinical samples. We report that sequence analysis of the rnnS region alone is sufficient for the identification of A. astaci and a partial characterization of haplogroups. In contrast, the rnnL region alone is not sufficiently informative for A. astaci identification as other oomycete species present sequences identical to those of A. astaci.
The initial penetration process of appressoria of Colletotrichum acutatum on almond leaves was st... more The initial penetration process of appressoria of Colletotrichum acutatum on almond leaves was studied using digital image analysis of light micrographs and scanning electron microscopy. For image analysis, a series of sequential, partially focused digital micrographs of appressoria was analyzed to generate a single, completely focused montage image with a continuous in-focus depth of field. In studies on the development of the internal light spot (ILS), we observed that 50.4% of the appressoria formed an ILS after leaves were inoculated and incubated for 12 h at 20 degrees C, and that this increased to 95.8% after 24 h. Comparative image analyses of appressoria with and without ILSs using depth relief mapping and line profile software options showed that the ILS had a depth relief that was below that of the leaf surface. Depth relief analysis in the ILS region during incubation revealed an increase in depth in this area of up to 1.8 mum in some of the appressoria. A comparative mor...
... Oomycete Genetics and Genomics: Diversity, Interactions, and Research Tools Edited by Kurt La... more ... Oomycete Genetics and Genomics: Diversity, Interactions, and Research Tools Edited by Kurt Lamour and Sophien Kamoun Copyright r 2009 John Wiley &amp;amp;amp;amp;amp;amp;amp; Sons, Inc. Emma Robertson and Vicky Anderson contributed equally to this work. 407 Page 2. ...
SUMMARYThe crayfish plague pathogen, Aphanomyces astaci, is one of the most serious threats to in... more SUMMARYThe crayfish plague pathogen, Aphanomyces astaci, is one of the most serious threats to indigenous European crayfish species. The North American invasive spiny-cheek crayfish, Orconectes limosus, is an important source of this pathogen in central and western Europe. We evaluated potential changes in A. astaci spore release rate from infected individuals of this species by experiments investigating the pathogen transmission to susceptible noble crayfish, Astacus astacus. We filtered defined volumes of water regularly to quantify spore concentration, and sampled crayfish tissues at the end of the experiment. The filters and tissues were then tested for the presence of A. astaci DNA by species-specific quantitative PCR. Additionally, we tested the efficiency of horizontal transmission to apparently uninfected O. limosus. The experiments confirmed that A. astaci can be transmitted to susceptible crayfish during intermoult periods, and that the pathogen was more frequently detecte...
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Papers by Javier Diéguez Uribeondo