Activities of peroxidase (soluble and cell wall bound) and of other H2O2 scavenging enzymes are markers of the flower bud development stage in lemon

Abstract

Listen

Translate article

Specific activities of H 2 O 2 scavenging enzymes, soluble peroxidase (G-POD), catalase (CAT) and ascorbate peroxidase (APX), and cell wall bound (CWB) G-POD, have been characterized in flower buds and leaves in potted lemon trees ( Citrus limon L. Burm.) growing in a glasshouse in Tunisia. In leaves during the winter rest period (from September to December), enzyme activities did not change markedly. Then, leaf G-POD (soluble and CWB activity) increased 4-5 fold in January as the buds reached dormancy release. In growing buds, the activities of the three enzymes increased strongly (10-100-fold) between dormancy and full bloom and decreased slightly (3-fold) post-bloom (beginning of fruit-set). Along the shoots, the developmental stages of flower buds advanced from node 1 to node 5. G-POD activity increased from the shoot apex toward the base of the twig in both leaves and buds. A similar trend was observed for APX and CAT but their activities tended to decrease slightly far from the apex. Retardation of flowering by application of growth regulators strongly reduced leaf-specific activities of the H 2 O 2 scavenging enzymes. Therefore, G-POD activity (APX and to a lesser extent CAT) appears to be a good marker of flower formation in lemon (from bud swelling to full bloom). The results also suggest a link between H 2 O 2 production and flower bud development.