Name and publication

Phytophthora mekongensis Cacciola & Hoa (2018)

Cacciola SO, La Spada F, Hoa NV, Jung MH, and Scanu B. 2017. Phytophthora mekongensis Cacciola & N.V. Hoa, sp. nov. Fungal Planet description sheet: 615. Persoonia 38: 363. In Crous et al. 2017. Fungal Planet description sheets: 558–624. Persoonia 38: 240–384.

Cacciola SO, La Spada F, Hoa NV, Jung MH, and Scanu B. 2018. Nomenclartrural novelties. Index Fungorum 367: 1-1.

Corresponding author: olgacacciola@unict.it

Nomenclature

from Cacciola et al. (2017)

Mycobank

MB554524  (Cacciola et al. 2018)

MB820796 (old code Cacciola et al. 2017)

Etymology

refers to the area from where the species was isolated, Mekong River Delta in Vietnam

Typification

Type: SOUTHERN VIETNAM, Vĩnh Long province, Mekong Delta region, from Citrus grandis (syn.: C. maxima) fruit, 2012, A. De Patrizio & G. Magnano di San Lio (holotype CBS 135136, Cacciola et al 2018)

Ex-type: PF6a2

Sequences for ex-type in original manuscript:  ITS KC875838 (as Phytophthora aff. meadii AdP-2013 isolate PF6a2); COI KT366920 (as Phytophthora sp. IP-2015 isolate PF6a2)

Ex-type in other collections

(ET) CBS 135136, NRRL 64108, PF6a2, TJ120 (Jung), S&T BL 218 (Abad)

Molecular identification

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

Phytophthora aff. meadii AdP-2013 isolate PF6a2 = ITS KC875838 

Phytophthora sp. IP-2015 isolate PF6a2 = COI KT366920 

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 PF6a2
• EPPO-Q-bank: Phytophthora mekongensis
• BOLDSYSTEMS: Phytophthora mekongensis (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

adapted from Cacciola et al. (2017)

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
morphology on V8A is stellate to rosaceous, and on PDA stellate. Minimum growth temperature 12°C, optimum 28°C, and maximum 36°C.

Conditions for growth and sporulation

Sporangia produced on V8-agar (V8A) flooded with both distilled water and non-sterile soil extract.

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
, frequently bipapillate and trilobed; often caducouscaducous:
pertaining to sporangia that become dislodged readily (i.e. deciduous) and separate from the sporangiophore (cf. persistent)
with medium 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)
(5–15 μm); limoniform, ovoid-obpyriform, 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
to fusiformfusiform:
spindle-shaped; wide in the middle while narrowing or tapering at each end
(25–50 μm length × 20–36 μm width); showing a conspicuous basal plugbasal plug:
a plug protruding into a sporangium from the basal cross wall, separating it from the sporangiophore
at the point where the 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)
attaches to the 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
; originated in dense sympodial sporangiophoresporangiophore:
the hyphal strand on which the sporangium is formed; may be branched or unbranched to form compound sympodia or simple sympodia
. Hyphal swellings and 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
not reported.

Sexual phase

Sterile.

Hosts and distribution

Distribution: Asia (Vietnam)
Substrate: roots, fruit
Disease note: root rot, fruit rot
Host: Citrus grandis (Rutaceae)

Retrieved January 31, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional references and links

Puglisi et al. 2017. Two previously unknown Phytophthora species associated with brown rot of Pomelo (Citrus grandis) fruits in Vietnam. PLOS

 

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

 

• Google All Phytophthora mekongensis
• Google Images Phytophthora mekongensis
• Google Scholar Phytophthora mekongensis

Fact sheet author

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