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
2013 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 is the final report which terminated 5/31/2013. During the past four years approximately twenty GEM lines were developed and identified with 70% amylose (amylomaize VII). Amylose is an important source of resistant starch and important for human health such as diabetes and obesity. The amylomaize VII lines include ten with stiff stalk heterotic background and ten non-stiff stalk. These lines were planted at Kirksville, MO, and a subset of the lines planted in the GEM nursery Ames, IA in 2013. The lines will be genotyped in Kirksville using an SSR gene specific marker developed at Truman State to ensure the presence of the sbe1::gm67 allele (indicates presence of amylomaize VII, which is 70% amylose). Yield trials consisting of fifty hybrids with two replications were planted in Ames, IA to continue evaluation for agronomic adaptability and yield performance. The newly developed marker lab at Truman State University will provide students an opportunity to understand plant breeding by using data sets derived from GEM germplasm sources developed over the past thirteen years. Computational tools include the Integrated Breeding Workflow System (IBWS) which provide a platform to facilitate bioinformatics, field data, pedigrees, and statistical programs for conducting simple interval mapping and composite interval mapping. Other research now in progress includes studies on the double mutant ae wx which may be a good source of slowly digestible starch (SDS). The double mutant is known to have poor grain quality and low kernel weight. Sources of ae wx with improved grain quality include GEM sources CUBA164:S2012-966-1-B and DK844:S1601-3-2. Double mutant ae wx lines are being advanced by inbreeding this summer in Kirksville, MO to obtain homozygous (true breeding) lines. A future goal is to develop a mapping population to identify genetic markers associated with improved grain quality and SDS.