Abscisic acid signal transduction in the barley aleurone is mediated by phospholipase D activity
AUTOR(ES)
Ritchie, Sian
FONTE
The National Academy of Sciences
RESUMO
The plant hormones abscisic acid (ABA) and gibberellic acid (GA) are important regulators of the dormancy and germination of seeds. In cereals, GA enhances the synthesis and secretion of enzymes (principally α-amylases) in the aleurone cells of the endosperm, which then mobilize the storage reserves that fuel germination. ABA inhibits this enhanced secretory activity and delays germination. Despite the central role of ABA in regulating germination, the signal transduction events leading to altered gene expression and cellular activity are essentially unknown. We report that the application of ABA to aleurone protoplasts increased the activity of the enzyme phospholipase D (PLD) 10 min after treatment. The product of PLD activity, phosphatidic acid (PPA), also increased transiently at this time. The application of PPA to aleurone protoplasts led to an ABA-like inhibition of α-amylase production, and induction of the ABA up-regulated proteins ASI (amylase subtilisin inhibitor) and RAB (responsive to ABA). Inhibition of PLD activity by 0.1% 1-butanol during the initial 20 min of ABA treatment resulted in inhibition of ABA-regulated processes. This inhibition coincided with the timing of PLD activation by ABA and was overcome by simultaneous addition of PPA. These results suggest that ABA activates the enzyme PLD to produce PPA that is involved in triggering the subsequent ABA responses of the aleurone cell.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=19466Documentos Relacionados
- Abscisic acid signal transduction in guard cells is mediated by phospholipase D activity
- Abscisic Acid Stimulation of Phospholipase D in the Barley Aleurone Is G-Protein-Mediated and Localized to the Plasma Membrane1
- Signal Transduction in Barley Aleurone Protoplasts Is Calcium Dependent and Independent.
- Abscisic Acid Structure-Activity Relationships in Barley Aleurone Layers and Protoplasts (Biological Activity of Optically Active, Oxygenated Abscisic Acid Analogs).
- Abscisic Acid Localization and Metabolism in Barley Aleurone Layers