Evaluation of PCR markers for Phytophthora infestans mating type determination

Abstract

Late blight is a devastating potato disease caused by Phytophthora infestans. This organism can reproduce asexually and sexually between the strains of two mating types named A1 and A2. Mating type is an important strain characteristic affecting the pathogen's population structure. We validate different PCR markers for P. infestans mating type determination by comparison of the results obtained with the markers (W16, S1, PHYB) with the pairing test results for 26 isolates collected worldwide and for a group of 146 Polish isolates. This study identifies an interesting feature of the isolates of genotype US-1. For all these A1 mating type isolates, the product specific for A2 isolates is amplified using the marker W16. Analysis of sequences of W16 PCR products indicates high similarity of the US-1 isolates with modern A2 mating type isolates. When US-1 isolates are excluded from analysis, 95 and 96% of isolates are correctly assigned by markers W16 and S1, respectively, when compared with the pairing test results. Marker PHYB produces 14% of discrepant results with the pairing test. Our results show that molecular markers can be useful tools for P. infestans mating type determination, but their application should be preceded by validation in each local population since their efficiency may vary depending on a pathogen's genotype.

Population Structure of Phytophthora infestans from a Single Location in Poland Over a Long Period of Time in Context of Weather Conditions

“…The amount of precipitation during the growing season was not correlated with the incidence of late blight in the field and severity of the disease. In the driest year, 2012, a moderate number of P. infestans [ 27 ] isolates were collected. We observed no statistically significant differences between samples of P. infestans collected in different years in terms of mating type, mitochondrial haplotype, or resistance to metalaxyl.…”

“…The mating type was tested for 235 P. infestans isolates using PCR markers (W16, S1) and pairing tests. We followed the procedures for mating type identification described previously by Brylińska et al [ 27 ]. The mating type of P. infestans isolates collected from 2000–2011 was assessed by a pairing test.…”

Genotypic and phenotypic characterization of Phytophthora infestans populations on Java, Indonesia

“…Brylińska et al . (2018) have reported that isolates were not completely (100%) assigned to specific mating types using these molecular markers (CAPS and Phyb assigning isolates correctly by 96% and 84%, respectively). As such, Brylińska et al .…”

“…As such, Brylińska et al . (2018) recommended that local populations such as these need to be validated with the pairing test method before these markers are used for DNA samples.…”