This paper represents the third contribution in the Genera of Phytopathogenic Fungi (GOPHY) serie... more This paper represents the third contribution in the Genera of Phytopathogenic Fungi (GOPHY) series. The series provides morphological descriptions, information about the pathology, distribution, hosts and disease symptoms for the treated genera, as well as primary and secondary DNA barcodes for the currently accepted species included in these. This third paper in the GOPHY series treats 21 genera of phytopathogenic fungi and their relatives including: Allophoma, Alternaria, Brunneosphaerella, Elsinoe, Exserohilum, Neosetophoma, Neostagonospora, Nothophoma, Parastagonospora, Phaeosphaeriopsis, Pleiocarpon, Pyrenophora, Ramichloridium, Seifertia, Seiridium, Septoriella, Setophoma, Stagonosporiopsis, Stemphylium, Tubakia and Zasmidium. This study includes three new genera, 42 new species, 23 new combinations, four new names, and three typifications of older names.
Purchase Short-Term Access Pay per Article - You may accessthis article(from the computer you are... more Purchase Short-Term Access Pay per Article - You may accessthis article(from the computer you are currently using) for 7daysfor US$7.00. Pay for Admission - You may accessall content in American Journal of Botany (from the computer you are currently using) for 14dayfor US ...
The genomes of Chrysoporthe austroafricana, Diplodia scrobiculata, Fusarium nygami, Leptographium... more The genomes of Chrysoporthe austroafricana, Diplodia scrobiculata, Fusarium nygami, Leptographium lundbergii, Limonomyces culmigenus, Stagonosporopsis tanaceti, and Thielaviopsis punctulata are presented in this genome announcement. These seven genomes are from endophytes, plant pathogens and economically important fungal species. The genome sizes range from 26.6 Mb in the case of Leptographium lundbergii to 44 Mb for Chrysoporthe austroafricana. The availability of these genome data will provide opportunities to resolve longstanding questions regarding the taxonomy of species in these genera, and may contribute to our understanding of the lifestyles through comparative studies with closely related organisms.
Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting... more Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting productivity and profitability of beet production worldwide. Fungicides are critical for the control of this disease and one of the most commonly used products is the quinone outside inhibitor (Q O I) azoxystrobin. In total, 150 C. beticola isolates were collected from two commercial processing table beet fields in Batavia, NY in 2014. The mating types of the entire population were determined, and genetic diversity of a subset of samples (n = 48) was assessed using five microsatellite loci. Sensitivity to azoxystrobin was tested using a spore germination assay. The cytochrome b gene was sequenced to check for the presence of point mutations known to confer Q O I resistance in fungi. High allelic diversity (H e = 0.50) and genotypic diversity (D* = 0.96), gametic equilibrium of the microsatellite loci, and equal ratios of mating types were suggestive of a mixed mode of reproduction for C. beticola. Resistance to azoxystrobin was prevalent because 41% of the isolates had values for effective concentrations reducing spore germination by 50% (EC 50) > 0.2 mg/ml. The G143A mutation, known to cause Q O I resistance in C. beticola, was found in isolates with EC 50 values between 0.207 and 19.397 mg/ml. A single isolate with an EC 50 of 0.272 mg/ml carried the F129L mutation, known to be associated with low levels of Q O I resistance in fungi. This is the first report of the F129L mutation in C. beticola. The implications of these findings for the epidemiology and control of CLS in table beet fields in New York are discussed.
Ray blight is a destructive disease of Asteraceae affecting chrysanthemum and pyrethrum industrie... more Ray blight is a destructive disease of Asteraceae affecting chrysanthemum and pyrethrum industries worldwide .
Morphological and molecular studies confirmed Paracercospora egenula as the primary cercosporoid ... more Morphological and molecular studies confirmed Paracercospora egenula as the primary cercosporoid fungus causing leaf spot of eggplant (Solanum melongena) in Hawaii. This is the first confirmed record of P. egenula in Hawaii, although it was previously reported as C. solani-melongenae, based on an interception at Oahu, Hawaii, in 1946. Another cercosporoid species, Cercospora melongenae, reported to cause leaf spot on eggplant in Hawaii, was not detected.
A novel pathogenesis-related protein 4 (PR4) encoding gene, LcPR4a, was induced in Lens culinaris... more A novel pathogenesis-related protein 4 (PR4) encoding gene, LcPR4a, was induced in Lens culinaris following Ascochyta lentis infection. LcPR4a encodes a predicted 146 amino acid protein of 15.8 kDa. The putative LcPR4a protein belongs to the class II PR4 family and has close phylogenetic affinity to PR4 proteins from related species. qPCR analysis revealed differential expression of the LcPR4a gene upon Ascochyta lentis infection in both resistant and susceptible cultivars. This, combined with preliminary in vitro antifungal assays of the recombinant protein expressed in E. coli, suggests the potential important role of LcPR4a in the defence response of lentil to Ascochyta lentis attack.
Ray blight disease of pyrethrum (Tanacetum cine-rariifolium) is shown to be caused by more than o... more Ray blight disease of pyrethrum (Tanacetum cine-rariifolium) is shown to be caused by more than one species of Stagonosporopsis. The Australian pathogen, previously identified as Phoma ligulicola var. inoxydabilis, represents a new species described as Stagonosporopsis tanaceti based on morphological characters and a five-gene phylogeny employing partial sequences of the actin, translation elongation factor 1-alpha, internal transcribed spacers and 5.8S of the nrDNA, 28S large subunit and beta-tubulin 2 gene sequences. Furthermore , the two varieties of Stagonosporopsis ligulicola are elevated to species level as S. chrysanthemi and S. inoxyda-bilis based on their DNA phylogeny and morphology.
Cercospora leaf spot (CLS), caused by Cercospora beticola, is a major disease of Beta vulgaris wo... more Cercospora leaf spot (CLS), caused by Cercospora beticola, is a major disease of Beta vulgaris worldwide. No sexual stage is known for C. beticola but in its asexual form it overwinters on infected plant debris as pseudostromata, and travels short distances by rain splash-dispersed conidiospores. Cercospora beticola infects a broad range of host species and may be seedborne. The relative contribution of these inoculum sources to CLS epidemics on table beet is not well understood. Pathogen isolates collected from table beet, Swiss chard and common lambsquarters in mixed-cropping farms and monoculture fields in New York and Hawaii, USA, were genotyped (n = 600) using 12 microsatellite markers. All isolates from CLS symptoms on lambsquarters were identified as C. chenopodii. Sympatric populations of C. beticola derived from Swiss chard and table beet were not genetically differentiated. Results suggested that local (within field) inoculum sources may be responsible for the initiation of CLS epidemics in mixed-cropping farms, whereas external sources of inoculum may be contributing to CLS epidemics in the monoculture fields in New York. New multiplex PCR assays were developed for mating-type determination for C. beticola. Implications of these findings for disease management are discussed. Population genetic studies of plant pathogens using selectively neutral genetic markers have made significant contributions to plant disease management in the past few decades 1, 2. These studies apply knowledge of the genetic composition and patterns of genetic diversity in pathogen populations to test hypotheses regarding their biology and plant disease epidemiology 3–5. Population genetics has been used to make inferences about the origin 6–9 , sources of inoculum 10, 11 , routes of introduction 12, 13 , migration pathways 7, 14–17 and reproductive biology 18, 19 of plant pathogens. Knowledge of the reproductive modes of plant pathogens is critical to disease management , due to its significant impacts on the evolutionary trajectory and epidemiology of pathogen populations. Recombination as a result of sexual reproduction is an influential evolutionary force that generates potentially adaptive genotypic diversity, purges deleterious mutations, and produces sexual propagules with enhanced survival and dispersal 20. In the absence of a known sexual stage for a plant pathogen, population genetic studies can provide indirect evidence to confirm the asexuality of pathogen populations 21–23 , or reveal historical or potentially cryptic sex in presumably asexual fungi 18, 19, 24. In pathogen populations with frequent sexual reproduction, high genotypic diversity, random association of selectively neutral genetic loci and equal distribution of the opposite mating-types (for heterothallic fungi) are expected. Alternatively, a strictly asexual population is characterized by low genotypic diversity, lack of recombinant genotypes, widespread occurrence of a few clonal lineages, non-random association of unlinked loci, and skewed distribution of alternate mating-types in the population 20. The presence of a sexual form remains unknown for the globally and economically important plant pathogen, Cercospora beticola, the cause of Cercospora leaf spot (CLS) of Beta vulgaris L. (sugar beet, table beet and Swiss chard) 25. Despite the lack of a known sexual form, C. beticola is considered to be a heterothallic, ascomycete fungus due to the discovery of two alternate mating-type genes (MAT1-1-1 and MAT1-2-1) at equal frequency in parts of Europe 26, 27. Population genetic studies have also suggested the potential presence of a sexual cycle for C. beticola in sugar beet production areas in North Dakota 28. In contrast, no evidence for sexual reproduction has been found in other parts of the USA 29 or the Middle East 30 .
Cercospora leaf spot caused by Cercospora beticola is a significant threat to the production of s... more Cercospora leaf spot caused by Cercospora beticola is a significant threat to the production of sugar and table beet worldwide. A de novo genome assembly of C. beticola was used to develop eight polymorphic and reproducible microsatellite markers for population genetic analyses. These markers were used, along with five previously described microsatellite loci to genotype two C. beticola populations from table beet fields in New York, USA. High allelic and genotypic diversity and low population differentiation were found between fields. Linkage disequilibrium of loci after clone-correction of datasets was attributed to the presence of two distinct clonal lineages within the populations. Linkage equilibrium of loci in one of the clusters supported the presence of sexual reproduction. The draft de novo genome assembly will help elucidate the reproductive system of C. beticola through investigating evidence of recombination in the C. beticola genome.
This paper represents the third contribution in the Genera of Phytopathogenic Fungi (GOPHY) serie... more This paper represents the third contribution in the Genera of Phytopathogenic Fungi (GOPHY) series. The series provides morphological descriptions, information about the pathology, distribution, hosts and disease symptoms for the treated genera, as well as primary and secondary DNA barcodes for the currently accepted species included in these. This third paper in the GOPHY series treats 21 genera of phytopathogenic fungi and their relatives including: Allophoma, Alternaria, Brunneosphaerella, Elsinoe, Exserohilum, Neosetophoma, Neostagonospora, Nothophoma, Parastagonospora, Phaeosphaeriopsis, Pleiocarpon, Pyrenophora, Ramichloridium, Seifertia, Seiridium, Septoriella, Setophoma, Stagonosporiopsis, Stemphylium, Tubakia and Zasmidium. This study includes three new genera, 42 new species, 23 new combinations, four new names, and three typifications of older names.
Purchase Short-Term Access Pay per Article - You may accessthis article(from the computer you are... more Purchase Short-Term Access Pay per Article - You may accessthis article(from the computer you are currently using) for 7daysfor US$7.00. Pay for Admission - You may accessall content in American Journal of Botany (from the computer you are currently using) for 14dayfor US ...
The genomes of Chrysoporthe austroafricana, Diplodia scrobiculata, Fusarium nygami, Leptographium... more The genomes of Chrysoporthe austroafricana, Diplodia scrobiculata, Fusarium nygami, Leptographium lundbergii, Limonomyces culmigenus, Stagonosporopsis tanaceti, and Thielaviopsis punctulata are presented in this genome announcement. These seven genomes are from endophytes, plant pathogens and economically important fungal species. The genome sizes range from 26.6 Mb in the case of Leptographium lundbergii to 44 Mb for Chrysoporthe austroafricana. The availability of these genome data will provide opportunities to resolve longstanding questions regarding the taxonomy of species in these genera, and may contribute to our understanding of the lifestyles through comparative studies with closely related organisms.
Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting... more Cercospora leaf spot (CLS), caused by Cercospora beticola, is one of the major diseases affecting productivity and profitability of beet production worldwide. Fungicides are critical for the control of this disease and one of the most commonly used products is the quinone outside inhibitor (Q O I) azoxystrobin. In total, 150 C. beticola isolates were collected from two commercial processing table beet fields in Batavia, NY in 2014. The mating types of the entire population were determined, and genetic diversity of a subset of samples (n = 48) was assessed using five microsatellite loci. Sensitivity to azoxystrobin was tested using a spore germination assay. The cytochrome b gene was sequenced to check for the presence of point mutations known to confer Q O I resistance in fungi. High allelic diversity (H e = 0.50) and genotypic diversity (D* = 0.96), gametic equilibrium of the microsatellite loci, and equal ratios of mating types were suggestive of a mixed mode of reproduction for C. beticola. Resistance to azoxystrobin was prevalent because 41% of the isolates had values for effective concentrations reducing spore germination by 50% (EC 50) > 0.2 mg/ml. The G143A mutation, known to cause Q O I resistance in C. beticola, was found in isolates with EC 50 values between 0.207 and 19.397 mg/ml. A single isolate with an EC 50 of 0.272 mg/ml carried the F129L mutation, known to be associated with low levels of Q O I resistance in fungi. This is the first report of the F129L mutation in C. beticola. The implications of these findings for the epidemiology and control of CLS in table beet fields in New York are discussed.
Ray blight is a destructive disease of Asteraceae affecting chrysanthemum and pyrethrum industrie... more Ray blight is a destructive disease of Asteraceae affecting chrysanthemum and pyrethrum industries worldwide .
Morphological and molecular studies confirmed Paracercospora egenula as the primary cercosporoid ... more Morphological and molecular studies confirmed Paracercospora egenula as the primary cercosporoid fungus causing leaf spot of eggplant (Solanum melongena) in Hawaii. This is the first confirmed record of P. egenula in Hawaii, although it was previously reported as C. solani-melongenae, based on an interception at Oahu, Hawaii, in 1946. Another cercosporoid species, Cercospora melongenae, reported to cause leaf spot on eggplant in Hawaii, was not detected.
A novel pathogenesis-related protein 4 (PR4) encoding gene, LcPR4a, was induced in Lens culinaris... more A novel pathogenesis-related protein 4 (PR4) encoding gene, LcPR4a, was induced in Lens culinaris following Ascochyta lentis infection. LcPR4a encodes a predicted 146 amino acid protein of 15.8 kDa. The putative LcPR4a protein belongs to the class II PR4 family and has close phylogenetic affinity to PR4 proteins from related species. qPCR analysis revealed differential expression of the LcPR4a gene upon Ascochyta lentis infection in both resistant and susceptible cultivars. This, combined with preliminary in vitro antifungal assays of the recombinant protein expressed in E. coli, suggests the potential important role of LcPR4a in the defence response of lentil to Ascochyta lentis attack.
Ray blight disease of pyrethrum (Tanacetum cine-rariifolium) is shown to be caused by more than o... more Ray blight disease of pyrethrum (Tanacetum cine-rariifolium) is shown to be caused by more than one species of Stagonosporopsis. The Australian pathogen, previously identified as Phoma ligulicola var. inoxydabilis, represents a new species described as Stagonosporopsis tanaceti based on morphological characters and a five-gene phylogeny employing partial sequences of the actin, translation elongation factor 1-alpha, internal transcribed spacers and 5.8S of the nrDNA, 28S large subunit and beta-tubulin 2 gene sequences. Furthermore , the two varieties of Stagonosporopsis ligulicola are elevated to species level as S. chrysanthemi and S. inoxyda-bilis based on their DNA phylogeny and morphology.
Cercospora leaf spot (CLS), caused by Cercospora beticola, is a major disease of Beta vulgaris wo... more Cercospora leaf spot (CLS), caused by Cercospora beticola, is a major disease of Beta vulgaris worldwide. No sexual stage is known for C. beticola but in its asexual form it overwinters on infected plant debris as pseudostromata, and travels short distances by rain splash-dispersed conidiospores. Cercospora beticola infects a broad range of host species and may be seedborne. The relative contribution of these inoculum sources to CLS epidemics on table beet is not well understood. Pathogen isolates collected from table beet, Swiss chard and common lambsquarters in mixed-cropping farms and monoculture fields in New York and Hawaii, USA, were genotyped (n = 600) using 12 microsatellite markers. All isolates from CLS symptoms on lambsquarters were identified as C. chenopodii. Sympatric populations of C. beticola derived from Swiss chard and table beet were not genetically differentiated. Results suggested that local (within field) inoculum sources may be responsible for the initiation of CLS epidemics in mixed-cropping farms, whereas external sources of inoculum may be contributing to CLS epidemics in the monoculture fields in New York. New multiplex PCR assays were developed for mating-type determination for C. beticola. Implications of these findings for disease management are discussed. Population genetic studies of plant pathogens using selectively neutral genetic markers have made significant contributions to plant disease management in the past few decades 1, 2. These studies apply knowledge of the genetic composition and patterns of genetic diversity in pathogen populations to test hypotheses regarding their biology and plant disease epidemiology 3–5. Population genetics has been used to make inferences about the origin 6–9 , sources of inoculum 10, 11 , routes of introduction 12, 13 , migration pathways 7, 14–17 and reproductive biology 18, 19 of plant pathogens. Knowledge of the reproductive modes of plant pathogens is critical to disease management , due to its significant impacts on the evolutionary trajectory and epidemiology of pathogen populations. Recombination as a result of sexual reproduction is an influential evolutionary force that generates potentially adaptive genotypic diversity, purges deleterious mutations, and produces sexual propagules with enhanced survival and dispersal 20. In the absence of a known sexual stage for a plant pathogen, population genetic studies can provide indirect evidence to confirm the asexuality of pathogen populations 21–23 , or reveal historical or potentially cryptic sex in presumably asexual fungi 18, 19, 24. In pathogen populations with frequent sexual reproduction, high genotypic diversity, random association of selectively neutral genetic loci and equal distribution of the opposite mating-types (for heterothallic fungi) are expected. Alternatively, a strictly asexual population is characterized by low genotypic diversity, lack of recombinant genotypes, widespread occurrence of a few clonal lineages, non-random association of unlinked loci, and skewed distribution of alternate mating-types in the population 20. The presence of a sexual form remains unknown for the globally and economically important plant pathogen, Cercospora beticola, the cause of Cercospora leaf spot (CLS) of Beta vulgaris L. (sugar beet, table beet and Swiss chard) 25. Despite the lack of a known sexual form, C. beticola is considered to be a heterothallic, ascomycete fungus due to the discovery of two alternate mating-type genes (MAT1-1-1 and MAT1-2-1) at equal frequency in parts of Europe 26, 27. Population genetic studies have also suggested the potential presence of a sexual cycle for C. beticola in sugar beet production areas in North Dakota 28. In contrast, no evidence for sexual reproduction has been found in other parts of the USA 29 or the Middle East 30 .
Cercospora leaf spot caused by Cercospora beticola is a significant threat to the production of s... more Cercospora leaf spot caused by Cercospora beticola is a significant threat to the production of sugar and table beet worldwide. A de novo genome assembly of C. beticola was used to develop eight polymorphic and reproducible microsatellite markers for population genetic analyses. These markers were used, along with five previously described microsatellite loci to genotype two C. beticola populations from table beet fields in New York, USA. High allelic and genotypic diversity and low population differentiation were found between fields. Linkage disequilibrium of loci after clone-correction of datasets was attributed to the presence of two distinct clonal lineages within the populations. Linkage equilibrium of loci in one of the clusters supported the presence of sexual reproduction. The draft de novo genome assembly will help elucidate the reproductive system of C. beticola through investigating evidence of recombination in the C. beticola genome.
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