Validating a Novel Pathotyping Method of Phytophthora sojae with Isolates From Minnesota
Phytophthora sojae is the causative agent of Phytophthora stem and root rot in soybean. It can infect soybeans at any stage and causes large yield losses. The most effective management strategy available to growers is the use of resistant soybean lines. Soybeans have resistance due to the presence of certain Rps genes. The Rps genes have “matching” avirulence genes (Avr) found in P. sojae, which negatively affect the pathogen’s ability to infect their host. Several Avr genes have recently been sequenced, allowing for a new method of determining the pathotype of P. sojae isolates. This study aimed to validate a molecular pathotyping method that utilizes the sequenced Avr genes and PCR to efficiently identify the pathotypes of P. sojae present in a field. A total of six isolates were pathotyped in a blinded study. All isolates had previously been pathotyped using the classic plant inoculation method. Through the use of primers, Avr genes in these P. sojae isolates can be accurately identified. This method provides an alternative to previous pathotyping methods that were not as efficient. Furthermore, this could be a tool to better understand the distribution of P. sojae pathotypes in Minnesota to help growers make informed decisions about which resistant varieties of soybeans to plant.