The efficiency of different transmission routes of Xanthomonas citri pv. fuscans and other seed-borne bacteria to bean seeds
Abstract
Seed transmission is a critical pathway for the dispersal of phytopathogenic bacteria. This transmission can occur through three main routes: floral, internal, and external. Yet the relative contribution of individual transmission routes remains poorly characterized. Using a pathosystem based on Xanthomonas citri pv. fuscans ( Xcf ) and common bean ( Phaseolus vulgaris cv. Flavert), we quantified the efficiency of each route. Under our experimental conditions, the vascular route was the most efficient with 25% of contaminated seeds and population sizes averaging 10 7 CFU per contaminated seed. Deploying this experimental framework to ten seed-borne bacterial strains isolated from bean revealed that almost none transmitted to seeds through any route, or at best at low efficiency. However, most of the strains were capable of surviving and disseminating within the vascular system. A major bottleneck for seed transmission was identified for pod vascular organs colonization and the similar behavior of an Xcf mutant, deficient in the T3SS, suggested that plant immunity could be involved at this step. Co-inoculation of a consortium composed of the seed-borne strains with Xcf reduced the number of seeds contaminated by Xcf at the highest inoculum concentration, although other consortia members were never recovered from seeds. This suggests that the strains are recognized by the plant and trigger defense responses. These findings also raise questions about the mechanisms used by seed-associated bacteria to colonize seeds in situ.
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BibTeX
@misc{chadelaud2026efficiency,
title = {{The efficiency of different transmission routes of Xanthomonas citri pv. fuscans and other seed-borne bacteria to bean seeds}},
author = {Thomas Chadelaud and Agathe Brault and Martial Briand and Matthieu Barret and Armelle Darrasse},
howpublished = {HAL},
year = {2026},
month = jun,
doi = {10.64898/2026.06.12.731840},
url = {https://hal.inrae.fr/hal-05739227v1},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The efficiency of different transmission routes of Xanthomonas citri pv. fuscans and other seed-borne bacteria to bean seeds
AU - Thomas Chadelaud
AU - Agathe Brault
AU - Martial Briand
AU - Matthieu Barret
AU - Armelle Darrasse
PY - 2026
DA - 2026/06/12
PB - HAL
DO - 10.64898/2026.06.12.731840
UR - https://hal.inrae.fr/hal-05739227v1
AB - Seed transmission is a critical pathway for the dispersal of phytopathogenic bacteria. This transmission can occur through three main routes: floral, internal, and external. Yet the relative contribution of individual transmission routes remains poorly characterized. Using a pathosystem based on Xanthomonas citri pv. fuscans ( Xcf ) and common bean ( Phaseolus vulgaris cv. Flavert), we quantified the efficiency of each route. Under our experimental conditions, the vascular route was the most efficient with 25% of contaminated seeds and population sizes averaging 10 7 CFU per contaminated seed. Deploying this experimental framework to ten seed-borne bacterial strains isolated from bean revealed that almost none transmitted to seeds through any route, or at best at low efficiency. However, most of the strains were capable of surviving and disseminating within the vascular system. A major bottleneck for seed transmission was identified for pod vascular organs colonization and the similar behavior of an Xcf mutant, deficient in the T3SS, suggested that plant immunity could be involved at this step. Co-inoculation of a consortium composed of the seed-borne strains with Xcf reduced the number of seeds contaminated by Xcf at the highest inoculum concentration, although other consortia members were never recovered from seeds. This suggests that the strains are recognized by the plant and trigger defense responses. These findings also raise questions about the mechanisms used by seed-associated bacteria to colonize seeds in situ.
ER -