In vitro selection of abiotic stress tolerant date palm (Phoenix dactylifera L.): A review

The advent of agricultural biotechnology offers new approaches for the genetic improvement of date palm (Phoenix dactylifera L.), an important economic fruit crop in arid regions. In vitro studies were conducted to recover date palm plants exhibiting enhanced tolerance to salinity and drought stress, two major agricultural problems in arid areas. The response of date palm callus cultures to salt stress was investigated by exposing cell suspension and callus cultures to varying concentrations of sodium chloride (NaCl). The reaction of callus to the duration of exposure to NaCl, potassium chloride (KCl) and calcium chloride (CaCl2) was evaluated. Similarly, drought tolerance was assessed in response to varying concentrations of polyethylene glycol (PEG-8000). Significant differences were reported in various parameters measured including callus growth, somatic embryogenesis, proline content and ion distribution. Calli with enhanced tolerance to these selection agents were obtained; however, plant regeneration from these cell lines was not realized. Although the available data provide an insight of the behavior of date palm callus in the presence of salt and drought stress, further research work is required to refine the selection procedures and plant regeneration from the selected tolerant cell lines.