Modification of fatty acid in rapeseed oil (Brassica napus) by an antisense methodologie

Abstract

Oil seed rape (Brassica napus) is the most productive oil seed crop grown in temperate climates. Regarding the oil quality of rapeseed, improvement has been achieved in the last years. However, the nutritional quality and uses can still be improved by increasing the levels of the oleic acid (C18:1) and decreasing the levels of dietary essential a-linolenic acid (C18:3) for industrial applications and human consumption. High concentrations of this latter fatty acid promote oxidation process which negatively affect the shelf life of oil. Improvement of the C18 fatty acid composition was achieved in the past by inducing high linoleic/Iow a-linolenic acid genotypes via chemical mutagenesis and selection. At present, the isolation of genes involved in lipid metabolism and the development of molecular techniques offer new possibilities to obtain transgenic plants in which target desaturases genes are overexpressed or suppressed. One possible biotechnological approach is based on seed-specific expression of antisense mRNA. In the developing embryo, oleic acid desaturation and the a-linolenic acid synthesis are mainly controlled by the microsomal _12 and _15 desaturases, respectively. Our objectives were to inhibit the expression of these genes via anti-sense RNA to specifically modify the levels of oleic and a-linolenic in rapeseed oil.