Generation Of High Oleic Acid Soybean Using Gene-silencing Technique

As a major component of plant fatty acid, oleic acid with the oxidative stability, flavor characteristics and physical properties contributes significantly to decrease the risk of cardiovascular disease due to the effect on lessening low-density lipoprotein cholesterol in the bloodstream. Recent researches showed that oleic acid could also decline the risk of the breast cancer development in women. There is a growing trend of producing high oleic crops using molecular techniques such as conventional selection, induced mutation and, more recently, post-transcriptional gene silencing (PTGS). In particular, PTGS has been used to down- regulate the activity of the desaturase enzymes that control the synthesis of the major seed fatty acids. However, the antisense and cosuppression strategies used in fatty acid modification have variable and unpredictable effectiveness and generally require the selection from large populations of transgenic plants to obtain an acceptable number of lines exhibiting sufficient degrees of target gene suppression. Recently, a much more effective methods of silencing plant genes have been developed based on the discovery that PTGS can be invoked at very high frequency using the inverted-repeat DNA constructs. Specifically designed genetic inverted repeats constructs resulted in gene silencing. This inverted repeats that encode RNA have regions of self-complementarity and can reliably generate hairpin RNA (hpRNA) transcripts that invoke sequence-specific RNA degradation. We have genetically modified the fatty acid composition of soybean (Glycine max) seed oil using the technique of hairpin RNA-mediated gene silencing. By this technique, the key fatty acid desaturease gene( gmFAD2-1) encoding oledyl-phosphatidylcholineω-6 desaturease was down-regulated resulting in the consequently modification of the fatty acid composition of peanut oil with high oleic oil content. Hairpin RNA-encoding gene constructs (HP) was driven by the seed-specific soybean lectin promoter and tranfered into soybean by Agrobacterium tumefacien-mediated method targetting against gmFAD2-1. Identification of transgenic plants by PCR revealed that the constructs had integrated in the plant genome.