Name and publication

Phytophthora podocarpi K. Dobbie, R.L. McDougal & P.M. Scott (2022)

Dobbie K, Scott P, Taylor P, Panda P, Sen D, Dick M, McDougal R. 2022. Phytophthora podocarpi sp. nov. from siseased needles and shoots of Podocarpus in New Zealand. Forests 13 (2): 214

Corresponding author: Kiryn.Dobbie@scionresearch.com

Nomenclature

Mycobank

MB841407

Etymology

‘podocarpi’ refers to Podocarpus, the host genus of this oomycete

Typification

Type: NEW ZEALAND, Gisborne, Hampton Forest, from needles of Podocarpus totara, July 2011, BJ Rogan. holotype NZFRIM 5991

Ex-type: ICMP 24118 = NZFS 3642

Sequences of ex-type in manuscript: genome sequence GenBank LGSN00000000

Ex-type in other collections

(ET) ICMP 24118, NZFS 3642

Molecular identification

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

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

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
15

Genome sequence

Phytophthora podocarpi strain ex-type NZFS 3642. Accession genome NZFS3642v1 reference, BioProject PRJNA290788, University of Exeter (2015), Studholme et al. 2015

Morphological identification

Colonies and cardinal temperatures

Very slow growing, slightly felted with slight striate pattern on CA. Minimum growth temperature 2°C, optimum 17°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 after 24–36 h in pond water. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
rare in single-strain culture on CA and V8 after about 8 weeks.

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 non to semi-papillate, both persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
and caducouscaducous:
pertaining to sporangia that become dislodged readily (i.e. deciduous) and separate from the sporangiophore (cf. persistent)
, 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 55.7 x 37 µm (overall range 47.6–64.5 x 31.3–41.1 µm). Sporangiophores simple or loose 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
. 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 25–30 µm OosporesOospores:
zygote or thick-walled spore that forms within the oogonium after fertilization by the antheridium; may be long-lived
pleroticplerotic:
pertaining to an oospore that fills the oogonium (cf. aplerotic)
, globoseglobose:
having a rounded form resembling that of a sphere
often with a tapering base and light golden brown on maturity, size ranged 22–27 µm. Oogonial stalk often globoseglobose:
having a rounded form resembling that of a sphere
, occasionally with digitate projections. AntheridiaAntheridia:
the male gametangium; a multinucleate, swollen hyphal tip affixed firmly to the wall of the female gametangium (the oogonium)
 absent or paragynousparagynous:
pertaining to the sexual stage in which the antheridium is attached to the side of the oogonium (cf. amphigynous)
.

Most typical characters

In phylogenetic analysis, P. podocarpi falls between cladeclade:
a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor
3 and cladeclade:
a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor
5 and has been placed in the new cladeclade:
a taxonomic group of organisms classified together on the basis of homologous features traced to a common ancestor
15 along with Perenospora hyoscyami. 

Additional specimen(s) evaluated

New Zealand, Gibsborne, Hampton Forest, Western Cape Province, from needles of Podocarpus totara, 2011, NZFS 3603, NZFS 3645, NZFS 3768; Gisborne, Mata Forest, 2012, NZFS 3702; 2014, NZFS 4074; Northland, Pipiwai Forest, 2012, NZFS 3727; Taranaki, Otunui Forest, 2017, NZFS 4473; Hawkes Bay, Crystals Forest, 2017, NZFS 4525; Bay of Plenty, Kinleith Forest, NZFS 4526

Hosts and distribution

Distribution: New Zealand
Substrate: leaves (needles)
Disease note: needle and shoot blight of Podocarpus totara
Host: Podocarpus totara

Additional references and links

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

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.