Name and publication

Phytophthora phaseoli Thaxt. (1889)

Thaxter R. 1889. A new American Phytophthora. Bot. Gaz. 14: 273–274. Phytophthora phaseoli.

Nomenclature

Mycobank

MB194478

Typification

from Thaxter (1889)

Type: UNITED STATES OF AMERICA, collected from lima beans (Phaseolus lunatus) in the vicinity of New Haven, Connecticut in September 1889 on pods, stems, and leaves of the lima bean

Ex-type: LOST

Well-authenticated specimen(s) selected by Gloria Abad: 
Selected specimen #1: CPHST BL 28 = P10150 (WPC) from Phaseolus lunatus in Delaware, Race F, UNITED STATES OF AMERICA
Selected specimen #2: CPHST BL 112 = P6609 (WPC) from Phaseolus lunatus in Maryland, Race C, UNITED STATES OF AMERICA

Selected specimen(s) in other collections

(SE) CBS 114105, NRRL 64338, WPC P10150, S&T BL 28 (Abad)

Molecular identification

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

Phytophthora phaseoli isolate CPHST BL 28 (= P10150 WPC) = ITS rDNA MG865564, COI MH136956

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 phaseoli CPHST BL 28
• NCBI: Phytophthora phaseoli P6609
• EPPO-Q-bank: Phytophthora phaseoli CBS 114106
• BOLDSYSTEMS: Phytophthora phaseoli (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
1c

Morphological identification

Colonies and cardinal temperatures

Colonies after 7 days of growth on V8 agar, potato dextrose agar, and malt extract agar with slow growth and no special pattern. Minimum temperature for growth is 9°C, optimum 15–20°C, and maximum 27°C. 

Conditions for growth and sporulation

Phytophthora phaseoli produces 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
abundantly on agar; oosporesoospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
produced abundantly on lima bean agar or in host tissue.

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
; caducouscaducous:
pertaining to sporangia that become dislodged readily (i.e. deciduous) and separate from the sporangiophore (cf. persistent)
with short pedicels (5–20 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
, obovoidobovoid:
inversely egg-shaped; ovoid, but with the widest part at the apex
, or irregular and some with tapered bases (18–54 µm L x 11–27 µm W); nonproliferating; originated in simple sympodial sporangiophores which are slightly swollen at the base of sporangiumsporangium:
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
. Hyphal swellings absent. 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

Homothallic. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
smooth-walled, subspherical (17–36 µm diam.); antheridiaantheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
predominantly amphigynousamphigynous:
pertaining to the sexual stage in which the antheridium completely surrounds the stalk of the oogonium (cf. paragynous)
, elongated cylindrical, 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
(7–19 µm L), and sometimes with digitate 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)
(13–27 µm diam.).

Specimen(s) evaluated

Phytophthora phaseoli CPHST BL 28 SE1 = P10150 (WPC)

Phytophthora phaseoli CPHST BL 112 SE2 = P6609 (WPC)

Hosts and distribution

Distribution: Africa (Congo, Zaire), Asia (Philippines, Sri Lanka, Russia), Europe (Italy, Romania), North America (Mexico, USA), Central America and Caribbean Islands, South America (Brazil)
Substrate: pods. Also on shoots, leaves, petioles. Overwinters in soil or infected plant debris.
Disease note: downy mildew. At least 6 races have been identified. Races D, E, F have recently caused serious outbreaks in the eastern USA (DE, MD).
Host: Phaseolus lunatus (also reported as P. limensis) (lima beans, Fabaceae). Capable of infecting plants from other families after inoculation (Erwin & Ribeiro 1996). Also reported from Phaseolus vulgaris (common bean).

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

Additional info:
Substrate: foliage/fruits

Additional references and links

 

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

 

• Google All Phytophthora phaseoli
• Google Images Phytophthora phaseoli
• Google Scholar Phytophthora phaseoli

Fact sheet author

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