Biochemical investigations on peroxidase contents of male and female inflorescences of date palm ( Phoenix dactylifera L.)

Abstract

Peroxidases (EC 1.11.1.7) were extracted from male and female inflorescences of date palm ( Phoenix dactylifera L.). Enzyme extraction by a progressive solubility method gave rise to soluble peroxidases (S) and ionically wall-bound peroxidases (I). When expressed in units g −1 fresh weight, peroxidase was present in inflorescence rachillae essentially as soluble fraction, where it represents 94% and 89% of the total activity (S + I) in male and female rachillae, respectively. In flowers, a tendency to increase of peroxidases I was observed, where this fraction, represents 51% and 78% of the total activity in female and male flowers, respectively. Low peroxidase activity was found in male flowers. When subjected to polyacrylamide gel electrophoresis, both S and I enzyme fractions exhibited each one, two forms based on their electric charges that occurred in basic and acidic gel media. Acidic peroxidase forms, resolved on basic gels, are more represented than basic forms, well separated on acidic gels. Acidic soluble peroxidases showed two migration zones on 6–15% gradient polyacrylamide gels. Acidic bound peroxidases are characterized by fast isoforms. Basic peroxidases, separated on 11% polyacrylamide gels and represented in fractions I, exhibited two major isoforms within three to five bands. Differences between female and male inflorescences are more marked on the basis of acidic peroxidases. Female inflorescences showed two major acidic isoperoxidases in rachillae with R f 0.32 and 0.35 in enzyme fractions S and I, while male material showed one major band of R f 0.35. Evaluation of peroxidases as sex markers in young date palm not yet at their reproductive stage is discussed in this study.