Researchers at Clemson University and partner organizations have received a $2.4 million, four-year grant to map genes that control leaf senescence in corn, work that aims to sustain photosynthesis longer, improve yield stability and support smarter on-farm nitrogen use.
Senescence is a genetically programmed aging process that winds down leaf photosynthetic activity and recycles nutrients, including nitrogen.
Lead investigator Rajandeep S. Sekhon, an associate professor in the Clemson Department of Genetics and Biochemistry, proposed the senescence focused approach and oversees the project.
“Our goal is to set the timing of leaf senescence so plants stay productive when it counts and still finish cleanly for harvest, which can also help keep more nitrogen working on the farm,” Sekhon said.
Yellow leaves
Leaf yellowing marks the start of senescence, when the plant shifts from capturing sunlight to recycling nutrients such as nitrogen to developing kernels and other organs. Some staygreen lines delay senescence, helping the plants maintain photosynthesis longer and withstand heat and drought better, supporting more reliable harvests.
During senescence, food crops like corn dismantle leaf proteins. Unlike trees that store nutrients in the trunk or roots to regrow leaves the next spring, corn completes its life cycle in one season, so these salvaged nutrients typically end up in grain.
“Our study focuses on senescence timing, which is one part of the equation,” he said. “The other part is nitrogen remobilization and the strength of competing sinks like roots versus grain. This research will eventually inform nitrogen partitioning.”
Essential component
Nitrogen is essential for protein formation in corn because it is a fundamental component of amino acids, the building blocks of all proteins.
“Most kernel protein is storage protein with limited amino acid balance, so lowering total kernel protein does not automatically reduce nutritional value. If we get the timing of leaf senescence right, we can keep yield steady and, over time, help more nitrogen remain on the farm.”
The project will determine when senescence begins and how quickly it proceeds.
Mapping the genes
Sekhon’s group will map the genes and regulatory switches that control senescence using a systems genetics approach that integrates high throughput physiology, metabolomics, transcriptomes, chromatin accessibility, and single cell RNA sequencing. Artificial intelligence, primarily large language models (LLMs), and machine learning, along with advanced statistical methods, will combine these data to pinpoint genes and regulatory switches that set senescence timing in corn.
“While we’re focused on the process of senescence, we are developing methods and datasets that can translate to other traits and crops,” he said.
Also involved in the research are Ed Buckler of the United States Department of Agriculture – Agricultural Research Service, Chris McMahan and Nishanth Tharayil of Clemson, Cinta Romay of the Buckler group at Cornell University and Kelly Balmant at the University of Florida.
This work is supported by the National Science Foundation through Plant Genome Research Program and the Cross-Directorate Activities program.
