Division of Plant Sciences
The primary focus of my research program is producing modifications of soybean proteins to improve composition, produce novel products, and reduce allergenicity. This will increase soybean utilization as both food and feed. Parallel objectives are to investigate the control and regulation of protein expression and accumulation, including collateral gene expression as the consequence of genetic modification. My laboratory has additional secondary projects that include two broad investigations with multi-institutional interactions. These projects include one focusing on the gene expression and cell biology of plants exposed to subfreezing temperatures and another on dinoflagellate genomics.
The immunodominant human allergen of soybean seeds is a cysteine protease family member called P34 or Gly m Bd 30K. P34 is accumulated at high levels in maturing seeds and in small quantities in vegetative tissues, where it may have a pathogen-resistance role. Among cysteine proteases, P34 is unique in possessing a glycine substitution for an otherwise invariant cysteine in the active site. Among soybean sensitive people, P34 accounts for a large majority of IgE crossreactivity. Soybean sensitivity is also widespread among farmed animals ranging from pigs to salmon. Human IgE binding epitopes have been mapped, and the allergenic epitopes consist of fourteen distinct sites.
A seed-specific silencing of P34 has been achieved, and homozygous lines completely lacking P34 are now growing in field tests. P34-silenced soybean seeds have identical protein composition and protein/oil ratios compared to the wild type. The P34-silenced lines grow normally and are apparently identical to the wild type in the development of the plant and in the formation of the seed. The protein storage vacuoles that would sequester the P34 protein are not altered in the silenced line. Proteomic analysis of the P34-silenced line in comparison with the wild type demonstrates there are no other collateral changes in protein composition in response to P34 suppression. These results show that it is feasible to use biotechnology to suppress a major human allergen in crops, implying that widespread use of this approach can improve the safety of food for sensitive people.