1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activating factor) stimulates plant H+ transport in vitro and growth.

1-Alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activating factor = PAF), a lipid with hormone-like properties in mammals, strongly stimulated ATP-dependent H+ transport in microsomes from zucchini hypocotyls. Stimulation of the maximal delta pH was 50-80% under optimal conditions at about 8 microM and growth was stimulated to about 20% at 2-4 microM 1-alkyl-2 acetyl-sn-glycero-3-phosphocholine. The effect on in vitro H+ transport was strongly dependent on the presence of phosphate. Chloride and nitrate were ineffective. Low concentrations of calcium interfered with the effect of 1-alkyl-2-acetyl-sn-glycero-3-phosphocholine on in vitro H+ transport.