Submitted to: Nature Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 18, 2007
Publication Date: August 15, 2007
Citation: Raboy, V. 2007. The ABCs of low-phytate crops. Nature Biotechnology 25: 874-875 Interpretive Summary: The "low-phytic acid/high available phosphorus" seed trait is of value when grain and legume crops are used in feeds and foods. However, production and use of "low-phytate" crops requires that they also have excellent agronomic characteristics such as high yield so that they are competitive with contemporary hybrids and cultivars. Genetic resources such as "low phytic acid" mutations can be used to produce the desired seed trait, but also can have a negative impact on plant performance and yield. One approach to developing crops that produce low-phytate seed but that have high yields utilizes biotechnology. In this approach, genes that are important to phytic acid synthesis are targeted for regulation just in developing seed, avoiding any changes in gene function during the parent plant's growth. Scientists are Dupont/Pioneer accomplished this by identifying the gene encoded by maize lpa1, it is an "ABC transporter", and using this gene to bioengineer low-phytate varieties of both corn and soybeans.
Technical Abstract: The maize (Zea mays L.) low phytic acid 1 gene, initially defined genetically and mapped by USDA-ARS research, was cloned by scientists at Dupont/Pioneer. Phytic acid (inositol hexaphosphate) represents the major form of phosphorus in seeds and is important to the management of phosphorus in livestock production, as well as important to human nutrition and health. Maize lpa1 was shown to encode an "ATP-binding cassette" (ABC) transporter, termed maize MRP4. The maize lpa1/MRP4 gene represents the first transport function identified as important to inositol hexaphosphate accumulation. Maize and soybean plants were transformed with constructs designed to knock out expression of the MRP4 gene specifically during seed development. This strategy may provide a way to produce high-yielding, low-phytate crops, in that it avoids negative impacts on important processes during vegetative growth.