Implication of indole acetic acid and biofilm production by Pseudomonas fluorescens during tomato (Solanum lycopersicum) plant interactions

Abstract

Pseudomonas fluorescens plays an important role in plant growth promotion and crop protection. This research focused on indole-3-acetic acid production and biofilm formation by P. fluorescens strain VSMKU3054 and assessed their implications on tomato plant interactions. IAA production was optimized with different physiochemical parameters. The IAA production was at the maximum level in King's B broth (KBB) containing L-tryptophan at 0.6 g/L, glucose and beef extract as carbon and nitrogen sources, respectively, at pH 7, 37 °C and 72 h of incubation. Production of IAA by P. fluorescens was confirmed by TLC, FT-IR and GC-MS studies. Tomato seed treatment with P. fluorescens remarkably enhanced the tomato plant growth, such as root and shoot length. The research on biofilm formation at different physiochemical parameters showed that the highest level of biofilm formation was noticed in tryptic soya broth containing glucose and potassium nitrate as carbon and nitrogen sources, respectively, at pH 7, 37 °C and on the 2nd day of the incubation period. Biofilm-related traits, such as motility tests including swimming (79 ± 1.52), swarming (36 ± 1.52) and twitching (22 ± 2) can help develop an organized surface community, leading to biofilm formation. Using Green fluorescent protein-tagged P. fluorescens, tomato root colonization was confirmed. Thus, the results revealed that IAA-producing and biofilm-forming abilities of P. fluorescens strain VSMKU3054 can improve plant growth and root colonization, respectively, and these traits of P. fluorescens can play major roles in plant-microbe interactions.