17 Sep Erythricium
Erythricium J. Erikss. & Hjortstam, Svensk bot. Tideskr. 64(2): 165 (1970)
Erythricium was introduced by Eriksson and Hjortstam (1970) and is typified by E. laetum. Erythricium species are saprotrophic, plant pathogenic, or lichenicolous. Erythricium salmonicolor is a noteworthy pathogen of several economically important trees such as coffee, rubber, citrus, especially in tropical areas.
Classification – Agaricomycetes, incertae sedis, Corticiales, Corticiaceae
Type species – Erythricium laetum (P. Karst.) J. Erikss. & Hjortstam, Svensk bot. Tideskr. 64(2): 165(1970)
Distribution – Worldwide
Disease Symptoms – Pink Disease
Initial symptoms may vary with the host. The symptoms include production of a salmon pink mycelium on branches and stems. The mycelium spreads mainly along the underside of the branch. Leaves distal to the infection turn light green in the interveinal areas and turn scorch brown colour from the margins. Discoloration of bark, gummosis and canker on woody stems can also be observed due to the infection (Sebastianes et al. 2007).
Hosts – Species of Erythricium causes pink disease on many economically important plants including Anacardium sp., Annona sp., Artocarpus sp. Camellia sp., Cinnamomum sp., Coffea sp., Eucalyptus sp., Hevea sp. Malus sp., Mangifera sp., Pyrus sp. and Theobroma cacao (Farr and Rossman 2018).
Morphological based identification and diversity
Erythricium currently consists of six species with highly similar morphology, but diverse ecology. The species share pink-coloured effused fruiting bodies with simple structure, monomitic hyphal system without clamps, flexuous basidia and large basidiospores. They inhabit a wide range of substrata (moss, dicotyledonous herb, Yucca, plant debris, and a number of fruit trees) and thrive in diverse habitats (coniferous forests, orchards, and chaparral). The significant species is the devastating plant pathogen E. salmonicolor (= Corticium salmonicolor) which is the agent of ‘pink disease’ in different tropical trees and woody plantations such as citrus, eucalypts, coffee, cacao, rubber and tea. The asexual state of the fungus has been known as Necator decretus Massee. The species was originally described from Paleotropics, but soon detected also in Neotropics as well as the areas in northern hemisphere influenced by tropical climates (Mordue and Gibson 1976; Sebastianes et al. 2007).
Erythricium species are characterized by pink-coloured, resupinate basidiomata with monomitic hyphal system and without clamps. However, the species have highly similar micro-morphology, therefore morphology based identification may lead to confusion.
Molecular based identification and diversity
The latest phylogeny of Erythricium based on ITS and nLSU sequences was provided by Ghobad-Nejhad and Hallenberg (2010). The genus appears polyphyletic and its boundaries with regard to other genera in Corticiaceae (especially with Laetisaria) are unclear.
Recommended genetic markers (Genus level) – nLSU (placement within Corticiaceae)
Recommended genetic markers (Species level) – ITS
As noted by Ghobad-Nejhad and Hallenberg (2010), the ITS sequences of the pathogenic species E. salmonicolor seem to be very divergent, and results in ambiguous alignment with other Erythricium sp.
Accepted number of species: There are seven species epithets in Index Fungorum (2018) under this genus. However, only six are accepted.
References: Eriksson and Hjortstam 1970 (morphology), Ghobad-Nejhad and Hallenberg 2010 (phylogeny).