Biochemical Studies of Alternaria blight of cluster bean

There was significant increase in peroxidase (PO), polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) activities in diseased leaves of all three varieties-RGC-936 (susceptible), RGC-1003 (moderately resistant) and RGC-986 (resistant) of clusterbean. Significant decrease in catalase activity was observed in diseased leaves than healthy ones and this decrease was more pronounced in susceptible variety RGC-936.The pathogen related enzymes polygalacturonase trans-eliminase (PGTE), pectin trans-eliminase (PME), polygalacturonase (PG) and cellulolytic (Cx) enzymes activities were found lower at initial stages of observations.The soluble protein content in healthy leaves of RGC-986 was highest followed by RGC-1003 while, it was lowest in RGC-936. It was significantly decreased in diseased leaves of all three varieties. Maximum decrease in soluble protein “due to infection” was observed in RGC-936 followed by RGC- 986 and RGC-1003.Total phenolic contents were higher in healthy leaves of RGC-986 followed by RGC-1003 and RGC-936.