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Copper excess triggers phospholipase D activity in wheat roots
Flavia Navari-Izzo1, Benedetta Cestone, Andrea Cavallini
1Dipartimento di Chimica e Biotecnologie Agrarie, Università di Pisa, Via del Borghetto 80, I-56124 Pisa, Italy. fnavari@agr.unipi.it
Phytochemistry
|June 13, 2006
Summary
Copper rapidly enters wheat roots, activating phospholipase D (PLD) and increasing phosphatidic acid. This copper-induced PLD activity and subsequent superoxide production are linked to G protein signaling pathways.
Area of Science:
- Plant Physiology
- Biochemistry
- Molecular Biology
Background:
- Copper (Cu2+) is an essential micronutrient for plants but can be toxic at higher concentrations.
- Phospholipase D (PLD) plays a role in plant stress responses, but its precise involvement in copper toxicity is not fully understood.
- G protein signaling pathways are implicated in various plant cellular processes, including stress perception.
Purpose of the Study:
- To investigate the early molecular and biochemical responses of wheat roots to copper (Cu2+) exposure.
- To elucidate the role of phospholipase D (PLD) activity and G protein signaling in copper-induced stress responses.
- To examine the relationship between PLD activity, G protein signaling, and reactive oxygen species (ROS) production.
Main Methods:
- Wheat seedlings (Triticum durum) were treated with 100μM Cu2+ for varying durations.
- Lipid analysis (phosphatidic acid, phosphatidylbutanol) to assess PLD activity.
- Gene expression analysis of a putative PLD gene.
- Treatment with G protein activators (mastoparan, cholera toxin) and inhibitors (suramin).
- Measurement of superoxide production via NADPH oxidase activity.
Main Results:
- Rapid uptake of Cu2+ into wheat roots was observed, leading to increased phosphatidic acid and phosphatidylbutanol within 1 minute.
- Phospholipase D (PLD) activity peaked at 2 hours, correlating with enhanced PLD gene expression.
- G protein activators mimicked copper-induced lipid changes, while G protein inhibitors blocked copper-induced superoxide production, implicating G protein signaling.
- Copper treatment induced early superoxide production, which was abolished by G protein and PLD inhibitors.
Conclusions:
- Copper exposure triggers a rapid increase in phospholipase D (PLD) activity in wheat roots, likely mediated by enhanced gene expression.
- G protein signaling pathways are involved in mediating copper-induced PLD activation and subsequent superoxide production.
- The study highlights a novel link between copper-induced PLD activity, G protein signaling, and oxidative stress in plants.