Miss Natalie Van Zuydam

MSc Student

Research Interests

I completed my undergraduate and honours at the University of Kwa-Zulu Natal where I majored in microbiology and genetics. I have a keen interest in molecular biology and am particularly fascinated by genetics. I find this field extremely interesting and enjoy its cross-disciplinary nature.

Leptographium microarray project

The Ophiostomatoid fungi include a number of species that are important plant pathogens; in addition some are human pathogens. One of the more prominent anamorph genera in the Ophiostoma complex is the genus Leptographium. This genus includes more than 20 anamorph species and is best known for causing blue stain in the phloem of conifer trees. Infection with Leptographium can also cause mortality in adult trees and seedlings but in most cases reduces the quality of the timber to such an extent that it cannot be sold and utilised. Leptographium is closely associated with bark beetles and this association may be correlated with virulence. Recently it has been demonstrated that not only does this group form a well-defined morphological group but that this morphology is supported by its phylogeny. The phylogeny of this group has been extensively studied through molecular data.

Phylogeny construction requires sequence data that exhibits many polymorphisms that reflect the evolutionary history of an organism. The sequence data for Leptographium is extensive and mostly complete for the known species. The genes sequenced for Leptographium were those that contain information important for building phylogenies – ITS (internal transcribed spacer), elongation factor 1α and beta tubulin. These gene sequences contain indels as well as single nucleotide polymorphisms (SNPs) that indicate the molecular evolution of these regions. These differences are useful when identifying species on a sequence level, as some sequence mutations can be species unique. The relative uniqueness of specific gene regions provides an opportunity to molecular taxonomists, and other persons interested in accurately identifying these and other fungal species, to apply more innovative molecular techniques for accurate identification. Identifying species through conventional sequencing and sequence analysis is labour intensive and expensive. However, there are methods to multiplex and analyse sequences in a high throughput manor by harnessing the power of sequence differences. These new methods have the potential to reduce costs and improve current knowledge.

Microarrays are a quick way to sample sequences from multiple isolates across the genome in one simple procedure. The latest application for microarrays is to SNP genotyping, where microarrays are used to assess variation levels in populations. The data is used to identify genes that contribute to hereditary diseases and suitable targets for drug development. This technology can be applied to other organisms for different outcomes such as identification of species in fungi.

In order to investigate the applications for microarray technology in fungi for diagnostic purposes a large amount of complete sequence data is required. There exists for Leptographium an extremely comprehensive sequence database that includes multiple genes across all of the species. Using this database as a basis, it should be theoretically possible to design a microarray that will be capable of discerning sequence disparity between species for diagnostic purposes.

Posters and Presentations

• Van Zuydam NR, De Vos L, Wingfield B, Wingfield M, Aldous C. 2006. Establishing synteny relationships among Fusarium circiantum, F. subglutinans and F. graminarum. 44th Congress of the Southern African Society for Plant Pathology, Hartbeespoort Dam, Gauteng, South Africa.
• Van Zuydam NR, Wingfield BD, Jacobs K, Wingfield MJ. 2007. Microarrays: A novel diagnostic technology for Leptographium. 45th Congress of the Southern African Society for Plant Pathology, Benoni, South Africa.