Molecular characterization of native pink pigmented facultative methylotrophs of chilli and their induced systemic resistance mechanism in management of anthracnose

Abstract

Aim: This study aimed to assess the plant growth promotional ability and biocontrol efficiency of native pink pigmented facultative methylotrophs (PPFMs) of chilli for management of chilli anthracnose disease through induced systemic resistance mechanism under pot culture experiments. Methodology: The selected native PPFMs were identified by analysis of 16S rRNA gene sequence. These isolates along with reference strain (Methylobacterium extorquens AM1) were inoculated to healthy chilli plants. The pathogen (Colletotrichum capsici) was later inoculated to these chilli plants, and induced systemic resistance (ISR) molecules were estimated at different intervals from one day after challenge inoculation of pathogen (DAI) upto 7 DAI. Influence of PPFM on plant growth parameters, yield, capsaicin content and PPFMs population load on phyllosphere and rhizosphere was studied. Results: The results of 16S rRNA gene sequence analysis revealed selected isolates as Methylobacterium populi (PPFM6) and Methylobacterium radiotolerans (PPFM170). The ISR molecules tested were significantly influenced by PPFM isolates. The peroxidase and phenyl alanine ammonia lyase (PALase) activity increased from 1 DAI to 7 DAI whereas chitinase, polyphenol oxidase (PPO) and phenol contents increased upto 5 DAI, after which gradual decrease was noticed. Inoculation of PPFMs to chilli crop significantly improved plant height, dry matter and chlorophyll content. Significantly lesser disease incidence, more yield and more capsaicin content was observed with application of M. populi as compared to control. Interpretation: The present study highlights native M. populi (PPFM6) of chilli as an effective plant growth promoter, exhibiting significant biocontrol efficiency against C. capsici.