Changes in gene expression in potato meristems treated with the sprout suppressor 1,4-dimethylnaphthalene are dependent on tuber age and dormancy status

Abstract

Commercial storage of potatoes often relies on the use of sprout inhibitors to prolong storage and reduce spoilage. The compound 1,4-dimethylnaphthalene (DMN) has seen increase application as a sprout inhibitor in the potato industry as older chemistries are being phased out. The mode of action of DMN is poorly understood as is the sensitivity of potato tissues to this new class of inhibitor. During storage potato tubers transition from a state of endo-dormant to eco-dormant and it is not known if the DMN response is consistent across this developmental transition. RNA-seq gene expression profiling was used to establish if stored potato tubers (Solanum tuberosum cv La Chipper) have differential sensitivity to DMN as tubers age. DMN was applied at three different times during storage; just after harvest when tubers are in endo-dormancy, midwinter at early eco-dormancy, and in spring during late eco-dormancy when sprouting was prevented via exposure to cold storage temperatures. Changes in gene expression were lowest during endo-dormancy while midwinter and spring treatments exhibited a greater and more diverse expression response. Functional analysis of differential gene expression demonstrated gene sets associated with DNA replication, cell division, and DNA methylation are suppressed after DMN treatment. However, gene sets associated with salicylic acid, jasmonic acid, abiotic and biotic stress responses are elevated by DMN only after endodormancy terminates. Gene clusters associated with pathogenesis related proteins PR-4 and PR-5 are also upregulated in response to DMN. These results indicate that DMN sensitivity changes as potato tubers age and transition from endo-dormant to eco-dormant in storage and the overall response is a shift in gene classes that regulate growth and response to stress.

Evaluating Ecologically Acceptable Sprout Suppressants for Enhancing Dormancy and Potato Storability: A Review

“…Analysis of the changes in transcriptional profiles of meristems isolated from 1,4-DMN-treated potato tubers showed the repression of cyclin or cyclin-like transcripts, thus suggesting that 1,4 DMN modifies genes involved in the maintenance of a G1/S phase block, most likely via the stimulation of the cell cycle inhibitors [22]. A recent report shows that sensitivity to 1,4-DMN changes as potato tubers age and transition from endo-dormant to eco-dormant in storage [29]. These are clear indications that 1,4-DMN may regulate sprouting by integrating external/ambient cues.…”

“…1,4-dimethyl naphthalene (1,4-DMN), a naturally occurring and endogenous methylsubstituted naphthalene in potatoes, is an alternate sprout inhibitor [22,23,29]. It is a volatile compound that contributes to the flavor and aroma of baked potatoes [23] and was isolated from potato skins and then synthesized for use as a plant growth regulator [30].…”

“…It is a volatile compound that contributes to the flavor and aroma of baked potatoes [23] and was isolated from potato skins and then synthesized for use as a plant growth regulator [30]. In particular, the chemical suppresses sprout production and etiolated development in stored potato tubers, thereby prolonging the effective storage period and preserving tuber quality [22,29]. Because the chemical has reversible effects, it may also be utilized on seed potatoes [23].…”

“…However, because it is a naturally occurring substance that is readily available in potato tubers, it is thought to suppress sprout development by extending endogenous dormancy conditions and via hormonal actions [22,23]. Although emerging, reports suggest that 1,4-DMN inhibits sprouting by repressing meristem cell proliferation [22,29]. Analysis of the changes in transcriptional profiles of meristems isolated from 1,4-DMN-treated potato tubers showed the repression of cyclin or cyclin-like transcripts, thus suggesting that 1,4 DMN modifies genes involved in the maintenance of a G1/S phase block, most likely via the stimulation of the cell cycle inhibitors [22].…”

Potatoes dormancy release and sprouting commencement: A review on current and future prospects

“…Potatoes contain a variety of vitamins C and B6 and minerals; according to United States Food and Drug Administration guidelines, potatoes are “excellent source” of vitamin C (Beals, 2018). In America, 63% of potatoes are used for food processing (Campbell et al., 2020). Potatoes are very versatile, capable of being processed into potato chips, potato starch, vermicelli, bread, French fries, cheesecake, cookies, and more.…”