Genetic diversity and population structure of Alternaria species from tomato and potato in North Carolina and Wisconsin

AbstractEarly blight (EB) caused by Alternaria linariae or Alternaria solani and leaf blight (LB) caused by A. alternata are economically important diseases of tomato and potato. Little is known about the genetic diversity and population structure of these pathogens in the United States. A total of 214 isolates of A. alternata (n = 61), A. linariae (n = 96), and A. solani (n = 57) were collected from tomato and potato in North Carolina and Wisconsin and grouped into populations based on geographic locations and tomato varieties. We exploited 220 single nucleotide polymorphisms derived from DNA sequences of 10 microsatellite loci to analyse the population genetic structure between species and between populations within species and infer the mode of reproduction. High genetic variation and genotypic diversity were observed in all the populations analysed. The null hypothesis of the clonality test based on the index of association $$\left( {\overline{r}_{d} } \right)$$ r ¯ d was rejected, and equal frequencies of mating types under random mating were detected in some studied populations of Alternaria spp., suggesting that recombination can play an important role in the evolution of these pathogens. Most genetic differences were found between species, and the results showed three distinct genetic clusters corresponding to the three Alternaria spp. We found no evidence for clustering of geographic location populations or tomato variety populations. Analyses of molecular variance revealed high (> 85%) genetic variation within individuals in a population, confirming a lack of population subdivision within species. Alternaria linariae populations harboured more multilocus genotypes (MLGs) than A. alternata and A. solani populations and shared the same MLG between populations within a species, which was suggestive of gene flow and population expansion. Although both A. linariae and A. solani can cause EB on tomatoes and potatoes, these two species are genetically differentiated. Our results provide new insights into the evolution and structure of Alternaria spp. and can lead to new directions in optimizing management strategies to mitigate the impact of these pathogens on tomato and potato production in North Carolina and Wisconsin.

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Genetic diversity and population structure of Rhipicephalus sanguineus sensu lato across different regions of Colombia

Parasites & Vectors ◽

10.1186/s13071-021-04898-w ◽

2021 ◽

Vol 14 (1) ◽

Author(s):

Luisa Páez-Triana ◽

Marina Muñoz ◽

Giovanny Herrera ◽

Darwin A. Moreno-Pérez ◽

Gabriel A. Tafur-Gómez ◽

...

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Dna Sequences ◽

Phylogenetic Trees ◽

Statistical Tests ◽

Population Expansion ◽

Rhipicephalus Sanguineus ◽

Tick Population ◽

12S Rdna ◽

Haplotype Networks

Abstract Background There has been a long-standing debate over the taxonomic status of Rhipicephalus sanguineus sensu lato. Different studies worldwide have reported the occurrence of different well-defined lineages, in addition to Rhipicephalus sanguineus sensu stricto. To date, there are very few studies examining the diverse aspects of this tick in Colombia. We assessed the population structure and genetic diversity of R. sanguineus s.l. in eight departmental regions across Colombia. Methods A total of 170 ticks were collected from dogs in different departments of Colombia. All specimens were morphologically compatible with R. sanguineus s.l. and subjected to genetic analysis. DNA sequences were obtained for the 12S rDNA, cytochrome oxidase I (COI) and internal transcribed spacer 2 (ITS2) markers. A concatenated set of all mitochondrial markers was also constructed. Next, maximum likelihood phylogenetic trees were constructed using the sequences generated herein and sequences available in GenBank. Finally, we assessed different summary statistics and analysed population structure and divergence with Fst and Dxy and demographic changes with Tajima's D and Fu and Li’s statistical tests. Results Analysis of the 12S rDNA and COI revealed that all R. sanguineus s.l. specimens collected across different regions of Colombia clustered within the tropical lineage. Micro-geographical analyses showed that the tick population from Amazonas formed a distinct cluster separated from the other sequences, with moderate Fst and Dxy values. However, no signs of a robust population structure were found within the country. The results of Fu’s FS tests, together with the haplotype networks and diversity values, signal a possible population expansion of this tick species in Colombia. Conclusions Evidence provided herein supports the tropical lineage as the main circulating lineage in Colombia, exhibiting a general lack of genetic structure except for the Amazonas region. Graphical Abstract

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Genetic diversity studies of alfalfa germplasm (Medicago sativa L. subsp. sativa) of United States origin using microsatellite analysis

Legume Research - An International Journal ◽

10.18805/lr-358 ◽

2017 ◽

Cited By ~ 1

Author(s):

Shuying Yin ◽

Yanrong Wang ◽

Zhibiao Nan

Keyword(s):

United States ◽

Genetic Diversity ◽

Population Structure ◽

Genetic Variation ◽

Polymorphic Information Content ◽

The United States ◽

Microsatellite Analysis ◽

Information Index ◽

Diversity Studies ◽

Two Populations

This study aimed to understand the genetic diversity and population structure of alfalfa germplasm from the United States. In this study, the population structure and genetic diversity of six alfalfa cultivars of United States origin were investigated by microsatellite analysis with 40 individuals per cultivar. A total of 312 discernible alleles were amplified from the whole genome with an average of 31.2 alleles per locus. The average values of polymorphic information content and Shannon’s information index were 0.928 and 0.133, respectively, showing high levels of genetic diversity. Two populations were identified by STRUCTURE software with principal coordinate analysis and neighbour-joining clustering. Analysis of molecular variance analysis (AMOVA) revealed that the majority of genetic variation was within cultivars (96.42%) rather than between cultivars (3.58%). In conclusion, analyses of genetic diversity and population structure may be useful for the genetic analysis and utilization of genetic variation in alfalfa breeding.

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Population Structure of the Blueberry Pathogen Monilinia vaccinii-corymbosi in the United States

Phytopathology ◽

10.1094/phyto-03-14-0074-r ◽

2015 ◽

Vol 105 (4) ◽

pp. 533-541 ◽

Cited By ~ 3

Author(s):

Kathleen M. Burchhardt ◽

Marc A. Cubeta

Keyword(s):

United States ◽

Genetic Diversity ◽

New York ◽

Population Structure ◽

Population Biology ◽

Random Mating ◽

The United States ◽

Restricted Gene Flow ◽

Southeast United States ◽

Genetic Diversity And Structure

The fungus Monilinia vaccinii-corymbosi causes disease of blueberry (Vaccinium section Cyanococcus) shoots, flowers, and fruit. The objective of our research was to examine the population biology and genetics of M. vaccinii-corymbosi in the United States. A total of 480 samples of M. vaccinii-corymbosi were collected from 18 blueberry fields in 10 states; one field in Georgia, Massachusetts, Maine, Michigan, Mississippi, New Jersey, New York, Oregon, and Washington and nine fields in North Carolina. Analysis with 10 microsatellite markers revealed 247 unique multilocus haplotypes (MLHs), with 244 MLHs detected within 11 fields in the Northeast, Northwest, Midwest, and Southeast and three MLHs detected within seven fields in the Southeast United States. Genetic similarity and low genetic diversity of M. vaccinii-corymbosi isolates from the seven fields in the Southeast United States suggested the presence of an expansive, self-fertile population. Tests for linkage disequilibrium within 10 fields that contained ≥12 MLHs supported random mating in six fields and possible inbreeding and/or self-fertilization in four fields. Analysis of molecular variance, discriminate analysis of principal components, and Bayesian cluster analysis provided evidence for population structure and restricted gene flow among fields. This research represents the first comprehensive investigation of the genetic diversity and structure of field populations of M. vaccinii-corymbosi.

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Genetic Diversity and Population Structure of Rhododendron rex Subsp. rex Inferred from Microsatellite Markers and Chloroplast DNA Sequences

Plants ◽

10.3390/plants9030338 ◽

2020 ◽

Vol 9 (3) ◽

pp. 338 ◽

Cited By ~ 1

Author(s):

Xue Zhang ◽

Yuan-Huan Liu ◽

Yue-Hua Wang ◽

Shi-Kang Shen

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Microsatellite Markers ◽

Chloroplast Dna ◽

Dna Sequences ◽

Demographic History ◽

Population Decline ◽

Population Expansion ◽

Distribution Models ◽

Recent Population Expansion

Genetic diversity is vital to the sustainable utilization and conservation of plant species. Rhododendron rex subsp. rex Lévl. is an endangered species endemic to the southwest of China. Although the natural populations of this species are facing continuous decline due to the high frequency of anthropogenic disturbance, the genetic information of R. rex subsp. rex is not yet elucidated. In the present study, 10 pairs of microsatellite markers (nSSRs) and three pairs of chloroplast DNA (cpDNAs) were used in the elucidation of the genetic diversity, population structure, and demographic history of 11 R. rex subsp. rex populations. A total of 236 alleles and 12 haplotypes were found. A moderate genetic diversity within populations (HE = 0.540 for nSSRs, Hd = 0.788 for cpDNA markers), high historical and low contemporary gene flows, and moderate genetic differentiation (nSSR: FST = 0.165***; cpDNA: FST = 0.841***) were detected among the R. rex subsp. rex populations. Genetic and geographic distances showed significant correlation (p < 0.05) determined by the Mantel test. The species exhibited a conspicuous phylogeographical structure among the populations. Using the Bayesian skyline plot and species distribution models, we found that R. rex subsp. rex underwent a population demography contraction approximately 50,000–100,000 years ago. However, the species did not experience a recent population expansion event. Thus, habitat loss and destruction, which result in a population decline and species inbreeding depression, should be considered in the management and conservation of R. rex subsp. rex.

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Canine echinococcosis: genetic diversity of Echinococcus granulosus sensu stricto (s.s.) from definitive hosts

Journal of Helminthology ◽

10.1017/s0022149x15000395 ◽

2015 ◽

Vol 89 (6) ◽

pp. 689-698 ◽

Cited By ~ 18

Author(s):

B. Boufana ◽

W. Lett ◽

S. Lahmar ◽

A. Griffiths ◽

D.J. Jenkins ◽

...

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Genetic Variation ◽

Echinococcus Granulosus ◽

Population Expansion ◽

Sensu Stricto ◽

Geographical Regions ◽

Self Fertilization ◽

Adult Tapeworm ◽

Asymptomatic Disease

AbstractCanids, particularly dogs, constitute the major source of cystic echinococcosis (CE) infection to humans, with the majority of cases being caused by Echinococcus granulosus (G1 genotype). Canine echinococcosis is an asymptomatic disease caused by adult tapeworms of E. granulosus sensu lato (s.l.). Information on the population structure and genetic variation of adult E. granulosus is limited. Using sequenced data of the mitochondrial cytochrome c oxidase subunit 1 (cox1) we examined the genetic diversity and population structure of adult tapeworms of E. granulosus (G1 genotype) from canid definitive hosts originating from various geographical regions and compared it to that reported for the larval metacestode stage from sheep and human hosts. Echinococcus granulosus (s.s) was identified from adult tapeworm isolates from Kenya, Libya, Tunisia, Australia, China, Kazakhstan, United Kingdom and Peru, including the first known molecular confirmation from Gaza and the Falkland Islands. Haplotype analysis showed a star-shaped network with a centrally positioned common haplotype previously described for the metacestode stage from sheep and humans, and the neutrality indices indicated population expansion. Low Fst values suggested that populations of adult E. granulosus were not genetically differentiated. Haplotype and nucleotide diversities for E. granulosus isolates from sheep and human origin were twice as high as those reported from canid hosts. This may be related to self-fertilization of E. granulosus and/or to the longevity of the parasite in the respective intermediate and definitive hosts. Improved nuclear single loci are required to investigate the discrepancies in genetic variation seen in this study.

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Phylogeography of Prunus armeniaca L. revealed by chloroplast DNA and nuclear ribosomal sequences

Scientific Reports ◽

10.1038/s41598-021-93050-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Wen-Wen Li ◽

Li-Qiang Liu ◽

Qiu-Ping Zhang ◽

Wei-Quan Zhou ◽

Guo-Quan Fan ◽

...

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Chloroplast Dna ◽

Population Expansion ◽

Prunus Armeniaca ◽

River Valley ◽

Nuclear Ribosomal Dna ◽

Glacial Refugium ◽

Ili River Valley ◽

Wild Apricot

AbstractTo clarify the phytogeography of Prunus armeniaca L., two chloroplast DNA fragments (trnL-trnF and ycf1) and the nuclear ribosomal DNA internal transcribed spacer (ITS) were employed to assess genetic variation across 12 P. armeniaca populations. The results of cpDNA and ITS sequence data analysis showed a high the level of genetic diversity (cpDNA: HT = 0.499; ITS: HT = 0.876) and a low level of genetic differentiation (cpDNA: FST = 0.1628; ITS: FST = 0.0297) in P. armeniaca. Analysis of molecular variance (AMOVA) revealed that most of the genetic variation in P. armeniaca occurred among individuals within populations. The value of interpopulation differentiation (NST) was significantly higher than the number of substitution types (GST), indicating genealogical structure in P. armeniaca. P. armeniaca shared genotypes with related species and may be associated with them through continuous and extensive gene flow. The haplotypes/genotypes of cultivated apricot populations in Xinjiang, North China, and foreign apricot populations were mixed with large numbers of haplotypes/genotypes of wild apricot populations from the Ili River Valley. The wild apricot populations in the Ili River Valley contained the ancestral haplotypes/genotypes with the highest genetic diversity and were located in an area considered a potential glacial refugium for P. armeniaca. Since population expansion occurred 16.53 kyr ago, the area has provided a suitable climate for the population and protected the genetic diversity of P. armeniaca.

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Average Number of Nucleotide Differences in a Sample From a Single Subpopulation: A Test for Population Subdivision

Genetics ◽

10.1093/genetics/117.1.149 ◽

1987 ◽

Vol 117 (1) ◽

pp. 149-153

Author(s):

Curtis Strobeck

Keyword(s):

Monte Carlo Simulation ◽

Population Structure ◽

Random Mating ◽

Population Subdivision ◽

Expected Number ◽

Migration Rates ◽

Mating Population ◽

Unbiased Estimates ◽

Increasing Function ◽

Stepping Stone Model

ABSTRACT Unbiased estimates of θ = 4Nµ in a random mating population can be based on either the number of alleles or the average number of nucleotide differences in a sample. However, if there is population structure and the sample is drawn from a single subpopulation, these two estimates of θ behave differently. The expected number of alleles in a sample is an increasing function of the migration rates, whereas the expected average number of nucleotide differences is shown to be independent of the migration rates and equal to 4N Tµ for a general model of population structure which includes both the island model and the circular stepping-stone model. This contrast in the behavior of these two estimates of θ is used as the basis of a test for population subdivision. Using a Monte-Carlo simulation developed so that independent samples from a single subpopulation could be obtained quickly, this test is shown to be a useful method to determine if there is population subdivision.

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Genetic Diversity of Wild Oat (Avena fatua)Populations from China and the United States

Weed Science ◽

10.1614/ws-06-108.1 ◽

2007 ◽

Vol 55 (2) ◽

pp. 95-101 ◽

Cited By ~ 21

Author(s):

Runzhi Li ◽

Shiwen Wang ◽

Liusheng Duan ◽

Zhaohu Li ◽

Michael J. Christoffers ◽

...

Keyword(s):

United States ◽

Genetic Diversity ◽

Gene Diversity ◽

Genetic Relationships ◽

The United States ◽

Mantel Test ◽

Wild Oat ◽

Chinese Populations ◽

Nei's Distance ◽

The Impact

Weed genetic diversity is important for understanding the ability of weeds to adapt to different environments and the impact of herbicide selection on weed populations. Genetic diversity within and among six wild oat populations in China varying in herbicide selection pressure and one population in North Dakota were surveyed using 64 polymorphic alleles resulting from 25 microsatellite loci. Mean Nei's gene diversity (h) for six wild oat populations from China was between 0.17 and 0.21, and total diversity (HT) was 0.23. A greater proportion of this diversity, however, was within (Hs= 0.19) rather than among (Gst= 0.15) populations. For the wild oat population from the United States,h= 0.24 andHT= 0.24 were comparable to the values for the six populations from China. Cluster analysis divided the seven populations into two groups, where one group was the United States population and the other group included the six Chinese populations. The genetic relationships among six populations from China were weakly correlated with their geographic distribution (r= 0.22) using the Mantel test. Minimal difference in gene diversity and small genetic distance (Nei's distance 0.07 or less) among six populations from China are consistent with wide dispersal of wild oat in the 1980s. Our results indicate that the wild oat populations in China are genetically diverse at a level similar to North America, and the genetic diversity of wild oat in the broad spatial scale is not substantially changed by environment, agronomic practices, or herbicide usage.

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Evaluation of a Diverse, Worldwide Collection of Wild, Cultivated, and Landrace Pepper (Capsicum annuum) for Resistance to Phytophthora Fruit Rot, Genetic Diversity, and Population Structure

Phytopathology ◽

10.1094/phyto-02-14-0031-r ◽

2015 ◽

Vol 105 (1) ◽

pp. 110-118 ◽

Cited By ~ 10

Author(s):

R. P. Naegele ◽

A. J. Tomlinson ◽

M. K. Hausbeck

Keyword(s):

Genetic Diversity ◽

Population Structure ◽

Phytophthora Capsici ◽

The United States ◽

Fruit Rot ◽

Sources Of Resistance ◽

Plant Introductions ◽

Genetic Clusters ◽

Commercial Breeding ◽

Moderately Resistant

Pepper is the third most important solanaceous crop in the United States and fourth most important worldwide. To identify sources of resistance for commercial breeding, 170 pepper genotypes from five continents and 45 countries were evaluated for Phytophthora fruit rot resistance using two isolates of Phytophthora capsici. Genetic diversity and population structure were assessed on a subset of 157 genotypes using 23 polymorphic simple sequence repeats. Partial resistance and isolate-specific interactions were identified in the population at both 3 and 5 days postinoculation (dpi). Plant introductions (PIs) 640833 and 566811 were the most resistant lines evaluated at 5 dpi to isolates 12889 and OP97, with mean lesion areas less than Criollo de Morelos. Genetic diversity was moderate (0.44) in the population. The program STRUCTURE inferred four genetic clusters with moderate to very great differentiation among clusters. Most lines evaluated were susceptible or moderately susceptible at 5 dpi, and no lines evaluated were completely resistant to Phytophthora fruit rot. Significant population structure was detected when pepper varieties were grouped by predefined categories of disease resistance, continent, and country of origin. Moderately resistant or resistant PIs to both isolates of P. capsici at 5 dpi were in genetic clusters one and two.

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Genetic variation in native and farmed populations of Tambaqui (Colossoma macropomum) in the Brazilian Amazon: regional discrepancies in farming systems

Anais da Academia Brasileira de Ciências ◽

10.1590/0001-376520130007 ◽

2013 ◽

Vol 85 (4) ◽

pp. 1439-1447 ◽

Cited By ~ 8

Author(s):

Jonas Aguiar ◽

Horacio Schneider ◽

Fatima Gomes ◽

Jeferson Carneiro ◽

Simoni Santos ◽

...

Keyword(s):

Genetic Diversity ◽

Genetic Variation ◽

Dna Sequences ◽

Amazon Basin ◽

Farming Systems ◽

Wild Populations ◽

The West ◽

Colossoma Macropomum ◽

Breeding Stock ◽

History Of

The tambaqui, Colossoma macropomum, is the most popular fish species used for aquaculture in Brazil but there is no study comparing genetic variation among native and farmed populations of this species. In the present study, we analyzed DNA sequences of the mitochondrial DNA to evaluate the genetic diversity among two wild populations, a fry-producing breeding stock, and a sample of fish farm stocks, all from the region of Santarém, in the west of the Brazilian state of Pará. Similar levels of genetic diversity were found in all the samples and surprisingly the breeding stock showed expressive representation of the genetic diversity registered on wild populations. These results contrast considerably with those of the previous study of farmed stocks in the states of Amapá, Pará, Piauí, and Rondônia, which recorded only two haplotypes, indicating a long history of endogamy in the breeding stocks used to produce fry. The results of the two studies show two distinct scenarios of tambaqui farming in the Amazon basin, which must be better evaluated in order to guarantee the successful expansion of this activity in the region, and the rest of Brazil, given that the tambaqui and its hybrids are now farmed throughout the country.

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