Changes in phenylalanine ammonia lyase activity and phenolic acid content in cluster bean after infection with Macrophomina Phaseolina

The biochemical response of guar against Macrophomina phaseolina infection was investigated by estimating the change in phenolic acid content and PAL enzyme activity in four cultivars of guar. Both showed the marked increase in elicitor treated guar plants as compared to control plants. The maximum accumulation of phenolic acids in infected plants was revealed to be 23% higher than in control after 120 hours of infection in all the four cultivars. Similarly, PAL activity was also significantly increased by 37% after 96 or 120 hours of infection depending upon the cultivar in comparison to control. Phenolic acid accumulation and enhanced PAL activity in the compatible host–pathogen combination presumes that both participated actively in the guar resistance to root rot.