Carbon storage in plants: a buffer for temporal light and temperature fluctuations

Carbon (C) storage allows a plant to support growth whenever there is a temporal asynchrony between supply (source strength) and demand of carbon (sink strength). This asynchrony is strongly influenced by changes in light and temperature. In most crop models, C storage is included as a passive process that occurs whenever there is an excess of C from photosynthesis compared with the demand of C for metabolism. However, there are numerous studies that challenged this concept, and provided experimental evidence that C storage is an active process that allows buffering of environmental fluctuations and supports long-term plant growth. We propose that an active C pool needs to be included in simulation models for a better understanding of plant growth patterns under fluctuating environment. Specifically, we propose that the two main mechanisms actively regulating C storage in plants are the partitioning of assimilates between soluble sugars and starch and the degradation and remobilization of storage compounds. The insights gained here are important to optimize crop performance under fluctuating conditions and thus for developing more resource-efficient crop production systems.