1
|
Bock CH, Frusso E, Zoppolo R, Ortiz ER, Shiller J, Charlton ND, Young CA, Randall JJ. Population Genetic Characteristics and Mating Type Frequency of Venturia effusa from Pecan in South America. Phytopathology 2022; 112:2224-2235. [PMID: 35596236 DOI: 10.1094/phyto-01-22-0031-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Scab, caused by the plant-pathogenic fungus Venturia effusa, is a major disease of pecan in South America, resulting in loss of quantity and quality of nut yield. Characteristics of the populations of V. effusa in South America are unknown. We used microsatellites to describe the genetic diversity and population structure of V. effusa in South America, and determined the mating type status of the pathogen. The four hierarchically sampled orchard populations from Argentina (AR), Brazil (BRC and BRS), and Uruguay (UR) had moderate to high genotypic and gene diversity. There was evidence of population differentiation (Fst = 0.196) but the correlation between geographic distance and genetic distance was not statistically significant. Genetic differentiation was minimal between the UR, BRC, and BRS populations, and these populations were more clearly differentiated from the AR population. The MAT1-1 and MAT1-2 mating types occurred in all four orchards and their frequencies did not deviate from the 1:1 ratio expected under random mating; however, multilocus linkage equilibrium was rejected in three of the four populations. The population genetics of South American populations of V. effusa has many similarities to the population genetics of V. effusa previously described in the United States. Characterizing the populations genetics and reproductive systems of V. effusa are important to establish the evolutionary potential of the pathogen and, thus, its adaptability-and can provide a basis for informed approaches to utilizing available host resistance and determining phytosanitary needs.
Collapse
Affiliation(s)
- Clive H Bock
- United States Department of Agriculture-Agriculture Research Service, Southeastern Fruit and Tree Nut Research Lab, 21 Dunbar Road, Byron, GA 31008, U.S.A
| | - Enrique Frusso
- Instituto de Recursos Biológicos, INTA Castelar, Las Cabañas y De Los Reseros s.n., (1686) Hurlingham, Buenos Aires, Argentina
| | - Roberto Zoppolo
- Instituto Nacional de Investigación Agropecuaria - INIA Las Brujas, Ruta 48 - km 10, El Colorado, Canelones, Uruguay, CP 90200
| | - Edson R Ortiz
- Divinut Indústria de Nozes Ltda., Rodovia BR-153, km 375, CEP 96504-800 - Cachoeira do Sul/RS, Brazil
| | | | - Nikki D Charlton
- Noble Research Institute, 2510 Sam Noble Parkway, Ardmore, OK 73401, U.S.A
| | - Carolyn A Young
- Noble Research Institute, 2510 Sam Noble Parkway, Ardmore, OK 73401, U.S.A
- Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater, 74078, U.S.A
| | | |
Collapse
|
2
|
Bock CH, Young CA, Zhang M, Chen C, Brannen PM, Adaskaveg J, Charlton ND. Mating Type Idiomorphs, Heterothallism, and High Genetic Diversity in Venturia carpophila, Cause of Peach Scab. Phytopathology 2021; 111:408-424. [PMID: 32748736 DOI: 10.1094/phyto-12-19-0485-r] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Scab (caused by Venturia carpophila) is a major disease affecting peach in the eastern United States. The aims of the study were to characterize the mating-type loci in V. carpophila, determine whether they are in equilibrium, and assess the population genetic diversity and structure of the pathogen. The mating-type gene MAT1-1-1 was identified in isolate JP3-5 in an available genome sequence, and the MAT1-2-1 gene was PCR amplified from isolate PS1-1, thus indicating a heterothallic structure. Mating-type loci structures were consistent with those of other Venturia spp. (V. effusa and V. inaequalis): the mating-type gene is positioned between APN2 encoding a DNA lyase and a gene encoding a Pleckstrin homology domain. Primers designed to each of the mating-type genes and a reference gene TUB2 were used as a multiplex PCR to screen a population (n = 81) of V. carpophila from various locations in the eastern United States. Mating types in five of the nine populations studied were in equilibrium. Among the 81 isolates, there were 69 multilocus genotypes. A population genetic analysis of the populations with >10 individuals (four populations) showed them to be genetically diverse. Linkage disequilibrium was found in five of nine populations with ≥4 isolates. A discriminant analysis of principal components indicated three genetic clusters, although extensive admixture was observed. Mating-type identification in V. carpophila provides a basis for understanding reproductive methods of the pathogen and can be a basis for further studies of the genetics of the peach scab pathogen.
Collapse
Affiliation(s)
- Clive H Bock
- United States Department of Agriculture-Agricultural Research Service-Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008
| | - Carolyn A Young
- Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401
| | - Minling Zhang
- United States Department of Agriculture-Agricultural Research Service-Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008
| | - Chunxian Chen
- United States Department of Agriculture-Agricultural Research Service-Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008
| | - Phillip M Brannen
- Department of Plant Pathology, University of Georgia, 2105 Miller Plant Sciences Building, Athens, GA 30602
| | - Jim Adaskaveg
- Department of Plant Pathology and Microbiology, University of California Riverside, Riverside, CA 92521
| | - Nikki D Charlton
- Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401
| |
Collapse
|
3
|
Abstract
Pecan scab, caused by Venturia effusa, is the most prevalent disease of pecan in the southeastern United States. Recent characterization of the mating type (MAT) distribution of V. effusa revealed that the MAT idiomorphs are in equilibrium at various spatial scales, indicative of regular sexual recombination. However, the occurrence of the sexual stage of V. effusa has never been observed, and the pathogen was previously considered to rely entirely on asexual reproduction. We were able to generate the sexual stage by pairing isolates of opposite mating types on oatmeal culture media. Cultures were incubated at 24 C for 2 mo to allow hyphae from isolates of each mating type to interact. Culture plates were then incubated at 4 C for 4 mo, after which immature pseudothecia were observed. Following exposure to a 12-h photoperiod for 2 wk at 24 C, asci and ascospores readily developed. Pseudothecium and ascospore production was optimal when incubated for 4 mo at 4 C. We utilized progeny from a cross of an albino isolate and wild-type (melanized) isolates to determine that recombination had occurred. Multilocus genotyping using 32 microsatellite markers confirmed that progeny were the result of recombination, which was further supported by segregation of mating types and culture pigmentation. Albino progeny were all confirmed to contain the same mutation in the polyketide synthase (PKS1) melanin biosynthesis gene as the albino parent. The results of this study demonstrate the heterothallic nature of V. effusa. The impact of determining the source of the overwintering ascostroma will aid in management decisions to reduce the primary inoculum in the disease cycle.
Collapse
Affiliation(s)
| | - Mihwa Yi
- Noble Research Institute , LLC, Ardmore, Oklahoma 73401
| | - Clive H Bock
- Southeastern Fruit and Tree Nut Research Laboratory, Agricultural Research Service, United States Department of Agriculture , Byron, Georgia 31008
| | - Minling Zhang
- Southeastern Fruit and Tree Nut Research Laboratory, Agricultural Research Service, United States Department of Agriculture , Byron, Georgia 31008
| | | |
Collapse
|
4
|
Gundel PE, Sun P, Charlton ND, Young CA, Miller TEX, Rudgers JA. Simulated folivory increases vertical transmission of fungal endophytes that deter herbivores and alter tolerance to herbivory in Poa autumnalis. Ann Bot 2020; 125:981-991. [PMID: 32010946 PMCID: PMC7218812 DOI: 10.1093/aob/mcaa021] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 01/31/2020] [Indexed: 05/02/2023]
Abstract
BACKGROUND AND AIMS The processes that maintain variation in the prevalence of symbioses within host populations are not well understood. While the fitness benefits of symbiosis have clearly been shown to drive changes in symbiont prevalence, the rate of transmission has been less well studied. Many grasses host symbiotic fungi (Epichloë spp.), which can be transmitted vertically to seeds or horizontally via spores. These symbionts may protect plants against herbivores by producing alkaloids or by increasing tolerance to damage. Therefore, herbivory may be a key ecological factor that alters symbiont prevalence within host populations by affecting either symbiont benefits to host fitness or the symbiont transmission rate. Here, we addressed the following questions: Does symbiont presence modulate plant tolerance to herbivory? Does folivory increase symbiont vertical transmission to seeds or hyphal density in seedlings? Do plants with symbiont horizontal transmission have lower rates of vertical transmission than plants lacking horizontal transmission? METHODS We studied the grass Poa autumnalis and its symbiotic fungi in the genus Epichloë. We measured plant fitness (survival, growth, reproduction) and symbiont transmission to seeds following simulated folivory in a 3-year common garden experiment and surveyed natural populations that varied in mode of symbiont transmission. KEY RESULTS Poa autumnalis hosted two Epichloë taxa, an undescribed vertically transmitted Epichloë sp. PauTG-1 and E. typhina subsp. poae with both vertical and horizontal transmission. Simulated folivory reduced plant survival, but endophyte presence increased tolerance to damage and boosted fitness. Folivory increased vertical transmission and hyphal density within seedlings, suggesting induced protection for progeny of damaged plants. Across natural populations, the prevalence of vertical transmission did not correlate with symbiont prevalence or differ with mode of transmission. CONCLUSIONS Herbivory not only mediated the reproductive fitness benefits of symbiosis, but also promoted symbiosis prevalence by increasing vertical transmission of the fungus to the next generation. Our results reveal a new mechanism by which herbivores could influence the prevalence of microbial symbionts in host populations.
Collapse
Affiliation(s)
- Pedro E Gundel
- IFEVA-CONICET, Department of Ecology, College of Agronomy, University of Buenos Aires, Buenos Aires, Argentina
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
- For correspondence. E-mail
| | - Prudence Sun
- Department of Biosciences, Rice University, Houston, TX, USA
| | | | | | - Tom E X Miller
- Department of Biosciences, Rice University, Houston, TX, USA
| | | |
Collapse
|
5
|
Winter DJ, Charlton ND, Krom N, Shiller J, Bock CH, Cox MP, Young CA. Chromosome-Level Reference Genome of Venturia effusa, Causative Agent of Pecan Scab. Mol Plant Microbe Interact 2020; 33:149-152. [PMID: 31631770 DOI: 10.1094/mpmi-08-19-0236-a] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Pecan scab, caused by Venturia effusa, is a devastating disease of pecan (Carya illinoinensis), which results in economic losses on susceptible cultivars throughout the southeastern United States. To enhance our understanding of pathogenicity in V. effusa, we have generated a complete telomere-to-telomere reference genome of V. effusa isolate FRT5LL7-Albino. By combining Illumina MiSeq and Oxford Nanopore MinION data, we assembled a 45.2-Mb genome represented by 20 chromosomes and containing 10,820 putative genes, of which 7,619 have at least one functional annotation. The likely causative mutation of the albino phenotype was identified as a single base insertion and a resulting frameshift in the gene encoding the polyketide synthase ALM1. This genome represents the first full chromosome-level assembly of any Venturia sp.
Collapse
Affiliation(s)
- David J Winter
- School of Fundamental Sciences and the Bio-Protection Research Centre, Massey University, Palmerston North 4442, New Zealand
| | | | - Nick Krom
- Noble Research Institute, LLC, Ardmore, OK 73401, U.S.A
| | - Jason Shiller
- Noble Research Institute, LLC, Ardmore, OK 73401, U.S.A
| | - Clive H Bock
- United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008, U.S.A
| | - Murray P Cox
- School of Fundamental Sciences and the Bio-Protection Research Centre, Massey University, Palmerston North 4442, New Zealand
| | | |
Collapse
|
6
|
Bushman BS, Singh D, Lamp R, Young CA, Charlton ND, Robins JG, Anderson N. Variation Among Orchardgrass (Dactylis glomerata) Germplasm for Choke Prevalence Caused by Epichloë typhina. Plant Dis 2019; 103:324-330. [PMID: 30522401 DOI: 10.1094/pdis-05-18-0867-re] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Orchardgrass, or cocksfoot (Dactylis glomerata L.), is a cool-season forage grass susceptible to the choke disease caused by Epichloë typhina. Choke has been reported in orchardgrass seed production fields across the temperate regions of the world, but fungicides have not been efficacious in reducing choke incidence or prevalence. To assess the potential for genetic resistance or tolerance of orchardgrass to choke, we evaluated the variation in orchardgrass cultivars and accessions for choke prevalence and characterized infected plants for endophyte secondary metabolite and mating type gene presence. Significant variation was detected across years and locations. Choke prevalence did not always increase with the age of the stand, nor did choke prevalence correlate with flowering time or swathing time of the entries. Both mating types of E. typhina were detected in approximately equal proportions, and no evidence for loline, ergot alkaloid, or indole-diterpene biosynthesis was found. Plants with multiple infected tillers often showed more than one mating type present in the plant, indicating multiple infection events rather than a single infection event that spread to multiple tillers. Both accessions and cultivars with significant choke, and no choke, were detected, which constitute sources of germplasm for further testing and breeding.
Collapse
Affiliation(s)
- B Shaun Bushman
- USDA-ARS Forage and Range Research Laboratory, Logan, UT 84322
| | | | | | | | | | - Joseph G Robins
- USDA-ARS Forage and Range Research Laboratory, Logan, UT 84322
| | - Nicole Anderson
- Department of Crop and Soil Science, Oregon State University, Corvallis, OR 97331
| |
Collapse
|
7
|
Bock CH, Young CA, Stevenson KL, Charlton ND. Fine-Scale Population Genetic Structure and Within-Tree Distribution of Mating Types of Venturia effusa, Cause of Pecan Scab in the United States. Phytopathology 2018; 108:1326-1336. [PMID: 29771192 DOI: 10.1094/phyto-02-18-0068-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Scab (caused by Venturia effusa) is the major disease of pecan in the southeastern United States. There is no information available on the fine-scale population genetic diversity or the occurrence of clonal types at small spatial scales that provides insight into inoculum sources and dispersal mechanisms, and potential opportunity for sexual reproduction. To investigate fine-scale genetic diversity, four trees of cultivar Wichita (populations) were sampled hierarchically: within each tree canopy, four approximately evenly spaced terminals (subpopulations) were selected and up to six leaflets (sub-subpopulations) were sampled from different compound leaves on each terminal. All lesions (n = 1 to 8) on each leaflet were sampled. The isolates were screened against a panel of 29 informative microsatellite markers and the resulting multilocus genotypes (MLG) subject to analysis. Mating type was also determined for each isolate. Of 335 isolates, there were 165 MLG (clonal fraction 49.3%). Nei's unbiased measure of genetic diversity for the clone-corrected data were moderate to high (0.507). An analysis of molecular variance demonstrated differentiation (P = 0.001) between populations on leaflets within individual terminals and between terminals within trees in the tree canopies, with 93.8% of variance explained among isolates within leaflet populations. Other analyses (minimum-spanning network, Bayesian, and discriminant analysis of principal components) all indicated little affinity of isolate for source population. Of the 335 isolates, most unique MLG were found at the stratum of the individual leaflets (n = 242), with similar total numbers of unique MLG observed at the strata of the terminal (n = 170), tree (n = 166), and orchard (n = 165). Thus, the vast majority of shared clones existed on individual leaflets on a terminal at the scale of 10s of centimeters or less, indicating a notable component of short-distance dispersal. There was significant linkage disequilibrium (P < 0.001), and an analysis of Psex showed that where there were multiple encounters of an MLG, they were most probably the result of asexual reproduction (P < 0.05) but there was no evidence that asexual reproduction was involved in single or first encounters of an MLG (P > 0.05). Overall, the MAT1-1-1 and MAT1-2-1 idiomorphs were at equilibrium (73:92) and in most populations, subpopulations, and sub-subpopulations. Both mating types were frequently observed on the same leaflet. The results provide novel information on the characteristics of populations of V. effusa at fine spatial scales, and provide insights into the dispersal of the organism within and between trees. The proximity of both mating idiomorphs on single leaflets is further evidence of opportunity for development of the sexual stage in the field.
Collapse
Affiliation(s)
- Clive H Bock
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Carolyn A Young
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Katherine L Stevenson
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Nikki D Charlton
- First author: U.S. Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; second and fourth authors: Noble Research Institute, LLC, 2510 Sam Noble Parkway, Ardmore, OK 73401; and third author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| |
Collapse
|
8
|
Young CA, Bock CH, Charlton ND, Mattupalli C, Krom N, Bowen JK, Templeton M, Plummer KM, Wood BW. Evidence for Sexual Reproduction: Identification, Frequency, and Spatial Distribution of Venturia effusa (Pecan Scab) Mating Type Idiomorphs. Phytopathology 2018; 108:837-846. [PMID: 29381450 DOI: 10.1094/phyto-07-17-0233-r] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Venturia effusa (syn. Fusicladium effusum), causal agent of pecan scab, is the most prevalent pathogen of pecan (Carya illinoinensis), causing severe yield losses in the southeastern United States. V. effusa is currently known only by its asexual (conidial) stage. However, the degree and distribution of genetic diversity observed within and among populations of V. effusa are typical of a sexually reproducing fungal pathogen, and comparable with other dothideomycetes with a known sexual stage, including the closely related apple scab pathogen, V. inaequalis. Using the mating type (MAT) idiomorphs from V. inaequalis, we identified a single MAT gene, MAT1-1-1, in a draft genome of V. effusa. The MAT1-1-1 locus is flanked by two conserved genes encoding a DNA lyase (APN2) and a hypothetical protein. The MAT locus spanning the flanking genes was amplified and sequenced from a subset of 14 isolates, of which 7 contained MAT1-1-1 and the remaining samples contained MAT1-2-1. A multiplex polymerase chain reaction screen was developed to amplify MAT1-1-1, MAT1-2-1, and a conserved reference gene encoding β-tubulin, and used to screen 784 monoconidial isolates of V. effusa collected from 11 populations of pecan across the southeastern United States. A hierarchical sampling protocol representing region, orchard, and tree allowed for analysis of MAT structure at different spatial scales. Analysis of this collection revealed the frequency of the MAT idiomorphs is in a 1:1 equilibrium of MAT1-1:MAT1-2. The apparent equilibrium of the MAT idiomorphs provides impetus for a renewed effort to search for the sexual stage of V. effusa. [Formula: see text] Copyright © 2018 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .
Collapse
Affiliation(s)
- Carolyn A Young
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Clive H Bock
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Nikki D Charlton
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Chakradhar Mattupalli
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Nick Krom
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Joanna K Bowen
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Matthew Templeton
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Kim M Plummer
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| | - Bruce W Wood
- First, third, fourth, and fifth authors: Noble Research Institute, LLC., Ardmore, OK 73401; second and ninth authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; sixth and seventh authors: The New Zealand Institute for Plant & Food Research, Auckland, New Zealand; seventh author: The School of Biological Sciences, University of Auckland, New Zealand; eighth author: Department of Animal, Plant and Soil Sciences, AgriBio, AgriBiosciences Research Centre, La Trobe University, 3086, Victoria, Australia
| |
Collapse
|
9
|
Yi M, Hendricks WQ, Kaste J, Charlton ND, Nagabhyru P, Panaccione DG, Young CA. Molecular identification and characterization of endophytes from uncultivated barley. Mycologia 2018; 110:453-472. [PMID: 29923795 DOI: 10.1080/00275514.2018.1464818] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Epichloë species (Clavicipitaceae, Ascomycota) are endophytic symbionts of many cool-season grasses. Many interactions between Epichloë and their host grasses contribute to plant growth promotion, protection from many pathogens and insect pests, and tolerance to drought stress. Resistance to insect herbivores by endophytes associated with Hordeum species has been previously shown to vary depending on the endophyte-grass-insect combination. We explored the genetic and chemotypic diversity of endophytes present in wild Hordeum species. We analyzed seeds of Hordeum bogdanii, H. brevisubulatum, and H. comosum obtained from the US Department of Agriculture's (USDA) National Plant Germplasm System (NPGS), of which some have been reported as endophyte-infected. Using polymerase chain reaction (PCR) with primers specific to Epichloë species, we were able to identify endophytes in seeds from 17 of the 56 Plant Introduction (PI) lines, of which only 9 lines yielded viable seed. Phylogenetic analyses of housekeeping, alkaloid biosynthesis, and mating type genes suggest that the endophytes of the infected PI lines separate into five taxa: Epichloë bromicola, Epichloë tembladerae, and three unnamed interspecific hybrid species. One PI line contained an endophyte that is considered a new taxonomic group, Epichloë sp. HboTG-3 (H. bogdanii Taxonomic Group 3). Phylogenetic analyses of the interspecific hybrid endophytes from H. bogdanii and H. brevisubulatum indicate that these taxa all have an E. bromicola allele but the second allele varies. We verified in planta alkaloid production from the five genotypes yielding viable seed. Morphological characteristics of the isolates from the viable Hordeum species were analyzed for their features in culture and in planta. In the latter, we observed epiphyllous growth and in some cases sporulation on leaves of infected plants.
Collapse
Affiliation(s)
- Mihwa Yi
- a Noble Research Institute, LLC , Ardmore , Oklahoma 73401
| | | | - Joshua Kaste
- a Noble Research Institute, LLC , Ardmore , Oklahoma 73401
| | | | - Padmaja Nagabhyru
- b Department of Plant Pathology , University of Kentucky , Lexington , Kentucky 40546
| | - Daniel G Panaccione
- c Division of Plant and Soil Sciences , West Virginia University , Morgantown , West Virginia 26506
| | | |
Collapse
|
10
|
Shymanovich T, Charlton ND, Musso AM, Scheerer J, Cech NB, Faeth SH, Young CA. Interspecific and intraspecific hybrid Epichloë species symbiotic with the North American native grass Poa alsodes. Mycologia 2017; 109:459-474. [PMID: 28723242 DOI: 10.1080/00275514.2017.1340779] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The endophyte presence and diversity in natural populations of Poa alsodes were evaluated along a latitudinal transect from the southern distribution range in North Carolina to New York. Two distinct Epichloë hybrid taxa were identified from 23 populations. Each taxon could easily be distinguished by polymerase chain reaction (PCR) genotyping with primers designed to mating type genes and alkaloid biosynthesis genes that encode key pathway steps for ergot alkaloids, indole-diterpenes, lolines, and peramine. The most commonly found Epichloë taxon, Poa alsodes Taxonomic Group-1 (PalTG-1), was detected in 22 populations at high infection frequencies (72-100%), with the exception of one population at high elevation (26% infection). The second taxon, PalTG-2, was observed only in five populations in Pennsylvania constituting 12% of infected samples. Phylogenetic analyses placed PalTG-1 as an interspecific hybrid of E. amarillans and E. typhina subsp. poae ancestors, and it is considered a new hybrid species, which the authors name Epichloë alsodes. PalTG-2 is an intraspecific hybrid of two E. typhina subsp. poae ancestors, similar to E. schardlii from the host Cinna arundinacea, which the authors propose as a new variety, Epichloë schardlii var. pennsylvanica. Epichloë alsodes isolates were all mating type MTA MTB and tested positive for dmaW, easC, perA, and some LOL genes, but only the alkaloid N-acetylnorloline was detected in E. alsodes-infected plant material. Epichloë schardlii var. pennsylvanica isolates were all mating type MTB MTB and tested positive for perA, but peramine was not produced. Both E. alsodes and E. schardlii var. pennsylvanica appeared to have complete perA genes, but point mutations were identified in E. alsodes that would render the encoded perA gene nonfunctional.
Collapse
Affiliation(s)
- Tatsiana Shymanovich
- a Department of Biology , University of North Carolina Greensboro , 312 Eberhart Building, Greensboro , North Carolina 27412
| | - Nikki D Charlton
- b Noble Research Institute, LLC ., 2510 Sam Noble Parkway, Ardmore , Oklahoma 73401
| | - Ashleigh M Musso
- c Department of Chemistry and Biochemistry , University of North Carolina Greensboro , 435 Patricia A. Sullivan Science Building, Greensboro , North Carolina 27402
| | | | - Nadja B Cech
- c Department of Chemistry and Biochemistry , University of North Carolina Greensboro , 435 Patricia A. Sullivan Science Building, Greensboro , North Carolina 27402
| | - Stanley H Faeth
- a Department of Biology , University of North Carolina Greensboro , 312 Eberhart Building, Greensboro , North Carolina 27412
| | - Carolyn A Young
- b Noble Research Institute, LLC ., 2510 Sam Noble Parkway, Ardmore , Oklahoma 73401
| |
Collapse
|
11
|
Bock CH, Hotchkiss MW, Young CA, Charlton ND, Chakradhar M, Stevenson KL, Wood BW. Population Genetic Structure of Venturia effusa, Cause of Pecan Scab, in the Southeastern United States. Phytopathology 2017; 107:607-619. [PMID: 28414611 DOI: 10.1094/phyto-10-16-0376-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Venturia effusa is the most important pathogen of pecan in the southeastern United States. Little information exists on the population biology and genetic diversity of the pathogen. A hierarchical sampling of 784 isolates from 63 trees in 11 pecan orchards in the southeastern United States were screened against a set of 30 previously characterized microsatellite markers. Populations were collected from Georgia (n = 2), Florida (n = 1), Alabama (n = 2), Mississippi (n = 1), Louisiana (n = 1), Illinois (n = 1), Oklahoma (n = 1), Texas (n = 1), and Kansas (n = 1). Clonality was low in all orchard populations (≤10.1% of isolates), and there were consistently high levels of genotypic diversity (Shannon-Weiner's index = 3.49 to 4.59) and gene diversity (Nei's measure = 0.513 to 0.713). Analysis of molecular variance showed that, although 81% of genetic diversity occurred at the scale of the individual tree, 16% occurred between orchards and only 3% between trees within orchards. All populations could be differentiated from each other (P = 0.01), and various cluster analyses indicated that some populations were more closely related compared with other pairs of populations. This is indicative of some limited population differentiation in V. effusa in the southeastern United States. Bayesian and nearest-neighbor methods suggested eight clusters, with orchards from Georgia and Florida being grouped together. A minimum spanning tree of all 784 isolates also indicated some isolate identification with source population. Linkage disequilibrium was detected in all but one population (Kansas), although 8 of the 11 populations had <20% of loci at disequilibrium. A Mantel test demonstrated a relationship between physical and genetic distance between populations (Z = 11.9, r = 0.559, P = 0.001). None of the populations were at mutation-drift equilibrium. All but 3 of the 11 populations had a deficiency of gene diversity compared with that expected at mutation-drift equilibrium (indicating population expansion); the remaining populations had an excess of gene diversity compared with that expected at mutation-drift equilibrium (indicating a recent bottleneck). These observations are consistent with the known history of pecan and pecan scab, which is that V. effusa became an issue on cultivated pecan in the last approximately 120 years (recent population expansion). Recently reported mating type genes and the sexual stage of this fungus may help explain the observed population characteristics, which bear a strong resemblance to those of other well-characterized sexually reproducing ascomycete pathogens.
Collapse
Affiliation(s)
- Clive H Bock
- First, second, and seventh authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; third, fourth, and fifth authors: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; sixth author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Michael W Hotchkiss
- First, second, and seventh authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; third, fourth, and fifth authors: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; sixth author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Carolyn A Young
- First, second, and seventh authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; third, fourth, and fifth authors: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; sixth author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Nikki D Charlton
- First, second, and seventh authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; third, fourth, and fifth authors: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; sixth author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Mattupalli Chakradhar
- First, second, and seventh authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; third, fourth, and fifth authors: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; sixth author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Katherine L Stevenson
- First, second, and seventh authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; third, fourth, and fifth authors: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; sixth author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| | - Bruce W Wood
- First, second, and seventh authors: United States Department of Agriculture-Agricultural Research Service Southeastern Fruit and Tree Nut Research Laboratory, Byron, GA 31008; third, fourth, and fifth authors: The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, OK 73401; sixth author: Department of Plant Pathology, Coastal Plain Experiment Station, University of Georgia, Tifton 31793
| |
Collapse
|
12
|
Affiliation(s)
| | - Marc A. Cubeta
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695-7616
| |
Collapse
|
13
|
Affiliation(s)
| | - Ignazio Carbone
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695-7616
| | - Stellos M. Tavantzis
- Department of Biological Sciences, University of Maine, Orono, Maine, 04469-5722
| | - Marc A. Cubeta
- Department of Plant Pathology, North Carolina State University, Raleigh, North Carolina, 27695-7616
| |
Collapse
|
14
|
Ghimire SR, Rudgers JA, Charlton ND, Young C, Craven KD. Prevalence of an intraspecificNeotyphodiumhybrid in natural populations of stout wood reed (Cinna arundinaceaL.) from eastern North America. Mycologia 2017; 103:75-84. [DOI: 10.3852/10-154] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Sita R. Ghimire
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Jennifer A. Rudgers
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas 77005
| | - Nikki D. Charlton
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Carolyn Young
- Forage Improvement Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| | - Kelly D. Craven
- Plant Biology Division, Samuel Roberts Noble Foundation, Ardmore, Oklahoma 73401
| |
Collapse
|
15
|
Shoji JY, Charlton ND, Yi M, Young CA, Craven KD. Vegetative hyphal fusion and subsequent nuclear behavior in Epichloë grass endophytes. PLoS One 2015; 10:e0121875. [PMID: 25837972 PMCID: PMC4383479 DOI: 10.1371/journal.pone.0121875] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 02/18/2015] [Indexed: 01/18/2023] Open
Abstract
Epichloë species (including the former genus Neotyphodium) are fungal symbionts of many agronomically important forage grasses, and provide their grass hosts with protection from a wide range of biotic and abiotic stresses. Epichloë species include many interspecific hybrids with allodiploid-like genomes, which may provide the potential for combined traits or recombination to generate new traits. Though circumstantial evidence suggests that such interspecific hybrids might have arisen from nuclear fusion events following vegetative hyphal fusion between different Epichloë strains, this hypothesis has not been addressed empirically. Here, we investigated vegetative hyphal fusion and subsequent nuclear behavior in Epichloë species. A majority of Epichloë strains, especially those having a sexual stage, underwent self vegetative hyphal fusion. Vegetative fusion also occurred between two hyphae from different Epichloë strains. Though Epichloë spp. are uninucleate fungi, hyphal fusion resulted in two nuclei stably sharing the same cytoplasm, which might ultimately lead to nuclear fusion. In addition, protoplast fusion experiments gave rise to uninucleate putative hybrids, which apparently had two markers, one from each parent within the same nucleus. These results are consistent with the notion that interspecific hybrids arise from vegetative hyphal fusion. However, we also discuss additional factors, such as post-hybridization selection, that may be important to explain the recognized prevalence of hybrids in Epichloë species.
Collapse
Affiliation(s)
- Jun-ya Shoji
- The Samuel Roberts Noble Foundation, Plant Biology Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Nikki D. Charlton
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Mihwa Yi
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Carolyn A. Young
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
| | - Kelly D. Craven
- The Samuel Roberts Noble Foundation, Plant Biology Division, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States of America
- * E-mail:
| |
Collapse
|
16
|
Berry D, Takach JE, Schardl CL, Charlton ND, Scott B, Young CA. Disparate independent genetic events disrupt the secondary metabolism gene perA in certain symbiotic Epichloë species. Appl Environ Microbiol 2015; 81:2797-807. [PMID: 25681180 PMCID: PMC4375322 DOI: 10.1128/aem.03721-14] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/05/2015] [Indexed: 01/23/2023] Open
Abstract
Peramine is an insect-feeding deterrent produced by Epichloë species in symbiotic association with C3 grasses. The perA gene responsible for peramine synthesis encodes a two-module nonribosomal peptide synthetase. Alleles of perA are found in most Epichloë species; however, peramine is not produced by many perA-containing Epichloë isolates. The genetic basis of these peramine-negative chemotypes is often unknown. Using PCR and DNA sequencing, we analyzed the perA genes from 72 Epichloë isolates and identified causative mutations of perA null alleles. We found nonfunctional perA-ΔR* alleles, which contain a transposon-associated deletion of the perA region encoding the C-terminal reductase domain, are widespread within the Epichloë genus and represent a prevalent mutation found in nonhybrid species. Disparate phylogenies of adjacent A2 and T2 domains indicated that the deletion of the reductase domain (R*) likely occurred once and early in the evolution of the genus, and subsequently there have been several recombinations between those domains. A number of novel point, deletion, and insertion mutations responsible for abolishing peramine production in full-length perA alleles were also identified. The regions encoding the first and second adenylation domains (A1 and A2, respectively) were common sites for such mutations. Using this information, a method was developed to predict peramine chemotypes by combining PCR product size polymorphism analysis with sequencing of the perA adenylation domains.
Collapse
Affiliation(s)
- Daniel Berry
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | | | | | | | - Barry Scott
- Institute of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | | |
Collapse
|
17
|
Kazenel MR, Debban CL, Ranelli L, Hendricks WQ, Chung YA, Pendergast TH, Charlton ND, Young CA, Rudgers JA. A mutualistic endophyte alters the niche dimensions of its host plant. AoB Plants 2015; 7:plv005. [PMID: 25603965 PMCID: PMC4354242 DOI: 10.1093/aobpla/plv005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2014] [Accepted: 12/05/2014] [Indexed: 05/25/2023]
Abstract
Mutualisms can play important roles in influencing species coexistence and determining community composition. However, few studies have tested whether such interactions can affect species distributions by altering the niches of partner species. In subalpine meadows of the Rocky Mountains, USA, we explored whether the presence of a fungal endophyte (genus Epichloë) may shift the niche of its partner plant, marsh bluegrass (Poa leptocoma) relative to a closely related but endophyte-free grass species, nodding bluegrass (Poa reflexa). Using observations and a 3-year field experiment, we tested two questions: (i) Do P. leptocoma and P. reflexa occupy different ecological niches? and (ii) Does endophyte presence affect the relative fitness of P. leptocoma versus P. reflexa in the putative niches of these grass species? The two species were less likely to co-occur than expected by chance. Specifically, P. leptocoma grew closer to water sources and in wetter soils than P. reflexa, and also had higher root colonization by mycorrhizal fungi. Endophyte-symbiotic P. leptocoma seeds germinated with greater frequency in P. leptocoma niches relative to P. reflexa niches, whereas neither endophyte-free (experimentally removed) P. leptocoma seeds nor P. reflexa seeds showed differential germination between the two niche types. Thus, endophyte presence constrained the germination and early survival of host plants to microsites occupied by P. leptocoma. However, endophyte-symbiotic P. leptocoma ultimately showed greater growth than endophyte-free plants across all microsites, indicating a net benefit of the symbiosis at this life history stage. Differential effects of endophyte symbiosis on different host life history stages may thus contribute to niche partitioning between the two congeneric plant species. Our study therefore identifies a symbiotic relationship as a potential mechanism facilitating the coexistence of two species, suggesting that symbiont effects on host niche may have community-level consequences.
Collapse
Affiliation(s)
- Melanie R Kazenel
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
| | - Catherine L Debban
- Department of Biology, University of Virginia, Charlottesville, VA 22904, USA
| | - Luciana Ranelli
- Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA Division of Science and Mathematics, University of Minnesota, Morris, Morris, MN 56267, USA
| | - Will Q Hendricks
- Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Y Anny Chung
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA
| | - Thomas H Pendergast
- Department of Crop and Soil Sciences, University of Georgia, Athens, GA 30602, USA
| | - Nikki D Charlton
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Carolyn A Young
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA
| | - Jennifer A Rudgers
- Department of Biology, University of New Mexico, Albuquerque, NM 87131, USA Rocky Mountain Biological Laboratory, Crested Butte, CO 81224, USA
| |
Collapse
|
18
|
Shymanovich T, Saari S, Lovin ME, Jarmusch AK, Jarmusch SA, Musso AM, Charlton ND, Young CA, Cech NB, Faeth SH. Alkaloid variation among epichloid endophytes of sleepygrass (Achnatherum robustum) and consequences for resistance to insect herbivores. J Chem Ecol 2014; 41:93-104. [PMID: 25501262 DOI: 10.1007/s10886-014-0534-x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2014] [Revised: 08/30/2014] [Accepted: 12/02/2014] [Indexed: 10/24/2022]
Abstract
Epichloid endophytes are well known symbionts of many cool-season grasses that may alleviate environmental stresses for their hosts. For example, endophytes produce alkaloid compounds that may be toxic to invertebrate or vertebrate herbivores. Achnatherum robustum, commonly called sleepygrass, was aptly named due to the presence of an endophyte that causes toxic effects to livestock and wildlife. Variation in alkaloid production observed in two A. robustum populations located near Weed and Cloudcroft in the Lincoln National Forest, New Mexico, suggests two different endophyte species are present in these populations. Genetic analyses of endophyte-infected samples revealed major differences in the endophyte alkaloid genetic profiles from the two populations, which were supported with chemical analyses. The endophyte present in the Weed population was shown to produce chanoclavine I, paspaline, and terpendoles, so thus resembles the previously described Epichloë funkii. The endophyte present in the Cloudcroft population produces chanoclavineI, ergonovine, lysergic acid amide, and paspaline, and is an undescribed endophyte species. We observed very low survival rates for aphids feeding on plants infected with the Cloudcroft endophyte, while aphid survival was better on endophyte infected plants in the Weed population. This observation led to the hypothesis that the alkaloid ergonovine is responsible for aphid mortality. Direct testing of aphid survival on oat leaves supplemented with ergonovine provided supporting evidence for this hypothesis. The results of this study suggest that alkaloids produced by the Cloudcroft endophyte, specifically ergonovine, have insecticidal properties.
Collapse
Affiliation(s)
- Tatsiana Shymanovich
- Department of Biology, University of North Carolina Greensboro, 312 Eberhart Bldg., Greensboro, NC, 27412, USA,
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Young CA, Charlton ND, Takach JE, Swoboda GA, Trammell MA, Huhman DV, Hopkins AA. Characterization of Epichloë coenophiala within the US: are all tall fescue endophytes created equal? Front Chem 2014; 2:95. [PMID: 25408942 PMCID: PMC4219521 DOI: 10.3389/fchem.2014.00095] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Accepted: 10/14/2014] [Indexed: 11/13/2022] Open
Abstract
Tall fescue (Lolium arundinaceum) is a valuable and broadly adapted forage grass that occupies approximately 14 million hectares across the United States. A native to Europe, tall fescue was likely introduced into the US around the late 1800's. Much of the success of tall fescue can be attributed to Epichloë coenophiala (formerly Neotyphodium coenophialum) a seed borne symbiont that aids in host persistence. Epichloë species are capable of producing a range of alkaloids (ergot alkaloids, indole-diterpenes, lolines, and peramine) that provide protection to the plant host from herbivory. Unfortunately, most tall fescue within the US, commonly referred to as "Kentucky-31" (KY31), harbors the endophyte E. coenophiala that causes toxicity to grazing livestock due to the production of ergot alkaloids. Molecular analyses of tall fescue endophytes have identified four independent associations, representing tall fescue with E. coenophiala, Epichloë sp. FaTG-2, Epichloë sp. FaTG-3, or Epichloë sp. FaTG-4. Each of these Epichloë species can be further distinguished based on genetic variation that equates to differences in the alkaloid gene loci. Tall fescue samples were evaluated using markers to simple sequence repeats (SSRs) and alkaloid biosynthesis genes to determine endophyte strain variation present within continental US. Samples represented seed and tillers from the Suiter farm (Menifee County, KY), which is considered the originating site of KY31, as well as plant samples collected from 14 states, breeder's seed and plant introduction lines (National Plant Germplasm System, NPGS). This study revealed two prominent E. coenophiala genotypes based on presence of alkaloid biosynthesis genes and SSR markers and provides insight into endophyte variation within continental US across historical and current tall fescue samples.
Collapse
Affiliation(s)
- Carolyn A Young
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Nikki D Charlton
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Johanna E Takach
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Ginger A Swoboda
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Michael A Trammell
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - David V Huhman
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| | - Andrew A Hopkins
- The Samuel Roberts Noble Foundation, Forage Improvement Division Ardmore, OK, USA
| |
Collapse
|
20
|
Charlton ND, Craven KD, Afkhami ME, Hall BA, Ghimire SR, Young CA. Interspecific hybridization and bioactive alkaloid variation increases diversity in endophytic Epichloë species of Bromus laevipes. FEMS Microbiol Ecol 2014; 90:276-89. [PMID: 25065688 DOI: 10.1111/1574-6941.12393] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/27/2014] [Accepted: 07/18/2014] [Indexed: 11/29/2022] Open
Abstract
Studying geographic variation of microbial mutualists, especially variation in traits related to benefits they provide their host, is critical for understanding how these associations impact key ecological processes. In this study, we investigate the phylogenetic population structure of Epichloë species within Bromus laevipes, a native cool-season bunchgrass found predominantly in California. Phylogenetic classification supported inference of three distinct Epichloë taxa, of which one was nonhybrid and two were interspecific hybrids. Inheritance of mating-type idiomorphs revealed that at least one of the hybrid species arose from independent hybridization events. We further investigated the geographic variation of endophyte-encoded alkaloid genes, which is often associated with key benefits of natural enemy protection for the host. Marker diversity at the ergot alkaloid, loline, indole-diterpene, and peramine loci revealed four alkaloid genotypes across the three identified Epichloë species. Predicted chemotypes were tested using endophyte-infected plant material that represented each endophyte genotype, and 11 of the 13 predicted alkaloids were confirmed. This multifaceted approach combining phylogenetic, genotypic, and chemotypic analyses allowed us to reconstruct the diverse evolutionary histories of Epichloë species present within B. laevipes and highlight the complex and dynamic processes underlying these grass-endophyte symbioses.
Collapse
Affiliation(s)
- Nikki D Charlton
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK, USA
| | | | | | | | | | | |
Collapse
|
21
|
Pan J, Bhardwaj M, Faulkner JR, Nagabhyru P, Charlton ND, Higashi RM, Miller AF, Young CA, Grossman RB, Schardl CL. Ether bridge formation in loline alkaloid biosynthesis. Phytochemistry 2014; 98:60-8. [PMID: 24374065 PMCID: PMC3929955 DOI: 10.1016/j.phytochem.2013.11.015] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2013] [Revised: 11/01/2013] [Accepted: 11/21/2013] [Indexed: 05/18/2023]
Abstract
Lolines are potent insecticidal agents produced by endophytic fungi of cool-season grasses. These alkaloids are composed of a pyrrolizidine ring system and an uncommon ether bridge linking carbons 2 and 7. Previous results indicated that 1-aminopyrrolizidine was a pathway intermediate. We used RNA interference to knock down expression of lolO, resulting in the accumulation of an alkaloid identified as exo-1-acetamidopyrrolizidine based on high-resolution MS and NMR. Genomes of endophytes differing in alkaloid profiles were sequenced, revealing that those with mutated lolO accumulated exo-1-acetamidopyrrolizidine but no lolines. Heterologous expression of wild-type lolO complemented a lolO mutant, resulting in the production of N-acetylnorloline. These results indicated that the non-heme iron oxygenase, LolO, is required for ether bridge formation, probably through oxidation of exo-1-acetamidopyrrolizidine.
Collapse
Affiliation(s)
- Juan Pan
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
| | - Minakshi Bhardwaj
- Department of Chemistry, 339 Chemistry-Physics Building, 505 Rose Street, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Jerome R Faulkner
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
| | - Padmaja Nagabhyru
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA
| | - Nikki D Charlton
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, OK 73401-2124, USA
| | - Richard M Higashi
- Graduate Center for Toxicology, 521 Biopharmacy Building, 1000 South Limestone, University of Kentucky, Lexington, KY 40536-0293, USA
| | - Anne-Frances Miller
- Department of Chemistry, 339 Chemistry-Physics Building, 505 Rose Street, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Carolyn A Young
- The Samuel Roberts Noble Foundation, Forage Improvement Division, 2510 Sam Noble Parkway, Ardmore, OK 73401-2124, USA
| | - Robert B Grossman
- Department of Chemistry, 339 Chemistry-Physics Building, 505 Rose Street, University of Kentucky, Lexington, KY 40506-0055, USA
| | - Christopher L Schardl
- Department of Plant Pathology, 201F Plant Sciences Building, 1405 Veterans Drive, University of Kentucky, Lexington, KY 40546-0312, USA.
| |
Collapse
|
22
|
Schardl CL, Young CA, Pan J, Florea S, Takach JE, Panaccione DG, Farman ML, Webb JS, Jaromczyk J, Charlton ND, Nagabhyru P, Chen L, Shi C, Leuchtmann A. Currencies of mutualisms: sources of alkaloid genes in vertically transmitted epichloae. Toxins (Basel) 2013; 5:1064-88. [PMID: 23744053 PMCID: PMC3717770 DOI: 10.3390/toxins5061064] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2013] [Revised: 05/17/2013] [Accepted: 05/29/2013] [Indexed: 11/17/2022] Open
Abstract
The epichloae (Epichloë and Neotyphodium species), a monophyletic group of fungi in the family Clavicipitaceae, are systemic symbionts of cool-season grasses (Poaceae subfamily Poöideae). Most epichloae are vertically transmitted in seeds (endophytes), and most produce alkaloids that attack nervous systems of potential herbivores. These protective metabolites include ergot alkaloids and indole-diterpenes (tremorgens), which are active in vertebrate systems, and lolines and peramine, which are more specific against invertebrates. Several Epichloë species have been described which are sexual and capable of horizontal transmission, and most are vertically transmissible also. Asexual epichloae are mainly or exclusively vertically transmitted, and many are interspecific hybrids with genomic contributions from two or three ancestral Epichloë species. Here we employ genome-scale analyses to investigate the origins of biosynthesis gene clusters for ergot alkaloids (EAS), indole-diterpenes (IDT), and lolines (LOL) in 12 hybrid species. In each hybrid, the alkaloid-gene and housekeeping-gene relationships were congruent. Interestingly, hybrids frequently had alkaloid clusters that were rare in their sexual ancestors. Also, in those hybrids that had multiple EAS, IDT or LOL clusters, one cluster lacked some genes, usually for late pathway steps. Possible implications of these findings for the alkaloid profiles and endophyte ecology are discussed.
Collapse
Affiliation(s)
- Christopher L. Schardl
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Carolyn A. Young
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA; E-Mails: (C.A.Y.); (J.E.T.); (N.D.C.)
| | - Juan Pan
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Simona Florea
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Johanna E. Takach
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA; E-Mails: (C.A.Y.); (J.E.T.); (N.D.C.)
| | - Daniel G. Panaccione
- Division of Plant and Soil Sciences, West Virginia University, Morgantown, WV 26506, USA; E-Mail:
| | - Mark L. Farman
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Jennifer S. Webb
- Advanced Genetic Technologies Center, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.S.W.); (J.J.)
| | - Jolanta Jaromczyk
- Advanced Genetic Technologies Center, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.S.W.); (J.J.)
| | - Nikki D. Charlton
- Forage Improvement Division, The Samuel Roberts Noble Foundation, Ardmore, OK 73401, USA; E-Mails: (C.A.Y.); (J.E.T.); (N.D.C.)
| | - Padmaja Nagabhyru
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
| | - Li Chen
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
- School of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou 730020, China
| | - Chong Shi
- Department of Plant Pathology, University of Kentucky, Lexington, KY 40546, USA; E-Mails: (J.P.); (S.F.); (M.L.F.); (P.N.); (L.C.); (C.S.)
- School of Grassland & Environmental Science, Xinjiang Agricultural University, Urumqi 830052, China
| | - Adrian Leuchtmann
- Institute of Integrative Biology, ETH Zürich, Zürich CH-8092, Switzerland; E-Mail:
| |
Collapse
|
23
|
Schardl CL, Young CA, Hesse U, Amyotte SG, Andreeva K, Calie PJ, Fleetwood DJ, Haws DC, Moore N, Oeser B, Panaccione DG, Schweri KK, Voisey CR, Farman ML, Jaromczyk JW, Roe BA, O'Sullivan DM, Scott B, Tudzynski P, An Z, Arnaoudova EG, Bullock CT, Charlton ND, Chen L, Cox M, Dinkins RD, Florea S, Glenn AE, Gordon A, Güldener U, Harris DR, Hollin W, Jaromczyk J, Johnson RD, Khan AK, Leistner E, Leuchtmann A, Li C, Liu J, Liu J, Liu M, Mace W, Machado C, Nagabhyru P, Pan J, Schmid J, Sugawara K, Steiner U, Takach JE, Tanaka E, Webb JS, Wilson EV, Wiseman JL, Yoshida R, Zeng Z. Plant-symbiotic fungi as chemical engineers: multi-genome analysis of the clavicipitaceae reveals dynamics of alkaloid loci. PLoS Genet 2013; 9:e1003323. [PMID: 23468653 PMCID: PMC3585121 DOI: 10.1371/journal.pgen.1003323] [Citation(s) in RCA: 271] [Impact Index Per Article: 24.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 12/31/2012] [Indexed: 01/01/2023] Open
Abstract
The fungal family Clavicipitaceae includes plant symbionts and parasites that produce several psychoactive and bioprotective alkaloids. The family includes grass symbionts in the epichloae clade (Epichloë and Neotyphodium species), which are extraordinarily diverse both in their host interactions and in their alkaloid profiles. Epichloae produce alkaloids of four distinct classes, all of which deter insects, and some-including the infamous ergot alkaloids-have potent effects on mammals. The exceptional chemotypic diversity of the epichloae may relate to their broad range of host interactions, whereby some are pathogenic and contagious, others are mutualistic and vertically transmitted (seed-borne), and still others vary in pathogenic or mutualistic behavior. We profiled the alkaloids and sequenced the genomes of 10 epichloae, three ergot fungi (Claviceps species), a morning-glory symbiont (Periglandula ipomoeae), and a bamboo pathogen (Aciculosporium take), and compared the gene clusters for four classes of alkaloids. Results indicated a strong tendency for alkaloid loci to have conserved cores that specify the skeleton structures and peripheral genes that determine chemical variations that are known to affect their pharmacological specificities. Generally, gene locations in cluster peripheries positioned them near to transposon-derived, AT-rich repeat blocks, which were probably involved in gene losses, duplications, and neofunctionalizations. The alkaloid loci in the epichloae had unusual structures riddled with large, complex, and dynamic repeat blocks. This feature was not reflective of overall differences in repeat contents in the genomes, nor was it characteristic of most other specialized metabolism loci. The organization and dynamics of alkaloid loci and abundant repeat blocks in the epichloae suggested that these fungi are under selection for alkaloid diversification. We suggest that such selection is related to the variable life histories of the epichloae, their protective roles as symbionts, and their associations with the highly speciose and ecologically diverse cool-season grasses.
Collapse
|
24
|
Charlton ND, Tavantzis SM, Cubeta MA. Detection of double-stranded RNA elements in the plant pathogenic fungus Rhizoctonia solani. Methods Mol Biol 2009; 508:171-182. [PMID: 19301755 DOI: 10.1007/978-1-59745-062-1_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Many species of fungi have been shown to harbor double-stranded RNA (dsRNA) elements. A single fungal isolate of Rhizoctonia solani may have as many as five different dsRNA elements within them. The presence of specific dsRNA elements influence pathogenicity in host plants.
Collapse
Affiliation(s)
- Nikki D Charlton
- Department of Plant Pathology, North Carolina State University, Raleigh, USA
| | | | | |
Collapse
|