POTENTIAL BIOLOGICAL CONTROL PSEUDOMONAS sp. PCI2 AGAINST DAMPING-OFF OF TOMATO CAUSED BY SCLEROTIUM ROLFSII

Fluorescent Pseudomonas spp. isolated from the roots of healthy tomato plants were screened for their antagonistic activities against Sclerotium rolfcii, Alternaria alternata and Fusarium solani, three phytopathogenic fungi of tomato and pepper. They were tested for phosphate solubilization ability and production of siderophores, hydrolytic enzymes, indole 3-acetic acid and hydrogen cyanid. The isolates were also characterized based on biochemical (API 20NE test) and genotypic (ERIC-PCR fingerprinting) features. A Pseudomonas sp. strain denoted PCI2 was chosen as a potential candidate for controlling tomato damping-off caused by Sclerotium rolfsii. PCI2 was identified at the genus level with a 16S rDNA partial sequence analysis and its phylogenetic relationship with previously characterized Pseudomonas species was determined. PCI2 clustered with the P putida species. Growth chamber studies resulted in statistically significant increases in plant stand (29%) as well as in root dry weight (58%). PCI2 was able to establish itself and survive in tomato rhizosphere after 40 days, following planting of bacterized seeds. PCI2 is a potential biological control agent that may contribute to the protection of tomato plants against damping-off caused by S. rolfrii.