Biocontrol Agents Induce Disease Resistance in Phyllanthus niruri Linn against Damping-Off Disease Caused by Rhizoctonia solani

Abstract

Five isolates each of Trichoderma viride and Pseudomonas fluorescens and four isolates of Bacillus subtilis
were evaluated for their ability to control Rhizoctonia solani, the causal agent of damping off of Phyllanthus niruri.
Among the isolates tested, TVUV10 (T. viride), PFMMP (P. fluorescens) and BSG3 (B. subtilis) showed maximum in
vitro inhibition of mycelial growth of R. solani. Isolate PFMMP was also very effective in reducing disease incidence
in greenhouse conditions. The effective isolates were evaluated for their ability to induce defense reactions in P.
niruri plants. Earlier and increased activity of phenylalanine ammonia lyase, peroxidase, polyphenoloxidase and
total phenolics were observed in the biocontrol-agent pretreated P. niruri plants challenged with R. solani. Isolate
PFMMP caused early and increased synthesis of all defense related enzymes and total phenol. The present study
showed that isolates TVUV10, PFMMP and BSG3 of T. viride, P. fluorescens and B. subtilis respectively are good
candidates for the control of R. solani in P. niruri.