EFFECT OF SALT STRESS AND PROLINE ON CHEMICAL CONTENT OF EMBRYOGENIC CALLUS AND SOMATIC EMBRYOS OF DATE PALM (PHOENIX DACTYLIFERA L. 'ASHKAR')

The objective of the current study is to find out the effect of salt stress as sodium chloride and proline in the culture media on total soluble carbohydrates, proteins, and proline content of embryogenic callus and somatic embryos of date palm ‘Ashkar’. Quarters of shoot tips were cultured on MS medium supplemented with NAA (30 mg/L) and 2-ip (3 mg/L) for callus initiation and multiplication. NAA was reduced to 1 mg/L and 2-ip to 0.1 mg/L for the development of somatic embryos. Sodium chloride was added at 0, 0.5, 1, 1.5 and 2% and proline at 0, 25, 50, 75 and 100 mg/L to the media of well developed callus and somatic embryos and the interaction between the two factors was also evaluated. Results showed that an increase of sodium chloride concentration in the medium led to a decrease of total soluble carbohydrates and proteins content of embryogenic callus and somatic embryos, however it increased free proline. When proline was added to the culture media, it increased carbohydrates, proteins, and free proline in both embryogenic callus and somatic embryos. The interaction between sodium chloride and proline in the culture media had a positive significant effect on all studied chemical contents of embryogenic callus and somatic embryos. It was concluded that salt stress caused a negative impact on date palm callus and somatic embryos and those effects could be decreased by the addition of proline which significantly improves carbohydrates and proteins content. This might also help in the selection of high salt resistant callus cells and regeneration of date palm plantlets growing well under high salt stress condition.