FLOWER-INDUCING ACTIVITY OF LYSINE IN LEMNA-PAUCICOSTATA-6746

Flowering of Lemna paucicostata 6746, a typical short-day plant, was i nduced by culture for 96 or 120 h in nitrogen-free medium under contin uous illumination. To examine the effects of lysine, we homogenized en tire plants of L. paucicostata 151 in a solution of lysine and the sup ernatant obtained after centrifugation of the homogenate was added to the medium to give various concentrations of lysine in the medium. Flo wering of strain 6746 in nitrogen-free or nitrogen-deficient culture m edium was effectively promoted by the addition of a lysine-containing supernatant to the medium. The suppressive effect of elastatinal, a pr otease inhibitor, on the induction of flowering was almost completely reversed by the simultaneous application of a lysine-containing supern atant to the medium. During nitrogen-free culture, the level of endoge nous free lysine, expressed on the basis of the amount of total free a mino acids, increased. Lysine-containing supernatants also induced flo wering of plants in nitrogen-rich medium under continuous illumination . These findings suggest that endogenons lysine is involved in the ind uction of flowering in L. paucicostata 6746 on nitrogen-free or nitrog en-deficient medium, as it is in the induction of flowering in L. pauc icostata 151.