Transcription factors in alkaloid engineering

Abstract

Plants produce a large variety of low-molecular-weight and specialized secondary com-pounds. Among them, nitrogen-containing alkaloids are the most biologically active and are often used in the pharmaceutical industry. Although alkaloid chemistry has been intensively investi-gated, characterization of alkaloid biosynthesis, including biosynthetic enzyme genes and their reg-ulation, especially the transcription factors involved, has been relatively delayed, since only a limited number of plant species produce these specific types of alkaloids in a tissue/cell-specific or de-velopmental-specific manner. Recent advances in molecular biology technologies, such as RNA se-quencing, co-expression analysis of transcripts and metabolites, and functional characterization of genes using recombinant technology and cutting-edge technology for metabolite identification, have enabled a more detailed characterization of alkaloid pathways. Thus, transcriptional regulation of alkaloid biosynthesis by transcription factors, such as basic helix–loop–helix (bHLH), APETALA2/ethylene-responsive factor (AP2/ERF), and WRKY, is well elucidated. In addition, jasmonate signaling, an important cue in alkaloid biosynthesis, and its cascade, interaction of transcription factors, and post-transcriptional regulation are also characterized and show cell/tissue-specific or developmental regulation. Furthermore, current sequencing technology provides more information on the genome structure of alkaloid-producing plants with large and complex ge-nomes, for genome-wide characterization. Based on the latest information, we discuss the application of transcription factors in alkaloid engineering.