26 May 2022, US: Researchers build on existing source-and-sink model to map complex interaction of traits that determine wheat yield throughout its growth cycle, as a guide for breeding and future research.
As crop yields are pushed closer to biophysical limits, achieving yield gains becomes increasingly challenging. Traditionally, scientists have worked on the premise that crop yield is a function of photosynthesis (source), the investment of assimilates into reproductive organs (sinks) and the underlying processes that enable and connect the expression of both. Although the original source-and-sink model remains valid, it must embrace more complexity, as scientific understanding improves.
A group of international researchers are proposing a new wiring diagram to show the interrelationships of the physiological traits that impact wheat yield potential, published on Nature Food. By illustrating these linkages, it shows connections among traits that may not have been apparent, which could serve as a decision support tool for crop scientists. The wiring diagram can inform new research hypotheses and breeding decisions, as well as research investment areas.
The diagram can also serve as a platform onto which new empirical data are routinely mapped and new concepts added, thereby creating an ever-richer common point of reference for refining models in the future.
“If routinely updated, the wiring diagram could lead to a paradigm change in the way we approach breeding for yield and targeting translational research,” said Matthew Reynolds, Distinguished Scientist and Head of Wheat Physiology at the International Maize and Wheat Improvement Center (CIMMYT) and lead author of the study. “While focused on yield potential, the tool can be readily adapted to address climate resilience in a range of crops besides wheat.”
The new wiring diagram represents a milestone in deterministic plant breeding. It dovetails simpler models with crop simulation models.
It takes into account how source and sink strengths may interact with wheat developmental stages to determine yield. For example, at the time of stem growth, spike growth or effective grain filling.
This diagram can be used to illustrate the relative importance of specific connections among traits in their appropriate phenological context and to highlight major gaps in knowledge. This graphical representation can also serve as a roadmap to prioritize research at other levels of integration, such as metabolomic or gene expression studies. The wiring diagram can be deployed to identify ways for improving elite breeding material and to explore untapped genetic resources for unique traits and alleles.
Yield for climate resilience
The wheat scientific community is hard at work seeking new ways to get higher yields more quickly to help the world cope with population growth, climate change, wars and stable supplies of calories and protein.
“To ensure food and nutritional security in the future, raising yields must be an integral component of making crops more climate-resilient. This new tool can serve as a roadmap to design the necessary strategies to achieve these goals,” said Jeff Gwyn, Program Director of the International Wheat Yield Partnership (IWYP).