Western Europe oleoproteaginous species like rapeseed mainly accumulate oil and protein in their seeds. To become competitive with soybean, seed protein quantity and quality should be improved in rapeseed. The negative correlation existing between seed protein and oil content apparently prevents the possibility to increase protein content without affecting oil content. Exploration of natural and induced genetic variability in the model plant Arabidopsis thaliana allows the identification of several genotypes impaired in this negative correlation. Different genetic approaches have been undertaken in order to isolate genetic factors responsible for the tight control of seed oil and protein homeostasis and this negative correlation. Once isolated in this model plant, such genetic determinants will be identified in important crops such as rapeseed or other oilseed crops in order to manipulate both components independently and thus produce on purposed seeds. In the long term, this research will help breed new varieties that could contribute to reduce Europe's dependence on US soybean import.