Name and publication

Phytophthora fallax K. Dobbie & M.A. Dick (2006)

Dick MA, Dobbie K, Cooke DEL, and Brasier CM. 2006. Phytophthora captiosa sp. nov. and P. fallax sp. nov. causing crown dieback of Eucalyptus in New Zealand. Mycol. Res. 110: 393–404 (pg 398).

Corresponding author e-mail: margaret.dick@ensisjv.co.nz

Nomenclature

from Dick et al. (2006)

Mycobank

MB357172

Etymology

‘fallax’ = elusive, referring to the elusive nature of the fungus and the disease it causes

Typification

Type: NEW ZEALAND, Southland, Katea, Owaka Valley, culture isolated from leaves of alpine-ash (Eucalyptus delegatensis), 3 June 1997, collected by R. Thum A0049703 NZFRI-M 5216-holotypus deposited at the New Zealand Forest Research Institute Herbarium – Mycology)

Ex-type: NZFS 310L deposited in the New Zealand Forest Research Institute Culture Collection, also deposited in the International Collection of Micro-organisms from Plants (ICMP 15575), and the World Phytophthora Collection

Sequences for ex-type in original manuscript: NZFS 310L = ITS DQ297391

NOTE: In the original paper, P. fallax was reported as being deposited in the World Phytophthora Collection as WPC P10721. However, in the WPC database, P10721 corresponds to P. captiosa and isolate P10722 corresponds to the type of P. fallax (G. Abad search on 5/12/15).

Ex-type in other collections

(ET) CBS 119109, NZFS 310L, ICMP 15575,WPC P10722, S&T BL 63 (Abad), PD 09 03282760, No Amance 1, 46J2 (Hong)

Molecular identification

Voucher sequences for barcoding genes (ITS rDNA and COI) of the ex-type (see Molecular protocols page)

Phytophthora fallax isolate CPHST BL 63 (= P10722 WPC) = ITS rDNA MG865489, COI MH136885

Sequences of selected specimen

Phytophthora fallax isolate CPHST BL 170 (= P10725 WPC) = ITS rDNA MG865490, COI MH136886

Voucher sequences for Molecular Toolbox with seven genes (ITS, β-tub, COI, EF1α, HSP90, L10, and YPT1

(see Molecular protocols page) (In Progress)

Voucher sequences for Metabarcoding High-throughput Sequencing (HTS) Technologies [Molecular Operational Taxonomic Unit (MOTU)]

(see Molecular protocols page) (In Progress)

Sequences with multiple genes for ex-type in other sources

• NCBI: Phytophthora fallax CPHST BL 63
• NCBI: Phytophthora fallax P10722
• NCBI: Phytophthora fallax NZFS310L
• EPPO-Q-bank: Phytophthora fallax CBS 119109
• BOLDSYSTEMS: Phytophthora fallax PHYTO074-10 = P10722 (barcoding COI & ITS)

Position in multigenic phylogeny with 7 genes (ITS, β-tub, COI, EF1α, HSP90, L10, and YPT1)

Clade clade:
a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor
9d

Morphological identification

adapted from Dick et al. (2006)

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
morphology after 7 days on V8-A, PDA, and MEA with light rosaceous pattern and relatively slow growth. Minimum growth temperature 2°C, optimum 25°C, and maximum 30°C.

Conditions for growth and sporulation

Gametangia produced abundantly on CA within 30 d, sporangiasporangia:
sac within which zoospores form, especially when water is cooled to about 10°C below ambient temperature; in solid substrates, sporangia usually germinate by germ tubes
produced in pea broth in 48 h.

Asexual phase

SporangiaSporangia:
sac within which zoospores form, especially when water is cooled to about 10°C below ambient temperature; in solid substrates, sporangia usually germinate by germ tubes
nonpapillatenonpapillate:
pertaining to the production of a non-distinct, or inconspicuous, papilla at the distal end of the sporangium (cf. papillate and semipapillate)
, persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
, obpyriformobpyriform:
inversely pear-shaped, i.e. with the widest part at the point of attachment (cf. pyriform)
to distorted, often with a distinctive elongated neck and conspicuous basal plugbasal plug:
a plug protruding into a sporangium from the basal cross wall, separating it from the sporangiophore
(44–60 L x 27–38 W µm), proliferating both internally and externally, and originated in unbranched or simple sympodial sporangiophore. Hyphal swellings absent. Chlamydospores spherical, terminal (12–26 µm diam).

Sexual phase

Homothallichomothallic:
pertaining to sexual reproduction that can take place within a single thallus (i.e. self-fertile, non-outcrossing) (cf. heterothallic).
. Oogonia smooth-walled, spherical (30–36 µm diam); antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
predominantly paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
; sometimes the distorted hyphaehyphae:
single, tubular filament of a fungal or oomycete thallus; the basic structural unit of a fungus or oomycete
of paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
coils around the oogonial stalk and is difficult to determine; paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
globose (6–10 µm diam), most often attached near the oogonial stalk. Amphigynousamphigynous:
pertaining to the sexual stage in which the antheridium completely surrounds the stalk of the oogonium (cf. paragynous)
antheridia are cylindrical (16–30 L x 12–13 W µm). OosporesOospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
are initially pleroticplerotic:
pertaining to an oospore that fills the oogonium (cf. aplerotic)
, becoming apleroticaplerotic:
pertaining to a mature oospore that does not fill the oogonium; i.e. there is room left between the oospore wall and oogonium wall (cf. plerotic)
with age (29–34 µm diam).

Most typical characters

Phytophthora fallax is characterized by the production of obpyriformobpyriform:
inversely pear-shaped, i.e. with the widest part at the point of attachment (cf. pyriform)
sporangia with a distinctive elongated neck, and by the presence of antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
predominantly paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
with hyphaehyphae:
single, tubular filament of a fungal or oomycete thallus; the basic structural unit of a fungus or oomycete
sometimes coiling around the oogonial stalk.

Additional specimen(s) evaluated

Phytophthora fallax ex-type CPHST BL 63, duplicate of P10722 (World Phytophthora Collection)

Hosts and distribution

Distribution: Australia, New Zealand
Substrate: living leaves; also twigs, petioles, seed capsules, and peduncles
Disease note: associated with crown disease
Host: Eucalyptus spp. (Myrtaceae)

Retrieved January 30, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

 

• SMML USDA-ARS: Phytophthora fallax
• EPPO Global Database: Phytophthora fallax
• Forest Phytophthoras of the world: Phytophthora fallax
• CABI Digital Library: Phytophthora fallax
• Encyclopedia of Life (EOL): Phytophthora fallax
• Index Fungorum (IF): Phytophthora fallax

 

• Google All Phytophthora fallax
• Google Images Phytophthora fallax
• Google Scholar Phytophthora fallax

Fact sheet author

Z. Gloria Abad, Ph.D., USDA-APHIS-PPQ-S&T Plant Pathogen Confirmatory Diagnostics Laboratory (PPCDL), United States of America.