A Time-Resolved Metabolomics Study of Potato Cultivar Responses to Pseudomonas syringae

Lindiwe Mahlangu¹Khayalethu Ntushelo¹Ntakadzeni Edwin Madala²Phumzile Sibisi^1*

• ¹Department of Agriculture and Animal Health, University of South Africa, Pretoria, South Africa
• ²Department of Biochemistry and Microbiology, University of Venda, Thohoyandou, South Africa

The bacterial plant pathogen Pseudomonas syringae poses a threat to various crops, including potato (Solanum tuberosum). Its pathogenicity and virulence are enabled by, among other factors, its type III secretion system, which delivers effectors into the host plant. While differences in cultivar responses offer a sustainable control strategy, the underlying temporal metabolic mechanisms in potatoes remain poorly characterised. This study employed an untargeted LC-MS metabolomics to investigate dynamic metabolic reprogramming in contrasting potato cultivars, Sifra and Valor, following inoculation with P. syringae. The metabolomic analysis was conducted at three intervals: 24 hours, 48 hours, and 72 hours post-inoculation. Our results revealed distinct, genotype-specific response kinetics. Neither cultivar exhibited significant pathogen-responsive metabolomic reprogramming at 24 hours post-inoculation. At 48 hours post-inoculation, levels of 14 metabolites were elevated in the inoculated Valor samples, while Sifra showed minimal reprogramming. The Valor responses were not sustained and had subsided at the 72 hour time point. Meanwhile, by 72 hours, a spike in 11 metabolites was observed in the inoculated Sifra, with almost no upregulation of these in Valor. Among the spiked metabolites in Valor and Sifra were metabolites with a proven role in pathogen response. In total, there were 5 overlapping heightened metabolites between Valor and Sifra. While cultivars are expected to This is a provisional file, not the final typeset article differ in their response to pathogen inoculation, resistance mechanisms and timing of response remain obscure and the present study uncovered varied time-dependent pathogen-induced metabolomic shifts of the two cultivars. This study added the much-needed knowledge of resistance responses with a new suite of response metabolites.