2014
The effect of rotations of host resistance genes (Rps) on pathogen avirulence genes (Avr) in the soybean Phytophthora sojae pathosystem
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Contributor/Checkoff:
Iowa Soybean Association
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Parent Project:
This is the first year of this project.
Lead Principal Investigator:
Alison Robertson, Iowa State University
Co-Principal Investigators:
Project Code:
Contributing Organization (Checkoff):
Iowa Soybean Association
(n/a)
Institution Funded:
Iowa State University
(n/a)
Brief Project Summary:

Phytophthora root and stem rot (PRR), caused by Phytophthora sojae, is an economically important disease of soybean in the United States. Currently, the disease is primarily managed by planting varieties with genes that confer resistance (Rps genes) to the pathogen. The effectiveness of an Rps gene relies on its ability to recognize the pathogens corresponding avirulence (Avr) gene.

From 2007 through 2011, researchers at Iowa State University conducted a microplot study to determine if cultivar rotation could be used to effectively minimize pathotype shifts in a population of P. sojae. The plots were inoculated with rice infested with a single isolate, PRl, which is virulent on Rps 7...

Unique Keywords:
#pathogenicity studies, #phytophtora root rot, #soybean diseases
Information And Results
Final Project Results

• The presence or absence of Avr1a, 1c, 1d and 3b in isolates recovered from a microplot rotation study that were virulent on the respective Rps genes varied as determined by PCR using specific primers. Similarly, transcripts of the genes also varied among isolates;
• Pathotype differences were detected in PR1 (race 1 of P. sojae; virulent of Rps7 only) in a culture that was grown in the lab on dV8 agar for 33 generations;
• Similarly pathotype differences were detected among three generations of single zoospore isolates recovered from PR1. These data indicate that changes in virulence can occur in the absence of selection pressure by Rps genes; and
• Three rotations of soybean have been planted in the greenhouse. A fourth rotation is in progress.

The United Soybean Research Retention policy will display final reports with the project once completed but working files will be purged after three years. And financial information after seven years. All pertinent information is in the final report or if you want more information, please contact the project lead at your state soybean organization or principal investigator listed on the project.