Transgenic Approach to Increase Lysine in Corn

Corn is one of the world's important staples that is consumed by humans and livestock, and a rich source of industrial raw materials. It provides carbohydrate, protein, and oil but low in the essential amino acid lysine. Many different strategies have been used and tested to increase corn lysine through breeding and genetic engineering. Recently, scientists at Monsanto headed by Alessandra Frizzi used a method of simultaneously expressing a deregulating lysine biosynthetic enzyme CordapA and reducing a bifunctional lysine degradation enzyme, LKR/SDH.

The transgene introduced in corn contains Cordap A gene and the inverted gene sequence of LKR/SDH, both genes controlled by one promoter. Expression of inverted sequences induces silencing of the target gene. Transgenic corn grain was found to accumulate free lysine to as much as 4000 ppm compared to 100 ppm in the control. These results proved that this transgenic approach is effective and can be used in manipulating other metabolic pathways that sometimes require expression of one gene and silencing of another.  

The full paper is available to subscribers at http://www.blackwell-synergy.com/action/showFullText?submitFullText=Full+Text+HTML&doi=10.1111%2Fj.1467-7652.2007.00290.x  Non subscribers can read the abstract at http://www.blackwell-synergy.com/doi/abs/10.1111/j.1467-7652.2007.00290.x