Copper exposure affects how grapevines process nitrogen. When exposed to copper, grapevines showed lower levels of total nitrogen, nitrate, and amino acids in their roots and leaves. The enzyme nitrate reductase, needed for nitrate assimilation, was significantly reduced in response to copper. Nitrogen metabolism was more affected in roots than in leaves. Roots may use an alternative system involving glutamate dehydrogenase for nitrogen assimilation, while leaves may rely on higher levels of ammonium and glutamine for organic nitrogen needs.