Hybrid Event
September 01-03, 2022 | Paris, France

Wahbi Djebali

Speaker for GPMB 2021 - Wahbi Djebali
Wahbi Djebali
University of Carthage, Tunisia
Title : NO induced chromium tolerance in maize (Zea mays L.) seedlings through regulating oxido-nitrosative events and metabolic homeostasis


Effects of exogenous NO application on chromium (Cr) induced oxido-nitrosative stress were investigated on 9-day-old maize seedlings. Enhancement of SOD and NADPH oxidase activities indicated that Cr (200 µM) induced oxidative stress. In both radicles and epicotyls, NADPH oxidase up-regulation leads to oxidative damage which is attested by application of diphenylene iodonium (DPI; NADPH oxidase inhibitor). Application of 500 µM of sodium nitroprusside (SNP, NO donor) suppressed Cr elicited stress symptoms on embryonic axis growth and suppressed NADPH oxidase activity. SNP attenuated the accumulation of hydrogen peroxide, methylglyoxal and proline in Cr-stressed seedlings. Chromium increased thiol and S-nitrosothiol levels but this was restored to control levels by SNP, in spite of a competing NO reaction leading to increase of S-nitrosoglutathione content. Simultaneously, Cr+SNP increased S-nitrosoglutathione contents probably to prevent excess NO deleteriously affecting cellular function. Endogenous NO over-production induced by Cr was declined by addition of arginine analogue N(ω)-nitro-arginine methyl ester (L-NAME) in the germinating medium.  L-NAME did not alleviate the negative effects of Cr on maize seedlings due to cellular NO deficiency. In addition, Cr+L-NAME significantly decreased the contents of arginine, spermidine and spermine in epicotyls as compared to Cr treatment alone. Similarly, exposure to Cr+SNP decreased spermidine and spermine levels in both radicles and epicotyls. This study helped to suggest a mechanism of NO-induced Cr tolerance through regulating oxido-nitrosative activities.


Wahbi Djebali studied Plant Biology at the University of Tunis El-Manar, and graduated as MS in 2000. He then joined the research group of “Physiological and Biochemical Reponses of Plants to Abiotic Constraints” at the Faculty of Sciences of Tunis, University of Tunis El-Manar, Tunisia. He received PhD degree in 2005 at the same University and HdR-Biology in 2014 at the University of Carthage, Tunisia. He obtained the position of Associate Professor at the Faculty of Sciences of Bizerte and he has published more than 30 research articles in SCI(E) journals.