BnVTE2-Mediated Vitamin E Modulation Is Associated with Antioxidant Capacity, Fatty Acid Stability, and Seed Longevity in Brassica napus

Vitamin E (tocopherols) is an important lipid-soluble antioxidant that contributes to plant redox homeostasis and seed longevity. To investigate relationships among BnVTE2-dependent tocopherol accumulation, antioxidant capacity, fatty acid stability, and seed storability in rapeseed, we generated Brassica napus lines overexpressing BnVTE2 (OE) and lines with RNA interference-mediated suppression of BnVTE2 (RNAi). BnVTE2 encodes homogentisate phytyltransferase, a key enzyme catalyzing the committed step in tocopherol biosynthesis. Modulation of BnVTE2 expression resulted in corresponding changes in total tocopherol content. OE lines exhibited higher superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities, lower H2O2 and malondialdehyde (MDA) accumulation, and improved seed performance after long-term storage, whereas RNAi lines showed the opposite trends. Transcriptome and network analyses identified lipid-related transcriptional changes and glycerolipid-associated candidate hubs; enrichments in phenylpropanoid biosynthesis and hormone signaling were treated as broader secondary responses rather than direct components of tocopherol metabolism. After 42 months of storage, seeds with higher tocopherol levels retained greater germination capacity and showed reduced lipid peroxidation relative to tocopherol-deficient lines. Together, these findings support an association among BnVTE2-mediated tocopherol accumulation, antioxidant defense, fatty acid stability, and seed longevity in B. napus. Direct validation of glycerolipid remodeling and hub-gene function will be required in future studies.