b'Bringing ImprovedProtein Quality to PopcornResearch paves the way for improved popcorn.Joe FunkNOTWITHSTANDING ITS UBIQUITYand widespread use, dent corn (zea maize) is an imperfect food crop with incomplete protein quality. Widely recognized as one of the worlds 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 selec-tion 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 typi-cally limiting and make corn an incomplete protein source. QPM cultivars retain the protein quality of conventional opaque-2David Holding in the field developing improved varieties of quality maize but have improved agronomic traits, notably higher yieldsprotein maize. and glassy, hard-grain endosperm. Field corn and popcorn are genetically less related than corn inbreds are to each other.improvement of the protein quality of popcorn as one way to These differences make successfully crossing these sub-speciesenhance sales and broaden its appeal, especially in the ready to more difficult. eat and organic sectors. Holding knew that to be successful, his team had to end up Essential amino acid contents (g/100 g protein) of fourwith competitively performing hybrids. Between 2013 and 2018, tropical quality protein maize (QPM) varieties and twoHoldings lab focused on breeding independent introgressions normal maize varieties resulting from several different QPM lines plus several elite pop-Lysine QPM varieties3.70 4.00 4.12 4.20 (ave. 4.0) corn inbreds. The result was a diverse pallet for hybrid produc-tion to take advantage of hybrid vigor. Holdings quality protein Normal varieties 2.36 3.10 2.6 (ave. 2.7) popcorn (QPP) inbreds had double the normal amount of lysine Tryptophan QPM varieties 1.03 1.01 1.21 1.01 (ave. 1.1) and, in most cases, maintained acceptable level pop volumes. Normal varieties 0.62 0.61 (ave. 0.6) This is one of the first examples of popcorn breeding for a biochemical improvement in grain quality, he says. Most Source: Kwaku Ahenkora, et. Al., Protein nutritional quality and con- popcorn breeding has been to improve the physical qualities sumer acceptability of tropical Ghanaian quality protein maize, Food and Nutrition Bulletin, vol. 20, no. 3 1999. such as yield and increased popping volume because that is how popcorn is sold to consumers.David Holding, PhD, associate professor, University ofHoldings results provide evidence that it is possible to take Nebraska-Lincoln (UNL), became involved with popcorn breed- traits from dent corn into popcorn without necessarily sacrificing ing in 2013 when ConAgra Foods brought their popcorn breed- popping quality. New varieties with new flavor and aroma char-ing program to UNL. The collaboration charged other UNLacteristics and different combinations of flake morphology from scientists with developing genomics-based breeding resources,butterfly to mushroom and everywhere in between are included including genome sequencing and marker development forin Holdings results. By the end of 2020, Holding anticipates commonly used popcorn inbreds.having the information necessary to advance the best hybrids to As far as we know, breeding for improved nutritional qual- large-scale production. This success can also pave the way for ity in popcorn has not been a major focus for popcorn breedersthe general improvement of popcorn as its genomics tools come as it has been for dent corn, Holding says. However, we seeonline.SW70/ SEEDWORLD.COMSEPTEMBER 2020'