Colonization of germinating tomato seeds with the plant growth-promoting rhizobacteria, Pseudomonas fluorescens 5.014 and its mutant 5-2/4

Abstract

In the present study the colonization pattern of Pseudomonas fluorescens, strain 5.014 and its mutant 5-2/4 with reinforced 2,4-diacetylphloroglucinol production, added to tomato seeds was investigated. The colonization of the roots and seeds was monitored during germination. Also, the effect of bacterization on the initial root development was examined. The wild strain 5.014,anditsmutant5-2/4,extensivelycolonizedtheseedsand roots during the germination phase. The added strains were distributed over the entire root and the distal segment was densely colonized compared to the proximal and the middle segment. When the strains were inoculated in a 1 : 1 suspension the mutant suppressed growth of the wild strain. The indigenous seed flora showed a large variation in density. Application of plant growthpromoting rhizobacteria, however, resulted in a stabilization of the bacterial density on the seeds and roots. The inoculated roots were more compact to the untreated control roots.