Figure 4.

Diversion of fatty acid flux into unusual monounsaturated fatty acids derived from the Δ⁹ desaturation of 16:0-ACP by expression of the G188L mutant of the castor Δ⁹-18:0-ACP DES. Consistent with its in vitro activity (see Fig. 3B), expression of the G188L mutant in transgenic Arabidopsis seeds results in preferential use of 16:0-ACP pools to produce the unusual plant fatty acids 16:1Δ⁹, 18:1Δ¹¹, and 20:1Δ¹³, as illustrated in A. This contrasts with the wild-type Δ⁹-18:0-ACP DES, which preferentially uses pools of 18:0-ACP to generate 18:1Δ⁹ and its elongation products 20:1Δ¹¹ and 22:1Δ¹³. (B) The total amount of 16:1Δ⁹, 18:1Δ¹¹, and 20:1Δ¹³ in single segregating seeds from a representative T1 plant transformed with expression constructs for either the wild-type castor Δ⁹-18:0-ACP DES (Wt Δ⁹), the G188L mutant (G188L), or the vector alone (Vector) in a wild-type or fab1 Arabidopsis background. Each data point represents the fatty acid composition of a single seed, and for each of the transformation events shown, 25–35 single seeds were analyzed.