Resolving the polyphyletic nature ofPyricularia(Pyriculariaceae)

Abstract

Species of Pyricularia (magnaporthe-like sexual morphs) are responsible for major diseases on grasses. Pyricularia oryzae (sexual morph Magnaporthe oryzae) is responsible for the major disease of rice called rice blast disease, and foliar diseases of wheat and millet, while Pyricularia grisea (sexual morph Magnaporthe grisea) is responsible for foliar diseases of Digitaria. Magnaporthe salvinii, M. poae and M. rhizophila produce asexual spores that differ from those of Pyricularia sensu stricto that has pyriform, 2-septate conidia produced on conidiophores with sympodial proliferation. Magnaporthe salvinii was recently allocated to Nakataea, while M. poae and M. rhizophila were placed in Magnaporthiopsis. To clarify the taxonomic relationships among species that are magnaporthe- or pyricularia-like in morphology, we analysed phylogenetic relationships among isolates representing a wide range of host plants by using partial DNA sequences of multiple genes such as LSU, ITS, RPB1, actin and calmodulin. Species of Pyricularia s. str. belong to a monophyletic clade that includes all P. oryzae/P. grisea isolates tested, defining the Pyriculariaceae, which is sister to the Ophioceraceae, representing two novel families. These clades are clearly distinct from species belonging to the Gaeumannomyces pro parte/Magnaporthiopsis/Nakataea generic complex that are monophyletic and define the Magnaporthaceae. A few magnaporthe- and pyricularia-like species are unrelated to Magnaporthaceae and Pyriculariaceae. Pyricularia oryzae/P. grisea isolates cluster into two related clades. Host plants such as Eleusine, Oryza, Setaria or Triticum were exclusively infected by isolates from P. oryzae, while some host plant such as Cenchrus, Echinochloa, Lolium, Pennisetum or Zingiber were infected by different Pyricularia species. This demonstrates that host range cannot be used as taxonomic criterion without extensive pathotyping. Our results also show that the typical pyriform, 2-septate conidium morphology of P. grisea/P. oryzae is restricted to Pyricularia and Neopyricularia, while most other genera have obclavate to more ellipsoid 2-septate conidia. Some related genera (Deightoniella, Macgarvieomyces) have evolved 1-septate conidia. Therefore, conidium morphology cannot be used as taxonomic criterion at generic level without phylogenetic data. We also identified 10 novel genera, and seven novel species. A re-evaluation of generic and species concepts within Pyriculariaceae is presented, and novelties are proposed based on morphological and phylogenetic data.

Towards incorporating asexual fungi in a natural classification: checklist and notes 2012–2016

“…Macgarvieomyces Klaubauf et al Klaubauf et al (2014) Hyde et al (2013) and Tian et al (2015) reported coelomycetous asexual morphs from this genus. Réblová Réblová et al (2016b) introduced this genus with a hyphomycetous asexual morph.…”

“…Bambusicularia Klaubauf et al Klaubauf et al (2014) introduced this genus and showed that it belongs in Pyriculariaceae, Magnaporthales in their phylogenetic analyses. Crous et al (2017) introduced this genus and showed that it belongs in Phaeosphaeriaceae.…”

“…Barretomyces Klaubauf et al Klaubauf et al (2014) (Phillips et al 2013, Wijayawardene et al 2016. Thus, Wijayawardene et al (2014Wijayawardene et al ( , 2017 proposed to reduce both latter asexual genera under Botryosphaeria.…”

“…Proxipyricularia Klaubauf et al Klaubauf et al (2014) introduced this genus and showed that it belongs to Pyriculariaceae, Magnaporthales in their phylogenetic analyses.…”

Characterization of Sarocladium oryzae and its reduction potential of rice leaf blast

“…Rice leaf blast, caused by Magnaporthe oryzae [B. Couch (anamorph: Pyricularia oryzae Cavara)] (Klaubauf et al 2014), is one of the most destructive diseases in rice crops (Fisher et al 2012) and may…”