Multifactor transcriptional profiling of potato during 2,4-D-induced resistance to common scab disease

Authors: FABIAN, MATTHEW - Oak Ridge Institute For Science And Education (ORISE); NGUYEN, HIEN - Oak Ridge Institute For Science And Education (ORISE); Stommel, John; Clarke, Christopher

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/24/2025
Publication Date: 8/17/2025
Citation: Fabian, M., Nguyen, H., Stommel, J.R., Clarke, C.R. 2025. Multifactor transcriptional profiling of potato during 2,4-D-induced resistance to common scab disease. Frontiers in Plant Science. https://doi.org/10.3389/fpls.2025.1641317.
DOI: https://doi.org/10.3389/fpls.2025.1641317

Interpretive Summary: Common scab is a devastating disease of potato, and other root and tuber crops, caused by multiple species of Streptomyces bacteria. There are no widely available, efficacious chemical and cultural disease management tools for common scab. Low-dose foliar applications of potato with the herbicide 2,4-D have been shown to moderately, but inconsistently, attenuate common scab disease incidence and disease severity. The mechanism through which 2,4-D treatments mitigate disease impact is unknown. We developed a greenhouse assay for measuring 2,4-D impact on common scab disease symptoms and utilized that assay to profile global changes in gene expression in both foliar and tuber tissue following 2,4-D treatment with and without the presence of Streptomyces pathogens. Multiple genetic pathways involved in plant pathogen defense, hormone signaling, tuber skin organization and structure including lipid metabolism, and sugar transport were identified as impacted by foliar 2,4-D treatments. 2,4-D applications altered sugar profiles in tuber tissues where pathogen infection occurs suggesting one potential mechanism of 2,4-D-induced resistance. Understanding of the mechanism of 2,-4D-induced disease resistance is expected to enable rational design of more efficacious and more consistent common scab disease management tools and benefit grower stakeholders.

Technical Abstract: Foliar application of low-dose 2,4-Dichlorophenoyxacetic acid (2,4-D) has been demonstrated to reduce potato common scab disease caused by phytopathogenic Streptomyces. Foliar-applied 2,4-D is translocated to the tubers but does not cause direct toxicity against the pathogen. The efficacy of 2,4-D treatment for common scab disease management is inconsistent among trials and the exact mode of action is unknown. Here, we identified transcriptomic responses of potato to low-dose 2,4-D treatment in both the presence and absence of the pathogen and in tuber periderm and foliar tissue. The presence of the pathogen primarily altered transcriptomic responses in tuber periderm tissue while foliar 2,4-D application caused much larger shifts in gene expression in leaf tissue, as expected. Gene ontology terms associated with pathogen defense, stress responses, and enzymatic inhibitors were significantly enriched among differentially expressed genes in tuber response to the pathogen. In 2,4-D-treated plants, the response to the pathogen was even more transcriptionally robust and included additional differentially expressed genes and GO terms related to lipases and transport. A more muted transcriptional response to foliar 2,4-D treatment was observed in tuber tissue than in leaf tissue as expected, but GO terms related to sucrose transport were enriched in tuber RNA samples from 2,4-D treated plants. Altered sugar levels in tuber medulla and periderm tissue, the site of common scab infection, were observed in 2,4-D-treated plants. Results suggest that foliar 2,4-D treatments lead to alterations in potato periderm organization and structure potentially underpinning improved resistance against common scab pathogens. Identifying tools to more consistently induce these changes may enable more robust and consistent disease management than indirect foliar 2,4-D treatments.