Lysine Reverses the Inhibition of Flowering by Elastatinal, a Protease Inhibitor, inLemna paucicostata151

摘要

The flowering ofLemna paucicostata151 that is normally induced by nitrogen-free culture was suppressed by the application of either of two protease inhibitors, namely, elastatinal and bestatin, to the medium. These protease inhibitors prevented the flower-inductive process(es) rather than the development of flower buds, suppressing of the degradation of some proteins. The amount of free lysine in plants increased during nitrogen-free culture and lysine had a flower-inducing effect on the plant. However, levels of endogenous lysine did not increase when elastatinal was present in the medium. The suppressive effect of elastatinal on flower induction was almost completely reversed by simultaneous application of lysine to the medium while the suppressive effect of bestatin was only partially reversed by lysine. These results suggest that induction of flowering by nitrogen deficiency is due to endogenous free lysine and that elastatinal suppresses the proteolytic processes by which free lysine is generated from protein(s) during nitrogen-free culture.