Linking fundamental science to crop improvement through understanding source and sink traits and their integration for yield enhancement

Understanding processes in sources and sinks that contribute to crop yields has taken years of painstaking research. For crop yield improvement, processes need to be understood as standalone mechanisms in addition to how these mechanisms perform at the crop level; currently there is often a chasm between the two. Fundamental mechanisms need to be considered in the context of crop ideotypes and the agricultural environment which is often more water than carbon limited. Different approaches for improvement should be considered i.e. is there genetic variation? Or if not, could genetic modification, genome editing, or alternative approaches be utilised? Currently, there are few examples where genetic modification has improved intrinsic yield in the field to commercial application in a major crop. Genome editing, particularly of negative yield regulators as a first step, is providing new opportunity. Here we highlight key mechanisms in source and sink, arguing that for large yield increases integration of key processes are likely to produce the biggest successes within the framework of crop ideotypes with optimised phenology. We highlight a plethora of recent papers which show breakthroughs in fundamental science and the promise of the trehalose 6-phosphate signalling pathway which regulates carbohydrate allocation which is key for many crop traits.