Name and publication

Phytophthora aleatoria P.M. Scott, R. McDougal & P.M. Taylor (2019)

Scott P, Taylor P, Gardner J, Puértolas A, Panda P, Addison S, Hood I, Burgess T, Horner I, Williams N, and McDougal R. 2019. Phytophthora aleatoria sp. nov., associated with root and collar damage on Pinus radiata from nurseries and plantations. Australasian Plant Pathology, 48 (4): 313–321.

Corresponding author: Peter Scott; peter.scott@plantandfood.co.nz

Nomenclature

Mycobank

MB830076

Etymology

from Spanish “aleatorio”, meaning random, fortuitous, casual, accidental, referring to the sporadic variable disease expression

Typification

Type: NEW ZEALAND (AOTEAROA), Nelson, isolate from a two-year-old Pinus radiata seedling. Collected by Rod Baigent, NZFS 4037 (live culture and dried culture on V8A medium, New Zealand Forest Research Mycological Herbarium, Rotorua, New Zealand).

Ex-type: living culture preserved in a metabolically inactive state as NZFS 4037 (New Zealand Forestry Service Culture Collection)

Sequences of ex-type in manuscript: ITS MK282209, β-tubulin MK294172, cox1 MK294177

Ex-type in other collections

(ET) NZFS 4037

Molecular identification

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

Phytophthora aleatoria ITS rDNA, COI

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 aleatoria
• EPPO-Q-bank: Phytophthora aleatoria
• BOLDSYSTEMS: Phytophthora aleatoria

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
1a

Genome sequence

Phytophthora aleatoria strain ex-type NZFS4037. Accession genome NZFS4037v1 reference, BioProject, PRJNA687640, University of Exeter (2021)

Morphological identification

Colonies and cardinal temperatures

Slow growing species and uniform without a pattern on V8A, MEA, and PDA. Minimum growth temperature 4°C, optimum 20°C, and maximum 25°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 (non-sterile pond water) and not observed in solid media. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
common in single culture.

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
 were papillatepapillate:
pertaining to the production of a distinct papilla at the distal end of the sporangium (cf. nonpapillate and semipapillate)
, mostly persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
(some caducouscaducous:
pertaining to sporangia that become dislodged readily (i.e. deciduous) and separate from the sporangiophore (cf. persistent)
sporangia were observed), and predominantly ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
in shape with no proliferationproliferation:
formation of a sporangium within an empty sporangium that has previously emitted zoospores (internal or nested) or after the sporangiophore has emerged from the empty sporangium (external)
. 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
averaged 31.7 x 23.3 µm (overall range 16.6–55.3 x 12.6–39.2 µm).Sporangiophores simple. Hyphal swellings present. 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
had smooth walls and size ranged from 24–45.6 µm; 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)
, globoseglobose:
having a rounded form resembling that of a sphere
, size ranged 20.8–39.1 µm, often aborting before the formation of the oosporeoospore:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
wall. AntheridiaAntheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
both amphigynousamphigynous:
pertaining to the sexual stage in which the antheridium completely surrounds the stalk of the oogonium (cf. paragynous)
and paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
.

Most typical characters

Phytophthora aleatoria is a sister species to P. catorum and P. hedraiandra in cladeclade:
a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor
1a, and morphological features overlap. The most distinguishing features are the slower growth rate and optimum and maximum temperature for growth.

Additional specimen(s) evaluated

New Zealand, Nelson, from a two-year-old Pinus radiata seedling. 2014, Rod Baigent, NZFS 4037; 1999, NZFS 351; Hawkes Bay, 2000, NZFS 451; Bay of Plenty, 2008, NZFS 3022; 2011, NZFS 4037

Hosts and distribution

Distribution: New Zealand
Substrate: stems, roots
Disease note: resin bleeding, cankers, discoloured foliage, and sometimes mortality in small seedlings
Host: Pinus radiata

Additional references and links

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

Fact sheet author

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.