Source–Sink Regulation in Crops under Water Deficit

To meet the food demands of an increasing world population, it is necessary to improve crop production; a task that is made more challenging by the changing climate. Several recent reports show that increasing the capacity of plants to assimilate carbon (source strength), or to tap into the internal carbon reservoir (sink strength), has the potential to improve plant productivity in the field under water-deficit conditions. Here, we review the effects of water deficit on the source-sink communication, as well as the respective regulatory mechanisms underpinning plant productivity. We also highlight stress-tolerant traits that can contribute to harness source and sink strengths towards producing high-yielding and drought-tolerant crops, depending on the drought scenario.