Name and publication

Phytophthora pseudotsugae Hamm & E.M. Hansen (1983)

Hamm PB and Hansen EM. 1983. Phytophthora pseudotsugae, a new species causing root rot of Douglas fir. Canadian Journal of Botany 61: 2630–2626.

Nomenclature

from Hamm and Hansen (1983)

Mycobank

MB107141

Etymology

named for its original host, Pseudotsuga menziesii

Typification

Type: UNITED STATES OF AMERICA, isolated from Douglas fir [Pseudotsuga menziesii (Mirb.) Franco] collected by R.G Pratt (USDA, Mississippi State University) in 1975 in a nursery in Westfir, Oregon; deposited in the American Type Culture Collection, Rockville, MD by Hamm (Hamm 268 = "Phytophthora sp. 1")

Ex-type: ATCC 52938 = Hamm 268 (Depositor PB Hamm, Chain of Custody Pratt to Hamm to ATCC)

NOTE: in the original publication of Hamm and Hansen (1983) no ATCC code is indicated. Everet Hansen sent an e-mail to G. Abad on 11.21.13 clarifying the code of Phytophthora sp. 1 corresponds to ATCC 52938.

Ex-type in other collections

(ET) NRRL 64376, ATCC 52938, CABI IMI331662 (AVA), WPC P10339, S&T BL 51 (Abad)

Molecular identification

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

Phytophthora pseudotsugae isolate CPHST BL 51 (= P10339 WPC) = ITS rDNA MG865575, COI MH136967

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 pseudotsugae CPHST BL 51
• NCBI: Phytophthora pseudotsugae P10339
• EPPO-Q-bank: Phytophthora pseudotsugae
• BOLDSYSTEMS: Phytophthora pseudotsugae (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
1a

Morphological identification

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
morphology on PDA, V8A, MEA with non-distinctive pattern. Minimum growth temperature 3°C, optimum 18–25°C, and maximum 27°C.

Conditions for growth and sporulation

Sporangia and hyphal swellings produced in soil extract liquid culture and rarely in solid media. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
readily produced in culture media. 

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
papillatepapillate:
pertaining to the production of a distinct papilla at the distal end of the sporangium (cf. nonpapillate and semipapillate)
and sometimes bipapillate; persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
and sometimes caducouscaducous:
pertaining to sporangia that become dislodged readily (i.e. deciduous) and separate from the sporangiophore (cf. persistent)
with short pedicels; globoseglobose:
having a rounded form resembling that of a sphere
, ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
, obpyriformobpyriform:
inversely pear-shaped, i.e. with the widest part at the point of attachment (cf. pyriform)
(26–47 L x 22–39 W µm) originated in unbranched and simple sympodial sporangiophores and with intercalaryintercalary:
positioned within a hypha (cf. terminal)
sporangia frequently produced. Hyphal swellings occasionally produced; globose, subglobose, many times with radiating hyphaehyphae:
single, tubular filament of a fungal or oomycete thallus; the basic structural unit of a fungus or oomycete
, and sometimes catenulated. ChlamydosporesChlamydospores:
an asexual spore with a thickened inner wall that is delimited from the mycelium by a septum; may be terminal or intercalary, and survives for long periods in soil
absent.

Sexual phase

Homothallichomothallic:
pertaining to sexual reproduction that can take place within a single thallus (i.e. self-fertile, non-outcrossing) (cf. heterothallic).
. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
smooth-walled; spherical to slightly globoseglobose:
having a rounded form resembling that of a sphere
(31–40 µm diam); antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
mostly paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
but also amphigynousamphigynous:
pertaining to the sexual stage in which the antheridium completely surrounds the stalk of the oogonium (cf. paragynous)
, spherical, ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
, club-shaped, or irregular shape; oosporesoospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
pleroticplerotic:
pertaining to an oospore that fills the oogonium (cf. aplerotic)
, 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)
, and slightly 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)
(24–34 µm diam).

Most typical characters

Phytophthora pseudotsugae is characterized by the presence of 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
papillatepapillate:
pertaining to the production of a distinct papilla at the distal end of the sporangium (cf. nonpapillate and semipapillate)
and sometimes bipapillate, mostly persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
and sometimes caducouscaducous:
pertaining to sporangia that become dislodged readily (i.e. deciduous) and separate from the sporangiophore (cf. persistent)
with short pedicels. The intercalaryintercalary:
positioned within a hypha (cf. terminal)
sporangia frequently produced in liquid cultures is another useful character for identification of the species.

Specimen(s) evaluated

Phytophthora pseudotsugae ex-type CPHST BL 51 duplicate of P10339 (World Phytophthora Collection)

Hosts and distribution

Distribution: North America (USA: WA, OR)
Substrate: roots
Disease note: root rot
Host: Pseudotsuga menziesii (Douglas fir, Pinaceae)

Retrieved February 01, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

 

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

 

• Google All Phytophthora pseudotsugae
• Google Images Phytophthora pseudotsugae
• Google Scholar Phytophthora pseudotsugae

Fact sheet author

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