By Andi Anderson
A new study led by researchers at the University of Illinois Urbana-Champaign has identified a major genetic weakness in one of the most important corn breeding groups used across the United States. Scientists found that genetic variation related to grain yield is becoming limited in a key group of intermediate-maturity corn lines that are widely used in commercial production.
Corn breeding depends on a process called hybrid vigor, or heterosis, where two genetically different parent lines are crossed to produce high-performing hybrids. For decades, breeders have relied on two major groups known as stiff-stalk (SS) and non-stiff-stalk (NSS). However, repeated use of the best-performing parent lines has gradually reduced genetic diversity within these groups.
"Our study reveals a significant genetic weakness that threatens maize breeders' ability to develop high-yielding hybrids, especially in the context of climatic challenges projected for the U.S. Corn Belt,” said Jenifer Camila Godoy dos Santos, a postdoctoral researcher in the Department of Crop Sciences, part of the College of Agricultural, Consumer and Environmental Sciences at U. of I.
The research team evaluated genetic variation in 13 SS and 28 NSS inbred corn lines representing different maturity groups. They examined important traits such as grain yield, plant height, and flowering time. Their findings showed that intermediate-maturity SS lines, which are commonly grown in the U.S. Corn Belt, have very limited genetic diversity for yield.
Researchers noted that this reduction in variability could make it more difficult to develop productive corn hybrids capable of handling future environmental and climate-related challenges. At the same time, the study found healthy levels of genetic diversity in early- and late-maturity corn lines, as well as in intermediate-maturity NSS lines.
The study was supported by the Genomes to Fields (G2F) initiative, a collaboration launched by U.S. university corn breeders to better understand corn genetics and performance across different growing environments.
“In 2015 or 2016, we started asking whether we still have genetic variation in our breeding germplasm. That's important because if we don't have variation, then we don't make progress. Without variation, we can’t adapt our germplasm to changing growing conditions, climate change, or diseases that might come up. And most importantly, we can’t produce hybrids that are high-yielding in these new environments,” said Martin Bohn, corn breeder and crop sciences professor at U. of I.
Researchers studied 162 corn hybrids across more than 30 locations in the United States and Canada. The large dataset helped them better understand the remaining genetic diversity within modern breeding materials.
“Our analysis can be distilled to a very powerful take-home message about the depletion of the genetic variability in an important group of corn: We are lining ourselves up for an emergency,” Lipka said. “The fact that we’ve observed insignificant genetic variability for yield in this heterotic group should be viewed as a canary in a coal mine. We have to do something about it.”
Scientists suggest introducing new genetic material into breeding programs to strengthen corn varieties. They emphasize that protecting and expanding genetic diversity will help breeders continue developing high-yielding, climate-resilient corn hybrids for future generations.
“While this study is a warning sign, it does not signify the end of maize breeding, which has been making tremendous progress for more than 100 years,” Godoy dos Santos said. “Our study reminds us of the importance of protecting and broadening the genetic diversity available to breeders. By introducing new sources of genetic diversity, breeding programs can continue developing better maize hybrids for future generations.”
Photo Credit: getty-images-n-sky
Categories: Illinois, Crops, Corn