Xanthomonas Infection Transforms the Apoplast into an Accessible and Habitable Niche for Salmonella enterica

Abstract

Bacterial spot disease caused by Xanthomonas species devastates tomato production worldwide. Salmonellosis outbreaks from consumption of raw produce have been linked to the arrival of Salmonella enterica on crop plants in the field via contaminated irrigation water.

Ralstonia solanacearumpandemic lineage strain UW551 overcomes inhibitory xylem chemistry to break tomato bacterial wilt resistance

“…Although co-infection of a single plant by two or more Ralstonia strains has not been observed in the field, this experiment suggests that a resistance-breaking strain can make the host more susceptible to other microbes, including other Ralstonia strains. This is consistent with the finding that tomato plants infected by plant pathogenic Xanthomonads are better hosts for the food-borne human pathogen Salmonella enterica (Dixon et al, 2022).…”

Time of arrival during plant disease progression and humidity additively influenceSalmonella entericacolonization of lettuce

“…For all other in planta experiments involving UV irradiation treatment, middle leaves that had been inoculated with S. enterica cells on both sides of the midrib were split in half after sampling-one half of the leaf was randomly selected for UV irradiation and the half left nonirradiated. Similar to what was demonstrated previously with S. enterica-inoculated tomato leaves (32), UV irradiation treatment significantly reduced the populations of S. enterica applied to the lettuce leaf surface while leaving apoplastic S. enterica cell populations intact (data not shown).…”

“…Lettuce leaves were cut from the plant and when applicable, UV irradiation was utilized to inactivate S. enterica cells colonizing the leaf surface and thus measure S. enterica colonizing the apoplast (32). Leaf tissue was irradiated with UV-C (254 nm) by placing samples adaxial side facing up inside a Stratalinker UV Crosslinker 1800 and dosing the tissue at an exposure level of 150,000 μJ/cm 2 .…”

“…Phytobacterial disease promotes the survival of S. enterica on plants (7,(19)(20)(21)(22)(23)(24)(25). A recently published study from our lab showed that tomato leaves infected by X. hortorum pv.…”

“…A recently published study from our lab showed that tomato leaves infected by X. hortorum pv. gardneri enabled S. enterica cells that arrive on the leaf surface to become internalized within the leaf apoplast and replicate (24). After completing this work, we questioned whether S. enterica would benefit from any bacterial leaf spot disease.…”