Abstract
Nicotine, a major alkaloid in tobacco plants, acts as a defensive compound against insects. When wounding signals are transmitted from leaves to roots, nicotine biosynthesis is activated via jasmonate signal pathway in roots. Nicotine is produced in tobacco roots and transported to leaves for storage, but transport mechanism of nicotine is unknown.
We isolated two transporter genes (MATE1, 2) from tobacco roots. Expression pattern of these genes was very similar to nicotine biosynthetic genes, indicating that NtMATE functions in nicotine biosynthetic cells.
Analysis of nicotine secretion in NtMATE1-overexpressing BY-2 cells and in NtMATE1-suppressed transgenic tobacco plants suggests that NtMATE1 promotes excretion of nicotine from the vacuoles to apoplasts, and consequently facilitates translocation of nicotine from roots to aerial parts.
The functional analysis of NtMATE1 using transgenic tobacco plants is in progress.
