Name and publication

Phytophthora siskiyouensis Reeser & E.M. Hansen (2008)

Reeser PW, Hansen EM, and Sutton W. 2008. Phytophthora siskiyouensis, a new species from soil, water, myrtlewood (Umbellularia californica), and tanoak (Lithocarpus densiflorus) in southwestern Oregon. Mycologia 99: 639–643.

Corresponding author: reeserp@science.oregonstate.edu

Nomenclature

from Reeser et al. (2008)

Mycobank

MB505953

Etymology

refers to the Siskiyou Mountains in SW Oregon where the new species was first identified

Typification

Type: UNITED STATES OF AMERICA collected from a seasonal tributary to the Chetco River, Curry County, Oregon in March 2003; type: WA5-030403

Ex-type: ATCC MYA-4187 = WA5-30403 = CBS 122779, P15122 WPC

Sequences for ex-type in original manuscript: WA5-030403 = ITS rDNA EF523386

Ex-type in other collections

(ET) CBS 122779, ATCC MYA-4187, WA5-30403, WPC P15122, S&T BL 56 (Abad), 41B7 (Hong) 

Molecular identification

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

Phytophthora siskiyouensis isolate CPHST BL 56 (= P15122 WPC) = ITS rDNA MG865586, COI MH136978

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 siskiyouensis CPHST BL 56
• NCBI: Phytophthora siskiyouensis P15122 WPC
• EPPO-Q-bank: Phytophthora siskiyouensis CBS 122779
• BOLDSYSTEMS: Phytophthora siskiyouensis (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
2b

Morphological identification

adapted from Reeser et al. (2008)

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
after 7 days of growth on potato dextrose agar, malt extract agar, and V8A with chrysanthemum pattern. Minimum growth temperature 3°C, optimum 21–25°C, and maximum 27°C.

Conditions for growth and sporulation

Sporangia formed abundantly on agar culture pieces placed in stream water; oogoniaoogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
formed abundantly on V8A.

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
semipapillatesemipapillate:
pertaining to the production of shallow having papilla that are not well developed, shallow and less nipple-like than fully papillate structures
, some with two and more rarely with three papillapapilla:
a small rounded or conic protuberance, generally translucent, on the wall of sporangia that breaks open and serves as the exit-point of zoospores
; persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
or caducouscaducous:
pertaining to sporangia that become dislodged readily (i.e. deciduous) and separate from the sporangiophore (cf. persistent)
with variable pedicelpedicel:
the hyphal base of a sporangium that remains attached after the sporangium separates, or is shed, from the sporangiophore; the pedicel may be short (< 5 µm), medium (5–20 µm), or long (> 20 µm)
length (2–66 µm L); ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
, 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
, reniformreniform:
kidney-shaped
(or kidney), distorted shapes (26–95 L x 23–50 W µm); hyphal swellings small, often associated with sporangiophoresporangiophore:
the hyphal strand on which the sporangium is formed; may be branched or unbranched to form compound sympodia or simple sympodia
; 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
originated terminal but often subterminal and occasionally intercalaryintercalary:
positioned within a hypha (cf. terminal)
in unbranched or simple sympodial sporangiophores. Hyphal swellings absent. ChlamydosporesChlamydospores:
an asexual spore with a thickened inner wall&nbsp;that is delimited from the mycelium by a septum; may be terminal or intercalary, and survives for long periods in soil
absent.

Sexual phase

Homothallic. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
globoseglobose:
having a rounded form resembling that of a sphere
to subglobose (23–42 µm diam), occasionally much elongated or with a funnel shape tapering toward the stalk, frequently sessile and occasionally laterally intercalaryintercalary:
positioned within a hypha (cf. terminal)
; antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
predominately paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
, spherical, 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
or ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
, club-shaped (10–18 L x 8–13 W µm), terminal, occasionally intercalaryintercalary:
positioned within a hypha (cf. terminal)
and usually diclinousdiclinous:
the hypha bearing the antheridium originated from a different hypha than that of the oogonium (cf. monoclinous)
, attached anywhere on the oogoniumoogonium:
the female gametangium in which the oospore forms after fertilization by the antheridium
; oosporesoospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
globoseglobose:
having a rounded form resembling that of a sphere
to subglobose (19–33 µm diam) and usually 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)
.

Most typical characters

Phytophthora siskiyouensis can be distinguished by the shape of the terminal and intercalaryintercalary:
positioned within a hypha (cf. terminal)
sporangia, and the shape of the antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
.

Additional specimen(s) evaluated

Phytophthora siskiyouensis CPHST BL 56, duplicate of ex-type P15122 (World Phytophthora Collection)

Hosts and distribution

Distribution: Europe (England), North America (USA: OR)
Substrate: stems
Disease note: associated with cankers, pathogenicity little known
Host: Lithocarpus densiflorus (Fagaceae), Umbellularia californica (Lauraceae)

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

Additional info:
Substrate:  rhizosphere

Additional references and links

 

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

 

• Google All Phytophthora siskiyouensis
• Google Images Phytophthora siskiyouensis
• Google Scholar Phytophthora siskiyouensis

Fact sheet author

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