A PCR-based Assay for Distinguishing between A1 and A2 Mating Types of Phytophthora capsici

Abstract

<jats:p>Sexual reproduction in the plant parasite <jats:italic>Phytophthora capsici</jats:italic> Leonian requires the interaction of two distinct mating types, A1 and A2. Co-occurrence of these mating types can enhance the genetic diversity of <jats:italic>P. capsici</jats:italic> and alter its virulence or resistance characteristics. Using an intersimple sequence repeat (ISSR) screen of microsatellite diversity, we identified, cloned, and sequenced a novel 1121-base pair (bp) fragment specific to the A1 mating type of <jats:italic>P. capsici</jats:italic>. Primers Pcap-1 and Pcap-2 were designed from this DNA fragment to specifically detect the A1 mating type. Polymerase chain reaction (PCR) using these primers amplified an expected 997-bp fragment from known A1 mating types, but yielded a 508-bp fragment from known A2 mating types. This PCR-based assay could be adapted to accurately and rapidly detect the co-occurrence of A1 and A2 <jats:italic>P. capsici</jats:italic> mating types from field material.</jats:p>

Genetic diversity among asexual and sexual progenies of Phytophthora capsici detected with ISSR markers

“…The data reported here support the conclusions of previous studies. Previous studies have shown that both A1 and A2 mating types of P. capsici were detected in a single-pepper field in Anhui, China (Qi et al 2012;Li et al 2017).…”

“…At the beginning of each growing season, the pathogen population may be composed of a series of new genotypes. Both A1 and A2 isolates of P. capsici from the same site in the northwest of Anhui does not prove that sexual reproduction is occurring, it does mean that sexual reproduction is possible (Fry et al 1992;Li et al 2017). The combination of high levels of genetic variation, thick-wall oospores and the development of polycyclic asexual diseases make P. capsici a for-midable pathogen.…”

Morphological and Molecular Identification of Phytophthora capsici Isolates with Differential Pathogenicity in Sechium edule

“…It is necessary to continue analyzing the genome of P. capsici to design primers that enable the identification and differentiation of the two mating types by PCR as a complementary analysis to the crosses carried out in vitro with reference strains, since the primers described by Li et al (2017) [28] were not functional in this study.…”

“…To confirm the mating type, PCRs were performed with the primers described by Li et al (2017) [28], using DNA from the three isolates and the two reference strains in duplicate; the DNA was extracted according to the methodology described above. Final volumes of 20 µL, 40 ng of DNA, 0.2 µM of each primer, and 10 µL of super mix (Promega ® ) were used.…”

“…DNA amplifications were verified by electrophoresis in 1% agarose gels. According to Li et al (2017), mating type A1 generates an amplicon of 1121 pb and mating type A2 of 508 bp [28].…”