The Effect of Proline on Growth and Ionic Composition of Embryogenic Callus and Somatic Embryos of the date Palm (Phoenix dactylifera L. CV. ASHKAR) Under NACL Stress

The present work was carried out with the objective of increasing salt tolerance of date palm cv. Ashkar using tissue culture technique and exogenous application of proline. Quarters of shoot tips were cultured on MS medium supplemented with NAA at 30 mgl-1 and 2-ip at 3 mgl-1 for callus initiation and proliferation. NAA concentration was reduced to 1 mgl-1 and 2-ip to 0.1 mgl-1 for the development of somatic embryos. The results showed that increasing NaCl concentration significantly decreased the fresh weight of both the embryogenic callus and somatic embryos, and the addition of proline significantly alleviated the effect of salinity. Increased sodium concentration reduced the concentrations of both nitrogen and potassium in the embryogenic callus and somatic embryos, while the addition of proline significantly increased the concentration of both elements. Increasing the salinity of the culture media also significantly increased the concentration of Na+ and Cl-, while the addition proline reduced the accumulation of both Na+ and Cl-. It is concluded, that salinity had adverse effects on growth and ionic composition of embryogenic callus and somatic embryos of the date palm cv. Ashkar, and their effects were greatly alleviated by the addition of proline. Furthermore, the strategies used in the present work could be exploited for the selection of highly salt tolerance callus cells and their regeneration into salt-tolerant date palm plantlets.