Survival of Two Biocontrol Pseudomonas Strains in Tomato Fruits After Inoculation at Flowering Through Fruit Ripening

Abstract

Pseudomonas syringae strain 1.1S and P. fluorescens strain A506 were applied to tomato plants to investigate their ability to survive during plant growth and ripening of fruits. Both strains were used to spray tomato flowers and green tomato fruits. Ripe tomato fruits were harvested and subjected to microbiological analysis. Peptone wash water and homogenates of fruit pulp were plated on selective media before and after enrichment. All tomatoes produced from inoculated flowers contained P. syringae on the surface of fruits (100% in enriched samples) as well as in the pulp homogenates (100% before and after enrichment). All tomatoes produced from inoculated green fruits contained P. syringae on the surface (38% and 100% in wash water and in enriched samples, respectively) as well as in the pulp homogenates (90% and 100% before and after enrichment, respectively). Of the P. fluorescens surface-positive tomatoes, 37% were from fruits receiving flower inoculation and 77% were from fruits receiving green fruit inoculation. P. fluorescens was harboured in higher percentages in pulp homogenates of tomatoes produced from treated flowers and green fruits (62% and 100%, respectively). Results suggest that antagonistic P. syringae and P. fluorescens strains survive in and on tomato fruits from the time of inoculation at flowering or at early stage of fruit development through fruit ripening. Tomato flower and green surfaces of fruits are possible sites at which Pseudomonas may attach and remain viable during fruit development.