2007 Annual Report 1a.Objectives (from AD-416) 1)To understand the mechanism of starch granule initiation and growth through investigation of granular and molecular structures of starch in the kernels of inbred B73 at different developmental stages. 2)To develop value-added products from GEM line starch that displays desirable properties, such as for manufacturing resistance starch and for production of corn syrup and alcohol. 1b.Approach (from AD-416) Starch granules will be isolated from kernels of B73 at varying development stages (from five days after pollination [DAP] to maturity) for studies of granule initiation and development by using scanning electron microscopy (SEM) and confocal microscopy to investigate the shape and size of granules and the internal structure development of the granule, respectively. Thermal properties, amylose content, and amylopectin branch-chain length will also be studied. To develop value-added products six GEM lines, AR17056:N2025-574-1-B-B-B, CUBA164:S15-118-6-9-B-B-B, CUBA164:S15-7-9-1-B-B-B, DKB844:S1601-206-1-B-B-B, DKB844SS1601-289-1-B-B-B, and DKB844:S1601-3-2-B-B-B 03, which display high retrogradation, have been selected for production of low-cost resistant starch using a novel extrusion technique developed in the PI's research group. Resistant starch thus produced will be subjected to enzyme hydrolysis following the AOAC method. Starch from GEM lines with low gelatinization temperature (AR16026:S17-237-2-B-B-B, and AR17056:N2025 select#10-B-B-B), and low retrogradation rate (CUBA164:S2008a-481-B-B-B, and CUBA164-S15-81-7-2-B-B-B) will be analyzed for amylopectin branch chains and selected for tests of enzyme digestibility. 3.Progress Report This report serves to document research conducted under a specific cooperative agreement between ARS and Iowa State University. Additional details of research can be found in the report of the parent project 3625-21000-047-00D, "Germplasm Enhancement of Maize Project (GEM)". This project relates to the primary objectives of the parent project which include the development and evaluation of genotypes for value-added traits such as starch digestibility, and "resistant" starch. Two specific objectives of this research are to (1) characterize high amylose maize starch, and identify desirable lines for resistant starch production, and (2) investigate enzyme digestibility of normal starch from various GEM lines, suitable for small animal feed. Studies were continued for the high amylose GEM line, GEMS-0067, pedigree GUAT209:S13//OH43ae/H99ae obtained from Truman State University. For the first objective starch granule structure and the mechanism of starch granule formation was examined by optical microscopy (bright field, dark field, phase contrast, and polarized light), and scanning electron microscopy images. The GEM line starch consisted of a large proportion (up to 32%) of elongated and filamentous granules which were substantially greater than the public high amylose check lines H99ae, OH43ae, B89ae, and B84ae (~5-8%). The filamentous structure of the granule appeared as an extension of spherical granule likely resulting from retrograded crystalline amylose and intermediate molecules. It is plausible that the crystalline amylose has a very high gelatinization temperature, >130 C, and this may partially explain the resistant starch properties found in GEMS-0067. For the second objective, enzymatic digestibility with porcine pancreatic alpha amylase was studied in nine GEM lines (normal maize) by isolating starch samples. The nine lines were selected based on previous data collected by the GEM Project's Quality Traits Lab on starch thermal properties, and protein, oil, and starch composition. Starch content varied from 66.2% to 75.2%. Enzyme hydrolysis rates varied from 89.4 to 97.0%. One line, 05GEM02989, had the highest enzyme hydrolysis rate, and greatest ethanol production based on a preliminary test. The methods for monitoring activities include progress reports submitted by the Cooperator in July and December for the Annual GEM Cooperator Meeting. E-mail and telephone communication were initiated regularly by the ADODR or the Cooperator to discuss status of nursery in Ames for germplasm used for joint experiments. Germplasm resources and technical information were provided to the Cooperator for selecting genotypes to be used for starch research. A site visit by the Cooperator to Ames is made each September.