'Jumping Jack': genomic microsatellites underscore the distinctiveness of closely related pseudoperonospora cubensis and pseudoperonospora humuli and provide new insights into their evolutionary past

  • Downy mildews caused by obligate biotrophic oomycetes result in severe crop losses worldwide. Among these pathogens, Pseudoperonospora cubensis and P. humuli, two closely related oomycetes, adversely affect cucurbits and hop, respectively. Discordant hypotheses concerning their taxonomic relationships have been proposed based on host–pathogen interactions and specificity evidence and gene sequences of a few individuals, but population genetics evidence supporting these scenarios is missing. Furthermore, nuclear and mitochondrial regions of both pathogens have been analyzed using microsatellites and phylogenetically informative molecular markers, but extensive comparative population genetics research has not been done. Here, we genotyped 138 current and historical herbarium specimens of those two taxa using microsatellites (SSRs). Our goals were to assess genetic diversity and spatial distribution, to infer the evolutionary history of P. cubensis and P. humuli, and to visualize genome-scale organizational relationship between both pathogens. High genetic diversity, modest gene flow, and presence of population structure, particularly in P. cubensis, were observed. When tested for cross-amplification, 20 out of 27 P. cubensis-derived gSSRs cross-amplified DNA of P. humuli individuals, but few amplified DNA of downy mildew pathogens from related genera. Collectively, our analyses provided a definite argument for the hypothesis that both pathogens are distinct species, and suggested further speciation in the P. cubensis complex.
Author:Marcin Nowicki, Denita Hadziabdic, Robert N. Trigiano, Sarah L. Boggess, Loukas Kanetis, Phillip A. Wadl, Peter S. Ojiambo, Marc A. Cubeta, Otmar Spring, Marco ThinesORCiDGND, Fabian Runge, Brian E. Scheffler
Parent Title (English):Frontiers in microbiology
Publisher:Frontiers Media
Place of publication:Lausanne
Document Type:Article
Date of Publication (online):2021/07/14
Date of first Publication:2021/07/14
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2021/10/26
Tag:downy mildew; evolution; genotyping; host specificity; obligate pathogens; oomycete; speciation
Issue:art. 686759
Page Number:17
First Page:1
Last Page:17
This research was funded fully by the United States Department of Agriculture - Agricultural Research Service grant (NACA 58−6062−6) to RT.
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 57 Biowissenschaften; Biologie / 570 Biowissenschaften; Biologie
Licence (German):License LogoCreative Commons - Namensnennung 4.0