Abstract

Nicotine and related pyridine alkaloids of the tobacco plant are synthesized in the root and subsequently translocated via the xylem to the leaf and other aerial tissues, where they are primarily stored in the vacuole as defensive chemicals against herbivorous insects. Tobacco alkaloid accumulation depends on both biosynthesis and transport, which can be influenced by environmental conditions, phytohormones, and developmental status. Jasmonate signaling and transcription factors, including ERFs are known to play predominant regulatory roles. Genetic manipulation of alkaloid accumulation via traditional breeding, mutation breeding, and genetic engineering has been effective, but adverse effects on yields and cured leaf quality are frequently observed. Prospects for developing tobacco cultivars with ultralow alkaloid levels to meet future potential regulation of combustible cigarette nicotine content are discussed.