Characterization of Marker-free Transgenic Soybeans with △6-fatty Acid Desaturase Gene Expressing γ-linolenic Acid Isolation and Identification of Fatty Acid Component from Seed Oil of Microula sikkimensis (Clarke) Hemsl Study on the encapsulation technique of high purity γ-linolenic acid, part 1 ——saponification reaction and saponification value Study on the Expression of Δ6-Fatty Acid Desaturase Gene of Mortierella alpina in Transgenic Tobacco