19 Sep Waitea
Waitea Warcup & P.H.B. Talbot, Trans. Br. Mycol. Soc 45(4): 503 (1962)
The genus Waitea was founded by Warcup and Talbot (1962) for W. circinata producing small pink-orange sclerotia in soil. The resemblance of hyphae to Rhizoctonia was noted upon the establishment of the genus, but at that time no described asexual morph was known. Waitea circinata was later found to be associated with the asexual Rhizoctonia zeae and shown to be a pathogen of legumes, cereals and turf grasses. Waitea circinata has a wide distribution, but is mostly tropical, and lives as a saprotroph or phytopathogen.
Classification – Agaricomycetes, incertae sedis, Corticiales, Corticiaceae
Type species – Waitea circinata Warcup & P.H.B. Talbot, Trans. Br. Mycol. Soc 45(4): 503 (1962)
Distribution – Worldwide
Disease Symptoms – Brown ring patch, Leaf and sheath blight
Leaf and sheath blight or spot disease is characterized by oval lesions with green-gray centers surrounded by a distinct brown margin. Several lesions can occur together (De la Cerda et al. 2010; Kammerer et al. 2011; Chang and Lee 2016). Circular or irregular small patches of tan to yellow-brown colour are the initial symptom of brown ring patch disease and eventually develop brownish rings. Leaf-blades turn from yellow to brown as the disease progress and die eventually (Toda et al. 2005; Ni et al. 2012).
Hosts – Fabaceae (legumes) and Poaceae (cereals and turf grasses)
Morphological based identification and diversity
Waitea currently contains only the type species W. circinata. Waitea nuda was reduced to synonymy by Roberts (1999). The numerous available GenBank sequences of W. circinata imply that the species is frequently isolated from different parts of the world. Several varieties have been proposed for W. circinata, all shown to be nomen invalid following Articles 39.1 and 40.1 of the Melbourne Code (see Index Fungorum 2018).
Molecular based identification and diversity
The assignment of Waitea to Corticiaceae was already speculated by Talbot (1965), even though the genus was later frequently attributed to Ceratobasidiales based on morphology (e.g. Roberts 1999). Eventually, the phylogenetic placement of Waitea in the corticioid clade (Corticiales) was established by DePriest et al. (2005). Subsequent division of Corticiales to three families confirmed that Waitea is nested within Corticiaceae (Ghobad-Nejhad et al. 2010). Laetisaria arvalis is a close relative of Waitea.
Recommended genetic marker (genus level) – nLSU
Recommended genetic marker (species level) – ITS
Amaradasa et al. (2013) showed that ITS is an effective marker to characterize the isolates of Waitea and similar agents of turfgrass blights to their ‘infraspecies’ level.
Accepted number of species: One species.
References: DePriest et al. 2005, Ghobad-Nejhad et al. 2010, Amaradasa et al. 2013 (phylogeny), De la Cerda et al. 2010; Kammerer et al. 2011; Chang and Lee 2016 (morphology, phylogeny, pathogenicity), Ghimire et al. 2011 (morphology and phylogeny).