Pathogenic variation among isolates ofPyricularia oryzaeaffecting rice, wheat, and grasses in Brazil

1992 ◽  
Vol 38 (4) ◽  
pp. 367-371 ◽  
Author(s):  
A. S. Prabhu ◽  
M. C. Filippi ◽  
N. Castro
Keyword(s):  
Pathogenic Variation

scholarly journals Pathogenic Variation of South American Phakopsora pachyrhizi Populations Isolated from Soybeans from 2010 to 2015

2017 ◽  
Vol 51 (3) ◽  
pp. 221-232 ◽  
Author(s):  
Hajime AKAMATSU ◽  
Naoki YAMANAKA ◽  
Rafael Moreira SOARES ◽  
Antonio Juan Gerardo IVANCOVICH ◽  
Miguel Angel LAVILLA ◽  
...  
Keyword(s):  
South American ◽  
Phakopsora Pachyrhizi ◽  
Pathogenic Variation

scholarly journals Molecular and Pathogenicity Characterization of Sphaceloma manihoticola Isolates from South-Central Brazil

Plant Disease ◽  
2003 ◽  
Vol 87 (11) ◽  
pp. 1322-1328 ◽  
Author(s):  
Elizabeth Alvarez ◽  
Juan Fernando Mejia ◽  
Teresa L. Valle
Keyword(s):  
Morphological Characteristics ◽  
Restriction Pattern ◽  
Poly Merase Chain Reaction ◽  
Highly Pathogenic ◽  
Central Brazil ◽  
Host Interaction ◽  
South Central ◽  
Pcr Product ◽  
Pathogenic Variation

Isolates of Sphaceloma manihoticola, the asexual stage of Elsinoe brasiliensis, were collected from several regions of south-central Brazil. The isolates were obtained from samples of leaves, stems, and petioles of cassava (Manihot esculenta) and the weedy Euphorbia heterophylla (“amendoim bravo”) by directly plating infected tissue onto acidified potato dextrose agar. For pathogenicity studies, 19 isolates were inoculated onto each of two cassava cultivars, MBRA 703 as a susceptible cultivar and MBRA 12 as a resistant cultivar to S. manihoticola. MBRA 703, with the greatest pathogenicity to 58% (11) of the isolates, showed an intermediate pathogenic reaction to 16% (3) of the isolates, and was less pathogenic to 26% (5) of the isolates. MBRA 12, with a less pathogenic reaction to 63% (12) of the isolates, showed an intermediate pathogenic reaction to 16% (3) of the isolates, and was highly pathogenic to 21% (4) of the isolates. The isolates were verified as belonging to the genus Sphaceloma based on their morphological characteristics, including conidia and hyphae of monoconidial isolate. Conidia of isolates were small, thin-walled, ellipsoid to (rarely) globose, commonly with one or two gut-tules. Conidiophores were phialides, hyaline to slightly pigmented 0-to-1 septate; conidiophores from the weedy specie were phialides, hyaline to brown 0-to-2 septate producing hyaline conidia. The isolates also were verified as belonging to the genus Sphaceloma by using a poly-merase chain reaction (PCR) assay, which detected a 645-bp band in all isolates except two (1 and 6) for which the PCR product had 600 bp. Digestion of the amplified product with the enzymes MspI and CfoI allowed differences to be detected in restriction patterns among isolates. A homogeneous banding pattern was obtained for 17 of the isolates but a different restriction pattern was obtained for isolates 1 and 6 of E. heterophylla. This suggests the possibility of another species within this group of isolates. The results indicate the presence of pathogenic variation among isolates of the fungus and an isolate-host interaction, because statistically significant differences were observed between the two cassava cultivars in response to inoculation with the isolates of S. manihoticola.

scholarly journals Pathogenic Variation of Phakopsora pachyrhizi Isolates on Soybean in the United States from 2006 to 2009

Plant Disease ◽  
2012 ◽  
Vol 96 (1) ◽  
pp. 75-81 ◽  
Author(s):  
M. Twizeyimana ◽  
G. L. Hartman
Keyword(s):  
United States ◽  
Resistance Genes ◽  
The United States ◽  
Soybean Rust ◽  
Phakopsora Pachyrhizi ◽  
Soybean Genotype ◽  
Pathogenic Variation ◽  
Differential Set ◽  
Soybean Genotypes ◽  
Soybean Leaves

The introduction of Phakopsora pachyrhizi, the cause of soybean rust, into the United States is a classic case of a pathogen introduction that became established in a new geographical region overwintering on a perennial host (kudzu, Pueraria lobata). The objective of our study was to classify the pathogenic variation of P. pachyrhizi isolates collected in the United States, and to determine the spatial and temporal associations. In total, 72 isolates of P. pachyrhizi collected from infected kudzu and soybean leaves in the United States were purified, then established and increased on detached soybean leaves. These isolates were tested for virulence and aggressiveness on a differential set of soybean genotypes that included six genotypes with known resistance genes (Rpp), one resistant genotype without any known characterized resistance gene, and a susceptible genotype. Three pathotypes were identified among the 72 U.S. P. pachyrhizi isolates based on the virulence of these isolates on the genotypes in the differential set. Six aggressiveness groups were established based on sporulating-uredinia production recorded for each isolate on each soybean genotype. All three pathotypes and all six aggressiveness groups were found in isolates collected from the southern region and from both hosts (kudzu or soybean) in 2008. Shannon's index based on the number of pathotypes indicated that isolates from the South region were more diverse (H = 0.83) compared with the isolates collected in other regions. This study establishes a baseline of pathogenic variation of P. pachyrhizi in the United States that can be further compared with variation reported in other regions of the world and in future studies that monitor P. pachyrhizi virulence in association to deployment of rust resistance genes.

Phenotypic, genotypic and pathogenic variation among streptomycetes implicated in common scab disease

1998 ◽  
Vol 27 (5) ◽  
pp. 255-260 ◽  
Author(s):  
P. A. Bramwell ◽  
P. Wiener ◽  
A. D. L. Akkermans ◽  
E. M. H. Wellington
Keyword(s):  
Common Scab ◽  
Pathogenic Variation

scholarly journals Characterization of Streptomyces scabies isolates from potato tubers its pathogenic variations in Rawalpindi District

2014 ◽  
Vol 4 (1) ◽  
pp. 1-6
Author(s):  
S. Shazia ◽  
F. Naz ◽  
A. Rauf ◽  
M. Inam-ul-Haq ◽  
S. Bushra
Keyword(s):  
Solanum Tuberosum L ◽  
Economic Loss ◽  
Streptomyces Scabies ◽  
Potato Tubers ◽  
Yield And Quality ◽  
Isolation And Characterization ◽  
Pathogenic Variation ◽  
Important Disease

Potato (Solanum tuberosum L.) has various biotic constraints in its production due to pest attack. Among these, common scab caused by streptomyces scabies is an important disease in potato which causes economic loss with respect to plant yield and quality of tubers. The present study was conducted to determine the pathogenicity, pathogenic variation, characterization of morphological, physiological and biochemical aspects of Streptomyces associated with potato tubers grown in Rawalpindi district. Severity data and pathogenic variation of disease was studied by using different isolation and characterization techniques.

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