scholarly journals Spatial Genetic Structure and Population Dynamics of Gummy Stem Blight Fungi Within and Among Watermelon Fields in the Southeastern United States

2016 ◽  
Vol 106 (8) ◽  
pp. 900-908 ◽  
Author(s):  
Hao-Xi Li ◽  
Marin Talbot Brewer
Keyword(s):  
United States ◽  
Population Structure ◽  
Genetic Structure ◽  
Spatial Genetic Structure ◽  
Southeastern United States ◽  
Principal Coordinates Analysis ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Principal Coordinates ◽  
Regional Population

The epidemiology of gummy stem blight (GSB) of cucurbits, particularly the sources of inoculum for epidemics, and the regional population genetic structure of the causal fungi Stagonosporopsis cucurbitacearum (syn. Didymella bryoniae), S. citrulli, and S. caricae are not well understood. Our goal was to better understand the population structure and fine-scale spatial genetic structure of Stagonosporopsis spp. in the southeastern United States. Overall, 528 isolates collected from nine fields in 2012, 2013, and 2014 were genotyped with 16 microsatellite markers. In 2013, S. caricae was first detected in the southeastern United States; however, S. citrulli remained the dominant species, representing 96.4% of the isolates. Principal coordinates analysis, discriminant analysis of principle components, and analysis of molecular variance indicated that most populations of S. citrulli were genotypically diverse, yet dominated by widely distributed clones that contributed to regional population structure. Spatial genetic structure resulting from aggregation of clonal genotypes at distances of less than 10 meters was detected within two of three fields in which isolate location was recorded. Studies on the epidemiological and fitness differences between S. citrulli and S. caricae and of prevalent and widespread clones will provide insight into the population structure and species dynamics observed in GSB epidemics.

scholarly journals Differences in Sensitivity to a Triazole Fungicide Among Stagonosporopsis Species Causing Gummy Stem Blight of Cucurbits

Plant Disease ◽  
2016 ◽  
Vol 100 (10) ◽  
pp. 2106-2112 ◽  
Author(s):  
Hao-Xi Li ◽  
Katherine L. Stevenson ◽  
Marin T. Brewer
Keyword(s):  
United States ◽  
Molecular Basis ◽  
Promoter Region ◽  
Target Gene ◽  
Southeastern United States ◽  
Promoter Regions ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Atp Binding Cassette Transporter ◽  
Multiple Copies

Gummy stem blight (GSB) is a destructive disease of cucurbits caused by three closely related Stagonosporopsis species. In the southeastern United States, GSB management relies heavily on triazole fungicides. Our objectives were to determine if resistance to triazoles has developed in populations of GSB fungi in the southeastern United States, and if so, to investigate the molecular basis of resistance. A tebuconazole sensitivity assay was conducted on 303 Stagonosporopsis citrulli and 19 S. caricae isolates collected from the southeastern United States in 2013 and 2014, as well as three S. citrulli, three S. cucurbitacearum, and six S. caricae isolates from other regions or years. Tebuconazole resistance was detected for all 19 S. caricae isolates from the southeastern United States and one S. caricae isolate from Brazil. All S. citrulli and S. cucurbitacearum isolates were sensitive to tebuconazole. For resistant and sensitive isolates of S. caricae, coding and promoter regions of the target gene Cyp51 were sequenced and expression levels of Cyp51 and ScAtrG (an ATP-binding cassette transporter) were measured. Tebuconazole resistance was not associated with mutations within Cyp51, multiple copies of Cyp51, changes in the promoter region, or increased expression of Cyp51 or ScAtrG. Tebuconazole resistance may explain the increase in frequency of S. caricae isolates recovered from GSB-infected cucurbits in Georgia.

scholarly journals Genotyping of Two Mediterranean Trout Populations in Central-Southern Italy for Conservation Purposes Using a Rainbow-Trout-Derived SNP Array

Animals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1803
Author(s):  
Valentino Palombo ◽  
Elena De Zio ◽  
Giovanna Salvatore ◽  
Stefano Esposito ◽  
Nicolaia Iaffaldano ◽  
...  
Keyword(s):  
Rainbow Trout ◽  
Genetic Structure ◽  
Fishery Management ◽  
Snp Array ◽  
Fine Scale ◽  
Principal Coordinates Analysis ◽  
Data Set ◽  
Management Actions ◽  
Principal Coordinates ◽  
Mediterranean Trout

Mediterranean trout is a freshwater fish of particular interest with economic significance for fishery management, aquaculture and conservation biology. Unfortunately, native trout populations’ abundance is significantly threatened by anthropogenic disturbance. The introduction of commercial hatchery strains for recreation activities has compromised the genetic integrity status of native populations. This work assessed the fine-scale genetic structure of Mediterranean trout in the two main rivers of Molise region (Italy) to support conservation actions. In total, 288 specimens were caught in 28 different sites (14 per basins) and genotyped using the Affymetrix 57 K rainbow-trout-derived SNP array. Population differentiation was analyzed using pairwise weighted FST and overall F-statistic estimated by locus-by-locus analysis of molecular variance. Furthermore, an SNP data set was processed through principal coordinates analysis, discriminant analysis of principal components and admixture Bayesian clustering analysis. Firstly, our results demonstrated that rainbow trout SNP array can be successfully used for Mediterranean trout genotyping. In fact, despite an overwhelming number of loci that resulted as monomorphic in our populations, it must be emphasized that the resulted number of polymorphic loci (i.e., ~900 SNPs) has been sufficient to reveal a fine-scale genetic structure in the investigated populations, which is useful in supporting conservation and management actions. In particular, our findings allowed us to select candidate sites for the collection of adults, needed for the production of genetically pure juvenile trout, and sites to carry out the eradication of alien trout and successive re-introduction of native trout.

scholarly journals Genetic structure provides insights into the geographic origins and temporal change in the invasive charru mussel (Sururu) in the southeastern United States

PLoS ONE ◽  
2017 ◽  
Vol 12 (7) ◽  
pp. e0180619 ◽  
Author(s):  
Sávio H. Calazans C ◽  
Linda J. Walters ◽  
Flavio C. Fernandes ◽  
Carlos E. L. Ferreira ◽  
Eric A. Hoffman
Keyword(s):  
United States ◽  
Genetic Structure ◽  
Temporal Change ◽  
Southeastern United States ◽  
Geographic Origins

scholarly journals Genetic Diversity and Population Structure of Cucurbit Gummy Stem Blight Fungi Based on Microsatellite Markers

2015 ◽  
Vol 105 (6) ◽  
pp. 815-824 ◽  
Author(s):  
Marin Talbot Brewer ◽  
Manisha Rath ◽  
Hao-Xi Li
Keyword(s):  
Genetic Diversity ◽  
Population Structure ◽  
Microsatellite Markers ◽  
Plant Diseases ◽  
Similar Species ◽  
Fine Scale ◽  
Stem Blight ◽  
Gummy Stem Blight ◽  
Rapid Polymerase Chain Reaction ◽  
Insight Into

Combining population genetics with epidemiology provides insight into the population biology of pathogens, which could lead to improved management of plant diseases. Gummy stem blight, caused by three closely related species of Stagonosporopsis—Stagonosporopsis cucurbitacearum (syn. Didymella bryoniae), S. citrulli, and S. caricae—is a devastating disease of cucurbits worldwide. Sources of inoculum for epidemics, mechanisms of dispersal, and the mating system of these species are not well understood. To improve our knowledge of gummy stem blight epidemiology, we developed 18 polymorphic microsatellite markers by combining microsatellite motif enrichment with next-generation sequencing. When tested on 46 isolates from diverse cucurbit hosts and regions, the markers were robust for the dominant and widely distributed S. citrulli. Within this species, we found no population structure based on broad-scale geographic region or host of origin. Using the microsatellites, a rapid polymerase chain reaction-based method was developed to distinguish the three morphologically similar species causing gummy stem blight. To better understand dispersal, reproduction, and fine-scale genetic diversity of S. citrulli within and among watermelon fields, 155 isolates from two field populations in Georgia, United States were genotyped with the 18 microsatellite loci. Although dominant and widespread clones were detected, we found relatively high genotypic diversity and recombinant genotypes consistent with outcrossing. Significant population genetic structure between the two field populations demonstrated that there is regional geographic structure and limited dispersal among fields. This study provides insight into the fine-scale genetic diversity and reproductive biology of the gummy stem blight pathogen S. citrulli in the field.

A preliminary genetic structure study of the non-native weed, common tansy (Tanacetum vulgare)

2011 ◽  
Vol 91 (4) ◽  
pp. 717-723 ◽  
Author(s):  
Benjamin Clasen ◽  
Nicole Moss ◽  
Monika Chandler ◽  
Alan Smith
Keyword(s):  
Genetic Structure ◽  
North America ◽  
Small Variation ◽  
Structure Study ◽  
Inter Simple Sequence Repeat ◽  
Principal Coordinates Analysis ◽  
Tanacetum Vulgare ◽  
Pair Group ◽  
Principal Coordinates ◽  
Disturbed Areas

Clasen, B. M., Moss, N. G., Chandler, M. A. and Smith, A. G. 2011. A preliminary genetic structure study of the non-native weed, common tansy (Tanacetum vulgare). Can. J. Plant Sci. 91: 717–723. Common tansy is an herbaceous perennial member of the Asteraceae and is considered a weed in North America. Common tansy was introduced deliberately for use as a funerary herb, medicine, preservative, and animal and insect repellent. It is known to escape cultivation and invade disturbed areas, spreading both sexually and asexually. This paper reports a preliminary analysis of the genetic structure of 10 invasive common tansy populations in Minnesota and Montana, USA, and Alberta, Canada. Ninety polymorphic loci were found using six inter simple sequence repeat (ISSR) primers used to amplify DNA from 40 individuals from 10 discrete populations. The diversity within and among populations was assessed using the Dice coefficient of similarity and AMOVA. The AMOVA showed that diversity within populations was generally high and that there was relatively small variation among populations. An unweighted pair-group with arithmetic mean (UPGMA) dendrogram was constructed based on the distance between populations, and demonstrated substantial and distinct clustering of a population from Ramsey County, Minnesota. A principal coordinates analysis clustered all individuals from Ramsey County distinctly from other individuals, indicating a possible limited gene flow among this population and the other populations sampled in this study. Understanding genetic diversity and the distribution of diversity within and among populations may help predict the potential for successful management of common tansy populations in North America.

scholarly journals Patterns of genetic variation in leading-edge populations of Quercus robur: genetic patchiness due to family clusters

2020 ◽  
Vol 16 (5) ◽  
Author(s):  
Pekka Vakkari ◽  
Mari Rusanen ◽  
Juha Heikkinen ◽  
Tea Huotari ◽  
Katri Kärkkäinen
Keyword(s):  
Population Structure ◽  
Genetic Structure ◽  
Genetic Differentiation ◽  
Population Genetic ◽  
Quercus Robur ◽  
Spatial Genetic Structure ◽  
Medium Size ◽  
Pedunculate Oak ◽  
Genetic Structures ◽  
Genetic Patchiness

Abstract The genetic structure of populations at the edge of species distribution is important for species adaptation to environmental changes. Small populations may experience non-random mating and differentiation due to genetic drift but larger populations, too, may have low effective size, e.g., due to the within-population structure. We studied spatial population structure of pedunculate oak, Quercus robur, at the northern edge of the species’ global distribution, where oak populations are experiencing rapid climatic and anthropogenic changes. Using 12 microsatellite markers, we analyzed genetic differentiation of seven small to medium size populations (census sizes 57–305 reproducing trees) and four populations for within-population genetic structures. Genetic differentiation among seven populations was low (Fst = 0.07). We found a strong spatial genetic structure in each of the four populations. Spatial autocorrelation was significant in all populations and its intensity (Sp) was higher than those reported in more southern oak populations. Significant genetic patchiness was revealed by Bayesian structuring and a high amount of spatially aggregated full and half sibs was detected by sibship reconstruction. Meta-analysis of isoenzyme and SSR data extracted from the (GD)2 database suggested northwards decreasing trend in the expected heterozygosity and an effective number of alleles, thus supporting the central-marginal hypothesis in oak populations. We suggest that the fragmented distribution and location of Finnish pedunculate oak populations at the species’ northern margin facilitate the formation of within-population genetic structures. Information on the existence of spatial genetic structures can help conservation managers to design gene conservation activities and to avoid too strong family structures in the sampling of seeds and cuttings for afforestation and tree improvement purposes.

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