Oxidative responses and genetic stability of date palm Phoenix dactylifera L. Barhi cv. under salinity stress.

This study was aimed to investigate the oxidative responses and genetic stability of date palm Phoenix dactylifera L. under different irrigation water salinity, date palm off shoots cv. Barhi subjected to different concentrations of NaCl (100, 200, 300 and 400 µM) for 180 days. The obtained results showed that, the date palm responses to salinity stress, this responses was increased of H2O2 level, Peroxidase activity and Malondialdehyde MDA concentration with increase NaCl concentration, while opposite trend with membrane stability index, which H2O2 was increased from(0.73 µM/g) in control to (2.20 µM/g) in 400 µM treatment, MDA was increased from (2.35 nmole/g) in control to (nmole/g) in 400 µM treatment, also peroxidase activity was reached to (39.59 U/min/g) in 400 µM treatment, while was (20.73 U/min/g) in control and Membrane stability index reduction significantly from (81.36%) in control to (64.13%) in 400 µM treatment.  In terms of genetic stability of date palm under salinity stress, the ISSR markers analysis showed that, the high concentrations of NaCl (200, 300 and 400 µM) produced more polymorphic fragments comparison to control treatment, while the DNA profile was identical between control and 100 µMtreatment.Dendogram was generated using similarity indices of ISSR markers showed, the lowest genetic similarity was found between 400 µM NaCl concentration and control and 100 µM treatment, followed with both 200 and 300 µM treatments, which the control and 100 µM treatment was grouped in one cluster, also treatments with 200 and 300 µM grouped in one cluster, while the treatment with 400 µM NaCl separated in cluster. Keywords: ISSR, Genetic stability, Oxidative stress, Peroxidase, MDA, membrane peroxidatio

The Impact of Salicylic and Jasmonic Acid in Mitigating Salinity Stress on Date Palm Phoenix dactylifera L. Barhi Cv.

Date palm is one of the most important trees for economic and social development in many countries and its fruits with high nutritional value. This aimed to determine the role of salicylic (SA) and jasmonic acids (JA) as antioxidants against salt stress. Salt stress was applied with water irrigation to two-year-old date palm offshoots by using 200 mM NaCl alone or in combination with foliar sprays of JA and SA at 1, 2 and 3 mgL-1. Results indicate that salinity at 200 mM NaCl remarkably increased the content of osmolytes (e.g., proline, glycine betaine and soluble sugars) in date palm leaves. Moreover, with the combination of 2 and 3 mg.L-1 SA and 1 mg.L-1 JA with salinity, the osmolyte content was remarkably higher than in salinity treatment alone. When date palm was exposed to salinity alone, the levels of oxidative markers, Malondialdehyde as a lipid peroxidation marker and H2O2 as a ROS accumulation marker, substantially increased compared with the control. Importantly, the levels of these oxidative markers remarkably decreased when plants were subjected to combined salinity and treatment with at 2 and 3 mg.L-1 SA and 3 mg.L-1 SA compared with the salinity treatment alone. In addition, spraying 2 and 3 mg.L-1 SA and 3 mg.L-1 JA on leaves combined with salinity treatment remarkably decreased the salinity effect on membrane stability index. Moreover, when 2 or 3 mg.L-1 were sprayed, no remarkable difference was detected for any investigated characteristics, and SA had a greater effect than JA in alleviating the salinity effect