Population Dynamics of the Plant Growth-Promoting Bacterium Azospirillum brasilense and the Pathogen Pseudomonas syringae pv tomato in the Tomato Rhizosphere and Foliage and its use as a Strategy to Control Bacterial Leaf Speck of Tomato
Tomato plants are a host for both Azospirillum brasilense, a plant growth- promoting bacterium (PGPB), and P. syringae pv tomato (P.s. tomato), the causal agent of bacterial speck disease of tomato, a disease of moderate economic importance. Whereas A. brasilense increases the growth and yield of tomato plants (5), P.s. tomato decreases these (13). A. brasilense is mainly a rhizosphere bacterium (3), and P.s. tomato is largely an epiphytic bacterium (8). However, both bacterial species are capable of colonizing seeds and the rhizosphere, but only colonize plant foliage under mist chamber conditions (2). The aim of this study was to measure fluctuations in the populations of the two bacterial strains on tomato foliage or in the tomato rhizosphere when inoculated alone or as a mixed culture. The effect of the relative population size on the development of bacterial leaf speck disease in tomato was monitored and discussed as a potential biocontrol strategy.
KeywordsTomato Plant Systemic Resistance Azospirillum Brasilense Angular Leaf Spot Seed Inoculation
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