The Study of Enzymatic Activities Changes in Roots of Cantaloupe Plant Infected with Fusarium Wilt (Fusarium oxysporum f. sp. melonis)

Fusarium wilt of cantaloupe caused by Fusarium oxysporum f. sp. melonis (Fom) is an important disease in the Iran and world. To find resistance source of melon, 18 landraces, collected from different parts if Iran, were evaluated against race 1.2 of fom in greenhouse experiment in a randomized complete block design with three replication in seed and plant improvement institute The root of seedlings in 1-2 true leaves stage were in 50ml spore suspension of Fusarium oxysporum f. sp. melonis with 106 concentration for 1-2 minute and were returned to trays. Between these landraces, Shadegani as most susceptible landrace and Samsuri as susceptible landrace and Suski as semi resistant landrace and Isablle as resistant landrace were selected for biochemical studies of peroxidase, poly phenol oxidase, catalase, superoxidase and the roots phenolic compounds. Root samples were taken in zero, two, four, six and eight days after inoculation, and used for study of changes enzymes activities and the total phenolic contents. Based on the results obtained, there is a significant difference in the activity of peroxidase, polyphenol oxidase, catalase and superoxide dismutase on different days and the maximum activity was recorded in the fourth and sixth day and the highest and lowest enzyme activity were in Isablle and Shadegani, respectively. Changes phenolic compounds in fourth, sixth and eighth were significant differences each other. Before infection (0 day) the greatest amount of phenolic compounds was recorded in Shadegani (very susceptible landrace), while the spread of disease agent the highest amount obtained on the fourth day after inoculation in Isablle landrace. In this study, the activity of peroxidase, polyphenol oxidase, catalase, superoxide dismutase and phenolics content increased as five factor in the interaction melon landraces with fusarium wilt.