Biochemical changes induced in the maize leaf sheath upon inoculation with Rhizoctonia solani incitant of banded leaf and sheath blight

Banded leaf and sheath blight (BLSB) of maize is an emerging disease in the northwest region of India. The present study investigates the potential role of defense-related enzymes in imparting resistance against Rhizoctonia solani in seven inbreds, viz., LMDR-2, CM-143, CM-600, LM-11, LM-12, LM-13 and LM-14, and four maize hybrids, viz., PMH1, PMH2, PMH4 and JH3459. The enzyme activities were determined from the leaf sheaths collected at 0, 24, 48, 72, 96, 120 and 144 h post-inoculation. The results indicated a spike in the expression of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO), peroxidase (POX) and catalase (CAT) at 72 h post-inoculation following pathogen challenge in different maize inbreds/hybrids. The moderately resistant group (LMDR-2 and JH3459) showed significantly higher activities than the susceptible group (LM-11, LM-12, CM-600, PMH4 and PMH2). A strong positive correlation was observed between different enzymes at 72 and 96 h after inoculation. Lesion length showed negative correlation with the activities of enzymes studied. Our results indicated that PAL, PPO, POX and CAT played key roles in providing BLSB resistance in maize inbreds/hybrids.