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.

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 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.

scholarly journals Pathogenic Diversity of Phytophthora sojae in Ohio Soybean Fields

Plant Disease ◽  
2003 ◽  
Vol 87 (2) ◽  
pp. 139-146 ◽  
Author(s):  
A. E. Dorrance ◽  
S. A. McClure ◽  
A. deSilva
Keyword(s):  
Shannon Index ◽  
Phytophthora Sojae ◽  
Reduced Tillage ◽  
Management Tools ◽  
Tillage Practices ◽  
Soybean Cultivars ◽  
The Mean ◽  
Production Practices ◽  
Rps Gene ◽  
Pathogenic Diversity

Problems with early season soybean stand establishment, and an increase in incidence of Phytophthora root and stem rot caused by Phytophthora sojae, prompted a reassessment of the pathogen population in Ohio. Earlier studies had indicated a potential for pathogen adaptation to commonly deployed Rps genes in soybeans. Fifty-seven fields, part of an earlier study in 1990 and 1991, along with 29 additional fields were sampled in either 1997 or 1999. Two soybean cultivars, Sloan (rps) and Resnik (Rps1k), were used as bait in a seedling bioassay to isolate P. sojae from the soil samples. P. sojae was recovered from 82 of the 86 fields sampled. Of the 429 isolates recovered from these soils, 325 and 104 were baited with soybean cultivars Sloan and Resnik, respectively. The P. sojae population in Ohio increased in the number of pathotypes (races) as well as in complexity since the earlier surveys. There were 72 and 202 pathotypes identified on 8 and 13 Rps gene differentials, respectively, in the current study. When the data were compared by location, 96, 65, 73, 78, 51, and 52% of the locations had at least one isolate with virulences to Rps1a, Rps1b, Rps1c, Rps1k, Rps3a, and Rps6, respectively. The mean complexity, the number of susceptible interactions on 8 differentials, increased from 3.01 to 4.06 between 1991 and 1997/1999. In addition, the pathogenic diversity as measured by the Shannon index increased from 2.71 to 3.28 for isolates recovered from the 57 fields sampled in both surveys. Producers whose fields were sampled were surveyed to determine if changes in the P. sojae population could be linked with production practices. There was a significant association between (P ≤ 0.05) reduced tillage practices and the presence of isolates that had virulence to Rps1k; reduced tillage fields also had isolates with virulence to a greater number of differentials. Due to the percentage of isolates that have virulence to many of the Rps genes, it is questionable how long a single Rps gene or several stacked Rps genes will remain viable disease management tools for P. sojae, unless a novel Rps gene is identified.

scholarly journals Virulence Composition of Phytophthora sojae in Michigan

Plant Disease ◽  
2001 ◽  
Vol 85 (10) ◽  
pp. 1103-1106 ◽  
Author(s):  
R. C. Kaitany ◽  
L. P. Hart ◽  
G. R. Safir
Keyword(s):  
Phytophthora Sojae ◽  
Control Measures ◽  
Stem Rot ◽  
Soybean Plant ◽  
Soybean Cultivars ◽  
Plant Samples ◽  
First Time

Knowing the virulence composition of Phytophthora sojae is important for the management of Phytophthora root and stem rot of soybean. Plant samples were collected in Michigan from diseased plants in soybean fields with Phytophthora root and stem rot symptoms. Eighty-seven isolates of P. sojae were evaluated for virulence using 13 differential soybean cultivars. Rps 3b, 3a, 1b, 1k, and 6 were resistant to 81, 77, 74, 69, and 66% of the isolates, respectively, while Rps 1a and 7 were resistant to only 12 to 13% of the isolates. Races 2, 25, 41, and 44 of P. sojae were identified among the isolates and reported for the first time in Michigan. Virulence formulae of 69 isolates did not match those of currently known races of P. sojae. Nine isolates were considered nonpathogenic. Incorporating Rps genes 1b, 1k, 3a, 3b, and 6 in soybean cultivars with good field tolerance, in conjunction with other control measures, should offer improved protection of soybeans from Phytophthora root and stem rot in Michigan.

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 Identification of Resistance Genes to Phytophthora sojae in Domestic Soybean Cultivars from China Using Particle Bombardment

Plant Disease ◽  
2020 ◽  
Vol 104 (7) ◽  
pp. 1888-1893
Author(s):  
Jin Yang ◽  
Sujiao Zheng ◽  
Xiaomen Wang ◽  
Wenwu Ye ◽  
Xiaobo Zheng ◽  
...  
Keyword(s):  
Resistance Genes ◽  
Particle Bombardment ◽  
Phytophthora Sojae ◽  
Stem Rot ◽  
Avirulence Genes ◽  
Breeding Programs ◽  
Soybean Cultivars ◽  
Primary Means ◽  
Soybean Plants ◽  
Source Materials

Phytophthora root and stem rot caused by Phytophthora sojae is a destructive disease that afflicts soybean plants throughout the world. The use of resistant soybean cultivars is the primary means of managing this disease, as well as the most effective and economical approach. There are abundant soybean germplasm resources in China that could be deployed for breeding programs; however, the resistance genes (Rps genes) in most cultivars are unknown, leading to uncertainty concerning which are resistant cultivars for use. The resistance genes Rps1a, Rps1c, and Rps1k prevent root and stem rot caused by most P. sojae isolates within a Chinese field population. This study identified three Rps genes in Chinese domestic soybean cultivars using three related avirulence genes by particle bombardment. The complex genetic diversity of soybean cultivars and P. sojae strains has made it difficult to define single Rps genes without molecular involvement. Gene cobombardment is a method for identifying Rps genes quickly and specifically. We showed that cultivars Dongnong 60 and Henong 72 contained Rps1a, while Hedou 19, Henong 76, 75-3, Wandou 21020, Zheng 196, Wandou 28, Heinong 71, and Wandou 29 all contained Rps1c. The cultivars Jidou 12, Henong 72, Heinong 71, and Wandou 29 contained Rps1k. The cultivar Henong 72 contained both Rps1a and Rps1k, while Wandou 29 and Heinong 71 contained both Rps1c and Rps1k. We then evaluated the phenotype of 11 domestic soybean cultivars reacting to P. sojae using the isolates P6497 and Ps1. The 11 domestic cultivars were all resistant to P6497 and Ps1. This research provides source materials and parent plant strains containing Rps1a, Rps1c, and Rps1k for soybean breeding programs.

scholarly journals Effect of Partial Resistance on Phytophthora Stem Rot Incidence and Yield of Soybean in Ohio

Plant Disease ◽  
2003 ◽  
Vol 87 (3) ◽  
pp. 308-312 ◽  
Author(s):  
A. E. Dorrance ◽  
S. A. McClure ◽  
S. K. St. Martin
Keyword(s):  
Partial Resistance ◽  
Phytophthora Sojae ◽  
Stem Rot ◽  
Environment Interaction ◽  
Genetic Traits ◽  
Soybean Cultivars ◽  
Negative Effect ◽  
Effect On Yield ◽  
Rps Gene ◽  
Disease Pressure

Phytophthora root and stem rot of soybean commonly causes losses in both stand and yield in Ohio. Environmental conditions which favor the pathogen typically occur in many areas of the state during late spring and summer. This study examined the performance of 12 soybean cultivars with partial resistance, with or without Rps genes, to different populations of Phytophthora sojae and various levels of disease pressure. The soybean cultivars were evaluated in seven field environments with and without metalaxyl over 4 years. There was a highly significant genotype-environment interaction which was due in part to variable disease pressure. The incidence of Phytophthora stem rot in subplots ranged from 0 to 10 plants in the most susceptible cultivar, Sloan, while significantly less stem rot developed in cultivars with high levels of partial resistance or partial resistance combined with an Rps gene in three of the seven environments. Metalaxyl applied in-furrow had a significant effect on early and final plant populations as well as yield (P < 0.001) in two of the seven environments, and for yield (P = 0.05) in one environment. This indicates that at these two environments, 2001 Lakeview and VanBuren, early season Phytophthora disease was controlled with the in-furrow fungicide treatment. When diverse populations of P. sojae were present, yields from soybean cultivars with high levels of partial resistance were significantly higher than those with low levels of partial resistance. Soybean cultivars with specific resistance genes Rps1k, Rps1k + Rps6, or Rps1k +Rps3a had higher yields than plants with only partial resistance in environments where race determination indicated that the populations of P. sojae present were not capable of causing disease on plants with the Rps1k gene. However, in an environment with very low disease pressure, yields of soybean cultivars with partial resistance were not significantly different from those with single Rps genes or Rps gene combinations. These results demonstrate that genetic traits associated with high levels of partial resistance do not have a negative effect on yield. Soybean cultivars that had the most consistent ranking across environments were those with moderate levels of partial resistance in combination with either Rps1k or Rps3a.

Comparison of Phytophthora sojae populations in Iowa and Nebraska to identify effective Rps genes for Phytophthora stem and root rot management

2021 ◽  
Author(s):  
Rashelle Matthiesen-Anderson ◽  
Clarice Schmidt ◽  
Vinicius C. Garnica ◽  
Loren Giesler ◽  
Alison E Robertson
Keyword(s):  
Root Rot ◽  
Partial Resistance ◽  
Specific Resistance ◽  
Phytophthora Sojae ◽  
Soybean Variety ◽  
Soybean Cultivars ◽  
Soybean Genotypes ◽  
Rps Gene ◽  
High Level ◽  
Almost All

Phytophthora stem and root rot (PSRR) of soybean, caused by the oomycete Phytophthora sojae, is prevalent in Iowa and Nebraska. Reducing losses to PSRR primarily relies on growing cultivars with specific resistance (Rps) genes. Predominant genes used in commercial soybean cultivars include Rps 1a, Rps 1c, Rps 1k, and Rps 3a. Knowing which Rps gene to deploy depends on knowledge of which genes are effective against the pathogen. From 2016 to 2018, 326 isolates of P. sojae from were recovered from fields in Iowa and Nebraska and classified into pathotypes based on their virulence on 15 soybean genotypes. A total of 15 and 10 pathotypes were identified in Iowa and Nebraska, respectively. Almost all isolates were virulent on Rps 1a, while over 70% of isolates were virulent on Rps 1c and Rps 1k. Only 2.3% of isolates from Iowa were virulent on Rps 3a. Among commercial soybean cultivars tested in the Illinois Soybean Variety trials from 2010 to 2020, Rps 1c was always the most frequently reported gene followed by Rps 1k. In contrast, Rps 1a and Rps 3a were present in less than 10% and less than 5 % of the cultivars tested, respectively. Since many of the P. sojae isolates in our study were virulent on Rps 1a, Rps 1c, and Rps 1k, soybean cultivars with these genes are unlikely to provide protection against PSRR unless they have a high level of partial resistance.

scholarly journals A Method for Combining Isolates of Phytophthora sojae to Screen for Novel Sources of Resistance to Phytophthora Stem and Root Rot in Soybean

Plant Disease ◽  
2016 ◽  
Vol 100 (7) ◽  
pp. 1424-1428 ◽  
Author(s):  
R. L. Matthiesen ◽  
N. S. Abeysekara ◽  
J. J. Ruiz-Rojas ◽  
R. M. Biyashev ◽  
M. A. Saghai Maroof ◽  
...  
Keyword(s):  
Root Rot ◽  
Yield Loss ◽  
Phytophthora Sojae ◽  
Single Source ◽  
Sources Of Resistance ◽  
Rxlr Effectors ◽  
Mixed Inoculum ◽  
Oomycete Pathogen ◽  
Rps Gene ◽  
Or Genes

Soybean cultivars with specific single resistance genes (Rps) are grown to reduce yield loss due to Phytophthora stem and root rot caused by the oomycete pathogen Phytophthora sojae. To identify novel Rps loci, soybean lines are often screened several times, each time with an isolate of P. sojae that differs in virulence on various Rps genes. The goal of this study was to determine whether several isolates of P. sojae that differ in virulence on Rps genes could be combined into a single source of inoculum and used to screen soybean lines for novel Rps genes. A set of 14 soybean differential lines, each carrying a specific Rps gene, was inoculated with three isolates of P. sojae, which differed in virulence on 6 to 10 Rps genes, individually or in a 1:1:1 mixture. Inoculum containing the 1:1:1 mixture of isolates was virulent on 13 Rps genes. The mixed-inoculum method was used to screen 1,019 soybean accessions in a blind assay for novel sources of resistance. In all, 17% of Glycine max accessions and 11% of G. soja accessions were resistant (≤30% dead plants), suggesting that these accessions may carry a novel Rps gene or genes. Advantages of combining isolates into a single source of inoculum include reduced cost, ability to screen soybean germplasm with inoculum virulent on all known Rps genes, and ease of identifying novel sources of resistance. This study is a precursor to identifying novel sources of resistance to P. sojae in soybean using RXLR effectors.

scholarly journals Screening and Morphological Characterization of Melons for Resistance to Fusarium oxysporum f.sp. melonis Race 1.2

HortScience ◽  
2010 ◽  
Vol 45 (7) ◽  
pp. 1021-1025 ◽  
Author(s):  
Hela Chikh-Rouhou ◽  
Rafael González-Torres ◽  
José María Alvarez ◽  
Ali Oumouloud
Keyword(s):  
Fusarium Oxysporum ◽  
Partial Resistance ◽  
Morphological Characteristics ◽  
Morphological Characterization ◽  
Sources Of Resistance ◽  
Breeding Programs ◽  
Commercial Cultivars ◽  
High Level ◽  
First Time

A total of 110 melon accessions with different geographical origins (18 countries) were screened for resistance to Fusarium oxysporum f.sp. melonis race 1.2 (pathotypes 1.2Y and 1.2W) using two artificial inoculation procedures. Twelve accessions showed some resistance to one or both strains. Three Japanese accessions, Shiro Uri Okayama (var. conomon), Kogane Nashi Makuwa, and C-211 (var. makuwa), and a Portuguese accession, BG-5384 (var. cantalupensis), showed the highest levels of resistance to both strains. The remaining eight accessions (all var. inodorus) had some level of partial resistance to 1.2W only. To our knowledge, this is the first time a high level of resistance to F. oxysporum f.sp. melonis race 1.2 has been identified in melon accessions of Western origin. The morphological traits of the 12 accessions that showed partial resistance were characterized to assess their suitability as resistance sources in melon breeding programs. Because most of the Western commercial cultivars belong to the cantalupensis, reticulatus, or inodorus botanical varieties, the resistant accessions from these varieties seem to be the most useful sources of resistance in breeding programs for developing melon cultivars of these types resistant to fusarium wilt race 1.2. The Portuguese accession BG-5384 had a high level of resistance within the Western types, and its morphological characteristics were fairly similar to some of the Western commercial cultivars.

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