Phytophthora meadii (to be redescribed 2022)

Name and publication

Phytophthora meadii McRae (1918)

McRae W. 1918. Phylophthora meadii n. sp. on Hevea brasiliensis. Mem. Dept. Agric. India Vol IX: 219–273.

Nomenclature

from McRae (1918)

Mycobank

MB120866

Etymology

named after Mr. A. H. Mead who first brought the disease to notice

Typification

Type: INDIA, Travancore, Cochin, and Malabar (at the present Kerala - in the South West Region India) collected from Hevea brasiliensis, the Para rubber tree. The first culture of the species was made on August 5th, 1915.

Ex-type: LOST

Well-authenticated specimen(s) selected by Gloria Abad:
Selected specimen #1: isolate CPHST BL 81 (= P19007  WPC) from Hevea brasiliensis INDIA
Selected specimen #2: isolate CPHST BL 82 (= P19023 WPC) from Hevea brasiliensis INDIA
Selected specimen #3: isolate CPHST BL 120 (= P19041 WPC) from Hevea brasiliensis INDIA

Well-authenticated specimen(s) in other collections

CPHST BL 81 = P19007 (WPC) 
CPHST BL 82 = P19023 (WPC) 
CPHST BL 120 = P19041 WPC) 

Molecular identification

Voucher sequences for barcoding genes (ITS rDNA and COI) of selected specimens (see Molecular protocols page)

Phytophthora meadii isolate CPHST BL 81 (= P19007 WPC) = ITS rDNA MG865529 COI MH136924
Phytophthora meadii isolate CPHST BL 82 (= P19023 WPC) = ITS rDNA MG865531, COI MH136926
Phytophthora meadii isolate CPHST BL 120 (= P19041 WPC) = ITS rDNA MG865530, COI MH136925

Sequences for selected specimen(s) in other sources


NOTE: NCBI: Phytophthora meadii isolate 61J9 (ex-type): citation of this specimen as ex-type is incorrect. This corresponds to specimen Phytophthora meadii IMI 129185 CBS 219.88 from Hevea brasiliensis (cited in Kroon et al. 2004 and Cooke et al. 2000). This isolate was collected in India in 1998 and is a well-authenticated specimen for the species, but not the ex-type.

Position in ITS phylogenetic tree

Clade 2a

Morphological identification

Colonies and cardinal temperatures

Colony morphology after 7 days of growth on potato dextrose agar and V8 agar with stellate pattern, on malt extract agar with light stellate pattern. Minimum temperature for growth is 6°C, optimum 25–30°C, and maximum 32°C. 

Conditions for growth and sporulation

Phytophthora meadii produces abundant sporangia and zoospores in V8 agar flooded with 10% soil solution.

Asexual phase

Sporangia papillate to semipapillate, sometimes bipapillate; caducous with medium to long pedicel (10–20 μm long); ovoid, ellipsoid, elongate, obpyriform, globose, irregular forms (17–44 L x 15–29 W μm); originated in sympodial branched sporangiophores. Hyphal swellings small, globose to elongate, produced mostly in sporangiophores. Chlamydospores rarely produced.

Sexual phase

Heterothallic/homothallic. Oogonia smooth-walled; antheridia amphigynous; oospores slightly aplerotic showing big ooplast.

Most typical characters

Phytophthora meadii is characterized by the morphological characters of the asexual phase including the sporangia originated in sympodial branched sporangiophores.

Specimen(s) evaluated

Phytophthora meadii CPHST BL 81, duplicate of P19007 (World Phytophthora Collection)

Phytophthora meadii CPHST BL 120, duplicate of P19041 (WPC)

Hosts and distribution

Distribution: Asia, Australia, Europe (Italy), Pacific Islands (USA: HI)
Substrate: fruits (pods), stems, inflorescences
Disease note: abnormal leaf fall of rubber, stem rot, fruit rot
Host: various plant families including Hevea spp. (rubber, Euphorbiaceae)

Retrieved January 31, 2018 from U.S. National Fungus Collections Nomenclature Database.

Additional info
Host: Hevea brasiliensis
Substrate: fruits/foliage

Quarantine status

USA: 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.).

Phytophthora meadii is also listed in the the U.S. Regulated Plant Pest Table (last modified Nov. 15, 2017).

Additional references and links

Fact sheet author

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