“OPHIOSTOMA QUERCUS IN SOUTH AFRICA”
Prepared by: Joha Grobbelaar (M.Sc. candidate working on a fungus commonly occurring on hardwood trees in South Africa)
Ophiostoma spp. include some of the most important tree pathogens and agents of sapwood stain. Ophiostoma quercus, is a saprophytic fungus that causes a blue-stained appearance on freshly felled hardwood trees. The fungus actively colonises wounds and is considered an economically significant agent of wood degradation. Ophiostoma quercus has a worldwide distribution and it is thought to be native to the Northern Hemisphere. This is curious given the fact that previous studies have shown that it is extensively distributed throughout South Africa on native and introduced hardwoods. It is also well known in other Southern Hemisphere countries including Australia, New Zealand, Brazil and Uruguay thus resulting in uncertainty concerning its centre of origin. There is a need to identify Ophiostomatoid fungi accurately in order to monitor their movement between countries.
The research team of the DST/NRF Centre of Excellence in Tree Health Biotechnology (CTHB) is keen to document the diversity of O. quercus species in South Africa. A key aim of my research has been to develop genetic markers to be used in screening isolates of O. quercus to identify the genetic variation. These markers have revealed two lineages in populations of O. quercus isolates and this led us to compare isolates based on comparisons of DNA sequence data for various gene regions. These comparisons have revealed a new species from hardwood trees in Africa which is closely related to O. quercus.
Research highlights
A highlight of my research project was a visit to Norway for 10 weeks in 2005 enabling me to conduct research at the Norwegian Forestry Research Institute (Skogforsk) in Ås. This opportunity arose from a bilateral agreement between the Governments of Norway and South Africa. The aim of this trip was to collect Ophiostomatoid fungi infecting wounds on broad leaf trees, specifically Ophiostoma quercus. This was in particular because very little is known regarding the biodiversity and pathogenecity of Ophiostomatoid fungi on hardwood trees in Norway. Surveys were conducted in both the Southern and the Northern part of Norway and samples were collected from sawmills and from the stumps of recently felled trees. I also had the opportunity to attend the Baltic Forest Pathology congress held in Norway where I met delegates from Norway, Sweden, Finland, Iceland, Lithuania, Estonia and Latvia.
Sampling from stumps in Southern Norway (below left). Oak and birch trees are commonly harvested and stored during summer in preparation for the cold winter months (below right).
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