Location: Soybean and Nitrogen Fixation Research2012 Annual Report
1a. Objectives (from AD-416):
To elucidate regulatory mechanisms of genes that control saturated fatty acid composition in sobyean seed; to characterize the mechanisms that control phytate content in seeds, and the impact of low phytate on seed viability and soy meal digestibility; to identify genes and gene products that cause immune responses to soybean and devise ways to mitigate these reactions.
1b. Approach (from AD-416):
Evaluate metabolite levels and expression of genes encoding enzymes of the phytate biosynthetic pathway of low and normal phytate seeds in response to increasing P supply; Evaluate amino acid substitution in desaturase genes; Evaluate differences in the amount of allergens bound to soy protein, determine their location in the protein, and assess variation in their structure. BSL-1. 10/01/06.
3. Progress Report:
The stability of seed set and seed composition for two conventional (20-30% oleic acid) and six mid-oleic (50-60% oleic acid) soybean genotypes was investigated using growth chambers set for 12 or 9 hour day lengths. Under short day (9 h) conditions, pod number and seed number at maturity declined significantly compared to a 12 h day for both conventional and mid-oleic genotypes. A bulk seed increase of low phytate soybean lines was completed. Poultry feeding experiments with low phytate and conventional phytate soybean were begun and preliminary data are being analyzed. Protein blot analyses clearly indicate that sera from dogs, pigs, rabbits and fish have antibodies against multiple proteins other than the seed storage proteins. We are collaborating with ARS-SRCC, New Orleans to determine if proteins bound to antibodies against the soy proteins can be identified directly by mass spectrometry. In brief, rabbit antibodies against non seed-storage proteins are enriched and attached to a magnetic bead. The antibody-bead complex is used to purify the antigenic soy proteins and the bound proteins identified using mass spectrometry. If this approach is unsuccessful standard two-dimensional gels electrophoresis can be employed. Carbohydrates associated with antinutritional factors (raffinose, stachyose and phytate) and taste components (monosaccharides, sucrose and starch) were measured in seeds of 1500 soybean mutants. Phytate was also indirectly measured by determining the level of free phosphate. Mutants with increased starch and/or sucrose and decreased levels of antinutritional factors were identified. Some lines planted in the winter nursery were lost because they shattered and were replanted this summer. One interesting line appears to have reduced levels of phytate, raffinose and stachyose.