Phytophthora oreophila

Name and publication

Phytophthora oreophila I. Khaliq and T.I Burgess (2019)

Khaliq I, Hardy GE, McDougall KL, Burgess TI. 2019. Phytophthora species isolated from alpine and sub-alpine regions of Australia, including the description of two new species; Phytophthora cacuminis sp. nov and Phytophthora oreophila sp. nov. Fungal Biology 123 (1): 29–41.

Nomenclature

Mycobank

MB825232

Etymology

‘oreos’ refers to a Greek word for a mountain and ‘phila’ means loving. The name is given to the species due to its mountainous origin, and its ability to grow at extremely low temperatures (less than 4°C).

Typification

Type: Australia: New South Wales, Merritts Creek; by baiting rhizosphere soil and associated roots collected from a disturbed alpine herbfield, Jan 2016. Collected by Keith McDougall, isolated by I. Khaliq. Holotype MURU 483 (dried culture on V8A, Herbarium of Murdoch University, Western Australia)

Ex-type: culture CBS 144709 = U11

Sequences of ex-type in manuscript: ITS MG542976, β-tubulin MG543037, HSP90 MG543025, cox1 MG543002, nadh1 MG543013

Molecular identification

Position in ITS phylogenetic tree

Clade 8a

Morphological identification

Colonies and cardinal temperatures

Colony morphology on V8 agar and CA was slightly petaloid, and rosaceous on PDA. Minimum growth temperature 4°C, optimum 20°C, and maximum 32.5°C.

Conditions for growth and sporulation

Sporangia are produced in water cultures (soil extract) and not observed in solid media. Oogonia are formed readily in single-strain culture on CA and V8 after about 14 d.

Asexual phase

Sporangia were non-papillate, persistent, and predominantly ovoid in shape with internal proliferation, both nested and extended. Sporangia averaged 40.9 x 26.7 µm (overall range 19.9–59.9 x 13.4–38.5 µm). Sporangiophores simple. Hyphal swellings present. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia had wavy walls and size ranged from 29.3–48.1 µm Oospores plerotic, globose with a large ooplast and pale on maturity, size ranged 26.8–42 µm. 90% of oospores aborted after formation of the walls. Antheridia paragynous often with multiple antheridia.

Most typical characters

Phytophthora oreophila is closely related to and morphologically resembles P. rosacearum and P. pseudorosacerum; the most distinguishing characteristics are the lower temperature optima and faster growth.

Hosts and distribution

Distribution: Australia
Substrate: roots
Disease note: no known disease
Host: native vegetation

Additional references and links

none available

Fact sheet author

Treena Burgess, Ph.D., Phytophthora Science and Management, Harry Butler Institute, Murdoch University