Analysis of phytohormones and phosphate solubilization in Photorhabdus spp.

Bacteria of the genus Photorhabdus are nematodes (Heterorhabditidae) symbiont and highly entomopathogenic in nature. Present study was concerned to investigate the effects of Photorhabdus temperata M1021 and Photorhabdus luminescens TT01 on plant morphology and physiology (‘Dongjin-beyo’ and ‘waitoc’). A significant (p<0.05) increase in the plant growth attributes including total plant length, root length, biomass, and chlorophyll contents were observed after treatment with culture extracts. Moreover indole-3-acetic acid (IAA) production by respective bacteria was confirmed by GCMS analysis. IAA production through tryptophan independent pathway was confirmed in P. temperata M1021 and P. luminescens TT01. Phosphate solubilization capability was also investigated by growing them on pikovskaya (PVK) agar as well as on PVK liquid medium with pH 7 at 28±2°C for 14 days. IAA production and phosphate solubilization capability of these bacteria could be the potential factors for plant growth promotion.