A new international study co-led by the University of Kentucky Martin-Gatton College of Agriculture, Food and Environment shows how a single genetic change helps protect corn seeds during storage. This offers plant breeders a clear target for developing varieties that stay vigorous longer and waste fewer seeds.
The research, published in The Plant Cell, focuses on a damaged protein repair enzyme called Protein repair L-isoaspartyl methyltransferase 1 (ZmPIMT1). The study showed how natural changes in the regulatory region of the gene encoding the enzyme - the DNA "on/off" region that controls how much of the ZmPIMT1 RNA, and then protein, is made - affect seed aging tolerance in maize.
The team found that some corn lines carry a version of this region that turns ZmPIMT1 on more strongly, helping seeds better survive the stress of long-term storage and harsh conditions.
For Bruce Downie, professor in the Department of Horticulture at Martin-Gatton CAFE and a leading member of UK's seed biology group, the work speaks directly to a simple reality: modern life runs on seeds.
"Roughly 70% of the human diet comes directly from seeds, and much of the rest depends on animals fed on seeds," Downie said. "We eat them, wear them as cotton, ferment them into beverages and fuel. If seed lots fail, the costs hit farmers, companies and consumers all the way down the line."
The study, conducted with in part with Tianyong Zhao at Northwest A&F University in China, Zhao's associate, Yumin Zhang, identifies two main versions of the ZmPIMT1 regulatory region across diverse corn lines. One version drives high levels of ZmPIMT1 mRNA production, while another carries a large DNA insertion that lowers expression and, consequently, weakens seed performance under aging stress. Seeds with more ZmPIMT1 protein kept higher germination percentages and produced healthier seedlings after accelerated aging tests, a standard measure of seed storability.
The ZmPIMT1 cellular repair crew
Over time, normal chemical reactions twist and damage proteins inside dry seeds, including proteins needed as soon as the seed starts to germinate - the period in which the plant starts to grow again after being dormant. Instead of discarding those damaged proteins and rebuilding them from scratch, ZmPIMT1 helps flip faulty pieces back into working shape. That saves energy and keeps critical systems running during the first hours of germination.
ZmPIMT1 is a "repair helper" in seeds that watches over a protein called PABP2, which helps choose which stored messages get turned into new proteins when a seed wakes up and takes in water. If PABP2 is damaged and not fixed, the seed can't make important proteins fast, so it loses vigor. When a seed has more ZmPIMT1, PABP2 works better, and the seed can handle aging and still sprout strong.
"This reinforces what seed biologists call 'Job's rule,'" Downie said. "If you want a seed to survive dry storage, you must protect and repair the machinery of protein synthesis. This work shows that in maize, ZmPIMT1 is a major part of that protection."
To study the importance of ZmPIMT1, the researchers used multiple approaches. Corn lines with reduced ZmPIMT1 showed poorer performance after aging. Lines with elevated ZmPIMT1 held up better in harsh storage tests.
Downie says the findings can give breeders and seed companies a concrete genetic marker to track as they strive to breed ever more resilient seeds.
"Seed producers invest heavily to deliver hybrids that farmers trust," Downie said. "If a batch loses vigor in storage, that means lost germination percentages, replanting costs and is frustrating for farmers. Choosing lines with the stronger ZmPIMT1 promoter is a practical step toward seed lots that stay reliable."
The study also highlights the strength of the cross-disciplinary group of scientists from Martin-Gatton CAFE and the College of Arts and Sciences that make up UK's seed biology group. They study how seeds develop, survive drying, resist damage and complete germination to produce new plants - work that connects molecular biology to food security, conservation and agricultural resilience.
"Many people never think about what keeps a seed alive from harvest to planting," Downie said. "Our group does, every day. This collaboration shows how basic science at the cellular level can point directly to tools that support farmers and safeguard the food supply."
