2010 Annual Report
1a.Objectives (from AD-416)
Develop maize germplasm for low-input and organic farming systems.
1b.Approach (from AD-416)
Organic farmers need germplasm that is not receptive to transgenic pollen from their neighbors as out-crossing risk is causing them to plant late, leading to reduced yields and profitability. Simple Sequence Repeat (SSR) markers will be applied in the context of an existing traditional breeding project using backcrossing to develop breeding materials homozygous for the genes Ga1-s (a gene that makes the lines non-recipient to foreign pollen), and Tcb1 and its positive modifier genes (another gene that makes the lines non-recipient to foreign pollen). We will determine the effect of combining different genetic mechanisms for producing corn with high levels of the essential amino acid methionine. Methionine is very important for organic poultry production in light of impending bans on the use of synthetic methionine for organic poultry farmers. A breeding project is conducted to provide farmers practicing organic and other low-input agricultural farming systems with high yielding corn, incorporating the traits described above among others, to meet their specialty markets.
Progress was made on all three subobjectives. Gametophytic incompatibility (a trait used by plants to avoid self fertilization) was crossed into elite corn lines and other breeding populations. Under organic systems, breeding priorities include yield and grain quality, in particular high methionine content. All selection and breeding work for yellow, food-grade white, and high methionine inbreds were planted on certified organic land in 2010, but breeding materials for starch and oil traits were planted on conventional land due to lack of organic land space. Lack of local certified organic land for nursery and yield plots is a continuing problem. An experiment is underway to test possible synergistic effects of high-methionine corn crosses. Stand problems related to seed quality in organic yield tests have been a continual problem so we have been paying greater attention to seed drying and storage. We have also begun increasing seed of lines and breeding populations so that we can improve seed quality. Most space in the winter nursery was devoted to these increases, advancing lines for altered fatty acid composition, and advancing white corn lines because wet conditions caused a loss of that part of the nursery in 2009. For the third year in a row, we have had wet conditions in the early part of the growing season that caused losses and excessive weed problems in nurseries and yield test locations. Lines with increased levels of slowly-digestible starch were increased to supply seed for a human study to measure effect of the starch on blood glucose levels. These lines are being increased in isolated plantings in 2010 for feeding trials with laboratory rats to investigate the benefits of this starch on colon health. We cooperate with Michael Fields Agricultural Institute in developing lines with higher methionine levels for organic poultry; with Practical Farmers of Iowa by participating in and conducting field days and farmer workshops, and with farmers in on-farm research.
Traditional corn breeding with exotic germplasm is a promising method to develop healthy corn foods. Developing corn types with higher levels of slowly-digestible starch could provide new sources of high-fiber products for the food industry. This starch could be used to develop healthier processed foods to reduce health risks associated with obesity. ARS scientists in Ames, Iowa in collaboration with scientists at Iowa State University developed corn lines with higher levels of slowly-digestible starch and studied the effects of the new starches on cooking-related characteristics. The slowly-digestible starch did affect cooking characteristics. This information will help the food industry develop appropriate cooking procedures when this healthy starch is used in food processing, especially processes that involve heating.
Exotic germplasm can improve corn hybrids destined for starch and ethanol processing. Exotic germplasm often has higher protein levels that make it more difficult to extract starch during milling. ARS scientists in Ames, Iowa, in collaboration with scientists at Iowa State University and industry, crossed elite corn lines bred with exotic germplasm to commercial lines to make experimental hybrids, and then tested milling traits in the laboratory. The hybrids had a large range of values for the milling traits, with some yielding more starch than commercial Corn Belt hybrid standards included in the study.
Rohlfing, K.A., Pollak, L.M., White, P.J. 2010. Exotic Corn Lines with Increased Starch and Impact on Starch Thermal Characteristics. Cereal Chemistry. 87:190-193.
Pollak, L.M. 2010. Corn Flavor. In: Hui, Y.H., editor. Handbook of Fruit and Vegetable Flavors. Hoboken, NJ: John Wiley & Sons, Inc. p. 803-819.
Carena, M., Pollak, L.M., Salhuana, W., Denuc, M. 2009. Development of Unique and Novel Lines for Early-Maturing Hybrids: Moving GEM Germplasm Northward and Eastward. Euphytica. 170:87-97.
Taboada-Gaytan, O., Pollak, L.M., Johnson, L.A., Fox, S.R., Montgomery, K.T. 2010. Variation among Physical, Compositional, and Wet-Milling Characteristics of the F1 Generation of Corn Hybrids of Introgressed Exotic and Adapted Inbred Lines. Cereal Chemistry. 87:175-181.