الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 247 |  |  |
| | | from | 247 | | |
Abstract
Drought stress by withholding water adversely affect wheat growth and physiological performance in both cultivars Masr-2 and Sakha-94. Based on stress tolerance test and analysis of the growth and the physiological parameters we can consider Masr-2 more tolerant to drought stress than Sakha-94.Applying exogenous PAs ameliorated the drought stress adversities and enhanced plant growth, physiological performances and yield parameters of wheat plants under drought stress. Foliar spraying method was more effective and superior on the seed-priming in both cultivars in enhancing various parameters.Sakha-94 cv. was more responsive to PAs application, so, we used it in further analysis to uncover the mechanism of mitigating drought stress in wheat by PAs. The advanced analysis included: quantification of the endogenous PAs by HPLC, quantification of gene expression by real time PCR and analysing mesophyll cells ultrastructure by TEM.
PAs improved cell water status, accumulated osmoprotectants, endogenous PAs and up-regulated PAs biosynthesis genes and DHS that involved in posttranslational modification of eIF5A the translation initiation factor.
SPDS up-regulated by drought although the endogenous Spd content decreased. This suggests an incidence of translational or posttranslational regulation of SPDS.PAs treatment with Mix either by seed-priming or foliar spraying was able to eliminate the drought-induced damage to chloroplasts. This could be possibly by the ability of PAs to bind to negatively charged ROS which destabilize membranes.