Identification and characterisation of phenolic based quantitative trait loci from wild tomato relatives

Quality traits associated with consumer health are an important aspect of modem plant breeding programmes. Of particular interest are phenolic compounds, a group that includes phenylpropanoids, flavonoids and anthocyanins. Previous studies have shown an inverse correlation between the incidence of chronic disease states and the intake of fruits and vegetables rich in phenolics. Molecular linkage mapping populations that utilise wild tomato relatives in traditional breeding strategies exploit wild germplasm for the identification of novel quantitative trait loci (QTL) without the use of genetic modification. In this study, the Solanum neorickii backcross inbred line population was screened for novel phenolic profiles. Marker data available within the EU Sol consortium were used to identify chromosomes 5 and 10 as possible QTL-containing regions for high rutin and p-coumaric acid phenotypes, and accessions neo-lll and neo- 123 were selected as candidate lines, respectively. Accession 3939 was incorporated from the Solanum habrochaites near isogenic line population because of its similarities with neo-ili. Each accession was characterised for metabolomic and physiological properties throughout fruit development and ripening. Results indicated multiple metabolic pathways were affected, including increases in isoprenoid intermediates; fruit ripening time was increased; and fruit size was altered. Antioxidant capacity of polar extracts increased, especially in fruit tissues accumulating phenolics. Transcriptomic analysis throughout fruit development identified 186 differentially expressed transcription factor (TF) genes. The promoter regions of two of these TF genes. a MYB-related in chromosome 5 and a LLM family in chromosome 10, were sequenced for differences between the wild relative and Solanum lycopersicum parents. These differences provide candidate QTL identities for the previously characterised phenotypes, and offer the potential for future utilisation in plant breeding programmes for high phenolic commercial lines.EThOS - Electronic Theses Online ServiceGBUnited Kingdo