Single gene discovery found to boost yield

Corteva researchers kept searching, despite indications that lone genes might not hold growth promises

Yield increases from the latest in plant breeding technologies have come mainly from making crops better able to defend against pests or other environmental harms.

True yield improvements, where crop-potential production is boosted, have proved elusive, until recently. Better yields have come through the traditional channels of selection, albeit enhanced by advanced genetic tools.

Typically, the yield puzzle has been thought of as containing too many genes, variables in habitat and outside stressors to be financially viable for creating improved genetic lines that would deliver in the field. Adding outside genetics, such as from soil bacteria and other sources, has been very successful.

Working with the plants’ own systems has been improving through the CRISPR-Cas9 technology, however even that has resulted in mostly improvements to defensive plant systems.

Researchers with Corteva Agriscience kept seeking gene functions that might lead to yield improvements brought about by added abilities within the plant itself, despite decades of limited success in the area.

Earlier this month, they published their discovery of a single gene and promoter that increases yield and have added it to the company’s commercial pipeline of crop development.

The genes are part of the MADS-box group. These act like main-switches for plant activities such as growth and seed development. Scientists decided to put efforts into a specific one, zmm28, in a corn plant. Working with a collection of DNA that turns this switch on and off, a promoter, they were able to boost yield under nearly any growing conditions by up to 10 percent.

Tom Greene is the senior research director at Corteva and said the ability to “reliably add yield” is key to this discovery’s importance.

“This particular yield-stability trait kept delivering results through years of (observation and testing),” he said.

“Historically, the challenge has been to deliver results across a set of environments that growers would be exposed to. High spots, low spots, fields with differing soils and in different (environments),” said Greene.

Tested in GM corn hybrids since 2014, with three years of trials through 2017, across all growing regions of the United States, the company was able to prove the reliability of their work.

“The early expression of that transcription factor triggers a cascade of genes and biological processes … (providing) a stronger stand, earlier, larger leaf-area index and higher level of photosynthesis and that improves the overall yield,” said Greene.

Corteva’s results were published earlier this month in the Proceedings of the National Academy of Sciences. The corn plants containing the genetic modifications where shown to use nitrogen 16 to 18 percent more efficiently and photosynthetic activity was up nine percent.

Greene said there are likely opportunities in other cereals, however corn will be the current target for Corteva breeders and developers.

The new genetics will be part of the company’s elite lines of stacked GM hybrids and the company has placed plants into the regulatory processes for approvals.

The work leverages a native gene in corn and uses a native gene promoter to do it, expanding and increasing expression of the genetic trait as compared to the genetic processes that typically take place.

“This is a maize gene being driven by a maize promoter. As a novel trait, we will take it through the regular regulatory process. Maybe because it is corn, it will let us get through some of the processes without some of the hurdles we often encounter, making it a bit easier,” he said.

“We are in Stage Three of our pipeline. Typically we are six to 10 years to market at this point,” said Greene.

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