Listen up! How to grow better corn

IOWA STATE (US) — When researchers re-sequenced six elite inbred corn lines, they found more than 100 genes present in some lines, but not in others.

The process,  called presence/absence variations, “was a real eye-opener,” says Patrick Schnable, professor of agronomy at Iowa State University. “One of the goals of the research is to try to identify how heterosis (hybrid vigor) works.”

Heterosis is the phenomenon in which the offspring of two different lines of corn grow better than either of the two parents—the attribute that enables corn breeders to produce better and better hybrids of corn.

For instance, two lines of corn can be bred to produce a hybrid that increases yield or resists drought or pests better than either of the parents.

Schnable says his research, which is the cover article for the current edition of the journal Nature Genetics, brings science a step closer to identifying which genes are responsible for which traits.

For example, if one inbred line is missing a gene and is drought susceptible, crossing that line with a line that includes the missing gene and is drought tolerant, might lead to a better hybrid.

“If we can understand how heterosis works, we might be able to make predictions about which inbreds to cross together,” he says.

“I don’t think we’ll be able to tell plant breeders which hybrids will be the absolute winners. But we might be able to say ‘These combinations are probably not worth testing.'”

Schnable sees combining genes from two lines as a chance to introduce the best from both plants.

“These are complementing somehow,” he says. “It’s like a really good marriage. She’s good at this, and he’s good at that, and together, they form a good team.”

The potential for improvement is great, but Schnable cautions that much work needs to be done.

“We are at the point where we think this is going to be important, but we don’t know which genes specifically are going to be important,” he says. “Now we need to figure out which genetic combinations will be predictive of hybrid success.”

Researchers from China Agricultural University and the Beijing Genomics Institute contributed to the study.

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