Prospects for obtaining low-alkaloid and adaptive forms of narrow-leafed lupinе based on the genome and transcriptome resources of the species

Abstract

The narrow-leafed lupinе (Lupinus angustifolius L.) is considered as a crop of untapped opportunities. The food and forage potential of the species is not fully exploited due to the presence of quinolizidine alkaloids (QA) in plants, which are secondary metabolites that make the seeds bitter and toxic to humans and animals. Varieties with a low content of QA (“sweet” varieties) created over the last 50-60 years turned out to be more susceptible to damage by sucking insects and insect-transmitted viruses than high alkaloid ones (“bitter” varieties). Based on the rapidly developing genomic, transcriptomic and metabolomic profiling of the species, some molecular determinants and features of alkaloid biosynthesis in narrow-leafed lupinе plants have been identified: alkaloids are formed in the vegetative organs of the plant and then transported to the seeds. This information substantiated the creation of “bitter-sweet” forms with a high content of alkaloids in the vegetative parts of the plant, which would make it possible to reduce the attack of pathogens, and a minimal content of alkaloids in the seeds. This review summarizes the existing prerequisites for obtaining such forms of narrow-leafed lupinе on the basis of the available scientific developments. Information on the creation of saturated genetic maps of the species, in which the iucundus (iuc) locus determining the overall low alkaloid content in seeds is integrated and is used in breeding programs. The use of the new generation sequencing allowed the identification of the RAP2-7 gene, encoding the transcription factor APETALA2/ETHYLENE RESPONSE FACTOR, which is coupled to the iuc locus and located in the area with the main QTLs that affect the composition of the QA. It is a likely candidate gene for regulating alkaloid content in narrow-leafed lupinе seeds. The initial stages of QA biosynthesis and its regulatory factors have been revealed. Two reference assemblies of the genome of narrow-leafed lupinе have been carried out. All these achievements constitute a valuable resource for the creation of forms of narrow-leafed lupinе with a high content of alkaloids in the vegetative mass and low in the seeds, which are absent in nature.