Abstract
In contrast to Eurasia and North America, powdery mildews (Ascomycota, Erysiphales) are understudied in Australia. There are over 900 species known globally, with fewer than currently 60 recorded from Australia. Some of the Australian records are doubtful as the identifications were presumptive, being based on host plant-pathogen lists from overseas. The goal of this study was to provide the first comprehensive catalog of all powdery mildew species present in Australia. The project resulted in (i) an up-to-date list of all the taxa that have been identified in Australia based on published DNA barcode sequences prior to this study; (ii) the precise identification of 117 specimens freshly collected from across the country; and (iii) the precise identification of 30 herbarium specimens collected between 1975 and 2013. This study confirmed 42 species representing 10 genera, including two genera and 13 species recorded for the first time in Australia. In Eurasia and North America, the number of powdery mildew species is much higher. Phylogenetic analyses of powdery mildews collected from Acalypha spp. resulted in the transfer of Erysiphe acalyphae to Salmonomyces, a resurrected genus. Salmonomyces acalyphae comb. nov. represents a newly discovered lineage of the Erysiphales. Another taxonomic change is the transfer of Oidium ixodiae to Golovinomyces. Powdery mildew infections have been confirmed on 13 native Australian plant species in the genera Acacia, Acalypha, Cephalotus, Convolvulus, Eucalyptus, Hardenbergia, Ixodia, Jagera, Senecio, and Trema. Most of the causal agents were polyphagous species that infect many other host plants both overseas and in Australia. All powdery mildews infecting native plants in Australia were phylogenetically closely related to species known overseas. The data indicate that Australia is a continent without native powdery mildews, and most, if not all, species have been introduced since the European colonization of the continent.
Highlights
Powdery mildews (Ascomycota, Erysiphales) are common obligate biotrophic fungal plant pathogens, comprising ∼900 species that infect more than 10,000 dicot and monocot plant species globally (Braun and Cook, 2012)
Searches were conducted in the NCBI nucleotide database, GenBank, with each genus name of the Erysiphales listed by Braun and Cook (2012), supplemented with “AND Australia” (e.g., “Oidium AND Australia”), to find all the publicly available DNA sequences for powdery mildew specimens collected in Australia
The Acclimatization Societies founded in different part of Australia in the nineteenth and early twentieth century to “enrich” the flora and fauna in Australia, and create landscapes that were more familiar for the European settlers (Cook and Dias, 2006) had an enormous contribution to the introduction and establishment of a high number of ornamental and other plant species from all over the world, together with the associated microbiota
Summary
Powdery mildews (Ascomycota, Erysiphales) are common obligate biotrophic fungal plant pathogens, comprising ∼900 species that infect more than 10,000 dicot and monocot plant species globally (Braun and Cook, 2012). Since the early 2000s, molecular phylogenetic analyses have shown that the traditional generic concept of the Erysiphales does not mirror their phylogeny based on the morphological characteristics of the sexual morphs (chasmothecia) (Braun et al, 2002). Grouping species according to the characteristics of their asexual morphs reflect their molecular phylogeny (for reviews, see Takamatsu, 2004, 2013a) This discovery triggered major taxonomic revisions (Braun et al, 2002), and the currently accepted generic concept is based on a combination of the morphological characteristics of the asexual and sexual morphs (Braun, 2011; Takamatsu, 2013b). A further genus, Bulbomicroidium, was described from Mexico (Marmolejo et al, 2018)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
