Caffeine hazards and their prevention in germinating seeds of coffee (Coffea arabica L.).

The inhibition of growth of seedlings of coffee (Coffea arabica L.) exposed to 10 m M caffeine was found to occur in the rootlet: mitosis and cell plate formation were also inhibited. Since concentrations of endogenous caffeine in the imbibed seed are 40-60 mM, 4-6 times as high as in the seedlings, we conclude that coffee embryos have specific means of avoiding caffeine autotoxicity. Observations indicate that cell divisions in root tips start only after the latter are pushed away from the caffeine-rich endosperm by elongation of the hypocotyl and maintained through cell elongation. Caffeine is introduced into the embryonic cotyledons mostly after cell division is completed there. Thus, coffee seedlings may avoid autotoxic effects of endogenous caffeine by separation between sites where mitosis is occurring and those where caffeine is stored. This is achieved in root tips by separation is space but in the cotyledons by separation in time. Caffeine is liberated from the tree litter in coffee plantations and eventually will produce autotoxic effects, resulting in some degeneration.