Faculty of Natural and Agricultural Sciences
School of Biological Sciences
Department of Genetics
Selected Highlights from Research Findings
Why do certain males fight over mates whereas others prefer to mate peacefully side by side. In pollinating fig wasps the life history is such that brothers compete with one another for mating opportunities.
We found that most species mate peacefully, but as soon as the ratio of males to females become too high they will fight, even their own sibs, to increase their own reproductive output. This work illustrates the obvious: a shortage of resources and an excess of consumers will lead to a struggle for existence, which can be so powerful that it can even overrule the unity of the family. In modern society we tend to focus on producing more resources, but the reality of continued survival is a limitation on consumers.
In a related study we found that mothers, rather than the sons themselves, determine if the sons will develop into large fighters or Romeos. In this case, the mother has more information on the adversities her sons may face. This work shows that natural selection is extremely efficient at shaping life, not only is male development plastic, but even the quality of information is “considered” in developmental “decisions”
Contact person: Prof JM Greeff.
Cellulose is a biopolymer produced by plants to strengthen their cell walls and together with other cell wall polymers it provides mechanical support for plant organs.
Large amounts of cellulose are synthesized in the woody stems of forest trees. This process consequently plays a major role in global carbon sequestration.
Cellulose-rich wood fibre harvested from fast-growing plantation trees constitutes a renewable source of raw materials for a variety of purposes including paper manufacturing and bioenergy production.
Eucalyptus tree species are the most widely planted hardwood trees in the world with approximately 18 million ha under cultivation in tropical and subtropical regions.
They have achieved this status through excellent productivity and superior wood properties sought after by the global pulp and paper industry.
Fast-growing eucalypt plantations can produce more than 50 m3 of wood per hectare per year and in the process sequester more than 10 tons of carbon per hectare per year, much of it in the form of cellulose.
Despite its commercial importance and fundamental role in plant biology, the genetic regulation and detailed molecular biology of cellulose biosynthesis is still not completely understood. In fact, the molecular machinery involved has proven largely intractable to direct scientific investigation, since it involves a very large protein complex embedded in the plasma membranes of plant cells.
The Forest Molecular Genetics (FMG) Programme directed by Prof Zander Myburg in the Department of Genetics and Forestry and Agricultural Biotechnology Institute (FABI) focuses on the molecular genetics of wood formation in Eucalyptus trees. In 2005 and 2006, the FMG programme achieved a major breakthrough when a MSc student Martin Ranik, isolated full-length copies of six cellulose synthase genes from actively growing tissues of a Eucalyptus tree.
Three of these genes were shown to encode the protein components that comprise the cellulose biosynthetic complex in woody tissues, while the three other genes were involved in cellulose biosynthesis in non-woody tissues such as young unfolding trees (work published in the journal Tree Physiology, Ranik and Myburg, 2006).
Access to the genes that encode the cellulose synthase proteins in wood fibre cells is now allowing Myburg and his students to study the genetic regulation of cellulose biosynthesis in these trees, as well as the molecular interactions that allow assembly and functionality of the cellulose biosynthetic machinery in trees. Their work has important implications for pulp and paper, as well as bioenergy production in fast-growing Eucalyptus plantations. This work is funded in part by the University, Mondi Business Paper South Africa, Sappi Forest Products, THRIP and the NRF
Contact person: Dr AA Myburg.
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