Endophytic Streptomyces spp. underscore induction of defense regulatory genes and confers resistance against Sclerotium rolfsii in chickpea

• Endophytic Streptomyces spp. triggered systemic resistance in chickpea under S. rolfsii stress.
• Streptomyces spp. primed plants also mitigate oxidative stress generated by S. rolfsii.
• PAL, PPO, and total phenolics accumulation was increased in S. griseus treatment.
• SOD, PO, APX and GPX was enhanced by priming with S. griseus.
• S. griseus induced gene expression of SOD, PO, PAL, APX, CAT, CHI and GLU in chickpea.

This study evaluated the potential of endophytic Streptomyces spp. viz., S. diastaticus, S. fradiae, S. olivochromogenes, S. collinus, S. ossamyceticus, and S. griseus to trigger systemic resistance and mitigate oxidative stress in chickpea against Sclerotium rolfsii. The role of endophytes stimulating systemic resistance was evaluated by seed treatments in pathogen inoculated chickpea. Substantial increase in defense related enzymes such as phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO), along with the accumulation of total phenolics and flavonoids in S. griseus was noticed in plants inoculated with S. rolfsii. Similarly, a significant increase of superoxide dismutase (SOD), peroxidase (PO), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) was observed in the same treatment which favors least lipid peroxidation in chickpea under pathogenic stress. In addition, under scanning electron microscope S. griseus primed plants showed undamaged tissue in the collar region. Furthermore, real-time polymerase chain reaction analysis of genes encoding SOD, PO, PAL, APX, catalase, chitinase and β-glucanase showed significant fold change which corroborated well with the above findings. These results indicate that the chickpea defense pathway is triggered after perception of endophytes to synthesize various enzymes, which led to an induced resistance against S. rolfsii.