2. Dr. Dani Eshel

Bud endodormancy (ED) is a crucial stage in the life cycle of many perennial plants and is regulated by genetic and environmental factors. ED release requires the accumulation of a certain amount of cold exposure, measured as chilling units. However, the mechanism governing the effect of cold on ED duration is poorly understood. We use the potato tuber system to investigate storage organ metabolism and signaling in response to chilling as associated with ED release. Cold-induced sweetening (CIS) is a well-known response of potato tuber to chilling. We developed sugars accumulation measure during CIS and defined it as sugar units. We showed that ED release was better correlated with sugar units’ accumulation than chilling units. In turn, CIS was associated with shorter ED. Heat exposure also caused sugar unit accumulation, followed by faster ED release. A logistic function was developed to predict ED duration based on sugar unit measurements. Modifying sugar unit level by knockout of the vacuolar invertase gene (StVInv) extended ED, while StVInv overexpression shortened it. We found that the time gap between sugar accumulation and ED release is associated with an abscisic acid (ABA) level that serves as a growth inhibitor. Our results suggest that sugar units are better predictors of ED duration than chilling units. We also found a novel interaction between ABA and sugar metabolism that determines the timing of bud growth. We believe that better understanding of the effect of climate change on bud dormancy will allow the development of cultivars that are more thermotolerant.