Internalization and survival of Pseudomonas corrugata from flowers to fruits and seeds of tomato plants

Pseudomonas corrugata, the causal agent of tomato pith necrosis, may cause severe losses on tomato worldwide. Control is based on the use of pathogen-free propagating materials and on the reduction of the inoculum in soil where the pathogen is apparently resident.Although P. corrugata has been isolated from soil, seeds and plantlets, little is known about its transmission, epidemiology and source of inoculum. Bioluminescent P. corrugata strain PVCT 4.3 lux 18 was spray-inoculated to flowers and immature tomato fruits of plant growing in greenhouse with the aim to monitor survival and transmission during fruit development and ripening. Bacterial population was evaluated on surface, pulp and seeds of tomato fruits harvested at the mature stage. Identity of P. corrugata 4.3t was confirmed by colony morphology on NDA, growth on selective medium and PCR assay. All tomato fruits produced from inoculated flowers and green tomatoes contained at the mature stage the pathogen on the surface (100% in enriched samples) as well as in the pulp homogenates (100% before enrichment). P. corrugata was recovered from the surface and from the pulp of tomatoes after 20 days of fruit storage at 4°C.The pathogen was also recovered from seeds of tomato fruits produced from inoculated flowers. Results suggest tha P. corrugata can be internalized and transmitted from flowers to fruits and seeds, thus surviving in the tissues and seeds during fruit development and ripening