Phytophthora acaciivora

Name and publication

Phytophthora acaciivora T.Q. Pham, T.I. Burgess and Q.N. Dang (2020)

Burgess TI, Dang QN, Le BV, Pham NQ, White D, Pham TQ. 2020. Phytophthora acaciivora sp. nov. associated with dying Acacia mangium in Vietnam. Fungal systematics and evolution 6 (1): 243–252.

Nomenclature

Mycobank

MB834471

Etymology

named after its host, Acacia mangium

Typification

Type: VIETNAM, Tuyen Quang, from dying  Acacia mangium seedlings, Mar. 2012, T.Q. Pham; holotype MURU 480

Ex-type: culture CBS 138638 = AMTQ1

Sequences of ex-type in manuscript: ITS KX011263, ß-tubulin MN991983, HSP90 KX011238, coxI MN991990, coxII KX011228, nadh1 KX011286

Molecular identification

Position in ITS phylogenetic tree

Clade 2d 

Morphological identification

Colonies and cardinal temperatures

Colony morphology on CA, V8A, MEA, and PDA was uniform and cottony with no distinctive growth pattern and smooth regular margins. except for rosaceous pattern on PDA. Minimum growth temperature 10°C, optimum 27.5°C, and maximum is greater than 37.5°C.

Conditions for growth and sporulation

Sporangia are produced in water cultures (soil extract or river water) and not observed in solid media. Oogonia formed in paired cultures on CA and V8 after about 14 d.

Asexual phase

Sporangia semi-papillate, persistent, and of various shapes. Sporangia averaged 56.3 x 13.4 µm (overall range 21–102 x 15–49 µm), external proliferation. Sporangiophores simple, often laterally attached. Hyphal swellings absent. Chlamydospores absent.

Sexual phase

Heterothallic. Oogonia had wavy walls and size ranged from 24.5–46.2 µm. Oospores aplerotic, size ranged from 22.6–39.2 µm, over 90% aborted after the formation of the oospore walls. Antheridia amphigynous

Most typical characters

Phytophthora acaciivora resides in clade 2d and is closely related to P. frigida, P. elongata and P. acaciae. Compared to these species it has larger sporangia and a temperature maximum for growth of over 37.5°C.

Specimen(s) evaluated

Vietnam, Tuyen Quang, from dying Acacia mangium seedlings T.Q. Pham, 2012, CBS 138638; CBS 138639: from canker of dying Melia azedarach, VTN18.

Hosts and distribution

Distribution: Vietnam
Substrate: roots and collar
Disease note: Phytophthora root and collar rot of young seedlings
Host: Acacia mangium, Melia azedarach

Additional references and links

none available

Fact sheet author

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