Quantitative trait locus mapping of oil yield and oil quality related traits in the biofuel crop Jatropha curcas

Jatropha curcas is a perennial shrub from the Euphorbiacea family. It is known for its stress resilience and high seed oil content, however little selective breeding has been carried out to fully domesticate this species. The aim of this project is to identify and map quantitative trait loci (QTL) for seed oil content, seed oil composition (oil quality), and oil yield, in order to identify loci suitable for introgression into an economically viable cultivar. In this study, an F2 population (G51xCV) consisting of 229 plants for linkage analysis, and 145 plants for QTL analysis, was used to identify and position 312 genetic markers and 8 quantitative traits onto a genetic linkage and QTL map. Over 288 short sequence repeat (SSR) markers were mined from genome sequence to complement single nucleotide polymorphism (SNP) markers from genomic and transcribed DNA. 132 of the mined SSRs were physically linked to candidate genes, leading to the mapping of a substantial portion of genes that form the seed oil biosynthetic pathway in Jatropha curcas. Integration of phenotypic datasets collected over 2 independent years, enabled the identification of 15 QTL regulating seed oil content (2QTL), seed oil composition; palmitate, stearate, oleate, linoleate content (10 QTL), seed weight (1 QTL), number of branches (1 QTL) and seed yield (1QTL). Combined PVE for these QTL accounted for between 9.34 % (palmitate content year 2) to 32.26 % (seed oil content Year 2) of observed variation. Analysis of final oil yield per plant, showed that seed yield (number of seeds) was most important for regulating oil yield in this mapping population, however seed oil content and seed weight were also important traits, highlighting that selection of both seed oil and vegetative traits are of utmost importance for optimising oil yield in Jatropha curcas.