ABSTRACT
This investigation aimed to focus on how cobalt can avoid the damage caused by salinity stress (NaCl) on Pineapple cv. Queen in vitro. Multiplicated pineapple explants (10 – 12 mm) were subjected for eight weeks to different NaCl conc. (0, 65, 135 or 200 mM) half of them were treated firstly with 5 mg/L Cobalt sulphate. Vegetative growth parameters (no.of shoots, no. of leaves, and shoot length/explant), mineral composition (N, P, K, Na, Cl, Fe, Mn, Zn, Cu and cobalt), proline and protein content were determined. Molecular characterization using PCR based RAPD was carried out to describe the genetic differences resulted from the studied treatments, (salinity and salinity combined with cobalt sulfate). Results show that, pineapple explants growth under salt stress wasn’t prohibited completely specially below 135 mM of NaCl, but it affected negatively with the highest salt stress 200 mM of NaCl. Explants treated with cobalt before subjected to salinity scored the highest significant percentage of vegetative growth characteristics compared with those untreated. Explants treated firstly with cobalt resulted in a significantly decrease of Na+ and Cl-. Cobalt has a positive effect on Macro and Micronutrients, proline and protein content. A total of 34 DNA fragments varying from 186-1456 (bp) were amplified, of which 16 were polymorphic and seven observed as a unique markers that revealed 64.03% polymorphism.