Developmental Regulation of the Expression of Amaryllidaceae Alkaloid Biosynthetic Genes in Narcissus papyraceus

Abstract

Amaryllidaceae alkaloids (AAs) have multiple biological effects, which are of interest to the pharmaceutical industry. To unleash the potential of Amaryllidaceae plants as pharmaceutical crops and as sources of AAs, a thorough understanding of the AA biosynthetic pathway is needed. However, only few enzymes in the pathway are known. Here, we report the transcriptome of AA-producing paperwhites (Narcissus papyraceus Ker Gawl). We present a list of 21 genes putatively encoding enzymes involved in AA biosynthesis. Next, a cDNA library was created from 24 different samples of different parts at various developmental stages of N. papyraceus. The expression of AA biosynthetic genes was analyzed in each sample using RT-qPCR. In addition, the alkaloid content of each sample was analyzed by HPLC. Leaves and flowers were found to have the highest abundance of heterocyclic compounds, whereas the bulb, the lowest. Lycorine was also the predominant AA. The gene expression results were compared with the heterocyclic compound profiles for each sample. In some samples, a positive correlation was observed between the gene expression levels and the amount of compounds accumulated. However, due to a probable transport of enzymes and alkaloids in the plant, a negative correlation was also observed, particularly at stage 2.