A Survey of Wound-Induced Changes in Cucurbita Pepo Leaves

ABSTRACT

The present study investigated the changes that occur in the leaves of Cucurbita pepo (zucchini) in the result of mechanical wounding. The second leaf of 19-days old plants was pierced with a fine sterile needle. Samples were taken on 0, 30 and 60 min, 3 and 24 h, and 7 d after the treatment, of directly treated leaves (to study the local effect) and non-treated leaves situated above the treated (to study the systemic effect). The results indicated that the rates of lipid peroxidation and electrolyte leakage were increased compared with the control in both treated and untreated leaves. The content of MDA showed peak at 7d, and the leakage of electrolytes reached maximum 24 h after wounding. H₂O₂ generation in response to wounding was observed. The response was systemic and maximizes at about 30 min in both wounded and unwounded leaves. The leaves of Cucurbita react by developing a necrotic zone around the points of wounding. The diameter of the resulted lesions was maximal 7d after the treatment. The cells in the treated zone lose their chlorophyll becoming yellow. The chlorophyll content remained almost unchanged in upper unwounded leaves compared with the control for all the period.

Keywords:

• Cucurbita pepo
• leaves
• wounding