- Agronomic: corn
- Production Systems: organic agriculture
Transgenic crop varieties, commonly referred to as GMO's (Genetically Modified Organisms), are prohibited from use in certified organic production. However, organic growers planting non-GMO corn varieties cannot control the varieties grown by nearby farmers, who may choose a GMO corn variety. Approximately 80% of commercial field corn seed sold in the U.S. each year is transgenic. A single GMO corn plant commonly produces more than two million pollen grains, which may be carried more than one-half mile by wind. This long distance cross-pollination can result in "adventitious presence" or GMO contamination of the grain of non-GMO varieties. GMO contamination of organically grown corn results in loss of market value for the organic farmer. A genetic "factor" (gene) was identified in corn as early as 1926 (1) that prevented fertilization by pollen that does not carry this gene. Thomas (2) presented a method to transfer this cross-sterility factor to popcorn in 1955. Corn breeding has been an ongoing project of The University of Tennessee for 90 years, and many parent corn lines have been developed (3,4). We will obtain genetic stocks that possess the cross-sterility gene Ga1-S (Ga for gametophyte factor, 1-S identifies the specific allele), and use the method given by Thomas to breed the gene into white and yellow grained public hybrids. All of the commercial dent or field corn hybrids marketed in the U.S. carry the allele ga1-S (recessive form of the gene), which is inactive on the silks of Ga1-S plants. The grain produced on Ga1-S hybrids will be the result of pollination by plants that have the Ga1-S gene. Grain on Ga1-S hybrids grown in the same field as non-Ga1-S GMO hybrids will be free of GMO DNA.
Project objectives from proposal:
1. Genetically convert yellow and white parent corn lines to cross-sterility, so they cannot be pollinated by GMO varieties.
2. Produce hybrid seed from lines developed in objective one, and test hybrids on farms of organic corn producers.