Phytophthora acaciae

Name and publication

Phytophthora acaciae A.F. dos Santos, T.C.A. Alves, D.J. Tessmann, K.L. Ivors & J.B. Ristaino (2019)

Alves TC, Tessmann DJ, Ivors KL, Ristaino JB, Dos Santos ÁF. 2019. Phytophthora acaciae sp. nov., a new species causing gummosis of black wattle in Brazil. Mycologia 4 111 (3): 445–455.

Nomenclature

Mycobank

MB823684

Etymology

“acaciae” referring to the genus of the host plant

Typification

Type: BRAZIL, Rio Grande Do Sul, Triunfo, 29°54′21.34″S, 51°42′27.05″W, 36 m alt, dried culture isolated from black wattle trunk, 12 Nov 1999, A. F. Santos, holotype MBM 415188.

Ex-type: culture AN02

Sequences for ex-type in original manuscript:  ITS KX396303, cox1 KX396267, cox2 KX396279, β-tubulin KX396338, RAS KX396313, TEF1α = KX396326

Molecular identification

Position in ITS phylogenetic tree

Clade 2d

Morphological identification

Colonies and cardinal temperatures

Colony morphology cottony with rosaceous pattern on CA. Minimum growth temperature 6°C, optimum 18–24°C, and maximum 36°C.

Conditions for growth and sporulation

Sporangia produced on 10% soil extract under constant light. Oogonia are formed readily on CA after 5 days when pair with opposite mating type.

Asexual phase

Sporangia were papillate, non-caducous, and predominantly ellipsoid in shape. Sporangia averaged 51 x 31 µm (overall range 28–85 x 21–50 µm); Sporangiophores simple or loose sympodia; Hyphal swellings absent. Chlamydospores present, abundant.

Sexual phase

Heterothallic. Oogonia smooth-walled, size ranged from 20–34 µm. Oospores aplerotic, thick-walled, size ranged 17–30 µm. Antheridia amphigynous.

Most typical characters

Morphologically similar to other species in Clade 2d.

Additional specimen(s) evaluated

Brazil, Rio Grand so Sul, Triunfo, from Acacia mearnsii trunk canker, AN05; AN12; AN13; AN14; AN23; AN905; AN906; AN907; AN908; AN909; AN910; AN911; AN912; AN913; AN914; AN915; AN916; Piratini, from Acacia mearnsii trunk canker, AN72; AN73; AN74; AN74B; AN87; AM5

Hosts and distribution

Distribution: Brazil
Substrate: trunk
Disease note: trunk lesions accompanied by gummosis or no gum exudation, from the trunk base to ~1.5 m of 2–6-year-old Acacia mearnsii commercial plantations
Host: Acacia mearnsii

Additional references and links

none available

Fact sheet author

Treena Burgess, Ph.D., Phytophthora Science and Management, Harry Butler Institute, Murdoch University