Effective rhizosphere colonization by plant growth promoting rhizobacteria (PGPR) is a prerequisite for its persistence performance under plant-root soil system. Therefore, to obtain effective strains, we have evaluated twelve strains of fluorescent Pseudomonas sp. from wheat rhizosphere exhibiting multifarious plant growth promoting (PGP) activities. These strains formed varying level of biofilm in vitro on abiotic surface. Two strains MW3 and MW4 with promising PGP activity but differing in biofilm forming ability. The biofilms were characterized by crystal violet assay, scanning electron and confocal laser scanning microscopy. The MW4 strain, a strong biofilm former is identified by16S rRNA gene sequence analysis. Strain MW4 showed strong biofilms compared to MW3. Similarly, wheat seeds treated with MW3 and MW4 revealed enhanced rhizospheric colonization by MW4 strain significantly (P ≤ 0.05) in higher number (logCFU g-1) up to 45 days after sowing compared to MW3. These findings suggested that strong biofilm forming ability of MW4 might have resulted in enhanced rhizosphere colonization. Therefore, biofilm forming ability of PGPR should be considered as an additional criterion in screening of fluorescent Pseudomonas sp.
Biofilm; Pseudomonas fluorescens; Triticum aestivum; root colonization; 16S rRNA gene; confocal laser scanning microscopy.
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