Abstract
Recently, it has been proposed that trigonelline (Tg) has various physiological functions, such as a signal in the response to oxidative stress, compatible solutes in drought and salt stress and as a leaf-closing factor. However, biosynthesis of Tg and its regulation have not yet been clearly demonstrated. In the present study, we examined the distribution and biosynthesis of Tg in coffee plants. The concentration of Tg was highest in young leaves and decreased with leaf development while its level in coffee fruits was increased with maturation. The content in roots was low. In coffee leaves, 60% of exogenously supplied [14C]-labelled nicotinic acid and nicotinamide was converted to Tg during an 18 h incubation. Tg synthesis from [14C]-nicotinamide was also demonstrated in both isolated seeds and pericarps. Tg synthesis was highest in green coffee beans and its activity was significantly reduced in red ripen fruits.
