Efecto de Pseudomonas fluorescentes en la germinación de semilla y vigor de plántulas de jitomate

The bacteria Clavibacter michiganensis subsp. michiganensis (Cmm) and Xanthomonas vesicatoria (Xv) are of great interest in tomato production because they cause major economic losses worldwide. They are transmitted by seeds and the management strategies for these pathogens in tomato production systems are not completely effective. Therefore, the objective of this research was to identify fluorescent Pseudomonas strains of different ecological origin and evaluate their antagonism against Cmm and Xv and their effect as growth promoters on tomato seed germination and seedling vigor. We evaluated 356 fluorescent Pseudomonas strains isolated from different ecological niches: roselle (Hibiscus sabdariffa L.) rhizosphere, tomato (Solanum lycopersicum L.) rhizosphere and Claviceps gigantean sclerotium mycosphere. Antagonism against C. michiganensis and Xanthomonas vesicatoria was evaluated in in vitro dual confrontation tests in King’s B culture medium, which generated 20 fluorescent P. strains antagonistic to one or both bacteria. The antagonistic strains (n = 20) were characterized metabolically by their production of 3-indole acetic acid (IAA) and siderophores (SID), and were identified genetically by the polymerase chain reaction (PCR) technique with the amplification and sequencing of the 16S rRNA gene by primers FD1 and RD1. The results of the metabolic characterization of the strains indicated that 65 % produced IAA and 100 % SID. Inoculation of these bacteria, by the Bio-priming technique, in tomato var. Rio Grande seeds showed that 95 % of them significantly (P ≤ 0.05) increased the germination rate (T50) and the dry biomass production of the seedling roots. The partial sequencing of the 16S rRNA gene identified the bacterial strains as Pseudomonas sp. (65 %), P. putida (25 %) and P. fluorescens (10 %).