scholarly journals Genotyping of Phytophthora infestans in Eastern Africa Reveals a Dominating Invasive European Lineage

2019 ◽  
Vol 109 (4) ◽  
pp. 670-680 ◽  
Author(s):  
Anne W. Njoroge ◽  
Björn Andersson ◽  
Alison K. Lees ◽  
Collins Mutai ◽  
Gregory A. Forbes ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Potato Production ◽  
Eastern Africa ◽  
Population Changes ◽  
Management Options ◽  
Planting Material ◽  
The Us ◽  
Specialized Form ◽  
Late Blight Of Potato

Strains of Phytophthora infestans, the pathogen causing late blight of potato and tomato, are thought to be moved around the world through infected planting material. Since its first appearance in 1941, late blight has caused important losses to potato production in the eastern-Africa region (EAR). In the current study, the genetic structure of the population in Kenya, Uganda, Tanzania, Burundi, and Rwanda was characterized using 12-plex microsatellite markers with the aim of testing the hypothesis that a strain originating from Europe, 2_A1, has recently dominated the population in EAR. Analyses of 1,093 potato and 165 tomato samples collected between 2013 and 2016 revealed the dominance on potato in all countries of the 2_A1 clonal lineage. On tomato, a host-specialized form of the US-1 lineage appears to persist in Rwanda, Uganda, and Tanzania whereas, in Kenya, most samples from tomato (72.5%) were 2_A1. The US-1 lineage in Tanzania had two private alleles at the Pi02 marker, suggesting a possible independent introduction into the region. US-1 had higher genetic variability than 2_A1, consistent with the earlier establishment of the former. Continuous tracking of P. infestans population changes should help identify new virulent and aggressive strains, which would inform strategic disease management options.

scholarly journals The Potency of Unassociated Trichoderma spp and the Fungicides Antagonistic of the Late Blight of Potato by Phytophthora infestans (Mont.) De-Bary

2021 ◽  
pp. 246-253
Author(s):  
Anuj Bansal ◽  
S. K. Biswas ◽  
Deepak Baboo ◽  
Vikram Singh
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Radial Growth ◽  
Potato Production ◽  
Dual Culture ◽  
Vegetable Crops ◽  
Culture Methods ◽  
Trichoderma Spp ◽  
Late Blight Of Potato

The potato (Solanum tuberosum) is one of the most important vegetable crops in the world, belonging to the family Solanaceae and is an important starchy food crop in both sub-tropical and temperate regions. Potato plants are subjected to attack by numerous diseases wherever the crop is grown. Among them, late blight of potato caused by Phytophthora infestans (Mont.) de-Bary is of major cause of concern in potato production at present. An experiment was conducted in the Department of Plant Pathology, College of Agriculture, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur. The antifungal activity of different fungicides was evaluated in-vitro through the food poison technique. The experimental finding showed that radial growth of mycelium of Phytophthora infestans was inhibited by fungicides over control. At 100 ppm, the minimum radial growth of mycelium was found in Equation Pro treatment as 5.3, 8.2, 11.4, 14.2, 16.2, 18.4 and 22.6 mm over control against 12.3, 19.1, 26.1, 35.9, 42.5, 51.4 and 64.8 mm at 1, 2, 3, 4, 5, 6 and 7 days after inoculation respectively. Similarly, at 500 and 1000 ppm the minimum radial growth of mycelium was found in Equation Pro treatment. Efficacy of bio-control agents on the radial growth of Phytophthora infestans was evaluated using Dual Culture Methods. Among the different concentrations, 1000 ppm was found most effective than 100 and 500 ppm. Among the different bio-agents, Trichoderma harzianum able to reduced maximum radial mycelial growth of fungus showing 4.6, 8.8, 10.1, 13.2, 15.6, 19.3 and 23.5 mm against 12.3, 19.1, 26.1, 35.9, 42.5, 51.4 and 64.8 mm at 1, 2, 3, 4, 5, 6 and 7 days after inoculation, respectively.

scholarly journals Classifying the Relative Host Reaction in Potato Cultivars and Breeding Lines to the US-8 Strain of Phytophthora infestans in Minnesota

Plant Disease ◽  
2003 ◽  
Vol 87 (8) ◽  
pp. 983-990 ◽  
Author(s):  
J. C. Jenkins ◽  
R. K. Jones
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Rank Correlation ◽  
The United States ◽  
Spearman Rank Correlation ◽  
Breeding Lines ◽  
Spearman Rank ◽  
Progress Curve ◽  
Tuber Blight ◽  
The Us

A total of 32 commercial cultivars grown in the United States and 15 potato breeding lines and non-U.S. cultivars were evaluated at Rosemount, MN for their reaction to the US-8 strain of Phytophthora infestans. Commercial red-, russet-, and white-skinned cultivars tested in the commercial cultivar trial (COMC) in 1996 and 1997 were susceptible (S) to moderately susceptible (MS) to this organism, except for Elba, which ranked as moderately resistant (MR). Yellow-fleshed cvs. Hertha, Santé, and Agria were screened in the late blight nursery (LB1) in 1997 and 1998 and classified as S to MS while Island Sunshine, Brador, and Aziza were classified as MR. The Scottish breeding line G6582-3 and U.S. breeding lines A90586-11, AWN86514-2, AWN85624-5, B0692-4, B0718-3, and B0767-2 were classified as resistant (R). Comparison among entries was based on the area under the disease progress curve (AUDPC). Spearman rank correlation for AUDPC in the 1996 and 1997 COMC trials at 14 to 18 days after inoculation (r = 0.65, P < 0.01) was greater than any other interval tested. The Spearman rank correlation for AUDPC in the 1997 and 1998 LB1 trials at 14 to 18 days after inoculation was r = 0.87, P < 0.01 and increased only slightly in successive assessment dates, suggesting that, in Minnesota, effective evaluation of the foliar infection of late blight can occur at 18 days after inoculation or later. The average tuber blight incidence for the COMC trials at harvest was 10.0% in 1996 and 9.7% in 1997. The average tuber blight incidence for the LB1 trials at harvest was 4.3% in 1997 and 14.6% in 1998. Pearson correlations between tuber blight incidence and foliar disease for the COMC trials was very low; however, for the LBl trials, it was significant in both 1997 (r = 0.53, P < 0.01) and 1998 (r = 0.53, P < 0.01). Asymptomatic tubers harvested from the COMC trials developed additional tuber blight when stored 28 days at ambient temperatures and still more when stored for another 5 months at 5°C. Surviving tubers of nine entries were planted in field trials during 1997 and 1998 to determine if plants that develop from tubers exposed to P. infestans could manifest late blight in the subsequent season. Late blight failed to develop throughout the trials in either year.

scholarly journals Characterization of Phytophthora infestans in Wisconsin from 1993 to 1995

Plant Disease ◽  
1998 ◽  
Vol 82 (4) ◽  
pp. 434-436 ◽  
Author(s):  
K. D. Marshall-Farrar ◽  
M. McGrath ◽  
R. V. James ◽  
W. R. Stevenson
Keyword(s):  
Solanum Tuberosum ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Mating Type ◽  
Production Problem ◽  
Significant Production ◽  
Allozyme Genotype ◽  
Late Blight Of Potato

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.

scholarly journals Did a novel virus contribute to late blight epidemics?

2018 ◽  
Author(s):  
Guohong Cai ◽  
Kevin Myers ◽  
William E. Fry ◽  
Bradley I. Hillman
Keyword(s):  
North America ◽  
Late Blight ◽  
Phytophthora Infestans ◽  
Molecular Mechanisms ◽  
Rna Virus ◽  
Causal Agent ◽  
Clonal Lineage ◽  
Significant Similarity ◽  
Tomato Production ◽  
The Us

AbstractPhytophthora infestansis the causal agent of potato and tomato late blight. In this study, we characterized a novel RNA virus, Phytophthora infestans RNA virus 2 (PiRV-2). The PiRV-2 genome is 11,170 nt and lacks a polyA tail. It contains a single large open reading frame (ORF) with short 5’- and 3’-untranslated regions. The ORF is predicted to encode a polyprotein of 3710 aa (calculated molecular weight 410.94 kDa). This virus lacks significant similarity to any other known viruses, even in the conserved RNA-dependent RNA polymerase region. Comparing isogenic strains with or without the virus demonstrated that the virus stimulated sporangia production inP. infestansand appeared to enhance its virulence. Transcriptome analysis revealed that it achieved sporulation stimulation likely through down-regulation of ammonium and amino acid intake inP. infestans. This virus was faithfully transmitted through asexual reproduction. Survey of PiRV-2 presence in aP. infestanscollection found it in most strains in the US-8 lineage, a very successful clonal lineage ofP. infestansin North America. We suggest that PiRV-2 may have contributed to its success, raising the intriguing possibility that a potentially hypervirulent virus may contribute to late blight epidemics.Author SummaryPotato late blight, the notorious plant disease behind the Irish Potato Famine, continues to pose a serious threat to potato and tomato production worldwide. While most studies on late blight epidemics focuses on pathogen virulence, host resistance, environmental factors and fungicide resistance, we present evidence in this study that a virus infecting the causal agent,Phytophthora infestans, may have played a role. We characterized a novel RNA virus, Phytophthora infestans RNA virus 2 (PiRV-2) and examined its effects on its host. By comparing identicalP. infestansstrains except with or without the virus, we found that PiRV-2 stimulated sporulation ofP. infestans(a critical factor in late blight epidemics) and increased its virulence. We also profiled gene expression in these strains and identified potential molecular mechanisms through which PiRV-2 asserted its sporulation stimulation effect. In a survey of PiRV-2 presence in aP. infestanscollection, we found PiRV-2 in most isolates of the US-8 clonal lineage, a very successfull ineage that dominated potato fields in North America for several decades. We suggest that PiRV-2 may have contributed to its success. Our findings raise the intriguing possibility that a potentially hypervirulent virus may contribute to late blight epidemics.

scholarly journals Late Blight of Potato (Phytophthora infestans) I: Fungicides Application and Associated Challenges

2017 ◽  
Vol 5 (3) ◽  
pp. 261 ◽  
Author(s):  
Abdul Majeed ◽  
Zahir Muhammad ◽  
Zabeeh Ullah ◽  
Rafi Ullah ◽  
Habib Ahmad
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Solanum Tuberosum L ◽  
Significant Proportion ◽  
Agricultural Crop ◽  
Irish Famine ◽  
Advantages And Disadvantages ◽  
Agricultural Mechanization ◽  
Global Food ◽  
Late Blight Of Potato

Potato (Solanum tuberosum L.) has been remained an important agricultural crop in resolving global food issues through decades. The crop has experienced enormous growth in terms of production throughout the world in recent decades because of improvement in agricultural mechanization, fertilizers application and irrigation practices. Nevertheless, a significant proportion of this valuable crop is still vulnerable to losses due to prevalence of different viral, bacterial, fungal and nematodes infestations. Late blight, caused by Phytophthora infestans (Mont.) de Bary, is one of the most threatening pathogenic diseases which not only results in direct crop losses but also cause farmers to embrace huge monetary expenses for disease control and preventive measures. The disease is well known for notorious ‘Irish Famine’ which resulted in drop of Irish population by more than 20% as result of hunger and potato starvation. Globally, annual losses of crop and money spend on fungicides for late blight control exceeds one trillion US dollars. This paper reviews the significance of late blight of potato and controlling strategies adopted for minimizing yield losses incurred by this disease by the use of synthetic fungicides. Advantages and disadvantages of fungicides application are discussed.

scholarly journals Identification of Avramr1 from Phytophthora infestans using long read and cDNA pathogen-enrichment sequencing (PenSeq)

2020 ◽  
Author(s):  
Xiao Lin ◽  
Tianqiao Song ◽  
Sebastian Fairhead ◽  
Kamil Witek ◽  
Agathe Jouet ◽  
...  
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Late Blight Resistance ◽  
Potato Production ◽  
Specific Cell ◽  
List Type ◽  
Rxlr Effector ◽  
Cell Death Response ◽  
Long Read ◽  
Solanum Americanum

SummaryPotato late blight, caused by the oomycete pathogen Phytophthora infestans, significantly hampers potato production. Recently, a new Resistance to Phytophthora infestans (Rpi) gene, Rpi-amr1, was cloned from a wild Solanum species, Solanum americanum. Identification of the corresponding recognized effector (Avirulence, or Avr) genes from P. infestans is key to elucidating their naturally occurring sequence variation, which in turn informs the potential durability of the cognate late blight resistance.To identify the P. infestans effector recognized by Rpi-amr1, we screened available effector libraries and used long read and cDNA pathogen-enrichment sequencing (PenSeq) on four P. infestans isolates to explore the untested effectors.By using SMRT and cDNA PenSeq, we identified 47 highly expressed effectors from P. infestans, including PITG_07569 which triggers a highly specific cell death response when transiently co-expressed with Rpi-amr1 in Nicotiana benthamiana, suggesting that PITG_07569 is Avramr1.Here we demonstrate that long read and cDNA PenSeq enables the identification of full-length RxLR effector families, and their expression profile. This study has revealed key insights into the evolution and polymorphism of a complex RxLR effector family that is associated with the recognition by Rpi-amr1.

scholarly journals Survival of Isolates of the US-22, US-23, and US-24 Clonal Lineages of Phytophthora infestans by Asexual Means in Tomato Seed at Cold Temperatures

Plant Disease ◽  
2016 ◽  
Vol 100 (1) ◽  
pp. 180-187 ◽  
Author(s):  
Kenneth E. Frost ◽  
Anna C. Seidl Johnson ◽  
Amanda J. Gevens
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Winter Season ◽  
Tomato Seed ◽  
Tomato Production ◽  
Cold Temperatures ◽  
Production Region ◽  
Degree Day ◽  
Management Concepts ◽  
The Us

Survival of Phytophthora infestans, causal agent of potato and tomato late blight, is thought to be negligible when exposed to freezing conditions typical of a Wisconsin winter. However, the persistence of relatively new P. infestans clonal lineages US-22, US-23, and US-24 within a production region during 2010 to 2014 warranted further investigation. We used tomato seed as a culture medium to determine the survival of P. infestans isolates representing the three lineages under temperatures of 18, 4, 0, −3, and −5°C for 11 time points (1 to 112 days postincubation). Survival varied interactively with temperature, duration of time at a temperature, and clonal lineage of the P. infestans isolate. US-22, -23, and -24 isolates survived for 112 days at 18 and 4°C, 84 days at 0°C, and 14 days at −3°C. US-23 survived longer at −3 and −5°C than did US-22 or US-24. The vigor of US-22 and US-24 isolates decreased with increasing exposure to cold temperatures, a trend that was not observed for the US-23 isolate. By calculating the length of time needed to kill the lineage isolates on infested tomato seed at five temperatures, we predicted that P. infestans would survive in 5% of tomato seed for 99, 25, and 16 days at 0, −3, and −5°C, respectively. We further applied a degree-day model to our empirical data to describe P. infestans survival as a function of cooling degree-day accumulations using archived soil temperatures at 5- and 10-cm depths at four Wisconsin locations over 27 years. The model indicated that survival of P. infestans in 5% of infested tomato seed would occur at 35 and 39% of the location–year combinations at 5- and 10-cm soil depths, respectively. Together, these data suggested that P. infestans has the potential to survive over the winter season by asexual means in infested tomato seed in Wisconsin and other Northern latitudes. Our cooling degree-day model for late blight in the tomato production system offers a tool for anticipating and mitigating disease based on integrated pest management concepts previously utilized for insects.

scholarly journals Investigating the Host Range of the US-22, US-23, and US-24 Clonal Lineages of Phytophthora infestans on Solanaceous Cultivated Plants and Weeds

Plant Disease ◽  
2014 ◽  
Vol 98 (6) ◽  
pp. 754-760 ◽  
Author(s):  
Anna C. Seidl Johnson ◽  
Amanda J. Gevens
Keyword(s):  
Late Blight ◽  
Phytophthora Infestans ◽  
Host Range ◽  
Management Strategies ◽  
The United States ◽  
Cultivated Plants ◽  
Production Region ◽  
Black Nightshade ◽  
The Us ◽  
Bittersweet Nightshade

Phytophthora infestans causes late blight, one of the most important diseases of potato and tomato worldwide. Recently in the United States, three newly identified clonal lineages, US-22, US-23, and US-24, have become widespread. While potato and tomato are the most commonly infected solanaceous hosts for P. infestans, new lineages may have a broader or different host range. Under controlled conditions, we determined the host range of isolates representing US-22, US-23, and US-24 genotypes of P. infestans on detached tissues of cultivated solanaceous plants and solanaceous weeds common to the upper midwestern production region. None of the isolates representing the clonal lineages produced late blight symptoms or signs on foliage of selected cultivars of eggplant, pepper, tomatillo, or ground cherry in a detached leaf assay. Symptoms and signs were evident on the potato and tomato cultivars tested, although with the US-24 isolate, infection on tomato was limited. None of the isolates sporulated on the common weed black nightshade, but some sporulation and necrosis was observed with all representatives of the lineages on bittersweet nightshade and petunia. Hairy nightshade supported abundant sporulation and symptoms, and sporangial production was not significantly different than that on tomato for each of the isolates representing the three lineages, indicating the potential for this weed to be a source of inoculum and contribute substantially to late blight epidemics. Interestingly, black nightshade had the highest incidence of sporulation on berries, but the lowest on leaves, suggesting the importance of testing multiple plant organs when determining susceptibility of a species. Our results update knowledge of the host range of the ever-changing P. infestans populations and will help to improve late blight management strategies by targeting these additional hosts.

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