Plant growth promoting rhizobacteria- Bacillus amyloliquefaciens improves plant growth and induces resistance in chilli against anthracnose disease

The present study was aimed to screen plant growth promoting rhizobacteria (PGPR) for their effect on induction of resistance in chilli (Capsicum annum L.) against anthracnose disease. A total of 59 PGPR were evaluated for their antagonistic activity against Colletotrichum truncatum and only fourteen PGPR were able to inhibit the mycelial growth of the pathogen. The pathogenicity and root colonization of the selected PGPR showed that out of fourteen isolates only eight isolates of Achromobacter, Bacillus, Burkholderia, Enterobacter, Ochrobactrum and Providencia genera were able to be both non-pathogenic and possessed the ability to colonize the host plant. Among the PGPR isolates, seed treatment with Bacillus amyloliquefaciens resulted in maximum enhancement of seed germination (84.75%), seedling vigor (1423.8) along with an increase in vegetative growth parameters. Significant disease protection of 71% against anthracnose disease was observed in plants pretreated with B. amyloliquefaciens followed by B. cepacia and P. rettgeri, under greenhouse conditions. The induced resistance obtained upon PGPR treatment was in line with higher activity of defense enzymes [phenylalanine ammonia lyase (PAL), peroxidase (POX), polyphenol oxidase (PPO) and β-1,3-glucanase]. It was observed that, almost one to two-fold increase in enzyme activities was observed in PGPR treated challenge inoculated seedlings compared to control inoculated seedlings. The results evidenced that the PGPR- B. amyloliquefaciens possesses immense potential to increase the plant growth apart from suppressing anthracnose disease in chilli.