Alkaloid concentration during development in three Lupinus species and the expression of genes for alkaloid biosynthesis in seedlings

Abstract

The distribution of alkaloids during development from seed germination to seed formation is described for three Lupinus species. Alkaloid levels in seedlings decrease after germination before increasing to ca 0.3–0.6% dry wt in vegetative tissue prior to first flowering. The accumulation of alkaloids from vegetative parts to seeds is extremely rapid during the later maturation phase of pods and seeds. At maturity the seeds contain more alkaloid than the total present in above ground tissues at 4–5 weeks before final harvest. Apart from the seeds, and parts of flowers and fruits which become alkaloid rich, vegetative tissues contain alkaloid levels which are at the threshold values which differentiate between ‘sweet’ and ‘bitter’ genotypes. The concentration of alkaloid during development is discussed in relation to protection against predation.