Field performance of terpene-producing Camelina sativa

Abstract

Bioengineered lines of the low-input oil seed crop Camelina sativa (Camelina), augmented to accumulate the monoterpene (4S)-limonene, the sesquiterpene (+)-δ-cadinene, or the sesquiterpene (+)-5-epi-aristolochene in seed, were evaluated for two growing seasons under field conditions to determine performance of the introduced traits in an agricultural setup including the effects on overall plant fitness, and total seed yield. Field-grown Camelina plants were further compared to greenhouse-grown plants to evaluate commonalities and differences resulting from cultivation under either controlled or agriculturally relevant growth conditions. Morphological appearance and plant height differed marginally between transgenic and wild-type plants under both greenhouse and field conditions, indicating low impact of the terpene production traits toward overall plant fitness. Total seed yield, however, was independent of the growth conditions and was reduced in Camelina lines producing (4S)-limonene by 48% on average and by 30% on average for (+)-5-epi-aristolochene producing lines. Conversely, (+)-δ-cadinene producing Camelina seed yields remained wild-type equivalent. Additional investigations included seed terpene accumulation, seed oil amount, and seed fatty acid composition. Terpene accumulation was reduced up to 22% for field-grown plants as compared to greenhouse-grown plants. Seed oil amounts were similar under greenhouse and field conditions but were consistently lowered by 2–5% for terpene producing lines. Similarly, seed oil composition remained stable under both field and greenhouse conditions, but generally favored a more energy dense phenotype in terpene producing Camelina lines. Lastly, outcrossing of transgenic traits to adjacent wild-type Camelina plants was observed under field but not greenhouse conditions.