Investigating the pathways of seed transmission in Xanthomonas campestris pv. incanae and the impact on the microbiome of Matthiola incana seeds

Seedborne pathogens pose a threat to agricultural seed production across the world. Managing seedborne diseases relies on a thorough understanding of the basic biology of plant pathogens threatening seed health and their transmission. In this work, we explored the pathways that Xanthomonas campestris pv. incanae (Xci), the causal agent of bacterial blight of Stock (Matthiola incana), uses to become seedborne in this high value cut flower crop. We conducted a series of experiments where a 10⁶ cfu/ml suspension of Xci was inoculated on potted M. incana ‘Iron Apricot’ plants via leaf clip, floral, and direct seed inoculations, and assessed the recovery of Xci from the offspring seeds through a culture-based approach. Plants were arranged in a RCBD with 3 blocks, with both an inoculated and non-inoculated treatment in each block. Results show that Xci is recoverable in the offspring seeds after leaf clip inoculations but not after floral or direct seed inoculation. Whole genome metagenomic sequencing is being completed to further understand the role Xci plays in influencing the microbiome composition of infested and non-infested M. incana seeds. Understanding the impact Xci has on the seed microbiome and the pathways it utilizes to become seedborne in stock plants will help provide researchers, seed producers, and those managing seedborne bacterial diseases with fundamental knowledge to help inform future disease management strategies.