Common Phytophthora sojae pathotypes occurring in South Dakota

2021 ◽  
Author(s):  
Rawnaq Chowdhury ◽  
Connie Tande ◽  
Emmanuel Z Byamukama
Keyword(s):  
Glycine Max ◽  
South Dakota ◽  
Resistance Genes ◽  
Phytophthora Sojae ◽  
Stem Rot ◽  
Inoculation Technique ◽  
Glycine Max L ◽  
Rps Gene ◽  
Important Disease

Phytophthora root and stem rot, caused by Phytophthora sojae, is an important disease of soybean (Glycine max L.) in South Dakota. Because P. sojae populations are highly diverse and resistance genes deployed in commercial soybean varieties often fail to manage the disease, this study was initiated to determine P. sojae pathotype distribution in South Dakota. A total of 216 P. sojae isolates were baited from soil collected from 422 soybean fields in South Dakota in 2013-2015 and 2017. The pathotype of each isolate was determined by inoculating 10 seedlings of 13 standard soybean P. sojae differential lines using the hypocotyl inoculation technique. Of the 216 pathotyped isolates, 48 unique pathotypes were identified. The virulence complexity of isolates ranged from virulence on one Rps gene (Rps7) to virulence on 13 Rps genes and mean complexity was 5.2. Harosoy (Rps7), Harlon (Rps1a), Williams 79 (Rps 1c), William 82 (Rps1k), Harosoy 13XX (Rps1b), were susceptible to 98, 80, 78, 73, 72% of the isolates, respectively. These results highlight the highly diverse P. sojae pathotypes in South Dakota and the likely Rps genes to fail in commercial soybean varieties

scholarly journals Response of Soybean Accessions from Provinces in Southern China to Phytophthora sojae

Plant Disease ◽  
1998 ◽  
Vol 82 (5) ◽  
pp. 555-559 ◽  
Author(s):  
D. E. Kyle ◽  
C. D. Nickell ◽  
R. L. Nelson ◽  
W. L. Pedersen
Keyword(s):  
Glycine Max ◽  
Resistance Genes ◽  
Southern China ◽  
Phytophthora Sojae ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Inoculation Technique ◽  
The World ◽  
Glycine Max L ◽  
Phytophthora Rot

Phytophthora rot, caused by Phytophthora sojae, is a damaging disease of soybean (Glycine max (L.) Merr.) throughout the soybean-producing regions of the world. The discovery of new sources of resistance in soybean is vital in maintaining control of Phytophthora rot, because races of the pathogen have been discovered that can attack cultivars with commonly used resistance genes. The objectives of this study were to investigate the distribution and diversity of Phytophthora-resistant soybean in southern China and identify sources that confer resistance to multiple races for implementation into breeding programs. Soybean accessions obtained from southern China were evaluated for their response to races 1, 3, 4, 5, 7, 10, 12, 17, 20, and 25 of P. sojae using the hypocotyl inoculation technique in the greenhouse at Urbana, Illinois in 1996 and 1997. Accessions were identified that confer resistant responses to multiple races of the pathogen. These accessions may provide sources of resistance for control of Phytophthora rot of soybean in the future. The majority of the accessions with resistance to eight or more of the ten races tested were from the provinces of Hubei, Jiangsu, and Sichuan in southern China. Based on the evaluated accessions, these provinces appear to be valuable sources of Phytophthora-resistant soybean.

scholarly journals Population Structure Among and Within Iowa, Missouri, Ohio, and South Dakota Populations of Phytophthora sojae

Plant Disease ◽  
2016 ◽  
Vol 100 (2) ◽  
pp. 367-379 ◽  
Author(s):  
S. Stewart ◽  
A. E. Robertson ◽  
D. Wickramasinghe ◽  
M. A. Draper ◽  
A. Michel ◽  
...  
Keyword(s):  
Gene Flow ◽  
South Dakota ◽  
Genotypic Diversity ◽  
Phytophthora Sojae ◽  
Field Variation ◽  
Limited Gene Flow ◽  
Rps Gene ◽  
Pathogen Populations ◽  
High Level ◽  
Important Disease

Phytophthora root and stem rot, caused by Phytophthora sojae, is an economically important disease of soybean throughout the Midwestern United States. This disease has been successfully managed with resistance (Rps) genes; however, pathogen populations throughout the Midwest have developed virulence to many Rps genes, including those that have not been deployed. To gain a better understanding of the processes that influence P. sojae evolution, the population genetic structure was compared among populations using one isolate collected from 17, 33, and 20 fields in Iowa, Ohio, and South Dakota, respectively, as well as multiple isolates from individual fields in Iowa, Ohio, and Missouri. Genotypic diversity was measured using 21 polymorphic microsatellite (simple-sequence repeat) markers. and pathotype diversity using 15 soybean differentials. For all but three of the populations with low sample size, there was a high level of pathotype diversity and a low to moderate level of genotypic diversity among the populations for both comparisons between states and within-field variation. None of the Rps-gene differentials were resistant to all of the isolates. There were 103 unique multilocus genotypes identified in this study and only 2 were identified from the same field. Although no clones were identified in more than one field, pairwise FST indicated that some gene flow within neighboring fields does occur but not across the region, including fields from neighboring states. These results suggest that there is a strong probability that each state may have their own or several regional populations, as well as provide further evidence of high diversity within this homothallic pathogen which may be due, in part, to limited gene flow, mutation, or outcrossing, and this likely affects the success of deployment of resistance.

Phytophthora sojae pathotype distribution and fungicide sensitivity in Michigan

Plant Disease ◽  
2021 ◽  
Author(s):  
Austin Glenn McCoy ◽  
Zachary Albert Noel ◽  
Janette L Jacobs ◽  
Kayla M Clouse ◽  
Martin I Chilvers
Keyword(s):  
Resistance Genes ◽  
Phytophthora Sojae ◽  
Significant Shift ◽  
Seed Treatments ◽  
Fungicide Sensitivity ◽  
History Of ◽  
Plant Stand ◽  
Rps Gene ◽  
Major Resistance Genes ◽  
Pathogen Populations

Identifying the pathotype structure of a Phytophthora sojae population is crucial for the effective management of Phytophthora stem and root rot of soybean (PRR). P. sojae has been successfully managed with major resistance genes, partial resistance, and fungicide seed treatments. However, prolonged use of resistance genes or fungicides can cause pathogen populations to adapt over time, rendering resistance genes or fungicides ineffective. A statewide survey was conducted to characterize the current pathotype structure and fungicide sensitivity of P. sojae within Michigan. Soil samples were collected from 69 fields with a history of PRR and fields having consistent plant stand establishment issues. Eighty-three isolates of P. sojae were obtained, and hypocotyl inoculations were performed on 14 differential soybean cultivars, all of which carry a single Rps gene or no resistance gene. The survey identified a loss of effectiveness of Rps genes 1b, 1k, 3b and 6, compared to a previous survey conducted in Michigan from 1993-1997. Three effective resistance genes were identified for P. sojae management in Michigan; Rps 3a, 3c, and 4. Additionally, the effective concentration of common seed treatment fungicides to inhibit mycelial growth by 50% (EC50) was determined. No P. sojae isolates were insensitive to the tested chemistries with mean EC50 values of 2.60x10-2 µg/ml for ethaboxam, 3.03x10-2 µg/ml for mefenoxam, 2.88x10-4 µg/ml for oxathiapiprolin, and 5.08x10-2 µg/ml for pyraclostrobin. Results suggest that while there has been a significant shift in Rps gene effectiveness, seed treatments are still effective for early season management of this disease.

Characterization of species of Fusarium causing root rot of Soybean (Glycine max L.) in South Dakota, USA

2020 ◽  
Vol 42 (4) ◽  
pp. 560-571
Author(s):  
Paul N. Okello ◽  
Kristina Petrovic ◽  
Asheesh K. Singh ◽  
Brian Kontz ◽  
Febina M. Mathew
Keyword(s):  
Glycine Max ◽  
South Dakota ◽  
Root Rot ◽  
Glycine Max L

scholarly journals Races of Phytophthora sojae and Their Virulences on Soybean Cultivars in Heilongjiang, China

Plant Disease ◽  
2010 ◽  
Vol 94 (1) ◽  
pp. 87-91 ◽  
Author(s):  
Shuzhen Zhang ◽  
Pengfei Xu ◽  
Junjiang Wu ◽  
Allen G. Xue ◽  
Jinxiu Zhang ◽  
...  
Keyword(s):  
Phytophthora Sojae ◽  
Heilongjiang Province ◽  
Plant Mortality ◽  
Pathogen Population ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Soybean Cultivars ◽  
Rps Gene ◽  
First Time ◽  
Important Disease

Phytophthora root and stem rot, caused by Phytophthora sojae, is an economically important disease of soybean (Glycine max) in Heilongjiang Province, China. The objectives of this research were to determine the race profile of P. sojae in Heilongjiang and evaluate soybean cultivars for reactions to the pathogen races. A total of 96 single-zoospore P. sojae isolates were obtained from soil samples collected from 35 soybean fields in 18 counties in Heilongjiang from 2005 to 2007. Eight races of P. sojae, including races 1, 3, 4, 5, 9, 13, 44, and 54, were identified on a set of eight differentials, each containing a single resistance Rps gene, from 80 of the 96 isolates. Races 1 and 3 were predominant races, comprising 58 and 14 isolates, and representing 60 and 7% of the pathogen population, respectively. Races 4, 5, 44, and 54 were identified for the first time in Heilongjiang, and each was represented by two to three isolates only. Sixty-two soybean cultivars commonly grown in Heilongjiang Province were evaluated for their resistance to the eight P. sojae races identified using the hypocotyl inoculation technique. Based on the percentage of plant mortality rated 5 days after inoculation, 44 cultivars were resistant (<30% mortality) to at least one race. These cultivars may be used as sources of resistance in soybean breeding programs.

Association mapping for partial resistance to Phytophthora sojae in soybean (Glycine max (L.) Merr.)

2014 ◽  
Vol 93 (2) ◽  
pp. 355-363 ◽  
Author(s):  
JUTAO SUN ◽  
NA GUO ◽  
JUN LEI ◽  
LIHONG LI ◽  
GUANJUN HU ◽  
...  
Keyword(s):  
Glycine Max ◽  
Association Mapping ◽  
Partial Resistance ◽  
Phytophthora Sojae ◽  
Glycine Max L

scholarly journals GmDRR1, a dirigent protein resistant to Phytophthora sojae in Glycine max (L.) Merr.

2018 ◽  
Vol 17 (6) ◽  
pp. 1289-1298 ◽  
Author(s):  
Qing-shan CHEN ◽  
Guo-long YU ◽  
Jia-nan ZOU ◽  
Jing WANG ◽  
Hong-mei QIU ◽  
...  
Keyword(s):  
Glycine Max ◽  
Phytophthora Sojae ◽  
Dirigent Protein ◽  
Glycine Max L ◽  
Protein Resistant

Pathotype Complexity and Genetic Characterization of Phytophthora sojae Populations in Illinois, Indiana, Kentucky, and Ohio

2021 ◽  
Author(s):  
Linda Weber Hebb ◽  
Carl A. Bradley ◽  
Santiago Xavier Mideros ◽  
Darcy E. P. Telenko ◽  
Kiersten Wise ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Resistance Genes ◽  
Genetic Characterization ◽  
Specific Resistance ◽  
Agricultural Practices ◽  
Phytophthora Sojae ◽  
Simple Sequence Repeat Markers ◽  
Rps Gene ◽  
Simple Sequence

Phytophthora sojae, the causal agent of Phytophthora root and stem rot of soybean, has been managed with single Rps genes since the 1960’s, but has subsequently adapted to many of these resistance genes, rendering them ineffective. The objective of this study was to examine the pathotype and genetic diversity of P. sojae from soil samples across Illinois, Indiana, Kentucky, and Ohio by assessing which Rps gene(s) were still effective and identifying possible population clusters. There were 218 pathotypes identified from 473 P. sojae isolates with an average of 6.7 out of 15 differential soybean lines exhibiting a susceptible response for each isolate. Genetic characterization of 103 P. sojae isolates from across Illinois, Indiana, Kentucky, and Ohio with 19 simple sequence repeat markers identified 92 multilocus genotypes. There was a moderate level of population differentiation among these four states, with pairwise FST values ranging from 0.026 to 0.246. There was also moderate to high levels of differentiation between fields, with pairwise FST values ranging from 0.071 to 0.537. Additionally, cluster analysis detected the presence of P. sojae population structure across neighboring states. The level of pathotype and genetic diversity, in addition to the identification of population clusters, supports the hypothesis of occasional outcrossing events that allow for an increase in diversity and the potential to select for a loss in avirulence to specific resistance genes within regions. The trend of suspected gene flow among neighboring fields is expected to be an ongoing issue with current agricultural practices.

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