EFFECT OF WATER DEFICIENCY ON THE CELLULAR STATUS AND ANTIOXIDANT DEFENCES IN ANTHYLLIS SERICEA, A SAHARIAN PLANT

Drought is known as an important restricting factor of plant productivity in arid and semi arid areas of the world. The intended increase of temperature in many areas will intensify this problem. In this study the effect of drought stress was studied in a Saharan plant, Anthyllissericea, by Poly-ethylene glycol (PEG-6000) in three different treatments (-0.2 MPa (control), -1.2 MPa (moderate stress) and -2.1 MPa (severe stress)) after 14 days. Nitric oxide (NO) content, Hydrogen peroxide (H2O2), RWC, lipid peroxidation and enzymatic antioxidant levels from the leaves were analyzed. Initially, plant growth, RWC and the water potentiel (Psi(w)) were decreased with increase of osmotic stress. Drought induces the increase of NO and hydrogen peroxide levels reaching maximum in severe stress period. MDA, proline content and soluble sugars were found to be higher under moderate and severe stress conditions. Plant employs enzymatic antioxidant system to avoid the subproduction of (ROS) resulting by drought. The analysis of CAT, APX and POD activities showed a significant increase during drought stress. Under moderate and severe stress treatments, the higher activities of H2O2, NO, CAT and POD showed a stronger system of antioxidant defences in the metabolic regulation during the applied stress. These results propose that A. sericea has the capacity to activate important adaptative mechanisms under dry conditions involving activation of enzymatic antioxidative defense system and higher osmoprotectants accumulation.