OOS 56-5 - A global examination of NSCs relationship with climate

Woody plant species store nonstructural carbohydrates (NSCs) for many functions. While known to buffer against fluctuations in photosynthetic supply, such as at night, NSC stores are also thought to buffer against environmental extremes, such as drought or freezing temperatures by serving as either back-up energy reserves or osmolytes. However, a clear picture of how NSCs are shaped by climate is still lacking. In this talk I’ll present data from a global database of NSCs gathered from the literature through 2020. We examined whether maximum total NSC stores and the amount of soluble sugars are associated with clinal patterns in low temperatures or aridity, indi- cating they may confer a benefit under freezing or drought conditions. We examine patterns using the average climate at each study site and the unique climatic condi- tions at the time and place in which the sample was taken. Altogether, our results sup- port the idea that NSC stores act as critical osmolytes. Soluble Sugars increase with both colder and drier conditions in aboveground tissues, indicating they can plastically increase a plants' tolerance of cold or arid conditions. However, maximum total NSCs increased, rather than decreased, with average site temperature and had no relationship to average site aridity. This result suggests that the total amount of NSC a plant stores may be more strongly determined by its capacity to assimilate carbon than by environmental stress. Thus, NSCs are unlikely to serve as reservoir of energy. This study is the most comprehensive synthesis to date of global NSC variation in relation to climate and supports the idea that NSC stores likely serve as buffers against environmental stress. By clarifying their role in cold and drought tolerance, we improve our ability to predict plant response to environment.