Marouane Ben Massoud

Title : Effect of exogenous treatment with nitric oxide (NO) on redox homeostasis in barley seedlings (Hordeum vulgare L.) under copper stress

Abstract:

The present research investigates the protective mechanism of nitric oxide (NO) in regulating tolerance to Cu-induced toxicity in shoots of barley (Hordeum vulgare L.). After 10 days, treatment with 200 µM CuCl₂ caused a significant reduction in growth and photosynthetic efficiency concomitant with a strong increase in the contents of reactive oxygen species (ROS), antioxidant enzymes activities such as catalase (CAT), superoxide dismutase (SOD), guaiacol peroxidase (GPOX) and glutathione peroxidase (GPX). An increase in the lipid peroxidation markers malondialdehyde (MDA) and lipoxygenase activity (LOX) indicated oxidative stress. Furthermore, inhibition of growth in 200 μM Cu-treated plants was associated with a reduction in carotenoids, chlorophyll and maximum photosystem II efficiency. However, copper treatment provoked a strong increase in activity of the glutathione-ascorbate cycle enzymes ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), monodehydroascorbate reductase (MDAR) and glutathione reductase (GR), but a decrease in levels of the non-enzymatic antioxidant compounds glutathione (GSH), ascorbate (AsA). The addition of 500 µM of the nitric oxide (NO) donor, sodium nitroprusside (SNP), to the growth medium alleviated Cu toxicity by reducing Cu uptake and enhancing antioxidant capacity, as indicated by increased contents of GSH and AsA. The current results show that NO addition can alleviate Cu toxicity by affecting the antioxidant defense system, photosynthetic system and maintaining the glutathione-ascorbate cycle status, suggesting that NO treatment protects proteins against oxidation by regulating the cellular redox homeostasis.

Audience Take Away:

• The present investigation was performed in order to better understand the NO-induced modulation of Cu toxicity, with special focus on the involvement of the AsA-GSH cycle.
• Test the role of nitric oxide (NO) in plant–heavy metal interactions.
• In summary, we show that NO restores the cellular redox homeostasis, photosynthesis, and antioxidant defense systems by reducing Cu-induced toxicity in the shoots of barley seedlings.
   

Biography:

Dr. Marouane Ben Massoud studied Biology at the University of Carthage, Tunisia and the University College Cork, Ireland. He currently works at the School of Biological, Earth and Environmental Sciences, University College Cork. Marouane does research in Cell Biology, Plant Physiology, Molecular Biology and Proteomics. Their current project is 'Alleviation of heavy metals toxicity in germinating seeds by exogenous chemical effectors'.