Phytophthora austrocedri

Name and publication

Phytophthora austrocedri Greslebin & Hansen (2007)

Greslebin AG, Hansen EM, and Sutton W. 2007. Phytophthora austrocedrae sp. nov., a new species associated with Austrocedrus chilensis mortality in Patagonia (Argentina). Mycol. Res. 111: 308–316.

Corresponding author: alina@ciefap.org.ar

Nomenclature

from Greslebin et al. (2007)

Mycobank

MB530225

Synonymy

Phytophthora austrocedrae Gresl. & E.M. Hansen (2007) [MB#510267] (orthographic variant)

Etymology

refers to the host Austrocedrus chilensis

Typification

Type: ARGENTINA, from roots and stem of Austrocedrus chilensis (Ciprés de la Cordillera or Cordilleran Cypress) collected on Oct. 2005 by A. Greslebin in Chubut, Parque Nacional Los Alerces (CIEFAP 203, Centro de Investigacion y Extension Forestal Andino Patagonico)

Ex-type: culture ATCC MYA-4074 (AG203)

Sequences for ex-type in original manuscript: Phytophthora sp. austrocedrae isolate AG203 = ITS rDNA: DQ995184 (1194bp 18S + ITS)

Ex-type in other collections

ATCC MYA-4074 = P16040  (WPC), CBS 122.911, CIEFAP 203, Gresbelin 203, CPHST BL 5 (Abad), 41B6 (Yang)

Molecular identification

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

Phytophthora austrocedri isolate CPHST BL 5 (= P16040 WPC) = ITS rDNA MG783380, COI MH136850

Sequences for ex-type in other sources
Position in ITS phylogenetic tree

Clade 8d

Morphological identification

adapted from Greslebin et al. (2007)

Colonies and cardinal temperatures

Colonies in CMA, V8, and PDA are uniform with non-distinctive pattern and with slow growth. Minimum temperature is 3°C, optimum 15–21°C, and maximum 24°C.

Conditions for growth and sporulation

Sporangia are produced in water cultures (soil extract or river water) and not observed in solid media. Oogonia are formed in single-strain culture in different media including CMA, V8-A, PDA, and HS with oil. Oogonia were usually formed in selective media after about 20 d.

Asexual phase

Sporangia semipapillate; persistent; ovoid, obpyriform, limoniform, or ellipsoid frequently with distorted shapes with average size of 50 x 36 µm (22–83 µm x 15–58 µm), and produced in unbranched sporangiophores. Sporangiophores frequently have hyphal swellings. Sporangia with hyphal projections and lateral attachment of the sporangiophore are frequently observed. Hyphal swellings are usually formed in liquid and solid media and are globose to subglobose, catenulated and sometimes with distorted shapes. Chlamydospores absent.

Sexual phase

Homothallic. Oogonia produced in approx. 20 days and are globose [39 µm diameter (22–56 µm)] with smooth walls; antheridia are amphigynous; and oospores are aplerotic.

Most typical characters

Phytophthora austrocedri is characterized by the production of persistent sporangia, hyphal swellings readily formed in water and solid culture, and slow growth rate.

Additional specimen(s) evaluated

Phytophthora austrocedrae CPHST BL 5 (Abad) = (P16040 World Phytophthora Collection – California, USA) duplicate of the ex-type CIEFAP 203

Hosts and distribution

Distribution: Asia (Iran), Europe (England, Germany, Scotland), South America (Argentina)
Substrate: isolated from necrotic lesions of stems and roots
Disease note: dieback, mortality; associated with 'mal del cipres' disease
Host: Austrocedrus chilensis, Juniperus communis, Cupressus sempervirens (Cupressaceae)

Retrieved January 17, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional information: The natural host of P. austrocedrae in South America is the Chilean cedar (Austrocedrus chilensis). In the UK, Lawson cypress (Chamaecyparis lawsoniana), Nootka cypress (Chamaecyparis nootkatensis), and the common juniper (Juniperus communis) have been confirmed as hosts in 2011. https://www.forestresearch.gov.uk/research/phytophthora-austrocedri/

Quarantine status

USA: Phytophthora austrocedrae is listed in the “Additional Pests of Concern” by the National Cooperative Agricultural Pest Survey (CAPS) for 2017, 2018, and 2019.

This species was listed as a species of concern during the 2009 Phytophthora prioritization project conducted by USDA APHIS PPQ CPHST PERAL (Schwartzburg et al.). 

Additional references and links

Forest Research UK Phytophthora austrocedrae

Forest Research: Phytophthora austrocedrae on juniper factsheet

Mackesy, D., and Sullivan, M. 2013. CPHST Pest Datasheet for Phytophthora austrocedrae USDA-APHIS-PPQ-CPHST. Revised in 2018 by L. Morales, D. Mackesy, and N. Miller.

Fact sheet author

Z. Gloria Abad, Ph.D., USDA-APHIS-PPQ-S&T Beltsville Laboratory, United States of America