Source–Sink Communication: Regulated by Hormone, Nutrient, and Stress Cross-Signaling

Communication between source organs (exporters of photoassimilates) and sink organs (importers of fixed carbon) has a pivotal role in carbohydrate assimilation and partitioning during plant growth and development. Plant productivity is enhanced by sink strength and source activity, which are regulated by a complex signaling network encompassing sugars, hormones, and environmental factors. However, key components underlying the signaling pathways that regulate source–sink communication are only now beginning to be discovered. Here, we discuss recent advances in our understanding of the molecular mechanisms regulating sugar mobilization during seed development and seedling establishment in cereals, which provide the majority of nutrition for humans. Insights into these mechanisms may provide strategies for improving crop productivity.

TrendsWith the rapidly expanding world population, food production must be substantially increased in the coming several decades to meet increasing global demands for food.Source–sink interactions modulate carbon (C) assimilation, translocation, partitioning, and storage throughout the plant and have a pivotal role in determining the productivity of harvestable organs.Crop yield is dependent on the source–sink relation, which is influenced by environmental changes.Understanding mechanisms by which plants control source activity and sink strength in the context of global climate changes, such as water limitation and high temperature, is of agronomic significance for the development of efficient breeding programs for improving crops.Many examples have demonstrated that manipulation of source activity and sink strength could significantly enhance crop productivity. However, crop productivity is determined by the combinatorial functions of multiple genes involved in signaling and metabolic pathways, which are still not well understood. Additionally, yield increase has not been evaluated in field trials in most studies. Therefore, more work is needed for the translation of basic findings to open field trials.