P. Vinoth, K. Subramani, R.K.
Natarajan, S.V. Subaiya,
S. Mahesh, B. Usha and
Genetic Engineering, School of Bioengineering,
SRM Institute of Science and Technology,
Kattankulathur-603 203, India
Author Email :
Aim: New species of
Plant Growth Promoting Rhizobacteria (PGPR), with varying growth promoting
and biocontrol ability are often being discovered. They facilitate plant
growth either directly by secreting nutrients and hormones or indirectly by
providing defence mechanism to the plant. The present study was undertaken to
isolate PGPR from the rhizosphere of Solanum lycopersicum and Arachis
hypogaea, and test their growth promoting ability and antifungal activity
against Fusarium oxysporum.
Methodology: PGPRs were
isolated from the rhizosphere of S. lycopersicum and A. hypogaea
by serial dilution of the rhizospheric soil and identified by 16s rDNA
sequencing. The isolates were analysed for antifungal activity against F.
oxysporum, indole 3-acetic acid (IAA) production and phosphate
solubilisation. For the growth promotion assay, aseptically grown Vigna
radiata seedlings were dipped separately in isolated bacterial suspension
of PGPR (109 CFU ml-1) and planted in autoclaved soil. Plants were
irrigated with 50% Hoagland solution for every 48 hr and maintained at 25 ± 2
°C with 16/8 hr of light and dark photoperiod. Growth promotion
was examined in terms of differences in shoot length, root length, fresh
weight and dry weight after 12 days of treatment.
Results: Six isolates were
found to have antifungal activity towards plant pathogen, F. oxysporum.
Five isolates showed similarity to Pseudomonas aeruginosa (B7-1,
B11-5, B3-1, Rh-1, Rh-2) and one to Pseudomonas putida (B53). All six
strains were able to produce IAA, where B53 and B13-1 showed the highest
production compared to other strains. P. putida B53 demonstrated the
highest plant growth promotion activity by significantly (p<0.05)
increasing the growth of V. radiata plants as evidenced by increase in
shoot length, root length, fresh and dry weight.
Interpretation: The results
obtained from the present study supports that PGPRs like Pseudomonas
sp. could serve as potential eco-friendly bio-fertilizer and bio- fungicide
Key words: Biofungicide, Fusarium oxysporum, Indole 3-acetic
acid, Phosphate solubilization, Plant growth promoting rhizobacteria