Name and publication

Phytophthora transitoria I. Milenković, Májek & T. Jung (2022)

Chen Q, Bakhshi M, Balci Y, Broders KD, Cheewangkoon R, Chen SF, Fan XL, Gramaje D, Halleen F, Horta Jung M, Jiang N, Jung T, Májek T, Marincowitz S, Milenković I, Mostert L, Nakashima C, Nurul Faziha I, Pan M, Raza M, Scanu B, Spies CFJ, Suhaizan L, Suzuki H, Tian CM, Tomšovský M, Úrbez-Torres JR, Wang W, Wingfield BD, Wingfield MJ, Yang Q, Yang X, Zare R, Zhao P, Groenewald JZ, Cai L, Crous PW, 2022. Genera of phytopathogenic fungi: GOPHY 4. Studies in Mycology. 101: 417–564.

Corresponding authors: L. Cai, cail@im.ac.cn; P.W. Crous, p.crous@wi.knaw.nl

Nomenclature

Mycobank

MB 839452

Etymology

referring to the transitional role of most primary 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
releasing their cytoplasm into a secondary emerging 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
which forms and releases zoospores

Typification

Type: CZECH REPUBLIC, Central Bohemian region, Obříství, isolated from rhizosphere soil of a Quercus robur (Fagaceae) seedling, Mar. 2018, I. Milenković (holotype CBS H-24578, dried culture on V8A)

Ex-type: culture CBS 147245 = CZ001

Sequences for ex-type in original manuscript:  ITS MZ753925, cox1 MZ736439, β-tubulin MZ736466, tigA MZ736493

Ex-type in other collections

(ET) CBS 147245, CZ001

Molecular identification

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

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

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
13

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 uniform and submerged on V8A and CA, uniform and felty on PDA. Minimum growth temperature <10°C, optimum 22.5°C, and maximum 30°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
produced on non-sterile soil extract. OogoniaOogonia:
the female gametangium in which the oospore forms after fertilization by the antheridium
are formed readily on CA after 5 days when pair with opposite mating typemating type:
molecular mechanisms that regulate compatibility in sexual reproduction in heterothallic species (also referred to as compatibility type); typically denoted as A1 or A2
.

Asexual phase

Primary sporangia were non-papillate, persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
, and predominantly sub-globose to ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
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
averaged 32.5 x 25.7 µm (overall range 20–42.5 x 15–33.3 µm). Sporangiophores unbranched. Secondary sporangia were sessile or on short stalks emerging at or near apex, non-papillate, persistentpersistent:
pertaining to sporangia that remain attached to the sporangiophore and do not separate or detach easily (cf. caducous)
, and predominantly sub-globose to ovoidovoid:
egg-shaped, with the widest part at the base of the sporangium and the narrow part at the apex
in shape. Hyphal swellings absent. 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
present.

Sexual phase

Sterile in culture.

Most typical characters

Phytophthora transitoria differs from all other know Phytophthora species by releasing zoosporeszoospores:
motile spore that forms within the sporangium and exits through the exit pore and is capable of swimming for several hours; it has both a tinsel flagellum and a whip-like flagellum
almost exclusively from secondary 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
which emerge from primary transient 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
.

Additional specimen(s) evaluated

Czech republic, Central Bohemian region, Obříství, isolated from rhizosphere soil of nursery-grown Quercus robur seedlings, Mar. 2018, I. Milenković, CBS 147246 = CZ118; CZ119; CZ120; CZ121; CZ123

Hosts and distribution

Distribution: Czech Republic
Substrate: roots
Disease note: rhizosphere of nursery grown Quercus robur seedlings
Host: Quercus robur

Additional references and links

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

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.