Biochemical characterisation of grain mould resistant and susceptible genotypes and PGPR-induced resistance in the host to Curvularia lunata and Fusarium proliferatum

Resistance to biotic stresses in plants is either due to the presence of preformed biochemical compounds or induced in response to external stimulus. In this study, 13 grain mould resistant and seven susceptible lines of sorghum were analysed for biochemical defence mechanism. The levels of total phenols and phenylalanine ammonia lyase were almost same in the resistant and susceptible genotypes. However, two additional isoforms of peroxidase were found in the three of the 13 resistant genotypes. The isoform peroxidase corresponding to the R _f value of 0.25 was found in the resistant genotypes IS 13969, ICSB 377 and IS 8219-1, and two genotypes IS 13969 and ICSB 377 had an additional isoform corresponding to the R _f value of 0.32. The results indicated the genotype specific association of peroxidases with grain mould resistance in sorghum. Nine bacterial strains (Bacillus pumilus SB 21, Bacillus megaterium HiB 9, Bacillus subtilis BCB 19, Pseudomonas plecoglossicida SRI 156, Brevibacterium antiquum SRI 158, B. pumilus INR 7, P. fluorescens UOM SAR 80, P. fluorescens UOM SAR 14, B. pumilus SE 34) were tested to induce systemic resistance in sorghum cultivars 296B and Bulk Y against the highly pathogenic grain mould pathogens Curvularia lunata and Fusarium proliferatum, respectively. The bacterial isolates were effective in inducing resistance in sorghum. Among the strains tested, SRI 158 was found highly effective in reducing grain mould severity in both the genotypes.