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Bringing Improved Protein Quality to Popcorn

David Holding, Associate Professor of Agronomy and Horticulture, and his team is pollenating popcorn hybrids at their East Campus field. July 17, 2019. Photo by Craig Chandler / University Communication.

Research paves the way for improved popcorn.

Notwithstanding its ubiquity and widespread use, dent corn (zea maize) is an imperfect food crop with incomplete protein quality. Widely recognized as one of the world’s major, high-energy feed crops, corn generally contains low levels of two essential amino acids, lysine and tryptophan.

Through backcrossing and several cycles of recurrent selection of maize, breeders at the International Center for Maize and Wheat Improvement (CIMMYT) in Mexico have combined the high-lysine potential of the opaque-2 gene with genetic endosperm modifiers. These new genotypes, collectively called “quality protein maize” (QPM), are of interest to seed producers and breeders for their potential advantages in human nutrition and animal feeding. This is a natural maize variant containing double the level of two essential amino acids, which are typically limiting and make corn an incomplete protein source. QPM cultivars retain the protein quality of conventional opaque-2 maize but have improved agronomic traits, notably higher yields and glassy, hard-grain endosperm. Field corn and popcorn are genetically less related than corn inbreds are to each other. These differences make successfully crossing these sub-species more difficult.

David Holding, PhD, associate professor, University of Nebraska-Lincoln (UNL), became involved with popcorn breeding in 2013 when ConAgra Foods brought their popcorn breeding program to UNL. The collaboration charged other UNL scientists with developing genomics-based breeding resources, including genome sequencing and marker development for commonly used popcorn inbreds. 

“As far as we know, breeding for improved nutritional quality in popcorn has not been a major focus for popcorn breeders as it has been for dent corn,” Holding says. “However, we see improvement of the protein quality of popcorn as one way to enhance sales and broaden its appeal, especially in the ready to eat and organic sectors.” 

Holding knew that to be successful, his team had to end up with competitively performing hybrids. Between 2013 and 2018, Holding’s lab focused on breeding independent introgressions resulting from several different QPM lines plus several elite popcorn inbreds. The result was a diverse pallet for hybrid production to take advantage of hybrid vigor. Holding’s quality protein popcorn (QPP) inbreds had double the normal amount of lysine and, in most cases, maintained acceptable level pop volumes. 

“This is one of the first examples of popcorn breeding for a biochemical improvement in grain quality,” he says. “Most popcorn breeding has been to improve the physical qualities such as yield and increased popping volume because that is how popcorn is sold to consumers.”

Holding’s results provide evidence that it is possible to take traits from dent corn into popcorn without necessarily sacrificing popping quality. New varieties with new flavor and aroma characteristics and different combinations of flake morphology from butterfly to mushroom and everywhere in between are included in Holding’s results. By the end of 2020, Holding anticipates having the information necessary to advance the best hybrids to large-scale production. This success can also pave the way for the general improvement of popcorn as its genomics tools come online.

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