Study of Changes in Peroxidase and Polyphenol Oxidase Activities in Root Knot Nematode (Meloidogyne javanica) Infected Cucumber when Treated with DL-β-Amino-n-Butyric Acid

The chemical compound DL-β-Amino-n-Butyric Acid (BABA) has been introduced as a promoter of induction of resistance in plants against plant pathogens. In this study, promotion of induction of some such defense compounds as peroxidase and polyphenol oxidase enzymes through DL-β-amino-n-butyric acid application against root knot nematode (Meloidogyne javanica) was investigated in cucumber. Results indicated that inoculation of cucumber by the nematode infected the plant's roots through BABA, stimulated peroxidase activity in root tissues one day after inoculation, enzyme activity reaching its maximum level in four days past nematode inoculation. Induction of polyphenol oxidase activity also showed significant difference in BABA treated plants in comparison control and with healthy plant's reaching its maximum level in four day after nematode inoculation. Native PAGE (Polyacrylamide Gel Electrophoresis) analysis indicated that the peroxidase isozymes in cucumber roots induced by BABA were different from those in roots infected with nematode. In BABA plus nematode inoculated plants, two isozymes (Rf= 0.31 and Rf= 0.34) were induced which were more condense in comparison with control (only inoculated with nematode).