Characterization of Phytophthora infestans in Wisconsin from 1993 to 1995

Late blight of potato (Solanum tuberosum), caused by Phytophthora infestans, recently reappeared in Wisconsin and was a significant production problem in 1994. P. infestans isolates collected in Wisconsin from 1993 to 1995 were characterized for the following traits: mating type, sensitivity to metalaxyl, and allozyme genotype for Glucose-6-phosphate isomerase (Gpi). Characterization of these isolates revealed that a new, more aggressive population (A2 mating type, metalaxyl resistant, and Gpi genotype 100/111/122) is displacing the old population (A1 mating type, metalaxyl sensitive, and Gpi genotype 86/100) in Wisconsin.

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The Appearance of Metalaxyl-Resistant Isolates of Phytophthora infestans in Delaware

Plant Disease ◽

10.1094/pdis.1997.81.9.1093d ◽

1997 ◽

Vol 81 (9) ◽

pp. 1093-1093 ◽

Cited By ~ 1

Author(s):

M. Sedegui ◽

R. B. Carroll ◽

A. L. Morehart ◽

R. P. Mulroony ◽

J. M. Whalen

Keyword(s):

Solanum Tuberosum ◽

Late Blight ◽

Phytophthora Infestans ◽

Mating Type ◽

Filter Paper ◽

Mycelial Growth ◽

Solanum Tuberosum L ◽

Tomato Plants ◽

Potato Foliage ◽

Allozyme Loci

Prior to 1995, late blight of potatoes (Solanum tuberosum L.) caused by Phytophthora infestans (Mont.) de Bary had not been reported from Delaware for decades. In that year, the fungus was isolated from potato foliage collected from fields in the Dover area that sustained severe foliage loss due to the disease. To establish pathogenicity, potato and tomato plants grown in the greenhouse were inoculated with the isolates obtained and Koch's postulates were completed. Analyses to determine mating type, genotype at two allozyme loci (2), Gpi and Pep, and sensitivity to metalaxyl were also completed. Measurements were made every 5 days and EC50 values were calculated for radial mycelial growth on metalaxyl-amended agar, for leaflets inoculated with P. infestans floated in metalaxyl solutions, and for inoculated potato tuber disks deposited on filter paper saturated with metalaxyl (1). Isolates were pathogenic to potatoes and tomatoes, were A2 mating type with Gpi 100/111/122 and Pep 100/100 (same as US-8), and displayed resistance to metalaxyl up to 140 mg/l. References: (1) K. L. Deahl et al. Am. Potato J. 70:779, 1993. (2) S. B. Goodwin et al. Plant Dis. 79:1181, 1995.

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Complete mitogenome mapping of potato late blight pathogen, Phytophthora infestans A2 mating type

Mitochondrial DNA Part B ◽

10.1080/23802359.2017.1280699 ◽

2017 ◽

Vol 2 (1) ◽

pp. 90-91

Author(s):

Virupaksh U. Patil ◽

G. Vanishree ◽

Debasis Pattanayak ◽

Sanjeev Sharma ◽

Vinay Bhardwaj ◽

...

Keyword(s):

Late Blight ◽

Phytophthora Infestans ◽

Mating Type ◽

Potato Late Blight ◽

Complete Mitogenome ◽

Late Blight Pathogen

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Phenotypic Characterization of Recent Clonal Lineages of Phytophthora infestans in the United States

Plant Disease ◽

10.1094/pdis-07-12-0682-re ◽

2013 ◽

Vol 97 (7) ◽

pp. 873-881 ◽

Cited By ~ 48

Author(s):

G. Danies ◽

I. M. Small ◽

K. Myers ◽

R. Childers ◽

W. E. Fry

Keyword(s):

United States ◽

Late Blight ◽

Phytophthora Infestans ◽

The United States ◽

Phenotypic Characterization ◽

Phenotypic Traits ◽

Mating Types ◽

Late Blight Disease ◽

Blight Disease

Phytophthora infestans, the causal agent of late blight disease, has been reported in the United States and Canada since the mid-nineteenth century. Due to the lack of or very limited sexual reproduction, the populations of P. infestans in the United States are primarily reproducing asexually and, thus, show a simple genetic structure. The emergence of new clonal lineages of P. infestans (US-22, US-23, and US-24) responsible for the late blight epidemics in the northeastern region of the United States in the summers of 2009 and 2010 stimulated an investigation into phenotypic traits associated with these genotypes. Mating type, differences in sensitivity to mefenoxam, differences in pathogenicity on potato and tomato, and differences in rate of germination were studied for clonal lineages US-8, US-22, US-23, and US-24. Both A1 and A2 mating types were detected. Lineages US-22, US-23, and US-24 were generally sensitive to mefenoxam while US-8 was resistant. US-8 and US-24 were primarily pathogenic on potato while US-22 and US-23 were pathogenic on both potato and tomato. Indirect germination was favored at lower temperatures (5 and 10°C) whereas direct germination, though uncommon, was favored at higher temperatures (20 and 25°C). Sporangia of US-24 released zoospores more rapidly than did sporangia of US-22 and US-23. The association of characteristic phenotypic traits with genotype enables the prediction of phenotypic traits from rapid genotypic analyses for improved disease management.

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Virulence of Phytophthora infestans isolates from potato in Spain

Plant Protection Science ◽

10.17221/39/2021-pps ◽

2021 ◽

Vol 57 (No. 4) ◽

pp. 279-288

Author(s):

Jose Ignacio Ruiz de Galarreta ◽

Alba Alvarez-Morezuelas ◽

Nestor Alor ◽

Leire Barandalla ◽

Enrique Ritter

Keyword(s):

Late Blight ◽

Phytophthora Infestans ◽

Late Blight Resistance ◽

Blight Resistance ◽

Genetic Changes ◽

Detached Leaves ◽

Severity Of The Disease ◽

Pathogen Populations ◽

Incompatibility Reactions

The oomycete Phytophthora infestans is responsible for the disease known as late blight in potato and tomato. It is the plant pathogen that has caused the greatest impact on humankind so far and, despite all the studies that have been made, it remains the most important in this crop. In Spain during the last years a greater severity of the disease has been observed in both, potato and tomato, probably due to genetic changes in pathogen populations described recently. The aim of this study was the characterization of the physiological strains of 52 isolates of P. infestans obtained in different potato-growing areas in Spain. For this purpose, inoculations on detached leaves were performed in order to determine compatibility or incompatibility reactions. A total of 17 physiological races were found. The less frequent virulence factors were Avr5 and Avr8. By studying the epidemiology of the pathogen, a specific breeding program for late blight resistance can be implemented.

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