Graduate student, Ph.D. candidate Pennsylvania State University Erie, Pennsylvania
Body of Abstract: The potato (Solanum tuberosum L.) is regularly ranked among the top 5 crops in terms of production and consumption. Tubers, which can be used for fresh market and processed food, can be stored for extended periods in a dormant or dormant-like state during which the greatest value for the crop occurs. As tubers exit dormancy they begin to sweeten, losing value. Sprout suppressors are often utilized to prolong dormancy, suppress growth, and delay sweetening. However, application at different dormancy stages may elicit altered responses, resulting in varying efficacy of treatments, and thus, a potential loss of product. The goal of this study was to utilize gene expression analyses to identify the response of tubers exposed to DMN treatment at two stages of dormancy and assess the changes in response once exposure has ceased. In both dormancy stages, the majority of identified genes were unique to a particular time point, while a small number showed sustained or changing expression patterns. Analysis of control samples revealed a population of genes likely associated with dormancy release. Comparison of these to DMN treated tubers revealed a limited number of genes significantly reduced in response to the sprout inhibitor and included transcripts that encoded for proteins associated with chlorophyll metabolism, detoxification of reactive oxygen species, and response to light and temperature. This study demonstrates that the response of tubers to DMN changes over time and depends on both the tuber dormancy stage and recency of treatment application. Changes in gene expression patterns between the time points of a dormancy stage suggest both an immediate and delayed response to treatment. A handful of genes, primarily associated with processes related to photosynthesis and response to external stimuli, were significantly suppressed by DMN, suggesting that DMN treatment results in tubers that are less responsive to growth promoting conditions.