Induction of Peroxidase and Polyphenol Oxidase Enzymes Production in Pumpkins, Cucurbita pepo L. to Enhance Resistance to Zucchini yellow mosaic virus Infection

Abstract

Results obtained in this study identified the occurrence of Zucchini yellow mosaic virus (ZYMV) on pumpkins, Cucurbita pepo plants collected from the Al-Abbasi district, Kirkuk governorate, and Al-Alam district, Salah al-Din governorate. Diagnosis was based on symptoms produced and serological tests (ELISA). Disease symptoms observed were mosaic and deformity of leaves in addition to reduced plant growth. The Shiitake mushroom (Lentinus edodes) was superior in reducing virus infection by stimulating virus resistance and increasing the production of the peroxidase and polyphenol oxidase enzymes, and consequently increased yield. The shiitake mushroom (100% treatment) gave the lowest virus disease incidence and disease index of 61.83 and 19.32%, respectively. The 50% shiitake treatment gave the highest specific activity for the peroxidase enzyme, amounting to 0.017 units/mg protein, whereas the Isabion bio-stimulant treatment, which included a mixture of amino acids, gave the highest specific activity for the polyphenol oxidase enzyme, amounting to 0.036 units/mg protein. The results obtained also showed that the treatment with the biostimulant Isabion gave the highest yield of 5.355 kg/plant.

Keywords:

Pumpkin, Zucchini yellow mosaic virus, ZYMV, peroxidase, polyphenol oxidase.