Non-ribosomal peptide synthetases from the genomes of selected Chrysoporthe species

Dissertation (MSc (Genetics))--University of Pretoria, 2019.

Chrysoporthe is a genus consisting of species that are pathogens to various plant hosts, including industrial Eucalyptus species. The pathogenicity of each species varies to different hosts and amongst themselves. The pathogenicity and virulence of most filamentous fungi is attributed to various factors, including siderophores (secondary metabolites). Secondary metabolites are bioactive compounds of small molecular weight. They are produced by genes that are located adjacent to each other and are co-regulated. Understanding the biology of fungi and their response to different environments is very crucial. This research was aimed at characterizing three Chrysoporthe species, C. austroafricana, C. cubensis and C. deuterocubensis, based on their secondary metabolite gene clusters with special focus on the Nonribosomal Peptide Synthetases (NRPS). Results from the research chapter (chapter two) showed that the three Chrysoporthe species possess almost equal numbers of secondary metabolite gene clusters. With the special focus on NRPS, the study revealed that NRPS genes are very large as compared to other genes, as expected. The results also revealed that, within the NRPS gene clusters, putative siderophore producing gene clusters were also present. The second part of the research chapter showed that near UV light has the ability to induce NRPS genes, resulting in upregulation of their expression. This dissertation provides the first investigation of secondary metabolite gene clusters in Chrysoporthe species. Functional studies are proposed to further characterize upregulated NRPS genes.

Tsonga: Chrysoporthe I genus Leyi yi endliwaka hiti species leti ti tisaka mavabyi ka swimilana swo hlaya, ku katsa na ti Eucalyptus species, ximilana xo hlawuleka eka ti industry ta nhova. Vu pathogenicity bya ti species leti bya hambana eka swimilana na le xikharhi ka tona. Ti ndlela leti ti fungus ti tisaka mavabyi eka swimilana ti hlayile, ti katsa na ti siderophore (secondary metabolites). Secondary metabolites iti bioactive compounds ta ntikelo wale hansi. Ti endliwa hiti genes leti ti kumekaka kusuhi na kusuhi na swona ti lawuleka xikanwe. Ku twisisa biology yati fungi na leswi ti hlamurisaka xiswona kati ndhawu to hambana-hambana swina nkonka swinene. Nlavisiso lowu, wu kongomisiwile eka ku katsa ti species ti nharhu ta Chrysoporthe, C. Austroafricana, C. Cubensis and C.deuterocubensis, hiti secondary metabolites gene clusters ta tona. Na ku langutisa ngopfu-ngopfu eka ti nonribosomal peptide synthetases (NRPS). Mbuyelo wa xilavisiso Lexi wu kombisile ku ti species leti tinharhu ta Chrysoporthe tina ti secondary metabolites gene clusters leti ati lavile ku ringana hiti nomboro. Ku langutisa ngopfu-ngopfu ka ti NRPS swi kombisile ku ti NRPS genes iti kulu ngopfu loko ti ringanisiwa na tinwani ta tona, na swona aswi languteriwile. Mbuyelo wu kombisile nakambe swaku, eka ti NRPS gene clusters, ti gene leti tingana vuswikoti byo endla ti siderophore ta kumeka. Xiphemu xavumbirhi xa nlavisiso xi kombisile swaku rivoni ra UV ra kota ku hlohlotela ti NRPS genes, swi endlaka leswaku ti tlakuseka kumbe ti hunguteka matirhelo ya tona. Matsalwa lawa ma tisa xilavisiso xo sungula xati secondary metabolites gene clusters eka ti species ta Chrysoporthe. Xilavisiso xama tirhelo yati genes leti tinga tlakusiwa xalaveka ku kota ku twisisa hivu enti ti NRPS genes leti tinga tlakusiwa eka mbuyelo lowu.

Genetics

MSc (Genetics)

Unrestricted

Faculty of Natural and Agricultural Sciences