2013
How does Phytophthora sojae evade detection by Rps genes in soybean
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Contributor/Checkoff:
Iowa Soybean Association
Category:
Sustainable Production
Keywords:
Crop protectionDiseaseField management
Parent Project:
How does Phytophthora sojae evade detection by Rps genes in soybean
Lead Principal Investigator:
Alison Robertson, Iowa State University
Co-Principal Investigators:
Anne Dorrance, The Ohio State University
Project Code:
Contributing Organization (Checkoff):
Iowa Soybean Association
(n/a)
Institution Funded:
Iowa State University
(n/a)
Brief Project Summary:

Phytophthora root rot is primarily managed by planting varieties with genes that confer resistance. Fourteen Rps genes have been identified and four genes are currently used in commercial soybean varieties to provide resistance to the disease. The effectiveness of a resistance gene relies on its ability to recognize the pathogen's corresponding avirulence gene. The goal of this continuing project is to characterize the genetic changes that occur within the avirulence gene(s) of Phytophthora sojae that enable the pathogen to escape detection by the corresponding resistance gene.

Unique Keywords:
#genetic resistance to diseases, #phytophtora root rot, #phytophtora sojae, #soybean diseases, #virulence genes
Information And Results
Final Project Results

Accomplishments
• The number of copies and transcription of Avr1a was determined in 88 isolates of P. sojae from Iowa and Ohio.
• The number of copies of the gene ranged from 0 to 2. Presence of the gene did not always indicate avirulence on Rps1a.
• Transcripts of Avr1a were detected in some strains but transcription did not necessarily indicate avirulence on Rps1a.
• The Avr1a locus of four representative isolates from OH was sequenced and genetic diversity was considerably greater than that previously reported.
• Four LTR retrotransposons (BEL) were found in proximity to the Avr1a locus
• Transcriptomic analysis of two cultivars without Rps genes inoculated with 5 different isolates of P. sojae is in progress, to compare the transcriptional changes that occur during the infection process from isolates with different combinations of Avr1a gene conformations.
• Previous research suggested deletion of Avr1a or loss of transcript resulted in virulence on Rps1a, in soybean. Our data suggest that there are other mutations playing a role in gain of virulence
• The genetic diversity of Avr1d within isolates from Iowa was assessed.
• A large deletion at either the 3’ or 5’ end of the Avr1d gene that contributed to virulence of Rps1d was detected. Previous published research indicated that deletion of the entire locus contributed to virulence. Therefore our data suggest that additional mutations may play a role.
• The data from this study are informing a current study (ISA funded project) The effect of rotations of host resistance genes (Rps) on pathogen avirulence genes (Avr) in the soybean-Phytophthora sojae pathosystem (2014-2016).

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.