A rapid response to a plant hormone: Auxin stimulates phospholipase A2in vivo and in vitro

Abstract

Addition of the active auxins indole-3-acetic acid, 2,4-dichlorophenoxyacetic acid or α-naphthylacetic acid to cultured soybean ($\text{Glycine max}$ L.) cells prelabeled with ethanolamine or choline increased the radioactivity in the lysophosphatidylethanolamine (LPE) or lysophosphatidylcholine (LPC) pool within 5 min. The inactive auxin analogue, β-naphthylacetic acid, was inactive in this response. In membranes prelabeled $\text{in vivo}$, either with ethanolamine or choline, and subsequently isolated from zucchini ($\text{Cucurbita pepo}$ L.) hypocotyls, indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid stimulated the conversion of phosphatidylethanolamine (PE) to LPE and of phosphatidylcholine (PC) to LPC $\text{in vitro}$ whereas the inactive auxin analogue 2,3-dichlorophenoxyacetic acid did not.