Tissue specific mechanisms of tuber dormancy after 1,4-dimethylnaphthalene treatment in potato

1,4-Dimethylnaphthalene (DMN) is gaining popularity as a postharvest sprout suppressant for potato storage. We hypothesized that DMN treatment impact critical phytohormone regulations in a tissue specific manner to suppress sprout growth of potato tubers. This study investigated transcriptional and hormonal responses in cv. 'Russet Burbank' tubers subjected to single or multiple DMN treatments during long-term storage. Tuber sprout growth was monitored during storage, and primary and secondary meristems, as well as tuber flesh tissues were collected from DMN treated and untreated tubers at three-week intervals for molecular and phytohormone analyses. Multiple DMN treatments were most effective in suppressing sprout growth up to 18 weeks in storage. Molecular responses to DMN treatments were tissue specific. Treatment of tubers with DMN altered the levels of hormones and their precursors as lower content of active forms of gibberellic acid, cytokinin, and jasmonic acid were observed in meristem tissues particularly with multiple DMN treatments. Aligning with phytohormone analyses results, multiple DMN treatments also altered the abundance of transcripts associated with abscisic acid, gibberellin, cytokinin, auxin, jasmonic acid, salicylic acid, and ethylene biosynthesis and signaling. DMN treatment impacted transcription factor families including APETALA2/ETHYLENE RESPONSIVE FACTOR, MYELOBLASTOSIS TRANSCRIPTION FACTOR, and BASIC HELIX-LOOP-HELIX associated with dormancy maintenance. Results of this research elucidate multiple DMN applications are needed to suppress sprout growth during long-term storage, and the underlying molecular mechanisms of DMN involve tuber tissue specific alteration of phytohormone regulation related to dormancy maintenance.