Patterns of Genetic Diversification in the Invasive Hybrid Plant Pathogen Phytophthora × alni and Its Parental Species P. uniformis.

Mizeriene G; Cerny K; Zyka V; Bakonyi J; Nagy ZÁ; Oliva J; Redondo MA; Corcobado T; Martín-García J; Prospero S

doi:10.1094/PHYTO-12-19-0475-R

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Patterns of Genetic Diversification in the Invasive Hybrid Plant Pathogen Phytophthora × alni and Its Parental Species P. uniformis.

Mizeriene G Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland.
Cerny K The Silva Tarouca Research Institute for Landscape and Ornamental Gardening (RILOG), Květnové náměstí 391, Průhonice 252 43, The Czech Republic.
Zyka V The Silva Tarouca Research Institute for Landscape and Ornamental Gardening (RILOG), Květnové náměstí 391, Průhonice 252 43, The Czech Republic.
Bakonyi J Plant Protection Institute, Centre for Agricultural Research, Herman Ottó Str. 15, H-1022 Budapest, Hungary.
Nagy ZÁ Phytophthora Research Centre, Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic.
Oliva J Department Crop and Forest Sciences, University of Lleida, Alcalde Rovira Roure 191, 25198, Lleida, Spain.
Redondo MA Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, Box 7026, 750 07 Uppsala, Sweden.
Corcobado T Phytophthora Research Centre, Department of Forest Protection and Wildlife Management, Faculty of Forestry and Wood Technology, Mendel University in Brno, Zemědělská 3, 61300 Brno, Czech Republic.
Martín-García J Department of Biology, CESAM (Centre for Environmental and Marine Studies), University of Aveiro, Campus Universitario de Santiago, 3810-193 Aveiro, Portugal.
Prospero S Swiss Federal Research Institute WSL, Zuercherstrasse 111, CH-8903 Birmensdorf, Switzerland.

2020-07-08

Published in:

Phytopathology. - 2020

English In pathogenic fungi and oomycetes, interspecific hybridization may lead to the formation of new species having a greater impact on natural ecosystems than the parental species. From the early 1990s, a severe alder (Alnus spp.) decline due to an unknown Phytophthora species was observed in several European countries. Genetic analyses revealed that the disease was caused by the triploid hybrid P. × alni, which originated in Europe from the hybridization of P. uniformis and P. × multiformis. Here, we investigated the population structure of P. × alni (158 isolates) and P. uniformis (85 isolates) in several European countries using microsatellite markers. Our analyses confirmed the genetic structure previously observed in other European populations, with P. uniformis populations consisting of at most two multilocus genotypes (MLGs) and P. × alni populations dominated by MLG Pxa-1. The genetic structure of P. × alni populations in the Czech Republic, Hungary and Sweden seemed to reflect the physical isolation of river systems. Most rare P. × alni MLGs showed a loss of heterozygosity (LOH) at one or a few microsatellite loci compared with other MLGs. This LOH may allow a stabilization within the P. × alni genome or a rapid adaptation to stress situations. Alternatively, alleles may be lost because of random genetic drift in small, isolated populations, with no effect on fitness of P. × alni. Additional studies would be necessary to confirm these patterns of population diversification and to better understand the factors driving it.

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