Methyl jasmonate and 1,4-dimethylnaphthalene differentially impact phytohormonal and stress protective pathway regulation involved in potato tuber dormancy

Finding safe sprout inhibitors to mitigate premature sprouting of potato tubers during postharvest storage is critical for preserving tuber quality and marketability within the potato industry. Investigating the impact of promising sprout inhibitor treatments on molecular mechanisms and metabolic pathways that regulate tuber dormancy has wider implications, especially to find relevant biomarkers and to identify their modes of action. In this study, dormant cv. Russet Burbank tubers were treated with 1,4-dimethylnaphthalene (DMN) and methyl jasmonate (MeJa) alone or in combination to determine their effects on sprout growth. Changes in expression of genes involved in phytohormonal pathways, cell cycle, and dormancy-related processes were determined 0–21 days after treatments. Biochemical regulation associated with carbohydrate metabolism and plant stress responses were also determined. Significant sprout suppression was observed with MeJa and DMN+MeJa treatments during long-term storage. These sprout inhibitor treatments also resulted in increased abundance of transcripts associated with abscisic acid, brassinosteroids, and dormancy regulation. While transcript abundance of cytokinin and select cell cycle genes decreased, especially with DMN treatment, lower metabolic activity related to carbohydrate metabolism was observed in bud meristem tissues when compared to tuber flesh. Overall, MeJa enhanced stress protective metabolites such as phenolic acids and increased antioxidant enzyme responses in bud meristem tissues. Collectively, results of this study indicate a stress inducive mode of action of MeJa, which might have played a role in sprout suppression during long-term storage of potato tubers.