Monitoring of Fusarium circinatum spore loads in South African forest seedling nurseries

• Main Author: De Wet, Lisa-Danélle
• Other Authors: Steenkamp, Emma Theodora
• Published: 2013
• Subjects: UCTD
• Online Access: http://hdl.handle.net/2263/31283; De Wet, L 2011, Monitoring of Fusarium circinatum spore loads in South African forest seedling nurseries, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/31283 >; http://upetd.up.ac.za/thesis/available/etd-09232011-091323/

This project focussed on the pine pathogen Fusarium circinatum as this fungus is responsible for great economic losses and endangering pine forests worldwide. A better understanding of this pathogen could lead to improved disease management, thus limiting the dispersal of the fungus. A diagnostic technique, whether non-DNA-based or DNA-based, should be chosen with care to ensure obtaining accurate results, limiting expenses and time needed to complete a project. This study reviewed the techniques used for the identification and detection of Fusarium species. Non-DNA-based and DNA-based techniques focus on the morphological or chemical traits, and nucleotide sequence respectively. This review enabled the selection of an appropriate detection and quantification technique for F. circinatum, as the advantages and disadvantages of all techniques were considered and compared. The intergenic spacer (IGS) region of the ribosomal RNA repeat module is a popular diagnostic marker for Fusarium species due to the region’s multiple copies in the genome and fast evolution rate. This marker was evaluated to determine if it could be used for F. circinatum diagnostics. The results confirmed the IGS region to be a good diagnostic marker, due to the region’s species specificity, by comparing the IGS region of F. circinatum and other G. fujikuroi complex species. The results of phylogenetic analysis of all the isolates included in this study were supported by those of previous studies that also focussed on the IGS region. Real-time PCR was used successfully for the detection and quantification of F. circinatum during past studies. Due to these successes, real-time PCR was chosen as the technique for the quantification of F. circinatum spores in a pine seedling nursery. The results of this study showed that the real-time PCR technique employed was specific and sensitive as it allowed detection of low spore concentrations. The study also showed that there is a correlation between spore production and temperature and that spore dispersal is possibly, but not exclusively, due to air movement. Real-time PCR can thus be used for future studies that focus on the detection and quantification of F. circinatum as this study has shown this technique to be effective. === Dissertation (MSc)--University of Pretoria, 2011. === Microbiology and Plant Pathology === Unrestricted