Name and publication

Phytophthora asiatica M.Z. Rahman, H. Mukobata & Kageyama (2014)

Rahman MZ, Mukobata H, Suga H, and Kageyama K. 2014. Phytophthora asiatica sp. nov., a new species causing leaf and stem blight of kudzu in Japan. Mycol. Progress 13: 759–769.

Corresponding author: rahman@green.gifu-u.ac.jp

Nomenclature

from Rahman et al. (2014)

Mycobank

MB804495

Synonymy

= Phytophthora cinnamomi var. robiniae H.H.Ho var. nov. Mycotaxon. 82:392. 2002

= Phytophthora cinnamomi H.H.Ho, W.Y. Zhang, Z.R. Liang & Y. N. Yu Mycologia. 75:883. 1983

Etymology

named after the location of isolation of this pathogen, Asia

Typification

Type: JAPAN, collected from leaf and stem blight of kudzu (Pueraria lobata) in Toyama Prefecture, Kurobe city in 2005, collector H. Mukobata. Holotypus: Isolate NBRC H-13112 (frozen dry specimen) deposited at the Biological Resource Center - Culture Collection Division (NBRC)

Ex-type: Cultures NBRC 109140 and CBS 133347 (Toku-1)

Sequences for ex-type in original manuscript: Phytophthora asiatica Toku-1: ITS AB688422, LSU AB688587, TEF 1-α AB539557, β-tub AB539560, 60S/ L10 AB539554, HSP90 AB539563, tigA AB894380, COI AB688314, COXII AB894377

Ex-type in other collections

(ET) CBS 133347, NRRL 64336, NBRC 109140, Toku-1, WPC P19977,  S&T BL 124 (Abad), 61H3 (Hong)

Molecular identification

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

Phytophthora asiatica isolate CPHST BL 124 (= P19977 WPC) = ITS rDNA MG783378

Phytophthora asiatica isolate Toku-1 = COI AB688314

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)

Selected specimen(s):

Phytophthora asiatica isolate CPHST BL 14 (=P16351 WPC) = ITS rDNA MG783379, COI MH136849

Sequences with multiple genes for ex-type in other sources

• NCBI: Phytophthora asiatica CPHST BL 124
• NCBI: Phytophthora asiatica Toku-1
• EPPO-Q-bank: Phytophthora asiatica
• BOLDSYSTEMS: Phytophthora asiatica N/A 6/6/15

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
7b

Morphological identification

adapted from Rahman et al. (2014)

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
morphology on V8-A, PDA, and MEA with light stellate pattern. Minimum growth temperature 5°C, maximum 35°C, and optimum 28°C.

Conditions for growth and sporulation

Sporangia absent on solid media, but present in grass leaf blade water cultures.

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)
, 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
, obpyriformobpyriform:
inversely pear-shaped, i.e. with the widest part at the point of attachment (cf. pyriform)
, obturbinate, or distorted (37–72 long x 16–33 μm wide), with internal (extended and nesting) and external proliferationexternal proliferation:
formation of a sporangium after a sporangiophore has emerged from beneath and external to an empty sporangium that has previously emitted its zoospores (cf. internal proliferation)
, borne in simple and unbranched or simple sympodial sporangiophores. Hyphal swellings occasionally observed, when present catenulatecatenulate:
having a chain-like form
lobate. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia smooth, spherical, with average diameter of (18–55 μm). Antheridia amphigynous, rarely paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
, regularly spherical or 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
in shape. 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)
, spherical, with average diameter of 15–43 μm.

Most typical characters

Phytophthora asiatica can be distinguished by the obturbinate, often distorted 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
with internal and external proliferationexternal proliferation:
formation of a sporangium after a sporangiophore has emerged from beneath and external to an empty sporangium that has previously emitted its zoospores (cf. internal proliferation)
and the shape of the catenulated hyphal swellings.

Additional specimen(s) evaluated

Phytophthora asiatica CPHST-BL 124 (Abad) = (P19977 World Phytophthora Collection – California, USA, duplicate of the ex-type CBS 133347).

Selected specimen CPHST-BL 14 (Abad) = P16351 WPC

Hosts and distribution

Distribution: Asia (China, Japan)
Substrate: leaf and stem
Disease note: leaf, petiole, and stem blight. The disease initially produced dark brown, irregular lesions on leaves, petioles, and stems. In advanced stages, the infected plant segments became dark and soft, leading to death of the plant.
Hosts: Peuraria lobata (kudzu)

Retrieved January 18, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

 

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

 

 

• Google All Phytophthora asiatica
• Google Images Phytophthora asiatica
• Google Scholar Phytophthora asiatica

 

  also see Phytophthora cinnamomi robineae

Fact sheet author

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