Development and Evaluation of Specialty Starch Germplasm Utilizing Gem Biodiversity to Optimize Grain Quality, Composition, and Yield
North Central Regional Plant Introduction Station, Ames, Iowa
2011 Annual Report
1a.Objectives (from AD-416)
1) Utilize GEM germplasm to develop germplasm with improved yield, grain quality, and specialty starch, such as high amylose for resistant starch, and double mutants of high amylose and waxy;.
2)Continue studies to closely identify linked markers for major high amylose modifiers (HAM) and implement these markers for marker assisted selection;.
3)Investigate allelic variation at the high amylose modifier gene; and.
4)Evaluate variation in endosperm starch and protein quantity and quality to determine attributes for kernel hardness and grain quality.
1b.Approach (from AD-416)
GEM derived high amylose inbred lines currently in the Truman State University program will undergo further inbreeding to fix the genes for high amylose. Inbreds will be selected based on ear grain quality, and amylose values generated in the lab. Inbreds will be crossed from the stiff stalk heterotic group to those from the non-stiff stalk group and evaluated in yield trials. A marker data base will be created using the SSR markers in collaboration with South Dakota State University. Lines in the breeding program will be genotyped and fragment types will be explored. Markers which co-segregate with HAM will be used in future work to implement marker assisted selection. To investigate variation in starch and protein and its role in grain quality, several laboratory methods will be used. Scanning electron microscopy (SEM) will be used to investigate starch granule structure in the endopserm. High Performance Liquid Chromatography (HPLC) will be used to extract storage proteins to assess the role of protein and starch interaction which may determine kernel hardness/grain quality. Differential scanning calorimetry (DSC) will be used to determine if starch thermal properties can be a diagnostic screen to identify double and triple endosperm mutants.
This project relates to the primary objectives of the parent project which include the development and evaluation of genotypes for value-added grain traits such as high amylose. Progress continued in evaluation of high amylose lines in yield trials in Ames, IA and Kirksville, MO. Forty entries were evaluated as F1 hybrids derived from GEMxGEM lines that were converted to 70% amylose using the GEMS-0067 inbred. GEMS-0067 was shown to have a high amylose modifier gene (HAM) which raises amylose content from 50% up to 70%. The most promising pedigree included a high amylose converted line derived from GEMS-0113 crossed to AR16035:S02-615-001 for the stiff stalk (SS) parent; and GEMN-0088 crossed to GEMN-0089, and then to GEMN-0071 for the non-stiff stalk (NS) line. In 2011, fifty entries were planted for further yield evaluation in three locations; Ames, IA, Kirksville, MO, and Champaign, IL. The nursery was planted in Kirksville in 2011 and included 152 inbreds which were double mutants having both the ae gene for high amylose and wx gene for waxy starch. Initial results indicate this germplasm may be promising as a source of (edible) resistant starch (RS). RS is beneficial to the human diet by providing a form of slowly digestible starch which reduces obesity. Three generations of inbreeding were completed with ae wx double mutants with no deleterious effects or deterioration of grain quality. Further research using the polymerase chain reaction (PCR) conclusively demonstrated that the source of the HAM gene is present in the tropical source from Guatemala, GUAT209 (PI 498583), and not present in the adapted line components of the GEMS-0067 pedigree. This demonstrates the importance of plant genetic resources to enhance the germplasm base for a value added grain trait with potential benefit for human health. Monitoring activities include (1) observing germplasm developed by the Cooperator in the GEM nursery and trials, and (2) progress reports submitted by the Cooperator in July and December for the Annual GEM Cooperator Meeting. E-mail exchanges were periodically initiated by the Authorized Departmental Officer's Designated Representative (ADODR) or the Cooperator to discuss status of experiments during the growing season. Germplasm resources and technical information were provided by the ADODR upon request of the Cooperator. High amylose hybrids developed by the Cooperator have been planted in the GEM Field Day demonstration plot in 2011. A site visit by the Cooperator to Ames is made each September.