Forest mycology and tree pathology

Research summary

The white rot fungus Rigidoporus microporus is the most economically important pathogen of the tropical tree Hevea brasiliensis with yearly economic losses of millions of dollars in the tropics. The control and management of the white rot disease of rubber in most tropical countries have been hampered due to limited knowledge of the population genetics of the different isolates as well as molecular basis of virulence mechanisms. Additionally, being a white rot fungi, members of the Rigidoporus genus are known to play major roles in nutrient and carbon cycling in tropical forest.

Description

Rigidoporus is a genus of basidiomycetes with about 80 described species. All the members of the genus are polypores (bracket fungi) and wood-inhabiting white-rotters. Rigidoporus is a highly polyphyletic genus. Most species belong to the Polyporales, but a distinct clade of species is found in the Hymenochaetales ("the Oxyporus clade", Larsson et al. 2006, Miettinen & Larsson 2011). It is this clade in the Hymenochaetales that contains parasitic species that are economically important, and consequently our focus. We are currently studying taxonomy and systematics of this clade under several projects, and have thus a good background for choosing species for genomic studies. Our research shows that the Rigidoporus clade in the Hymenochaetales is well-supported and can be further divided into three subclades:
- Rigidoporus ulmarius clade (contains about 7 species; 4 species proposed for genome sequencing). These species have parasitic habit. The fruiting bodies are pileate, large, tough and perennial with a pinkish or reddish pore surface. No cystidia are present.
- Rigidoporus populinus clade (contains about 5 species; 1 species proposed for genome sequencing). Life style ranges from parasitic to saprotropic species with tough, white fruiting bodies on hardwoods in temperate areas. Thick-walled, encrusted cystidia abundant.
- Rigidoporus corticola clade (contains about 15 species). Saprotrophic species with short-lived, light-coloured fruiting bodies on hardwoods and conifers. Also corticioid species of the genus Botryodontia belong to this clade. Gloeocystidia and thin-walled encrusted cystidia present, large spores.

Rigidoporus ulmarius clade
Rigidoporus microporus (=Rigidoporus lignosus), is a well-known and serious pathogen of rubber plantations in the old-world tropics causing white root rot disease. It also affects other tropical woody crops such as cacao, coffee, tea, coconut and oil palm. It thrives in plantations but is less abundant in natural forests. Our on-going studies on the taxonomy of R. microporus have revealed that the current species concept includes four to five species: one in Africa, two in Southeast Asia and one to two in South and Central America. Two of these, the African and one Asian species, appear to be serious plantation pests, but they are all probably tree parasites of numerous hardwoods that spread through root contact and continue to rot the wood long after the tree has fallen.

Research info

Research title
Forest mycology and tree pathology

Research timeline
1.1.2011 - 1.12.2016

Keywords
biocontrol Forest trees fungi microbial ecology Rigidoporus spp Rubber tree

Region
Africa

Countries
Finland, Ghana

Institution
University of Helsinki
Department of Forest Sciences
Helsinki, Finland

Head of research
Fred Asiegbu

Research team
Abbot Oghenekaro

Partners
University of Benin, Benin, Nigeria Rubber Research Institute of Nigeria, Benin, Nigeria

Contact information
Fred Asiegbu
09 191 58109
Fred.Asiegbu@Helsinki.fi
Open link

Record last updated
17.1.2014