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In plants, the enzymes fatty acid dehydrogenase 2 (FAD2) and fatty acid elongase 1 (FAE1) have been shown in previous studies to play important roles in the de novo biosynthesis of fatty acids. However, the effects of depressed expression of FAD2 and FAE1 on seed storage compounds accumulation remains to be elucidated. In this study, we produced RNA interfering transgenic rapeseeds lines, BnFAD2-Ri, BnFAE1-Ri and BnFAD2/BnFAE1-Ri, which exhibited depressed expression of the BnFAD2 and BnFAE1 genes under the control of seed-specific napin A promoter. These transgenic rapeseeds showed normal growth and development as compared with the wild type (CY2). Depressed expression of BnFAD2 and BnFAE1 genes modified fatty acid profiles, leading to increased oleic acid and decreased erucic acid contents in transgenic seeds. Consistent with these results, the ratios of C18:1/C18:2 and C18:1/C18:3 in C18 unsaturated fatty acids were greatly increased due to increased oleic acid content in transgenic seeds. Moreover, depressed expression of BnFAD2 and BnFAE1 genes resulted in slightly decreased oil contents and increased protein contents in transgenic seeds. Our results demonstrated that depressed expression of BnFAD2 and BnFAE1 greatly improves seed nutritional quality by modulating the fatty acid metabolism and storage products accumulation and that BnFAD2 and BnFAE1 are reliable targets for genetic improvement of rapeseed in seed nutritional quality., (Copyright © 2017 Elsevier B.V. All rights reserved.)

The expression of At4g34880 gene encoding amidase in Arabidopsis was characterized in this study. A promoter region of 1.5 kb on the upstream of the start codon of the gene (referred as AmidP) was fused with uidA (GUS) reporter gene, and transformed into Arabidopsis plant for determining its spatial expression. The results indicated that AmidP drived GUS expression in vascular system, predominately in leaves. Truncation analysis of AmidP demonstrated that VASCULAR VEIN ELEMENT (VVE) motif with a region of 176 bp sequence (-1500 to -1324) was necessary and sufficient to direct the vascular vein specific GUS expression in the transgenic plant. Tandem copy of VVE increased vascular system expression, and 5'- and 3'- deletions of VVE motif in combination with a truncated -65 CaMV 35S minimal promoter showed that 11bp cis-acting element, naming DOF2 domain, played an essential role for the vascular vein specific expression. Meanwhile, it was also observed that the other cis-acting elements among the VVE region are also associated with specificity or strength of GUS activities in vascular system.