Electrophoretic patterns of acid soluble proteins and active isoforms of peroxidase and polyphenoloxidase typifying calli and somatic embryos of two reputed date palm cultivars in Morocco

Summary When subjected to micropropagation by tissue culture, the two reputed cultivars of date palm (Phoenix dactylifera L.); Bou-Sthammi noire, resistant to Bayoud disease and Bou-Feggous, of high fruit quality, give rise to three types of calli, called white and root-forming callus, hyperhydric and degenerating callus and friable and embryogenic callus. All explant sources, calli and germinated embryos were analysed by denaturing polyacrylamide gel electrophoresis (SDS-PAGE) for acid soluble protein composition. Phenol-oxidizing enzymes; peroxidase and polyphenoloxidase, were also, evaluated and the isoforms separated by polyacrylamide gel electrophoresis. When compared with the explant and germinated embryos, embryogenic calli of the two date palm cultivars could be identified by a concentrated polypeptide of molecular weight 27 500 and polypeptides of molecular weights 70 000 and 11 500. Hyperhydric and degenerating callus contained the polypeptide exhibiting the molecular weight 32 000. Embryogenic calli showed high levels of soluble, ionically and covalently bound peroxidases. The soluble acidic isoperoxidase of R _f 0.60, revealed in these calli and germinated embryos could be a marker of the two tissues. White and root-forming calli of Bou-Feggous cultivar were typified by soluble acidic isoperoxidases with high mobility (R _f 0.75) and anodic ionically wall-bound polyphenoloxidases similar to those of the explant sources. Polyphemoloxidase activities detected in calli and embryos were very low when compared with those of explants. Used as an early test to screen embryogenic calli of date palm, acid soluble proteins, peroxidase and polyphenoloxidase data could lead to introduce lightening and economy in the tissue culture technique.