PLASMALEMMA ATPASE ACTIVITY MODIFICATIONS INDUCED BY TRAUMATISMS IN BIDENS-PILOSA

It has previously been shown that cotyledonary pricks induced modifica tions of ion levels (H+ and K+) in hypocotyl cells of Bidens pilosa, T hese modifications differed according to the light quality: H+ levels increased and K+ levels decreased in white light (WL), whereas H+ leve ls decreased and K+ levels increased in blue light (BL), In this study , in order to determine the mechanism responsible for these ionic modi fications, plasma membrane vesicles have been isolated and characteriz ed from hypocotyl cells, The effects of light quality and cotyledonary pricks on plasmalemma ATPase activity (EC 3.6.1.3) were studied, Coty ledonary pricks induced, in WL, rapid (5 min) and transient (restorati on in 60 min) inhibition of plasmalemma ATPase activity, Conversely, i n BL, a rapid and transient stimulation was observed, These results su ggest that, in Bidens pilosa, plasmalemma ATPase is involved in 'short -term' ionic level modifications induced by traumatisms.