Name and publication

Phytophthora constricta A. Rea, Stukely & T. Jung (2011

Rea AJ, Burgess TI, Hardy GE StJ, Stukely MJC, and Jung T. 2011. Two novel and potentially endemic species of Phytophthora associated with episodic dieback of Kwongan vegetation in the south-west of Western Australia. Plant Pathol. 60: 1055–1068.

Corresponding author: tburgess@murdoch.edu.au

Nomenclature

from Rea et al. (2011)

Mycobank

MB518793

Etymology

refers to the fragile constriction of most sporangiophores towards the sporangial base

Typification

Type: AUSTRALIA, Fitzgerald River National Park, isolated from soil sample collected in dying native Kwongan vegetation, August 2006, M. Stukely. Holotype: MURU 454 (dried culture on V8A in the Herbarium of Murdoch University, Western Australia)

Ex-type: CBS 125801 and VHS 16130

Sequences for ex-type in original manuscript: Phytophthora constricta CBS 125801 = ITS HQ013225, coxI HQ013207

Ex-type in other collections

(ET) CBS 125801, VHS 16130, WPC P19614, S&T BL 61 (Abad), 55C3 (Hong)

Molecular identification

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

Phytophthora constricta isolate CPHST BL 61 (= P19614 WPC) = ITS rDNA MG865480, COI MH136876

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 constricta CPHST BL 61
• NCBI: Phytophthora constricta CBS 125801
• EPPO-Q-bank: Phytophthora constricta 
• BOLDSYSTEMS: Phytophthora constricta (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
9d

Genome sequence

Phytophthora constricta strain ex-type BL 61. Accession genome USDA_Pcon_61_1.0 reference, BioProject PRJNA612532, USDA-APHIS-PPQ-S&T (2020)

Morphological identification

Colonies and cardinal temperatures

Colony colony:
assemblage of hyphae which usually develops form a single source and grows in a coordinated way
morphology is petaloid on CA, V8A, MEA, and PDA. Minimum growth temperature 5°C, optimum 22.5°C, and maximum 32.5°C.

Conditions for growth and sporulation

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
 are produced in water cultures (soil extract or river water) and not observed in solid media. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
are formed readily in single-strain culture on CA and V8A after about 14 d.

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
 are 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)
, and ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
to broad-ovoid in shape. 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
average 59.8 ± 8.7 x 48.8 ± 7.4 mm (total range 39.1–83.9 x 31.4–68.8 mm). Sporangiophores in simple sympodiasympodia:
a type of sporangiophore which appears simple, but where each successive sporangium develops on a branch behind and to one side of the previous apex, where growth has already ceased
, constricted towards the base of 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
, with internal proliferationinternal proliferation:
internal proliferation occurs when the sporangiophore continues to grow through an empty sporangium
, both nested and extended. Hyphal swellings ellipsoid, but rare. 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. Oogonia are predominantly globoseglobose:
having a rounded form resembling that of a sphere
with smooth walls, although elongated and eccentric oogoniaoogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
are observed, average size 48.0 ± 4.8 mm (31.8–59.6 µm). OosporesOospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
are slightly 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)
, globoseglobose:
having a rounded form resembling that of a sphere
, turning pale golden-brown on maturity, average size 40.4 ± 4.3 µm (23.8–49.8 µm). AntheridiaAntheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
 are paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
.

Most typical characters

The most typical feature of Phytophthora constricta is the constriction of the sporangiophores toward the base of the 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
.

Specimen(s) evaluated

Australia; Western Australia, Fitzgerald River National Park, isolated from soil sample collected in dying native kwongan vegetation, August 2006, M. Stukely CBS 125801 = VHS 16130; VHS 16127; VHS 16134; from Banksia cirsioides, VHS 16125; from Banksia falcate, DDS 3543; Nannup, from Pinus radiata, July 1980, DCE 177; MJS186

Additional isolates CPHST BL 61 = P19614 WPC

Hosts and distribution

Distribution: Australia
Substrate: roots, collar; isolated from soil
Disease note: root and collar rot
Host: Proteaceae

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

Additional info:
Distribution: Western Australia and Victoria
Substrate: roots, collars, and rhizosphere soil
Disease note: pathogenic toward Banksia attenuata
Hosts: numerous Proteaceous plant species including Banksias spp., Hakea spp., Adenanthos spp., and Isopogon spp.

Additional references and links

Burgess TI, Webster JL, Ciampini JA, White DW, Hardy GESJ, Stukely MJC. 2009. Re-evaluation of Phytophthora species isolated during 30 years of vegetation health surveys in Western Australia using molecular techniques. Plant Disease 93, 215-223.

Dick MA, Dobbie K, Cooke DEL, Brasier CM. 2006. Phytophthora captiosa sp. nov. and P. fallax sp. nov. causing crown dieback of Eucalyptus in New Zealand. Mycological Research 110: 393-404.

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

 

• Google All Phytophthora constricta
• Google Images Phytophthora constricta
• Google Scholar Phytophthora constricta

Fact sheet authors

Treena Burgess, Ph.D., Phytophthora Science and Management, Harry Butler Institute, Murdoch University, Australia

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