No abstract

Two types of crude extracts were obtained from 10 cultivars of date palm (Phoenix dactylifera L.); the Tris buffer extracts from acetone powder were assayed for peroxidase activity and the phosphate buffer extracts were subjected to polyacrylamide gel electrophoresis. The gels were stained for esterase activity using α-naphthylacetate and α-naphthylbutyrate as substrates. The cultivars were divided into four sets on the basis of their esterase isoenzyme phenotypes. These sets were further separated into their individual cultivars on the basis of peroxidase activities. The results are discussed with respect to the possible relationship of the peroxidase activity in the vascular fusariosis of date palm (Bayoud disease). This study has potential for practical application; however, some additional refinements in procedures appear necessary to reduce extraction time.

The date palm, Phoenix dactylifera, is a palm extensively cultivated for its edible fruit. The chemical composition and the water content of ten Tunisian date varieties were determined. For all analysis, the Deglet Nour variety was taken as reference. Compositional analysis showed that the littoral varieties were very rich in reducing sugars (26 to 51%) than Deglet Nour which was rich in sucrose (54%). The relative results of the moisture content showed that the littoral varieties were classified as soft dates. The vitamin C analysis showed that the littoral varieties were very rich in this compound (24 to 46 mg/100 g) than Deglet Nour (1.12 mg/100 g). The mineral analysis showed that the littoral dates were relatively rich in potassium (283 to 733 mg/100 g) and presented a weak content in sodium (0.06 to 0.09 mg/100 g).

Seedlings of date palm (Phoenix dactylifera L .), obtained from seven cultivars crossed with two males, were analyzed by polyacrylamide gel electrophoresis for esterase (EST), glutamate oxaloacetate transaminase (GOT), endopeptidase (ENP) and alcohol dehydrogenase (ADH) polymorphisms . Eleven, eight, five and two phenotypes were revealed for the enzymes tested, respectively . Seedlings of F, populations derived from Bayoud (Fusarium)-resistant and low fruit quality cultivars were characterized by . a high electrophoretic polymorphism, when compared with progenies of Bayoud-susceptible and high fruit quality cultivars . In almost all cases, the most frequent electrophoretic phenotypes scored for each enzyme in different F, populations, were similar to those of the corresponding parent cultivars . Heterozygous phenotypes have been found for, at least, 3 loci ; Got-2, Est-1 and Enp, indicating that such loci could be used to screen for hybrid seedlings . The expected Mendelian segregation of allozymes has been observed for these 3 loci, in many F, populations . It seems that progenies of Bayoud-resistant cultivars are characterized by a high level of electrophoretic polymorphism . The estimation of this index and the search for genetic linkage with segregating allozymes, may be biochemical criteria useful as an aid in distinguishing date palm seedling populations derived from Bayoud-resistant cultivars and suitable for breeding programs .

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 1 1 500. 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 Rf 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 (Rf 0 .75) and anodic ionically wall-bound polyphenoloxidases similar to those of the explant sources . Polyphenoloxidase 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 .