Phytophthora × vanyenensis

Name and publication

Phytophthora × vanyenensis Q.N. Dang and T. I. Burgess (2021)

Dang QN, Pham TQ, Arentz F, Hardy GE, Burgess TI. 2021. New Phytophthora species in clade 2a from the Asia-Pacific region including a re-examination of P. colocasiae and P. meadii. Mycological Progress 20 (2): 111–129.

Nomenclature

Mycobank

MB836443

Etymology

referring to the locality (Van Yen) where this species was recovered

Typification

Type: VIETNAM, Yen Bai, Van Yen, water from Cinnamomum cassia plantation, Sep. 2018, Q.N. Dang, Holotype MURU488

Ex-type: culture CBS 146554

Sequences of ex-type in manuscript:  ITS MT568651, β-tubulin MT583634, hsp90 MT583680, cox1 MT583648, cox2 MT583665, nadh1 MT583695, rps10 MT583709

Molecular identification

Position in ITS phylogenetic tree

Clade 2a

Morphological identification

Colonies and cardinal temperatures

Colony morphology cottony and stellate on CA, dense and stellate on PDA, smooth and thin on MEA, and submerged and stellate on V8A. Minimum growth temperature 4°C, optimum 30°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 paired cultures on V8A after about 21 d.

Asexual phase

Sporangia were semi-papillate to papillate often bipapillate, mostly persistent, and variable in shape with external proliferation. Sporangia averaged 52.8 x 33.5 µm (overall range 36.4–74.3 x 19.6–51.7 µm). Sporangiophores simple. Hyphal swellings rare. Chlamydospores absent.

Sexual phase

Heterothallic. Oogonia had smooth walls, and size ranged from 20–26.9 µm. Oospores plerotic to semi-aplerotic, globose, size ranged 17.1–24.8 µm. Copious oospores produced but about 60% aborted after the formation the wall. Oospores often aborted after formation of the walls. Antheridia amphigynous often with digitate projections.

Most typical characters

Phytophthora × vanyenensis resides in clade 2a, and P. mekongensis is one of the parent species; the other is unknown.

Additional specimen(s) evaluated

Viet Nam, Yen Bai, Van Yen, rhizosphere soil from Cinnamomum cassia plantations, 2018, Q.N. Dang, QD12; water from Cinnamomum cassia plantations QD30; QD32

Hosts and distribution

Distribution: Vietnam
Substrate: roots
Disease note: root rot of Cinnamomum cassia, in conjunction with P. cinnamomi
Host: Cinnamomum cassia

Additional references and links

none available

Fact sheet author

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