scholarly journals Stem Rot of Branched Broomrape (Orobanche ramosa) Caused by Sclerotium rolfsii in Chile

Plant Disease ◽  
2010 ◽  
Vol 94 (10) ◽  
pp. 1266-1266 ◽  
Author(s):  
R. Galdames ◽  
J. Diaz
Keyword(s):  
Ribosomal Rna ◽  
Biological Control Agent ◽  
Direct Sequencing ◽  
Sclerotium Rolfsii ◽  
Central Zone ◽  
Stem Rot ◽  
Its2 Region ◽  
Rrna Gene ◽  
Fungal Culture ◽  
Tobacco Plants

Branched broomrape is a holoparasitic weed present in some areas of central and southern Chile (33°S to 38°S), which is often found parasitizing tomato and tobacco crops. During an extensive survey conducted in different tomato-growing areas during the summer of 2010, branched broomrape plants with stem rot symptoms were detected in a commercial tomato crop located in the central zone (34°14′S, 71°1′W). Rotten stems were observed with white mycelia and approximately 1-mm-diameter spherical sclerotia on affected tissue below the soil surface. Parasitized tomato plants showed no symptoms. Sclerotia were taken directly from affected stems with a dissecting needle under a stereoscopic microscope in a flow chamber and placed on potato dextrose agar (PDA) medium. Germinating sclerotia consistently produced colonies similar to Sclerotium rolfsii with new sclerotia formed within 6 to 7 days. Mycelia produced hyphal clamp connections under the light microscope (2). DNA was extracted from one fungal culture. The ITS1 region, 5.8S rRNA gene, and the ITS2 region of the nuclear-encoded ribosomal RNA gene were amplified with primers ITS1 and ITS4 (4). The sequence was deposited in GenBank (Accession No. HM222638) and showed ≥99% identity values with sequences of similar regions from Athelia rolfsii (anamorph S. rolfsii; Accession Nos. AB075304, DQ0595578, AF499018, and AB075305). Different pathogenicity tests were performed. Inoculum was prepared by placing mycelia plugs from a PDA-grown, 6-day-old colony in a flask with sterilized wheat seeds and incubated for 2 weeks. Three Orobanche plants, each one with 10 to 15 shoots at different aerial stages (starting emergence, flowering, and formed capsules) were gently planted separately in 35-cm pots. Inoculum (10 g per pot) was placed in the soil surrounding the plants. One pot was used as a control. Forty-five-day-old tomato and tobacco plants were additionally inoculated by a similar procedure. After 12 days, inoculated Orobanche plants showed reduced vigor and stem decay. After 9 days, tomato and tobacco plants showed wilt. In all cases, the fungus was reisolated on PDA from all inoculated plants. To our knowledge, this is the first report of S. rolfsii on O. ramosa (1). A previous report of S. rolfsii parasitizing O. cernua has also been made (3). The high susceptibility of tomato and tobacco plants to this isolate of S. rolfsii precludes the use of this pathogen as a biological control agent against broomrape. References: (1) D. F. Farr and A. Y. Rossman. Fungal Databases. Systematic Mycology and Microbiology Laboratory, ARS, USDA. Retrieved May 14, 2010, from http://nt.ars-grin.gov/fungaldatabases . (2) Z. K. Punja and A. Damiani. Mycologia 88:694, 1996. (3) C. A. Raju et al. Phytoparasitica 23:235, 1995. (4) T. J. White et al. Amplification and direct sequencing of fungal ribosomal RNA genes for phylogenetics. Page 315 in: PCR Protocols: A Guide to Methods and Applications. M. A. Innis et al., eds. Academic Press, New York, 1990.

scholarly journals VARIAN SOMAKLONAL KACANG TANAH RESISTEN SCLEROTIUM ROLFSII HASIL SELEKSI IN VITRO MENGGUNAKAN FILTRAT KULTUR CENDAWAN

2010 ◽  
Vol 10 (1) ◽  
pp. 35-46
Author(s):  
Yusnita Yusnita ◽  
Hajrial Aswidinnoor ◽  
Rita Megia ◽  
Rusmilah Suseno ◽  
Sudarsono Sudarsono
Keyword(s):  
In Vitro Selection ◽  
Healing Process ◽  
Sclerotium Rolfsii ◽  
Selective Medium ◽  
Stem Rot ◽  
Wound Healing Process ◽  
Fungal Culture ◽  
Somaclonal Variants ◽  
Culture Filtrates

Peanut somaclonal variants resistant to Sclerotium rolfsii derived from in vitro selection with fungal culture filtrates. Sclerotium stem rot is one of the most important peanut disease which often caused significant yield loss.  The use of peanut cultivars resistant to Sclerotium rolfsii infection is the most efficient way to control the disease.  Attempts to obtain peanut lines with tolerance or resistance to Sclerotium stem rot through induction of somaclonal variation and in vitro selection using fungal culture filtrates (CF) have been conducted previously. Somatic embryo (SE) clumps that had been maitained in culture for approximately one year in regeneration medium were exposed onto selective medium containing 30% S. rolfsii CF for three consecutive 1 month –passages, and the SE formed after selection periods were considered to be insensitive to the fungal CF. A number R0 peanut lines have been regenerated from CF-insensitive SE, and their R1 and R2 progenies were grown in a plastic house for evaluation on qualitative and quantitative variant characters.  Early identification for tolerance to S. rolfsii was also conducted among R0 peanut lines, and the results have shown enhanced resistance when compared to the original non-selected cultivar.  However, further evaluation is needed to study responses of the R1 and R2 progenies of the somaclones against S. rolfsii infection.  The objective of this particular study was to evaluate responses of R1 and R2 peanut somaclones derived from fungal CF-insensitif SE against S. rolfsii infection in the plastic house.  Results of this experiment showed, a number of resistant somaclonal variants were obtained among R1 and R2 population, which segregated as resistance and susceptible to S. rolfsii infection.  The resistance somaclonal variants initially showed stem rot symptoms after inoculation with S. rolfsii with disease score (DS) of 1 to 3.  However, as the plants grew and developed, they showed wound-healing process at the lesio and they were able to produce the same or higher number of filled pod as the original non-inoculated peanut plants.

scholarly journals Dermacentor variabilis is the Predominant Dermacentor spp. (Acari: Ixodidae) Feeding on Dogs and Cats Throughout the United States

2021 ◽  
Author(s):  
Kathryn T Duncan ◽  
Meriam N Saleh ◽  
Kellee D Sundstrom ◽  
Susan E Little
Keyword(s):  
United States ◽  
Spotted Fever ◽  
Rocky Mountain ◽  
The United States ◽  
Dermacentor Variabilis ◽  
Western United States ◽  
Its2 Region ◽  
Rrna Gene ◽  
Rocky Mountain Spotted Fever ◽  
Dermacentor Albipictus

Abstract Throughout North America, Dermacentor spp. ticks are often found feeding on animals and humans, and are known to transmit pathogens, including the Rocky Mountain spotted fever agent. To better define the identity and distribution of Dermacentor spp. removed from dogs and cats in the United States, ticks submitted from 1,457 dogs (n = 2,924 ticks) and 137 cats (n = 209 ticks) from veterinary practices in 44/50 states from February 2018-January 2020 were identified morphologically (n = 3,133); the identity of ticks from regions where Dermacentor andersoni (Stiles) have been reported, and a subset of ticks from other regions, were confirmed molecularly through amplification and sequencing of the ITS2 region and a 16S rRNA gene fragment. Of the ticks submitted, 99.3% (3,112/3,133) were Dermacentor variabilis (Say), 0.4% (12/3,133) were D. andersoni, and 0.3% (9/3,133) were Dermacentor albipictus (Packard). While translocation of pets prior to tick removal cannot be discounted, the majority (106/122; 87%) of Dermacentor spp. ticks removed from dogs and cats in six Rocky Mountain states (Montana, Idaho, Wyoming, Nevada, Utah, and Colorado) were D. variabilis, suggesting this species may be more widespread in the western United States than is currently recognized, or that D. andersoni, if still common in the region, preferentially feeds on hosts other than dogs and cats. Together, these data support the interpretation that D. variabilis is the predominant Dermacentor species found on pets throughout the United States, a finding that may reflect recent shifts in tick distribution.

scholarly journals Molecular Detection of Filamentous Fungi in Formalin-Fixed Paraffin-Embedded Specimens in Invasive Fungal Wound Infections Is Feasible with High Specificity

2019 ◽  
Vol 58 (1) ◽  
Author(s):  
Anuradha Ganesan ◽  
Justin Wells ◽  
Faraz Shaikh ◽  
Philip Peterson ◽  
William Bradley ◽  
...  
Keyword(s):  
Filamentous Fungi ◽  
Rapid Identification ◽  
Lower Sensitivity ◽  
Its2 Region ◽  
Fungal Culture ◽  
Wound Infections ◽  
Formalin Fixed Paraffin ◽  
Formalin Fixed Paraffin Embedded ◽  
Panfungal Pcr ◽  
Formalin Fixed

ABSTRACT Trauma-related invasive fungal wound infections (IFIs) are associated with significant morbidity and mortality. Early identification and treatment are critical. Traditional identification methods (e.g., fungal cultures and histopathology) can be delayed and insensitive. We assessed a PCR-based sequencing assay for rapid identification of filamentous fungi in formalin-fixed paraffin-embedded (FFPE) specimens obtained from combat casualties injured in Afghanistan. Blinded FFPE specimens from cases (specimens positive on histopathology) and controls (specimens negative on histopathology) were submitted for evaluation with a panfungal PCR. The internal transcribed spacer 2 (ITS2) region of the fungal ribosomal repeat was amplified and sequenced. The PCR results were compared with findings from histopathology and/or culture. If injury sites contributed multiple specimens, findings for the site were collapsed to the site level. We included 64 case subjects (contributing 95 sites) and 102 controls (contributing 118 sites). Compared to histopathology, panfungal PCR was specific (99%), but not as sensitive (63%); however, sensitivity improved to 83% in specimens from sites with angioinvasion. Panfungal PCR identified fungi of the order Mucorales in 33 of 44 sites with angioinvasion (75%), whereas fungal culture was positive in 20 of 44 sites (45%). Saksenaea spp. were the dominant fungi identified by PCR in specimens from angioinvasion sites (57%). Panfungal PCR is specific, albeit with lower sensitivity, and performs better at identifying fungi of the order Mucorales than culture. DNA sequencing offers significant promise for the rapid identification of fungal infection in trauma-related injuries, leading to more timely and accurate diagnoses.

A Comparison of Disease Assessment Methods for Southern Stem Rot of Peanut

2002 ◽  
Vol 29 (1) ◽  
pp. 66-71 ◽  
Author(s):  
S. L. Rideout ◽  
T. B. Brenneman ◽  
K. L. Stevenson
Keyword(s):  
Alternative Assessment ◽  
Disease Incidence ◽  
Sclerotium Rolfsii ◽  
Correlation Coefficients ◽  
Assessment Method ◽  
Assessment Methods ◽  
Alternative Methods ◽  
Stem Rot ◽  
Disease Assessment ◽  
Time Required

Abstract Southern stem rot (caused by the soilborne fungus Sclerotium rolfsii Sacc.) of peanut (Arachis hypogaea L.) traditionally has been assessed based on the percentage of infected 30.5-cm row segments, commonly referred to as disease incidence. Several alternative disease assessment methods were evaluated in four fungicide trials during the growing season (aboveground ratings) and immediately after peanut inversion (belowground ratings). Pearson's correlation coefficients compared disease assessments and yields for all trials. Across all disease assessment methods, belowground assessments at inversion showed a stronger correlation with yield than in-season aboveground assessments. Several of the alternative assessment methods showed a stronger negative correlation with yield than did the traditional disease incidence rating. However, none of the alternative methods were consistently more precise across all assessment dates and trials. There was a significant positive correlation between many of the alternative methods and the traditional disease incidence method. Furthermore, none of the alternative methods was better than the traditional method for detecting differences among fungicide treatments when subjected to ANOVA and subsequent Waller-Duncan mean separation tests (k-ratio = 100). Based on comparisons of the time required to assess disease intensity, the traditional disease assessment method was found to be the most time efficient method of those tested in this study.

Two main clusters within Trypanosoma cruzi zymodeme 3 are defined by distinct regions of the ribosomal RNA cistron

Parasitology ◽  
2002 ◽  
Vol 124 (2) ◽  
pp. 177-184 ◽  
Author(s):  
M. B. A. MENDONÇA ◽  
N. S. NEHME ◽  
S. S. SANTOS ◽  
E. CUPOLILLO ◽  
N. VARGAS ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Ribosomal Rna ◽  
Southern Blotting ◽  
Pcr Amplification ◽  
Rrna Gene ◽  
Pcr Products ◽  
Phylogenetic Lineages ◽  
Definition Of ◽  
Ribosomal Cistron ◽  
Panstrongylus Geniculatus

Trypanosoma cruzi is currently classified into 2 major phylogenetic lineages, T. cruzi I and II, that correlate with the formerly described zymodeme 1 and 2, respectively. Another isoenzymic group (zymodeme 3–Z3) was also described. In this study, we analysed the genetic diversity among Z3 isolates of the Brazilian Amazon by restriction fragment length polymorphism of the intergenic transcribed spacers (ITSs) of the ribosomal RNA cistron and the size of the divergent domain D7 of the 24Sα rRNA gene. DNAs from 12 T. cruzi Z3 isolates obtained from humans (2), Panstrongylus geniculatus (1), and Rhodnius brethesi (9) were submitted to PCR amplification of the ITSs plus the 5·8S rDNA. The PCR products were digested with 4 distinct endonucleases and the profiles analysed by a numerical methodology. The phenetic dendrogram revealed a clear dichotomy in the Z3 group, defining 2 groups that were named Z3-A and Z3-B. Dimorphism was also found in the band sizes of the amplified D7 divergent domain of the 24Sα rDNA, which showed a perfect correlation with the ITSs clustering. The organization of the ribosomal cistron was investigated by Southern blotting and shown to be conserved in the genome of the 2 Z3 groups. This study shows that the rDNA cistron allows the definition of 2 distinct subclusters in Z3 isolates.

scholarly journals Unique clade of alphaproteobacterial endosymbionts induces complete cytoplasmic incompatibility in the coconut beetle

2017 ◽  
Vol 114 (23) ◽  
pp. 6110-6115 ◽  
Author(s):  
Shun-ichiro Takano ◽  
Midori Tuda ◽  
Keiji Takasu ◽  
Naruto Furuya ◽  
Yuya Imamura ◽  
...  
Keyword(s):  
Cytoplasmic Incompatibility ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Biological Control Agent ◽  
Illumina Miseq ◽  
Distinct Species ◽  
Rrna Gene ◽  
Asian Clade ◽  
The Pacific ◽  
Bacterial Endosymbionts ◽  
Unique Clade

Maternally inherited bacterial endosymbionts in arthropods manipulate host reproduction to increase the fitness of infected females. Cytoplasmic incompatibility (CI) is one such manipulation, in which uninfected females produce few or no offspring when they mate with infected males. To date, two bacterial endosymbionts,WolbachiaandCardinium, have been reported as CI inducers. OnlyWolbachiainduces complete CI, which causes 100% offspring mortality in incompatible crosses. Here we report a third CI inducer that belongs to a unique clade of Alphaproteobacteria detected within the coconut beetle,Brontispa longissima. This beetle comprises two cryptic species, the Asian clade and the Pacific clade, which show incompatibility in hybrid crosses. Different bacterial endosymbionts, a unique clade of Alphaproteobacteria in the Pacific clade andWolbachiain the Asian clade, induced bidirectional CI between hosts. The former induced complete CI (100% mortality), whereas the latter induced partial CI (70% mortality). Illumina MiSeq sequencing and denaturing gradient gel electrophoresis patterns showed that the predominant bacterium detected in the Pacific clade ofB. longissimawas this unique clade of Alphaproteobacteria alone, indicating that this endosymbiont was responsible for the complete CI. Sex distortion did not occur in any of the tested crosses. The 1,160 bp of 16S rRNA gene sequence obtained for this endosymbiont had only 89.3% identity with that ofWolbachia, indicating that it can be recognized as a distinct species. We discuss the potential use of this bacterium as a biological control agent.

scholarly journals Production of lytic enzymes by Trichoderma strains during in vitro antagonism with Sclerotium rolfsii, the causal agent of stem rot of groundnut

2015 ◽  
Vol 9 (6) ◽  
pp. 365-372 ◽  
Author(s):  
J Parmar H ◽  
P Bodar N ◽  
N Lakhani H ◽  
V Patel S ◽  
V Umrania V ◽  
...  
Keyword(s):  
Sclerotium Rolfsii ◽  
Causal Agent ◽  
Stem Rot ◽  
Lytic Enzymes

Soil-Borne Pests of Peanut in Growers' Fields with Different Cropping Histories in Alabama1

1996 ◽  
Vol 23 (1) ◽  
pp. 36-42 ◽  
Author(s):  
K. L. Bowen ◽  
A. K. Hagan ◽  
J. R. Weeks
Keyword(s):  
Aspergillus Flavus ◽  
Meloidogyne Incognita ◽  
Leaf Spot ◽  
Sclerotium Rolfsii ◽  
Stem Rot ◽  
Peanut Seed ◽  
Control Programs ◽  
Aflatoxigenic Fungi ◽  
Peanut Production ◽  
Seed Invasion

Abstract Pest levels and yields of peanut were monitored in growers' fields in 1991 through 1993. Yields ranged from 2085 to 6440 kg/ha and averaged 3947 kg/ha over the 3 yr. Incidence of southern stem rot (SSR) (caused by Sclerotium rolfsii) averaged 7.6 foci (up to 30 cm in length) per 30.5 m row and ranged from 0 to 31.0 foci. Peanut yield tended to be inversely related to incidence of SSR and directly related to the number of years between peanut crops. Incidence of SSR was inversely related to number of years between peanut crops and was consistently greater in fields cropped to peanut every other year compared to other fields with less intensive peanut production. Yields obtained from irrigated fields averaged 11.4% greater than those without irrigation. Leaf spot control programs used by growers provided consistent levels of control. Peanut seed invasion by aflatoxigenic fungi and plant damage by larvae of the lesser cornstalk borer (Elasmopalus lignosellus) generally were low. Seed invasion by Aspergillus flavus-type fungi was positively correlated (P < 0.05) with damage due to lesser cornstalk borer in 1993. Juvenile populations of root knot nematodes (Meloidogyne incognita) were positively correlated (P < 0.001) with incidence of SSR in 1992.

On-Farm Evaluations of Reduced Input Fungicide Programs in Peanut Fields with Low, Moderate, or High Levels of Disease Risk

2014 ◽  
Vol 41 (1) ◽  
pp. 50-57 ◽  
Author(s):  
J. E. Woodward ◽  
T. B. Brenneman ◽  
R. C. Kemerait ◽  
A. K. Culbreath ◽  
N. B. Smith
Keyword(s):  
Leaf Spot ◽  
Cultural Practices ◽  
Disease Risk ◽  
Sclerotium Rolfsii ◽  
Stem Rot ◽  
Cercospora Arachidicola ◽  
Production Region ◽  
Net Returns ◽  
Peanut Production ◽  
On Farm

ABSTRACT In 2003, 2004, and 2005 standard and reduced input fungicide programs were evaluated throughout the peanut production region of Georgia for control of early leaf spot (Cercospora arachidicola), late leaf spot (Cercosporidium personatum), and southern stem rot (Sclerotium rolfsii). Disease risk was determined for each field based on the cultural practices implemented and ranged from low to high. Six to eight fungicide applications were made in the standard programs, versus three to six applications in reduced programs. Leaf spot ratings were higher for the reduced programs in five of the fourteen trials with substantial defoliation occurring in one trial. Overall, southern stem rot control for the reduced programs was equal to or better than that for the standard program, which could be attributed to the differences in fungicide selection or timing. Pod yields for the reduced programs were equal to or greater than the standard programs in all but one trial. Net returns were higher for the reduced programs in half of the trials; however, the reduced program resulted in lower net returns in one trial in 2004. Our results indicate that reduced input fungicide programs can be used to adequately manage fungal diseases of peanut without compromising yield or profitability, and that the use of cultivars with moderate levels of disease resistance may enhance disease control.

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