CONICET | Buscador de Institutos y Recursos Humanos

Phosphatidic acid (PA) is the common lipid product in abscisic acid (ABA) and gibberellic acid (GA) response. In this work we investigated the lipid metabolism in response to both hormones. We could detect an in vivo phospholipase D activity (PLD, EC 3.1.4.4). This PLD produced [32P]PA (phosphatidic acid) rapidly (minutes) in the presence of ABA, con!rming PA involvement in signal transduction, and transiently, indicating rapid PA removal after generation. The presence of PA removal by phosphatidate phosphatase 1 and 2 isoforms (E.C. 3.1.3.4) was veri!ed in isolated aleurone membranes in vitro, the former but not the latter being speci!cally responsive to the presence of GA or ABA. The in vitro DGPP phosphatase activity was not modi!ed by short time incubation with GA or ABA while the in vitro PA kinase e that allows the production of 18:2-DGPP from 18:2-PA e is stimulated by ABA. The long term effects (24 h) of ABA or GA on lipid and fatty acid composition of aleurone layer cells were then investigated. An increase in PC and, to a lesser extent, in PE levels is the consequence of both hormone treatments. ABA, in aleurone layer cells, speci!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.32P]PA (phosphatidic acid) rapidly (minutes) in the presence of ABA, con!rming PA involvement in signal transduction, and transiently, indicating rapid PA removal after generation. The presence of PA removal by phosphatidate phosphatase 1 and 2 isoforms (E.C. 3.1.3.4) was veri!ed in isolated aleurone membranes in vitro, the former but not the latter being speci!cally responsive to the presence of GA or ABA. The in vitro DGPP phosphatase activity was not modi!ed by short time incubation with GA or ABA while the in vitro PA kinase e that allows the production of 18:2-DGPP from 18:2-PA e is stimulated by ABA. The long term effects (24 h) of ABA or GA on lipid and fatty acid composition of aleurone layer cells were then investigated. An increase in PC and, to a lesser extent, in PE levels is the consequence of both hormone treatments. ABA, in aleurone layer cells, speci!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.!rming PA involvement in signal transduction, and transiently, indicating rapid PA removal after generation. The presence of PA removal by phosphatidate phosphatase 1 and 2 isoforms (E.C. 3.1.3.4) was veri!ed in isolated aleurone membranes in vitro, the former but not the latter being speci!cally responsive to the presence of GA or ABA. The in vitro DGPP phosphatase activity was not modi!ed by short time incubation with GA or ABA while the in vitro PA kinase e that allows the production of 18:2-DGPP from 18:2-PA e is stimulated by ABA. The long term effects (24 h) of ABA or GA on lipid and fatty acid composition of aleurone layer cells were then investigated. An increase in PC and, to a lesser extent, in PE levels is the consequence of both hormone treatments. ABA, in aleurone layer cells, speci!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.!ed in isolated aleurone membranes in vitro, the former but not the latter being speci!cally responsive to the presence of GA or ABA. The in vitro DGPP phosphatase activity was not modi!ed by short time incubation with GA or ABA while the in vitro PA kinase e that allows the production of 18:2-DGPP from 18:2-PA e is stimulated by ABA. The long term effects (24 h) of ABA or GA on lipid and fatty acid composition of aleurone layer cells were then investigated. An increase in PC and, to a lesser extent, in PE levels is the consequence of both hormone treatments. ABA, in aleurone layer cells, speci!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.!cally responsive to the presence of GA or ABA. The in vitro DGPP phosphatase activity was not modi!ed by short time incubation with GA or ABA while the in vitro PA kinase e that allows the production of 18:2-DGPP from 18:2-PA e is stimulated by ABA. The long term effects (24 h) of ABA or GA on lipid and fatty acid composition of aleurone layer cells were then investigated. An increase in PC and, to a lesser extent, in PE levels is the consequence of both hormone treatments. ABA, in aleurone layer cells, speci!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.!ed by short time incubation with GA or ABA while the in vitro PA kinase e that allows the production of 18:2-DGPP from 18:2-PA e is stimulated by ABA. The long term effects (24 h) of ABA or GA on lipid and fatty acid composition of aleurone layer cells were then investigated. An increase in PC and, to a lesser extent, in PE levels is the consequence of both hormone treatments. ABA, in aleurone layer cells, speci!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.e that allows the production of 18:2-DGPP from 18:2-PA e is stimulated by ABA. The long term effects (24 h) of ABA or GA on lipid and fatty acid composition of aleurone layer cells were then investigated. An increase in PC and, to a lesser extent, in PE levels is the consequence of both hormone treatments. ABA, in aleurone layer cells, speci!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.!cally activates a PLD whose product, PA, could be the substrate of PAP1 and/or PAK activities. Neither PLD nor PAK activation can be monitored by GA treatment. The increase in PAP1 activity monitored after ABA or GA treatment might participate in the increase in PC level observed after 24 h hormone incubation.