Detoxification of oxalic acid by Pseudomonas fluorescens strain PfMDU2

Implications for the biological control of rice sheath blight caused by Rhizoctonia solani

M. Nagarajkumar, J. Jayaraj, S. Muthukrishnan, R. Bhaskaran, R. Velazhahan

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

Rhizoctonia solani isolates varying in their virulence were tested for their ability to produce oxalic acid (OA) in vitro. The results indicated that the virulent isolates produced more OA than the less virulent isolates. In order to isolate OA-detoxifying strains of Pseudomonas fluorescens, rhizosphere soil of rice was drenched with 100 mM OA and fluorescent pseudomonads were isolated from the OA-amended soil by using King's medium B. These isolates were tested for their antagonistic effect towards growth of R. solani in vitro. Among them P. fluorescens PfMDU2 was the most effective in inhibiting the mycelial growth of R. solani. P. fluorescens PfMDU2 was capable of detoxifying OA and several proteins were detected in the culture filtrate of PfMDU2 when it was grown in medium containing OA. To investigate whether the gene(s) involved in OA-detoxification resides on the plasmids in P. fluorescens PfMDU2, a plasmid-deficient strain of P. fluorescens was generated by plasmid curing. The plasmid-deficient strain (PfMDU2P-) failed to grow in medium containing OA and did not inhibit the growth of R. solani. Both PfMDU2 and PfMDU2P- were tested for their efficacy in controlling sheath blight of rice under greenhouse conditions. Seed treatment followed by soil application of rice with P. fluorescens strain, PfMDU2, reduced the severity of sheath blight by 75% compared with the control, whereas PfMDU2P- failed to control sheath blight disease.

Original languageEnglish
Pages (from-to)291-298
Number of pages8
JournalMicrobiological Research
Volume160
Issue number3
DOIs
Publication statusPublished - Jul 6 2005

Fingerprint

Rhizoctonia
Oxalic Acid
Pseudomonas fluorescens
oxalic acid
Thanatephorus cucumeris
blight
biological control
rice
Plasmids
plasmids
Soil
Growth
Oryza
plasmid curing
Rhizosphere
rice soils
culture filtrates
seed treatment
soil treatment
acid soils

Keywords

  • Biological control
  • Detoxification
  • Oryza sativa
  • Oxalic acid
  • Pseudomonas fluorescens
  • Rhizoctonia solani
  • Toxin

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Applied Microbiology and Biotechnology
  • Microbiology

Cite this

Detoxification of oxalic acid by Pseudomonas fluorescens strain PfMDU2 : Implications for the biological control of rice sheath blight caused by Rhizoctonia solani. / Nagarajkumar, M.; Jayaraj, J.; Muthukrishnan, S.; Bhaskaran, R.; Velazhahan, R.

In: Microbiological Research, Vol. 160, No. 3, 06.07.2005, p. 291-298.

Research output: Contribution to journalArticle

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