Location: Plant Introduction Research2011 Annual Report
1a. Objectives (from AD-416)
Characterize the molecular structure of starch granule formation, and develop analytical methods to identify germplasm for high digestibility and resistant starch. Secondly, characterize GEM germplasm for starch nutritional value (for humans and livestock), biofuel potential, and ethanol yield.
1b. Approach (from AD-416)
Ethanol fermentation tests, and starch digestibility analysis will be conducted on GEM germplasm previously identified with high starch content and/or ethanol content. In addition, other sources of germplasm will be analyzed for resistant starch content. Analytical methods including differential scanning calorimetry (DSC) will be studied to determine applicability for identifying GEM germplasm with desirable starch attributes. The identified germplasm will be recombined for future trials as hybrids, and new breeding crosses made and evaluated.
3. Progress Report
This project relates to the primary objectives of the parent project which include the development, evaluation, and methodology to release germplasm with resistant starch, high digestibility, and ethanol potential. Second year data was collected on waxy and normal germplasm to characterize the molecular structure of starch granules and the interrelationship of granular starch, protein, and lipids to determine how they contribute to and influence digestibility and ethanol yield. Three normal (non-waxy) inbreds, GEMN-0070 (06GEM02119), 03GEM00138 (high protein), and 09GEM07913 (high oil), were studied by analyzing grain harvested in the 2010 Ames GEM nursery. The high oil line's lipid content (5.4%) exceeded that of 06GEM02119 (3.3%) and 03GEM00138 (4.0%), and had the lowest starch digestibility based on starch hydrolysis with porcine pancreatic alpha-amylase. This may be due to formation of an amylose-lipid complex. Five other GEM lines selected for high protein and oil traits (GEMS-0003, GEMS-0162, GEMN-0136, GEMN-0131, and GEMN-111) were evaluated for starch hydrolysis rates (digestibility). Digestibility ranged from 59.9% to 68.1%, similar to the B73 check (68.9%). Four normal and nine waxy GEM sources with high ethanol potential were evaluated using a cold starch fermentation process. Ethanol yields of the four normal lines ranged from 18.7% for GEMS-0115 to 17.3% for GEMS-0003. Of interest: among the normal inbreds, GEMS-0115 and GEMN-0156 had the highest ethanol content in 2009 and 2010, and the highest starch content of the normal lines sampled (74.3 and 74.4%, respectively). Ethanol content of the waxy lines was 18.9% for GEMS-0206, 18.5% for GEMS-0223 18.4% for GEMS-0185, 18.0% (08GEM05039), 17.6% (08GEM05040), 17.4% for GEMN-0186, 17.7% (08GEM05043), and 17.8% (08GEM05044). Data for 08GEM05041 was missing due to low sample size. GEMS-0206 had the highest ethanol content in 2009 and 2010, while GEMS-0223 ranked second for ethanol content in both years. The average starch conversion efficiency of GEM waxy lines (92.4%) was greater than GEM normal lines (88.3%). These results were consistent with previous findings that starch ethanol conversion efficiency increased when amylose starch content decreased. Waxy germplasm may potentially be a better source of ethanol than non-waxy sources if grain yield and agronomic performance is similar. Monitoring activities included 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 Authorized Departmental Officer's Designated Representative (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. The Cooperator participates in the GEM Field Day each year.