The causal mutation leading to sweetness in modern white lupin cultivars.

Lupins are high-protein crops that are rapidly gaining interest as hardy alternatives to soybean; however, they accumulate antinutritional alkaloids of the quinolizidine type (QAs). Lupin domestication was enabled by the discovery of genetic loci conferring low QA levels (sweetness), but the precise identity of the underlying genes remains uncertain. We show that , the most common sweet locus in white lupin, encodes an acetyltransferase (AT) unexpectedly involved in the early QA pathway. In plants, a single-nucleotide polymorphism (SNP) strongly impairs AT activity, causing pathway blockage. We corroborate our hypothesis by replicating the chemotype in narrow-leafed lupin via mutagenesis. Our work adds a new dimension to QA biosynthesis and establishes the identity of a lupin sweet gene for the first time, thus facilitating lupin breeding and enabling domestication of other QA-containing legumes. A single-nucleotide mutation enabled the modern domestication of white lupin by blocking the production of toxic alkaloids.

Funder

Funder name	Awards
Villum Fonden, Denmark	Project 15476
Novo Nordisk Fonden< Denmark	Project NNF2019OC53580
Ministry of Agriculture and Rural Development, Poland	Multiannual Programme RM-111-222-15
Innovate UK, United Kingdom	Project 133048
European Research Council< European Union	Horizon 2020 research and innovation program Starting Grant LUPINROOTS grant agreement no. 637420