scholarly journals Genetic Diversity, Fungicide Sensitivity, and Host Resistance to Ceratocystis fimbriata Infecting Sweetpotato in North Carolina

Plant Disease ◽  
2017 ◽  
Vol 101 (6) ◽  
pp. 994-1001 ◽  
Author(s):  
A. C. Scruggs ◽  
T. Basaiah ◽  
M. L. Adams ◽  
L. M. Quesada-Ocampo
Keyword(s):  
Genetic Diversity ◽  
North Carolina ◽  
Control Strategies ◽  
Management Strategies ◽  
Pcr Amplification ◽  
The United States ◽  
Black Rot ◽  
Ceratocystis Fimbriata ◽  
Fungicide Application

Black rot of sweetpotato, caused by Ceratocystis fimbriata, has recently reemerged as a significant threat to sweetpotato production in North Carolina and other states across the United States. This disease has historically been controlled largely through cultural management strategies and, in some cases, fungicide application. The sudden and destructive reemergence of this disease in 2015 created the need for rapidly evaluating disease control strategies. Genetic diversity of current C. fimbriata isolates infecting sweetpotato in North Carolina was assessed using ITS, TEF, and MAT-2 sequences. All 50 tested isolates were confirmed to be of a single mating type, MAT-2, based on PCR amplification. Alignment of ITS, TEF, and MAT-2 sequences revealed all isolates were identical at each locus. Fourteen common sweetpotato cultivars and advanced breeding lines were screened for black rot resistance using two isolates. None of the cultivars were completely resistant to the disease and most were equally susceptible. ‘Stokes Purple’ and ‘Covington’ were the least susceptible, but significantly (P < 0.05) differed only from ‘Bellevue’, the most susceptible cultivar. Sensitivity of 50 C. fimbriata isolates to difenoconazole, fludioxonil, thiabendazole, dicloran, azoxystrobin, pyraclostrobin, fenamidone, and fluazinam was evaluated in vitro. Difenoconazole, thiabendazole, and fluazinam were most effective in reducing mycelia growth. Postharvest fungicide application on black rot-infected roots provided similar results. Low efficacy of dicloran, as well as a range of EC50 values among isolates, suggests potential resistance to this commonly applied fungicide. Results obtained in this study provide current and useful information so that improved recommendations can be made to reduce losses in sweetpotato to black rot.

scholarly journals Susceptibility of Some Corylus avellana L. Cultivars to Xanthomonas arboricola pv. corylina

2021 ◽  
Vol 12 ◽  
Author(s):  
John Bryan Webber ◽  
Sugae Wada ◽  
Virginia O. Stockwell ◽  
Nik G. Wiman
Keyword(s):  
Bacterial Blight ◽  
Control Strategies ◽  
Management Strategies ◽  
The United States ◽  
Corylus Avellana ◽  
Xanthomonas Arboricola ◽  
Time Required ◽  
Symptom Progression

Bacterial blight of hazelnut (Corylus avellana L.) is caused by Xanthomonas arboricola pv. corylina (Xac). In the past, bacterial blight has been a key disease impacting the Oregon hazelnut industry where 99% of the United States hazelnut crop is grown. The disease is re-emerging in young orchards, as acreage of newly released hazelnut cultivars rapidly increases. This increase in hazelnut acreage is accompanied by renewed interest in developing control strategies for bacterial blight. Information on susceptibility of hazelnut cultivars to Xac is limited, partially due to lack of verified methods to quantify hazelnut cultivar response to artificial inoculation. In this research, Xac inoculation protocols were adapted to two hazelnut growing environments to evaluate cultivar susceptibility: in vitro tissue culture under sterile and controlled conditions, and in vivo potted tree conditions. Five hazelnut cultivars were evaluated using the in vitro inoculation protocol and seven hazelnut cultivars were evaluated using the in vivo inoculation protocol. Under in vitro conditions, there were severe bacterial blight symptoms on each cultivar consistent with those seen in the field, but no significant differences in the susceptibility of the newly released cultivars were observed compared to known Xac-susceptible cultivar (“Barcelona”). Under in vivo conditions, the proportion of necrotic buds were significantly higher in “Jefferson” and “Dorris” compared to all of the other tested cultivars, including “Barcelona.” The symptom progression seen in vivo mirrored the timing and symptom progression of bacterial blight reported from field observations. The in vitro conditions significantly reduced the amount of time required to measure the inoculation efficiency compared to the in vivo environment and allowed for greater replication. Further studies on the effects of Xac can use the results of these experiments to establish a dose–response model for bacterial blight, a wider range of germplasm can be tested under in vitro conditions, and management strategies that can be evaluated on large populations of new cultivars using the in vivo methods.

scholarly journals Assessing the Role of Temperature, Inoculum Density, and Wounding on Disease Progression of the Fungal Pathogen Ceratocystis fimbriata Causing Black Rot in Sweetpotato

Plant Disease ◽  
2020 ◽  
Vol 104 (3) ◽  
pp. 930-937 ◽  
Author(s):  
M. Stahr ◽  
L. M. Quesada-Ocampo
Keyword(s):  
Disease Management ◽  
Disease Incidence ◽  
Management Strategies ◽  
The United States ◽  
Storage Conditions ◽  
Inoculum Density ◽  
Separate Experiment ◽  
Black Rot ◽  
Disease Development ◽  
Ceratocystis Fimbriata

In 2014, Ceratocystis fimbriata, causal agent of black rot in sweetpotato, reemerged and inflicted large financial losses on growers in the United States. Black rot continues to damage sweetpotatoes and has become a priority to the industry since then. In contrast, little is known about the biology of C. fimbriata and the epidemiology of sweetpotato black rot. In this study, effects of environmental factors such as inoculum density, RH, and temperature on sweetpotato black rot were determined. Cured sweetpotatoes were wounded with a toothpick to simulate puncture wounds, inoculated with different spore suspensions (inoculum density) (104, 105, or 106 spores/ml), and incubated under different RH (85.53, 94.09, or 97.01%) and temperature (13, 18, 23, 29, or 35°C) for 21 days. In a separate experiment, five root wounding types (cuts, punctures, abrasions, end breaks, and macerating bruises) were compared. All wounded roots were subsequently soaked in a 103 spores/ml suspension and incubated at 100% RH and 23°C for 21 days. This study found 29 and 23°C to be the optimal temperature for black rot disease development and sporulation, respectively. No pathogen growth was observed at 13 and 35°C. Increased inoculum density significantly (P < 0.0001) increased disease incidence, but increasing RH had an effect only on sporulation area. All wound types resulted in increased disease incidence and sporulation as early as 7 days postinoculation. Our results highlight the importance of characterizing factors that affect disease development for achieving successful disease management strategies. Findings from this study will be used to improve disease management for sweetpotato black rot by suggesting tighter regulation of curing and storage conditions and better postharvest handling of sweetpotato roots to avoid unnecessary wounding.

scholarly journals Limited Genetic Diversity in North American Isolates of Phytophthora erythroseptica Pathogenic to Potato Based on RAPD Analysis

Plant Disease ◽  
2005 ◽  
Vol 89 (4) ◽  
pp. 380-384 ◽  
Author(s):  
Rick D. Peters ◽  
Rod J. Clark ◽  
Albert D. Coffin ◽  
Antony V. Sturz ◽  
David H. Lambert ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
North America ◽  
New Brunswick ◽  
Prince Edward Island ◽  
Random Amplified Polymorphic Dna ◽  
Geographic Origin ◽  
The United States ◽  
Vitro Assay ◽  
Phytophthora Erythroseptica

Pink rot of potato (Solanum tuberosum), caused by Phytophthora erythroseptica, is found wherever potatoes are grown, and in the last decade, it has reemerged as an economically important disease in Canada and the United States. A selection of isolates of P. erythroseptica from major potato-growing regions in North America, namely Prince Edward Island and New Brunswick, Canada, and Maine and Idaho, U.S.A., was assessed for genetic diversity with randomly chosen decanucleotide primers which were used to amplify regions of DNA to reveal polymorphisms among templates (random amplified polymorphic DNA [RAPD]). The isolates varied in their geographic origin as well as in their sensitivity to mefenoxam, as determined by an in vitro assay. In three separate RAPD screens (I, II, and III) with 23 isolates of P. erythroseptica chosen from a larger collection, 1,410, 369, and 316 robust, scorable bands were amplified, respectively. However, among the bands amplified in screens I, II, and III, only 3, 1, and 3 bands, respectively, were polymorphic. When three primers yielding polymorphisms were used to screen 106 isolates from Prince Edward Island and New Brunswick, or a representative collection of 32 isolates from Prince Edward Island, New Brunswick, Maine, and Idaho, no major variation was discovered. RAPD markers were not correlated with geographic origin or mefenoxam sensitivity of the isolates. From an evolutionary standpoint, the absence of genetic diversity among the isolates of P. erythroseptica we examined may be attributable to the relatively recent introduction of a small founding population of the pathogen in North America.

scholarly journals Genetic Diversity of phlD from 2,4-Diacetylphloroglucinol-Producing Fluorescent Pseudomonas spp.

2001 ◽  
Vol 91 (1) ◽  
pp. 35-43 ◽  
Author(s):  
Olga V. Mavrodi ◽  
Brian B. McSpadden Gardener ◽  
Dmitri V. Mavrodi ◽  
Robert F. Bonsall ◽  
David M. Weller ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Fungal Pathogens ◽  
Essential Gene ◽  
Random Amplified Polymorphic Dna ◽  
Rflp Analysis ◽  
The United States ◽  
Gaeumannomyces Graminis ◽  
Pseudomonas Spp ◽  
Fluorescent Pseudomonas

Fluorescent Pseudomonas spp. that produce 2,4-diacetylphloroglucinol (2,4-DAPG) have biocontrol activity against damping-off, root rot, and wilt diseases caused by soilborne fungal pathogens, and play a key role in the natural suppression of Gaeumannomyces graminis var. tritici, known as take-all decline. Diversity within phlD, an essential gene in the biosynthesis of 2,4-DAPG, was studied by restriction fragment length polymorphism (RFLP) analysis of 123 2,4-DAPG-producing isolates from six states in the United States and six other locations worldwide. Clusters defined by RFLP analysis of phlD correlated closely with clusters defined previously by BOX-polymerase chain reaction (PCR) genomic fingerprinting, indicating the usefulness of phlD as a marker of genetic diversity and population structure among 2,4-DAPG producers. Genotypes defined by RFLP analysis of phlD were conserved among isolates from the same site and cropping history. Random amplified polymorphic DNA analyses of genomic DNA revealed a higher degree of polymorphism than RFLP and BOX-PCR analyses. Genotypic diversity in a subset of 30 strains representing all the phlD RFLP groups did not correlate with production in vitro of monoacetylphloroglucinol, 2,4-DAPG, or total phloroglucinol compounds. Twenty-seven of the 30 representative strains lacked pyrrolnitrin and pyoluteorin biosynthetic genes as determined by the use of specific primers and probes.

scholarly journals 34 Reproductive management of beef females in tropical and sub-tropical environments

2019 ◽  
Vol 97 (Supplement_3) ◽  
pp. 37-37
Author(s):  
Nicola Oosthuizen ◽  
Pedro Levy Piza Fontes ◽  
G Cliff Lamb
Keyword(s):  
Assisted Reproductive Technologies ◽  
Bos Taurus ◽  
Management Strategies ◽  
Bos Indicus ◽  
The United States ◽  
Reproductive Technologies ◽  
Pregnancy Rates ◽  
Embryo Production ◽  
Reproductive Management

Abstract Bos indicus and Bos taurus cattle diverged from an evolutionary standpoint more than 110,000 years ago. Since then, Bos indicus cattle have undergone genetic adaptations beyond the commonly discussed increased thermo-tolerance and parasite resistance. Several physiological differences exist between Bos indicus and Bos taurus cattle, and it is important to consider these differences when establishing reproductive management strategies. It has been well described that Bos indicus cattle have a delayed onset of puberty and longer periods of postpartum anestrus, yet through the utilization of estrus synchronization protocols these challenges can be attenuated. However, when Bos indicus females are exposed to these protocols, they are known to have smaller dominant follicles, lower expression of estrus, and decreased pregnancy rates to artificial insemination (AI) when compared to Bos taurus females. These factors can be overcome through the utilization of estradiol and progesterone based synchronization protocols, which improve follicular dynamics and yield acceptable pregnancy rates to assisted reproductive technologies in cattle adapted to tropical or subtropical conditions. However, the use of estrogens for synchronization purposes is not permitted in the United States, and cattle producers need to rely on GnRH-based protocols. Another key difference between subspecies, is that Bos indicus females have greater antral follicle counts than Bos taurus females, which proves beneficial for in vitro embryo production. Therefore, an opportunity exists to explore the greater productivity of donors in embryo production in order to improve genetics in herds that utilize these breeds.

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

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Tika B. Adhikari ◽  
Norman Muzhinji ◽  
Dennis Halterman ◽  
Frank J. Louws
Keyword(s):  
Genetic Diversity ◽  
North Carolina ◽  
Population Structure ◽  
Genetic Variation ◽  
Dna Sequences ◽  
Random Mating ◽  
Population Expansion ◽  
The United States ◽  
Population Subdivision ◽  
The Impact

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.

scholarly journals Evaluation of QoI Fungicide Application Strategies for Managing Fungicide Resistance and Potato Early Blight Epidemics in Wisconsin

Plant Disease ◽  
2008 ◽  
Vol 92 (4) ◽  
pp. 561-568 ◽  
Author(s):  
N. Rosenzweig ◽  
Z. K. Atallah ◽  
G. Olaya ◽  
W. R. Stevenson
Keyword(s):  
Fungicide Resistance ◽  
Early Blight ◽  
Field Experiments ◽  
Management Strategies ◽  
Alternaria Solani ◽  
The United States ◽  
Nucleotide Polymorphisms ◽  
Mutant Type ◽  
Potato Acreage

Potato early blight (Alternaria solani) is a yield-limiting disease and control depends primarily on multiple fungicide applications. Azoxystrobin, registered in the United States in 1999, initially provided outstanding early blight control. Within 3 years, approximately 80% of the total potato acreage was being treated with azoxystrobin and other quinone outside inhibitor (QoI), fungicides registered subsequently. Alternaria solani isolates with decreased in vitro sensitivity to azoxystrobin were detected in Wisconsin during 2001. Field experiments were conducted in 2001 to 2003 to evaluate season-long fungicide programs and test fungicide resistance management strategies. The fungicide program recommended to growers at that time, which consisted of three applications of azoxystrobin for weeks 1, 3, and 5 alternated with applications of chlorothalonil at label recommended rates, was effective in controlling early blight when conditions were conducive to disease development. Mean sensitivity in vitro of A. solani isolates from fungicide efficacy field experiments in 2001 to 2003 was numerically highest for isolates from the untreated control plots, chlorothalonil-alone plots, or plots treated with three applications of azoxystrobin alternated with chlorothalonil compared with other treatments tested. Three single-nucleotide polymorphisms (SNPs) can cause the F129L substitution (TTC to TTA, CTC, or TTG) that results in decreased sensitivity to azoxystrobin of A. solani. The TTA mutant was the most frequently recovered mutant type in the field experiments. The frequency of recovery of wild-type isolates in experiments was 22% in 2001, 4% in 2002, and 22% in 2003.

scholarly journals Phenotypic and Genetic Diversity of Xanthomonas perforans Populations from Tomato in North Carolina

2019 ◽  
Vol 109 (9) ◽  
pp. 1533-1543 ◽  
Author(s):  
Pragya Adhikari ◽  
Tika B. Adhikari ◽  
Sujan Timilsina ◽  
Inga Meadows ◽  
Jeffrey B. Jones ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
North Carolina ◽  
Management Practices ◽  
Citrate Synthase ◽  
Elongation Factor ◽  
Copper Tolerance ◽  
Bacterial Spot ◽  
Sequence Alignments ◽  
Phenotypic And Genetic Diversity

Bacterial spot caused by Xanthomonas spp. is one of the most devastating diseases of tomato in North Carolina (NC). In total, 290 strains of Xanthomonas spp. from tomato in NC collected over 2 years (2015 and 2016) were analyzed for phenotypic and genetic diversity. In vitro copper and streptomycin sensitivity assays revealed that >95% (n = 290) of the strains were copper tolerant in both years, whereas 25% (n = 127) and 46% (n = 163) were streptomycin tolerant in 2016 and 2015, respectively. Using BOX repetitive element PCR assay, fingerprint patterns showed four haplotypes (H1, H2, H3, and H4) among the strains analyzed. The multiplex real-time quantitative PCR on a subset of representative strains (n = 45) targeting the highly conserved hrcN gene identified Xanthomonas strains from tomato in NC that belonged to X. perforans. Race profiling of the representative strains (n = 45) on tomato and pepper differentials confirmed that ∼9 and 91% of strains are tomato races T3 and T4, respectively. Additionally, PCR assays and sequence alignments confirmed that the copL, copA, copB (copLAB copper tolerance gene cluster), and avrXv4 genes are present in the strains analyzed. Phylogenetic and comparative sequence analyses of six genomic regions (elongation factor G [fusA], glyceraldehyde-3-phosphate dehydrogenase A [gapA], citrate synthase [gltA], gyrase subunit B [gyrB], ABC transporter sugar permease [lacF], and GTP binding protein [lepA]) suggested that 13 and 74% of X. perforans strains from NC were genetically similar to races T3 and T4 from Florida, respectively. Our results provide insights that bacterial spot management practices in tomato should focus on deploying resistance genes to combat emerging pathogenic races of X. perforans and overcome the challenges currently posed by intense use of copper-based bactericides.

scholarly journals Sweetpotato cultivar susceptibility to infection by Ceratocystis fimbriata

2011 ◽  
Vol 64 ◽  
pp. 1-6 ◽  
Author(s):  
S.L. Lewthwaite ◽  
P.J. Wright ◽  
C.M. Triggs
Keyword(s):  
Crop Production ◽  
Ipomoea Batatas ◽  
Lateral Roots ◽  
The United States ◽  
Black Rot ◽  
Storage Roots ◽  
Ceratocystis Fimbriata ◽  
Susceptibility To Infection ◽  
Cultivar Susceptibility ◽  
Japanese Cultivar

The fungus Ceratocystis fimbriata causes a disease of the sweetpotato (Ipomoea batatas) plant commonly known as black rot This study evaluated sweetpotato cultivar susceptibility to C fimbriata infection During crop production infection of sweetpotato storage roots may take place by transmission from contaminated transplants but generally the pathogen is introduced directly through openings in the periderm These openings may take the form of damaged secondary lateral roots lenticels or wounds In a laboratorybased bioassay storage roots were punctured then pointinoculated with the pathogen Following incubation under warm humid conditions the dimensions of black rot lesions were compared The predominant New Zealand cultivar Owairaka Red was demonstrably less susceptible to C fimbriata than the Japanese cultivar Beniazuma but significantly more susceptible than Beauregard from the United States of America (P

scholarly journals Phylogenetic Analysis of the Hypervariable Region of the 18S rRNA Gene of Cryptosporidium Oocysts in Feces of Canada Geese (Branta canadensis): Evidence for Five Novel Genotypes

2004 ◽  
Vol 70 (1) ◽  
pp. 452-458 ◽  
Author(s):  
Kristen L. Jellison ◽  
Daniel L. Distel ◽  
Harold F. Hemond ◽  
David B. Schauer
Keyword(s):  
Genetic Diversity ◽  
Phylogenetic Analysis ◽  
18S Rrna ◽  
Hypervariable Region ◽  
Pcr Amplification ◽  
The United States ◽  
18S Rrna Gene ◽  
Rrna Gene ◽  
Canada Geese ◽  
Pcr Products

ABSTRACT To assess genetic diversity in Cryptosporidium oocysts from Canada geese, 161 fecal samples from Canada geese in the United States were analyzed. Eleven (6.8%) were positive for Cryptosporidium spp. following nested PCR amplification of the hypervariable region of the 18S rRNA gene. Nine PCR products from geese were cloned and sequenced, and all nine diverged from previously reported Cryptosporidium 18S rRNA gene sequences. Five sequences were very similar or identical to each other but genetically distinct from that of Cryptosporidium baileyi; two were most closely related to, but genetically distinct from, the first five; and two were distinct from any other sequence analyzed. One additional sequence in the hypervariable region of the 18S rRNA gene isolated from a cormorant was identical to that of C. baileyi. Phylogenetic analysis provided evidence for new genotypes of Cryptosporidium species in Canada geese. Results of this study suggest that the taxonomy of Cryptosporidium species in geese is complex and that a more complete understanding of genetic diversity among these parasites will facilitate our understanding of oocyst sources and species in the environment.

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