Changes in the Activity of Enzymes Phenylalanine Ammonia-Lyase, Polyphenol Oxidase, and Peroxidase in Some Wheat Genotypes against Take-All Disease

Enzymes play a crucial role in plant-pathogen interactions and are very important to manage plant diseases. Take-all is a disease (Gaeumannomyces graminis var. tritici) affecting the crowns and roots in wheat. So far, the resistance mechanism of this disease has not been identified; therefore, this research was performed to identify the components of resistance to this disease in a number of wheat genotypes. In this study, ۸ bread wheat genotypes were cultured, and the changes in “peroxidase, Polyphenol Oxidase (PPO), Phenylalanine Ammonia-Lyase (PAL), and total protein” was assessed in ۰, ۴, ۷, ۹, and ۱۲ days after inoculation. The results showed that different genotypes of wheat had different pathogenicity reactions to the take-all disease. Based on the average disease intensity, the genotypes were divided into three groups: resistant, moderately resistant, and susceptible. The results indicated that the level of polyphenol oxidase and phenylalanine ammonia-lyase, and the total protein increased in the resistant and moderately resistant groups. Cluster analysis by K-means was performed to produce three clusters. Polyphenol oxidase activity, phenylalanine ammonia-lyase activity, and total protein content in the second (resistant) and third (moderately resistant) clusters were higher than the first cluster (susceptible). Multivariate analysis indicated that peroxidase enzyme might indirectly influence the resistance. The results have clarified the role of polyphenol oxidase enzymes and total protein in enhancing resistance to take-all disease.