Location: Plant Introduction Research2012 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.
3. Progress Report:
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 on evaluation of high amylose lines in yield trials in Ames, IA and Kirksville, MO. In 2012, 25 entries were planted at two densities, 79,000 plants per hectare (pph) and 61,750 pph in two replications in Ames, IA, to determine the effect of population density on grain yield, quality and amylose content. The nursery was planted in Kirksville in 2012 but heat and dry weather resulted in loss of most rows. Further research in collaboration with Iowa State University will characterize GEM background effect on expression of the two alleles (ae and sbe1a:gm67). They will provide expertise for high performance liquid chromatography (HPLC) separation of amylose and amylopectin, differential scanning calorimetry (DSC) analysis using high pressure cuvettes, microscopy, quantity of resistant starch, starch enzyme hydrolysis rate, and branch chain length distribution. Plans are to identify ten stiff stalk (SS) and ten non-stiff stalk (NSS) lines with favorable starch properties and yield trial performance for registration application in the Journal of Plant Registrations. Research on the development of a polymerase chain reaction (PCR) specific marker for routine selection of new Amylomaize VII lines using (sbe1:gm67) is still in progress. This is an important goal since near infrared spectroscopy (NIR) analysis has not been a reliable indicator to identify germplasm with 70% amylose. Our previous report indicated that the double mutant, ae wx, may be a good source of slowly digestible starch (SDS) although kernel quality, seed weight, and germination were very poor. A preliminary study on different genetic GEM backgrounds converted to homozygous ae wx identified Cuba164:S2012-966-1-B, DK844:S1601-3-2, and FS8A(S):S09-362-1-B as sources that contribute favorably for seed weight, density and ability to germinate. Students at Truman State University are now participating in the "MathBio Project" that will provide bioinformatics training to advanced undergraduates. Students will get valuable experience linking phenotypic data collected over the past 13 years with genotype.