High environmental stress yields greater tocotrienol content while changing vitamin E profiles of wild emmer wheat seeds

Vitamin E is an essential human nutrient that was first isolated from wheat. Emmer wheat, the cereal of Old World agriculture and a precursor to durum wheat, grows wild in the Fertile Crescent. Evolution Canyon, Israel, provides a microsite that models effects of contrasting environments. The north-facing and south-facing slopes exhibit low and high stress environments, respectively. Wild emmer wheat seeds were collected from both slopes and seed tocochromanol contents measured to test the hypothesis that high stress alters emmer wheat seed tocol-omics. Seeds from high stress areas contained more total vitamin E (108±15 nmol/g) than seeds from low stress environments (80±17 nmol/g, P=.0004). Vitamin E profiles within samples from these different environments revealed significant differences in isoform concentrations. Within each region, β- plus γ-tocotrienols represented the highest concentration of wheat tocotrienols (high stress, P<.0001; low stress, P<.0001), while α-tocopherol represented the highest concentration of the tocopherols (high stress, P=.0002; low stress, P<.0001). Percentages of both δ-tocotrienol and δ-tocopherol increased in high stress conditions. Changes under higher stress apparently are due to increased pathway flux toward more tocotrienol production. The production of more δ-isoforms suggests increased flow through a divergent path controlled by the VTE1 gene. Hence, stress conditions alter plant responses such that vitamin E profiles are changed, likely an attempt to provide additional antioxidant activity to promote seed viability and longevity.