EFFECT OF PHENOLICS ON MODIFICATION OF SEX EXPRESSION AND MODULATION OF LEAF PEROXIDASE IN PAPAYA (CARICA PAPAYA L.)

A study was conducted to find out the effect of phenolics on quantitative and qualitative changes on leaf peroxidase (EC.1.11.1.7) with respect to sex expression in Pant Papaya-1, a dioecious variety of papaya. All the test phenolics were found to stimulate female sex expression in papaya. The phenolic compounds not only modified the modulation of leaf peroxidase activity but also affected quantitatively at a specific period of plant growth. Generally, female plants were richer in peroxidase levels than that in male and remained unaffected. Electrophoretic analysis for leaf peroxidases of male and female plants revealed the expression of certain isomorphs de novo (isoperoxidase IP₁, Rm 0.08-09) while certain isomorphs (IP₆, Rm 0.23-0.24) could not be expressed at all during the ontogeny of different growth periods. They were found specific to the growth phases. Exogenous application of phenolics induced some marked changes in the pattern of isoperoxidases de novo in both sexes during the ontogeny of plant growth. Such variations revealed not only early expression (IP₁) or delayed expression (IP₂, Rm 0.10-0.11) but also their specific activity either increased or decreased. The isomorphs of peroxidase viz., IP₄, IP₆, IP₁₁ and IP₁₃ were found expressed de novo while some of the existing isomorphs such as IP₁₅ (0.48-0.49) were found vanished when compared to those in control plants. Though, the isoperoxidase pattern could not show any correlation with the type of sex, the flowering stage could be signified with the appearance of altogether a new isoperoxidase, IP₂ may serve as a biochemical marker to diagnose flowering stage.