Plant oil biosynthesis and genetic improvement: progresses, challenges and opportunities

Plant oil production is crucial for meeting the global demand for vegetable oils providing essential fatty acids and energy, and for various industry uses. Plant oil biosynthesis is a complex biological process. Understanding the process is essential for improving oil crop productivity and nutritional quality. To target genetic improvement strategies of oil content, this review attempts to provide a broad view of oil biosynthesis in terms of the oil biosynthesis chain and was thus arranged into four sections: the code/control center of oil production―genetic and genomic insight into seed oil content control; the manufacture center of oil production―oil biosynthesis and its regulation; the upstream raw material supply chains of oil production―carbon source, energy and reductants; and the progresses, challenges and strategies―oil content improvement by conventional and biotechnological breeding in the past and future. Within these sections, we highlight major-effect quantitative trait loci (QTLs) of oil content and the WRINKLED1 (WRI1)- and SEEDSTICK (STK)-centered regulatory networks of oil biosynthesis, and revisit/update the significance of both photosynthetic and maternal effect on oil content and the central metabolic pathways and related bypasses in oil accumulation. Strategies for further improvement of oil content are discussed toward constructing integrated frameworks for increasing oil productivity. Overall, the review aims to consolidate the recent progress regarding oil biosynthesis in crops and to provide insights into future research and practical applications to crop oil production.