Growth Dynamics and Disease Resistance of Cluster Beans Were Associated with Antioxidant Enzymes Feedback Against Soil Rhizospheric Pathogens

Cluster beans (Cyamopsis tetragonoloba L.) are economically valuable vegetables, but their growth is severely affected by (root rot and wilt) rhizosphere pathogens. Rhizospheric soil samples were collected for the first time to study soil-borne pathogens (Macrophomina phaseolina, Rhizoctonia solani, and Fusarium solani) associated with cluster beans. A growth experiment was performed to isolate and colonize these pathogens, and antioxidant enzyme activities were measured at 2, 5, 10, and 15 days after infection (DAI). R. solani, M. phaseolina, and F. solani have reduced plant growth, but root development was more deteriorated than the shoot. Root colonization by R. solani, M. phaseolina, and F. solani significantly increased over time. Protein levels, polyphenoloxidase, and phenylalanine ammonia lyase activities were enhanced in infected plants at 10 and 15 DAI compared to those in non-infected controls. Catalase, ascorbate peroxidase, and guaiacol peroxidase activities were higher at 10 and 15 DAI in diseased plants than in the controls. Root colonization by R. solani, M. phaseolina, and F. solani increased enzyme activity. Pathogens residing in the soil rhizosphere are critical for reducing cluster bean growth, and increased activation of antioxidant enzyme activities can enhance disease resistance and crop fitness, thereby promoting long-term plant survival. .