Soybean LL27 and LL55 Genes
This molecular test applies to the screening of soybean seeds for their tolerance to Liberty® herbicide. Liberty-Link soybeans are genetically modified soybeans that have resistance to topical applications of glufosinate. Glufosinate-ammonium, the active ingredient of Liberty® herbicide, acts by inhibition of the glutamine synthetase enzyme, which causes ammonia build-up in the cell of a plant. The ammonia is toxic to the cells of the plant. Plants containing the LL27 and LL55 events contain a bacterial gene that encodes for a protein called phosphinothricin acetyl transferase (PAT). PAT is an enzyme that controls resistance by detoxifying the Liberty herbicide molecule (glufosinate-ammonium). Genetically engineered plants can make the PAT enzyme and breakdown Liberty before it can bind to the enzyme glutamine synthetase. This enzyme allows plants to make certain amino acids and recycle ammonium.
A sample of 200 seeds is to be submitted for testing. A sample of 200 seeds allows for retesting in the case of failure of the test, or other reasons.
Discovery Seed Labs will test 32 individual seeds by PCR for the presence of LL27 and LL55 for CFIA variety registration purposes. If all 32 individual seeds test positive by PCR for the LL27 and LL55 events, it can be concluded that the seed lot has >90% purity for the event LL27 and LL55. If any one of the 32 seeds tests negative for the event, then the lot is not certified as >90% pure for LL27 and LL55, and the applicant could ask for a further 68 seeds to be tested by PCR to confirm that the purity is above 90%. Lots will be certified >90% pure (@95% certainty) if a total of 4 or less of the total 100 seeds tested are negative for the LL27 and LL55 events.