As the world population continues to rise, so does the demand for a sustainable plant-based source of protein for human consumption and animal feed. In particular, Europe is in great need of a locally produced high-protein crop as it imports 70% of its protein requirements, relying heavily on genetically modified soybean. Narrow-leafed lupin (Lupinus angustifolius L.) is a grain legume crop that represents an excellent alternative to soybean; the grain contains high protein levels (30‒40%), the crop can be used for sustainable agriculture as it fixes nitrogen in the soil (reducing fertiliser requirements), and it serves as a disease break for other crops. Most importantly, narrow-leafed lupin is a native European species and is grown as a minor grain crop in several countries throughout the European Union.
The major barrier preventing lupin from becoming a more widely cultivated grain crop is the accumulation of toxic specialised metabolites in the grain—the quinolizidine alkaloids. While modern lupin cultivars have been bred to accumulate substantially lower alkaloid levels than their wild counterparts, grain alkaloid levels vary seasonally, often exceeding the threshold for use in industry. Moreover, modern lupin cultivars are more susceptible to herbivores, which is not surprising considering the proposed role of the alkaloids in plant defense. Although little is known about how alkaloids are synthesised, it is accepted that they are synthesised in vegetative tissues and must be transported throughout the plant via the phloem to accumulate in the grain.
The main objective of this UnleashLupin was to identify and characterise transporters involved in the long-distance transport of the alkaloids into the seeds of narrow-leafed lupin. Upon achieving this objective, ‘transport engineering’ of these alkaloids was to be initiated, by knocking out selected transporters to block alkaloid accumulation in the seeds while preserving alkaloid accumulation (and insect deterrence) elsewhere in the plant. This project has achieved most of its objectives and milestones for the period.
