scholarly journals Evolution of morphological but not aggressiveness‐related traits following a major resistance breakdown in the poplar rust fungus, Melampsora larici‐populina

2020 ◽  
Author(s):  
Agathe Maupetit ◽  
Bénédicte Fabre ◽  
Jérémy Pétrowski ◽  
Axelle Andrieux ◽  
Stéphane De Mita ◽  
...  
Keyword(s):  
Rust Fungus ◽  
Resistance Breakdown

A point mutation and large deletion at the candidate avirulence locus AvrMlp7 in the poplar rust fungus correlate with poplar RMlp7 resistance breakdown

2021 ◽  
Author(s):  
Clémentine Louet ◽  
Méline Saubin ◽  
Axelle Andrieux ◽  
Antoine Persoons ◽  
Mathilde Gorse ◽  
...  
Keyword(s):  
Point Mutation ◽  
Rust Fungus ◽  
Large Deletion ◽  
Resistance Breakdown

High-pressure freezing and freeze substitution of teliospores of the rust fungus Gymnosporangium clavipes

1990 ◽  
Vol 48 (3) ◽  
pp. 692-693
Author(s):  
Robert W. Roberson
Keyword(s):  
High Pressure ◽  
Room Temperature ◽  
Pathogenic Fungus ◽  
Rust Fungus ◽  
Freeze Substitution ◽  
Ice Crystals ◽  
High Pressure Freezing ◽  
Thin Walled Structures ◽  
Cytological Changes ◽  
Dextran Solution

The use of cryo-techniques for the preparation of biological specimens in electron microscopy has led to superior preservation of ultrastructural detail. Although these techniques have obvious advantages, a critical limitation is that only 10-40 μm thick cells and tissue layers can be frozen without the formation of distorting ice crystals. However, thicker samples (600 μm) may be frozen well by rapid freezing under high-pressure (2,100 bar). To date, most work using cryo-techniques on fungi have been confined to examining small, thin-walled structures. High-pressure freezing and freeze substitution are used here to analysis pre-germination stages of specialized, sexual spores (teliospores) of the plant pathogenic fungus Gymnosporangium clavipes C & P.Dormant teliospores were incubated in drops of water at room temperature (25°C) to break dormancy and stimulate germination. Spores were collected at approximately 30 min intervals after hydration so that early cytological changes associated with spore germination could be monitored. Prior to high-pressure freezing, the samples were incubated for 5-10 min in a 20% dextran solution for added cryoprotection during freezing. Forty to 50 spores were placed in specimen cups and holders and immediately frozen at high pressure using the Balzers HPM 010 apparatus.

Virulent New Strains of Rust Fungus Endanger World Wheat

2010 ◽  
Vol 5 (10) ◽  
pp. 423-428
Author(s):  
Marcia Stone
Keyword(s):  
Rust Fungus

scholarly journals Terpene and resin acid contents in Scots pine stem lesions colonized by the rust fungus Cronartium pini

2021 ◽  
Author(s):  
Juha Kaitera ◽  
Juha Piispanen ◽  
Ulrich Bergmann
Keyword(s):  
Scots Pine ◽  
Rust Fungus ◽  
Resin Acid ◽  
Stem Lesions

scholarly journals Genetically Divergent Types of the Wheat Leaf Fungus Puccinia triticina in Ethiopia, a Center of Tetraploid Wheat Diversity

2016 ◽  
Vol 106 (4) ◽  
pp. 380-385 ◽  
Author(s):  
J. A. Kolmer ◽  
M. A. Acevedo
Keyword(s):  
Leaf Rust ◽  
Common Wheat ◽  
Hexaploid Wheat ◽  
Rust Fungus ◽  
Tetraploid Wheat ◽  
Low Frequency ◽  
Puccinia Triticina ◽  
Leaf Rust Resistance ◽  
Virulence Phenotype ◽  
Wheat Leaf

Collections of Puccinia triticina, the wheat leaf rust fungus, were obtained from tetraploid and hexaploid wheat in the central highlands of Ethiopia, and a smaller number from Kenya, from 2011 to 2013, in order to determine the genetic diversity of this wheat pathogen in a center of host diversity. Single-uredinial isolates were derived and tested for virulence phenotype to 20 lines of Thatcher wheat that differ for single leaf rust resistance genes and for molecular genotypes with 10 simple sequence repeat (SSR) primers. Nine virulence phenotypes were described among the 193 isolates tested for virulence. Phenotype BBBQJ, found only in Ethiopia, was predominantly collected from tetraploid wheat. Phenotype EEEEE, also found only in Ethiopia, was exclusively collected from tetraploid wheat and was avirulent to the susceptible hexaploid wheat ‘Thatcher’. Phenotypes MBDSS and MCDSS, found in both Ethiopia and Kenya, were predominantly collected from common wheat. Phenotypes CCMSS, CCPSS, and CBMSS were found in Ethiopia from common wheat at low frequency. Phenotypes TCBSS and TCBSQ were found on durum wheat and common wheat in Kenya. Four groups of distinct SSR genotypes were described among the 48 isolates genotyped. Isolates with phenotypes BBBQJ and EEEEE were in two distinct SSR groups, and isolates with phenotypes MBDSS and MCDSS were in a third group. Isolates with CCMSS, CCPSS, CBMSS, TCBSS, and TCBSQ phenotypes were in a fourth SSR genotype group. The diverse host environment of Ethiopia has selected and maintained a genetically divergent population of P. triticina.

scholarly journals Isolates of Uromyces appendiculatus with Specific Virulence to Landraces of Phaseolus vulgaris of Andean Origin

Plant Disease ◽  
1999 ◽  
Vol 83 (2) ◽  
pp. 108-113 ◽  
Author(s):  
Craig M. Sandlin ◽  
James R. Steadman ◽  
Carlos M. Araya ◽  
Dermot P. Coyne
Keyword(s):  
Phaseolus Vulgaris ◽  
Rapd Analysis ◽  
Random Amplified Polymorphic Dna ◽  
Rust Fungus ◽  
Distinct Group ◽  
Uromyces Appendiculatus ◽  
Bean Rust ◽  
Banding Patterns ◽  
Highly Virulent ◽  
Specific Virulence

Five isolates of the bean rust fungus Uromyces appendiculatus were shown to be specifically virulent on bean genotypes of Andean origin. This specificity was demonstrated by the virulence of five pairs of isolates on a differential set of 30 Phaseolus vulgaris landraces. Each isolate pair was from a different country in the Americas and consisted of one Andean-specific isolate and one nonspecific isolate. Of the differential P. vulgaris landraces, 15 were of Middle American origin and 15 were of Andean origin. The Andean-specific rust isolates were highly virulent on Andean landraces but not on landraces of Middle American origin. Rust isolates with virulence to Middle American landraces were also generally virulent on Andean material; no truly Middle American-specific isolates were found. Random amplified polymorphic DNA (RAPD) analysis of the rust isolates also distinguished the two groups. Four of the Andean-specific rust isolates formed a distinct group compared to four of the nonspecific isolates. Two of the isolates, one from each of the two virulence groups, had intermediate RAPD banding patterns, suggesting that plasmagomy but not karyogamy occurred between isolates of the two groups.

Relationships between Microstructure and Mechanical Properties of Polycristalline Alumina

2014 ◽  
Vol 625 ◽  
pp. 192-195
Author(s):  
Lillia Haddour ◽  
Mourad Keddam ◽  
Nadir Mesrati
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Alumina Ceramics ◽  
Intergranular Phase ◽  
Microstructural Parameters ◽  
Mechanical And Electrical Properties ◽  
Resistance Breakdown ◽  
Dielectrical Properties ◽  
Scaning Electron Microscopy ◽  
Fundamental Mechanism

Some low purity alumina ceramics with an alumina content ranging from 86% to 93% were investigated, in order to explore the effects of microstructural parameters (grain size, intergranular phase) on mechanical (wear) and dielectrical parameters. The microstructure and worn surfaces were analysed using scaning electron microscopy. The correlation between microstructural, dielectrical properties and wear is discussed. It has been proposed that mechanical and electrical properties are two aspects of the same fundamental mechanism. Key words: Al2O3, Microstructure final, Wear resistance, Breakdown.

Genetic dissection of partial resistance to race 6 of Venturia inaequalis in apple

Genome ◽  
2003 ◽  
Vol 46 (2) ◽  
pp. 224-234 ◽  
Author(s):  
C E Durel ◽  
L Parisi ◽  
F Laurens ◽  
W E Van de Weg ◽  
R Liebhard ◽  
...  
Keyword(s):  
Resistance Gene ◽  
Malus Domestica ◽  
Quantitative Trait ◽  
Partial Resistance ◽  
Venturia Inaequalis ◽  
Genetic Dissection ◽  
Resistance Breakdown ◽  
Trait Locus ◽  
New Races ◽  
Genomic Regions

Scab, caused by the fungus Venturia inaequalis, is one of the most important diseases of apple (Malus × domestica). The major resistance gene, Vf, has been widely used in apple breeding programs, but two new races of the fungus (races 6 and 7) are able to overcome this gene. A mapped F1 progeny derived from a cross between the cultivars Prima and Fiesta has been inoculated with two monoconidial strains of race 6. These strains originated from sporulating leaves of 'Prima' and a descendant of 'Prima' that were grown in an orchard in northern Germany. 'Prima' carries the Vf resistance gene, whereas 'Fiesta' lacks Vf. A large variation in resistance and (or) susceptibility was observed among the individuals of the progeny. Several quantitative trait loci (QTLs) for resistance were identified that mapped on four genomic regions. One of them was located in the very close vicinity of the Vf resistance gene on linkage group LG-1 of the 'Prima' genetic map. This QTL is isolate specific because it was only detected with one of the two isolates. Two out of the three other genomic regions were identified with both isolates (LG-11 and LG-17). On LG-11, a QTL effect was detected in both parents. The genetic dissection of this QTL indicated a favourable intra-locus interaction between some parental alleles.Key words: Malus × domestica, partial resistance, Venturia inaequalis, resistance breakdown, quantitative trait locus.

scholarly journals Diversifying selection in the wheat stem rust fungus acts predominantly on pathogen-associated gene families and reveals candidate effectors

2014 ◽  
Vol 5 ◽  
Author(s):  
Jana Sperschneider ◽  
Hua Ying ◽  
Peter N. Dodds ◽  
Donald M. Gardiner ◽  
Narayana M. Upadhyaya ◽  
...  
Keyword(s):  
Stem Rust ◽  
Rust Fungus ◽  
Gene Families ◽  
Wheat Stem Rust ◽  
Diversifying Selection
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