Actively growing twigs and branches of P. euphratica were sampled from selected and marked adult trees from 3 different locations in the Ein Avdat forest, according to their distance from the water stream and uphill (sites A, B and C), and thus at different degrees of salt/drought stress. This material served for in vitro propagation (cloning) for distribution to additional partners, for use in controlled salinity/drought experiments, as well as for collecting plant material for expression profiling by micro-arrays.
In addition, leaves were collected from adult trees for micro-arrays, as well as for protein, ion and other physiological analyses. Callus was first initiated from one-node stems explants, subcultured, and then adventitious buds regenerated. Plantlets were established, acclimatized ex vitro, and distributed to some of the partners to be used for growth, physiological and molecular studies. Leaves and other plant parts, from both the in vitro cloned plants and from adult trees in the different field sites, were analyzed fresh (growth and development, several physiological parameters), or frozen in liquid nitrogen, then kept at -80 or lyophilized and used for protein analysis and micro-array studies.
Thus, the protocol for micropropagation of P. euphratica plantlets is now well established, and an unlimited amount of clonal material can be supplied to interested researchers, to be used for assessing salt/droght tolerance and for additional expression profiling by micro-arrays. Likewise, leaves from adult trees in situ can be supplied at limited amounts.