A monograph of the fungal order Magnaporthales

By Ning Zhang and Jing Luo, Rutgers University

Summer patch is a common and destructive root disease of fine fescue grasses. It causes root, crown and stem rot that develops during periods of summer stress (Smiley et al., 2005). The known causal agents of summer patch are two fungal species, Magnaporthiopsis poae and M. meyeri-festucae that belong to the order Magnaporthales (Luo et al., 2017).

a series of four images depicting symptoms of four plant diseases
Figure 1. Plant diseases caused by fungal pathogens in the order Magnaporthales.

The fungal order Magnaporthales includes economically and scientifically important cereal and grass pathogens, such as the rice blast fungus Pyricularia oryzae (syn. Magnaporthe oryzae), the take-all root rot pathogen Gaeumannomyces graminis, as well as the turfgrass summer patch pathogens (Fig. 1). To date, over 200 species have been described in Magnaporthales, about 50% of which are pathogens of domesticated and wild monocotyledon plants (Ou, 1985). Despite their scientific and economic importance, the taxonomy and phylogenetic relationships of this group of fungi had been unsettled for a long time due to a paucity of studies for the non-model species in Magnaporthales, which has caused inconsistency and confusion among scientists, the United States Animal and Plant Health Inspection Services (APHIS) and other user communities around the world. Recent advancement in gene, transcriptome, and genome sequencing of these fungi has resulted in robust phylogenies, which correspond well with their pathogenicity, ecology, and biology. The taxonomy has thereby been revised in recent studies (Hernández-Restrepo et al., 2016; Klaubauf et al., 2014; Luo et al., 2017; Luo et al., 2015a; Luo et al., 2015b; Luo and Zhang, 2013; Thongkantha et al., 2009; Vines et al., 2019).

The knowledge of taxonomy, phylogeny, biogeography and pathology of the Magnaporthales is scattered through an increasingly wide range of periodicals and books, which extend back for over 140 years. In the past several years, we have been developing a monograph of Magnaporthales. The aim of this monograph is to provide an overview of these fungi, which includes both historic records in literature and recent advancements. We are pleased to announce that the APS PRESS book The Rice Blast Fungus and Allied Species: A Monograph of the Fungal Order of Magnaporthales is in production and will be available in June 2022 (Luo and Zhang, 2022, Fig. 2). Morphological descriptions, diagnostic illustrations, type designations, geographical distributions, host ranges, and references are provided for representative taxa, with an emphasis on economically important species. Dichotomous keys to the three families and 38 genera in Magnaporthales are generated, and all accepted species names are included. In addition, GenBank accessions for fungal DNA barcodes, several other phylogenetic markers and genome sequences for the representative taxa are also provided.

As the authors of this new book, we believe it will be an invaluable resource for mycologists, plant pathologists, and other researchers, along with plant clinics and broader-user communities worldwide regarding plant protection and quarantine. The online version of the monograph (https://magnaporthales.sebs.rutgers.edu) is being developed.

press release image
Figure 2. The monograph of Magnaporthales is recently published by APS Press.

Literature Cited

Hernández-Restrepo, M., Groenewald, J., Elliott, M., Canning, G., McMillan, V., and Crous, P. 2016. Take-all or nothing. Studies in Mycology 83:19-48.

Klaubauf, S., Tharreau, D., Fournier, E., Groenewald, J. Z., Crous, P. W., de Vries, R. P., and Lebrun, M. H. 2014. Resolving the polyphyletic nature of Pyricularia (Pyriculariaceae). Studies in Mycology 79:85-120.

Luo, J., Vines, P. L., Grimshaw, A., Hoffman, L., Walsh, E., Bonos, S. A., Clarke, B. B., Murphy, J. A., Meyer, W. A., and Zhang, N. 2017. Magnaporthiopsis meyeri-festucae, sp. nov., associated with a summer patch-like disease of fine fescue turfgrasses. Mycologia 109:780-789.

Luo, J., Walsh, E., Blystone, D., and Zhang, N. 2015a. Five new Pseudophialophora species from grass roots in the oligotrophic pine barrens ecosystem. Fungal Biology 119:1205-1215.

Luo, J., Walsh, E., and Zhang, N. 2015b. Toward monophyletic generic concepts in Magnaporthales: species with Harpophora asexual states. Mycologia 107:641-646.

Luo, J., and Zhang, N. 2013. Magnaporthiopsis, a new genus in Magnaporthaceae (Ascomycota). Mycologia 105:1019-1029.

Luo, J., and Zhang, N. 2022. The Rice Blast Fungus and Allied Species: A Monograph of the Fungal Order Magnaporthales. APS Press.  ISBN: 978-0-89054-682-6

Smiley, R. W., Dernoeden, P. H., and Clarke, B. B. 2005. Compendium of turfgrass diseases. The American Phytopathological Society (APS) Press, St. Paul, MN.

Ou, S. H. 1985. Rice diseases. IRRI.

Thongkantha, S., Jeewon, R., Vijaykrishna, D., Lumyong, S., McKenzie, E. H. C., and Hyde, K. D. 2009. Molecular phylogeny of Magnaporthaceae (Sordariomycetes) with a new species Ophioceras chiangdaoense from Dracaena loureiroi in Thailand. Fungal Diversity 34:157-173.

Vines, P. L., Hoffmann, F. G., Meyer, F., Allen, T. W., Luo, J., Zhang, N., and Tomaso-Peterson, M. 2019. Magnaporthiopsis cynodontis, a novel turfgrass pathogen with widespread distribution in the United States. Mycologia:1-12.