Enhanced Tolerance to Water Deficit By Overexpressing of The Enzyme Superoxide Dismutase (Sod) in Some Algerian Populations of Peanut (Arachis Hypogaea L.)

Abstract

Water stress is known to induce active oxygen species in plants. The accumulation of these harmful species must be prevented by plants as rapidly as possible to maintain growth and productivity. This study was carried out for understanding of antioxidant mechanisms of peanut under water stress conditions. For this aim, after six weeks of growth (47 DAS), four peanut (Arachis hypogaea L.) landraces: EL FRIN (FR), TONGA (TO), OUED SOUF (OS) and SEBSEB (SEB) were subjected to drought stress for 25 days. Plants were submitted to water stress by withholding water supply and the attention was given to the expression analysis of the superoxide dismutase (SOD) gene, in view of its central role for antioxidant defence in all aerobic organisms and of its involvement in antioxidant responses to water shortage. PCR conditions for SOD antioxidant enzyme were optimized. Then, total RNA was isolated from stressed and non-stressed plant shoots. The gene expression levels SOD were examined by semiquantitative reverse transcription polymerase chain reaction (RT-PCR) technique. Results show how water stress regulates the synthesis and the activity of superoxide dismutase and how these enzymes contribute to protect against the damageable effects of superoxide radicals in peanut. Relative expression levels of SOD increased after 25 days of drough treatment in shoots of Tonga (TO) landrace. On the other hand, expression levels of SOD decreased on SEBSEB (SEB) landrace after 25 days of water stress in shoot tissues. Although in the presence of an equal sample loading, still the results reveal ample “constitutive” differences in SOD gene expression among the four peanut landraces. Indeed, SOD transcripts appeared to be most abundant in TO and least abundant in SEB. Further work will reveal whether contrasting SOD expression maybe associated to varying responsiveness to water stress in the peanut landraces at study.