Name and publication

Phytophthora trifolii E.M. Hansen & D.P. Maxwell (1991)

Hansen EM and Maxwell DP. 1991. Species of the Phytophthora megasperma-complex. Mycologia 83: 376–381.

Nomenclature

from Hansen and Maxwell (1991)

Mycobank

MB127933

Etymology

named for the principal host

Typification

Type: UNITED STATES, collected from clover (Trifolium vesiculosum) in Raymond, Mississippi by R.G. Pratt; holotype Pratt No. 105 in Oregon State University herbarium (OSU collection)

Ex-type: American Type Culture Collection

Notes:

Isolate No. 32 is also cited as the holotype in original manuscript as follows: "Pratt no. 105 et no. 32 in OSU collectione culturis". Isolate 32 corresponds to P. B. Hamm (Hamm 32) as cited at P6980 (WPC).

ATCC only has ATCC MYA-3901 and ATCC 48604 which do not correspond with the codes of Pratt No 105 or Hamm 32.

Ex-type in other collections

(ET) CBS 117687, WPC P6980, S&T BL 57 (Abad), 62A9 (Hong), Pratt. 105, Ham 32 

Molecular identification

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

Phytophthora trifolii isolate CPHST BL 57 (= P6980 WPC) = ITS rDNA MG865594, COI MH136986

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 trifolii CPHST BL 57 
• NCBI: Phytophthora trifolii CBS 117687
• EPPO-Q-bank: Phytophthora trifolii CBS 117687
• BOLDSYSTEMS: Phytophthora trifolii (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
8a

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 CMA, PDA, V-8A, MEA with no distinctive shape. Minimum temperature for growth 5°C, optimum 20–25°C, maximum 30°C.

Conditions for growth and sporulation

Sporangia formed in liquid culture.

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)
; 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)
, ellipsoidellipsoid:
refers to a solid body that forms an ellipse in the longitudinal plane and a circle in cross section; many fungal spores are ellipsoidal or elliptic
and with distorted shapes (27–50 µm length x 21–32 µm width), showing internal proliferationinternal proliferation:
internal proliferation occurs when the sporangiophore continues to grow through an empty sporangium
and intercalaryintercalary:
positioned within a hypha (cf. terminal)
hyphal swellings; originated in long, irregular branched or simple sympodial sporangiophores. Hyphal swellings globoseglobose:
having a rounded form resembling that of a sphere
, subglobose, radiating hyphaehyphae:
single, tubular filament of a fungal or oomycete thallus; the basic structural unit of a fungus or oomycete
individual or in chains. 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 (27–46 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)
, spherical, ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
, club-shaped, irregular, producing some digitated projections; oosporesoospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
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)
(23–37 µm diam.).

Most typical characters

Small 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
and large oogoniaoogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
are distinctive.

Specimen(s) evaluated

Phytophthora trifolii ex-type CPHST BL 57, duplicate of P6980 (World Phytophthora Collection)

Hosts and distribution

Distribution: North America (USA: MS)
Substrate: roots; sometimes shoots
Disease note: severe stand-depleting root rot; infection can extend up to the crown
Host: Trifolium spp. (Fabaceae)

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

Additional references and links

Pratt RG. 1981. Morphology, pathogenicity and host range of Phytophthora megasperma, P. erythroseptica, and P. parasitica from arrow leaf clover. Phytopathology 71: 276-282.

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

 

• Google All Phytophthora trifolii
• Google Images Phytophthora trifolii
• Google Scholar Phytophthora trifolii

Fact sheet author

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