Name and publication

Phytophthora citrophthora (R.E. Sm. & E.H. Sm.) Leonian (1925)

Leonian LH. 1925. Physiological studies on the genus Phytophthora. American Journal of Botany 12: 444–498. (Phytophthora citrophthora)

Nomenclature

Mycobank

MB251464

Synonymy

≡ Pythiacystis citrophthora R.E. Sm. & E.H. Sm., Botanical Gazette Crawfordsville 42 (3): 215 (1906) [MB#168281]
≡ Phytophthora imperfecta var. citrophthora (R.E. Sm. & E.H. Sm.) Sarej., Annales de l'Institut Phytopathologique Benaki 2: 46 (1936) [MB#348623]

Typification

from Leonian (1925)

Type: UNITED STATES OF AMERICA, California, from citrus in Southern California, Fawcett (isolate)

Ex-type: P0479 (WPC) = Fawcett 1309A

NOTE: Remarks by Leonian (1925) P. citrophthora (Pythiacystis citrophthora Sm. & Sm.) obtained from H. S. Fawcett: "Fungus abundant in winter and spring in Southern California lemon orchards and packing houses, causing serious losses." [notes for basionym: Pythiacystis citrophthora R.E. Sm. & E.H. Sm. (1906)]

Selected specimen in other collections

(SE) CBS 950.87, NRRL 64128, ATCC 52231, WPC P0479, UCR P749, S&T BL 60 (Abad), Fawcett 1309A, P.O. 479 (P. Oudemans) 

Molecular identification

Voucher sequences for barcoding genes (ITS rDNA and COI) of the selected specimen (see Molecular protocols page)

Phytophthora citrophthora isolate CPHST BL 60 (= P0479 WPC) = ITS rDNA MG865476, COI MH136872

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 selected specimen in other sources

• NCBI: Phytophthora citrophthora CPHST BL 60
• NCBI: Phytophthora citrophthora P0479
• EPPO-Q-Bank: Phytophthora citrophthora CBS 950.87
• BOLDSYSTEMS: Phytophthora citrophthora (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
2a

Morphological identification

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
grown for 7 days on V8-A, PDA, and MEA with chrysanthemum pattern. Minimum growth temperature 6°C, optimum 24–28°C, maximum 33°C.

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 papillae; 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
, limoniform, 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
, globoseglobose:
having a rounded form resembling that of a sphere
, and with distorted shapes, (17–48 x 20–110 µm) some with tapered bases, and with intercalaryintercalary:
positioned within a hypha (cf. terminal)
position, borne in simple sympodial or irregularly branched sporangiophores. 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
globoseglobose:
having a rounded form resembling that of a sphere
, subglobose, lateral, terminal, and intercalaryintercalary:
positioned within a hypha (cf. terminal)
(24–37 µm diam). Hyphal swellings absent.

Sexual phase

Sterile-heterothallic. OosporesOospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
rarely produced.

Most typical characters

Phytophthora citrophthora is characterized by the shapes of the semipapillatesemipapillate:
pertaining to the production of shallow having papilla that are not well developed, shallow and less nipple-like than fully papillate structures
, persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
sporangia and the 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
.

Specimen(s) evaluated

Phytophthora citrophthora, CPHST BL 60, a duplicate of P0479 (World Oomycetes/Phytophthora Collection), which is a duplicate of Fawcett 1309A

Hosts and distribution

Distribution: cosmopolitan
Substrate: roots, stems, bark of trunk, twigs, leaves, fruits, pods
Disease note: serious gummosis of citrus trees; in historical outbreaks nearly all citrus trees were destroyed (Erwin & Ribeiro 1996). Also root rot, stem necrosis, canker, fruit rot, twig blight, seedling blight; see Erwin & Ribeiro for disease symptoms by host.
Hosts: 88 genera in 51 families

Retrieved January 29, 2018 from U.S. National Fungus Collections Nomenclature Database.

Quarantine status

no quarantine for Phytophthora citrophthora as it is very prevalent and widely distributed around the world

Additional references and links

Leonian LH. 1925. Physiological studies on the genus Phytophthora. American Journal of Botany 12 (7): 444-498. (Phytophthora citrophthora)

Smith RE, Smith EH. 1906. A new fungus of economic importance. Botanical Gazette, 42: 215-221. (Pythiacystis citrophthora)

Mchau GRA and Coffey M. 1994. An integrated study of morphological and isozymeisozyme:
variant forms of an enzyme that share the same catalytic function; used for studying genetic diversity and evolution
patterns found within a worldwide collection of Phytophthora citrophthora and a redescription of the species. Mycol Re. 98: 1291-1299. NOTE: Not a valid redescription as it is based on multiple isolates and not a neotype or epitype (GA 6.30.14).

 

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

 

• Google All Phytophthora citrophthora
• Google Images Phytophthora citrophthora
• Google Scholar Phytophthora citrophthora

Fact sheet author

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