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FIGURE 3.4 DGAT activities with different substrates expressing Vernonia DGAT1a and DGAT1b (VgDGAT1a and VgDGAT1b). Va-CoA, vernoyl-CoA; DODAG, dioleoyl-diacyl-glycerol (DAG); DVDAG, divernoyl-DAG.

FIGURE 3.4 DGAT activities with different substrates expressing Vernonia DGAT1a and DGAT1b (VgDGAT1a and VgDGAT1b). Va-CoA, vernoyl-CoA; DODAG, dioleoyl-diacyl-glycerol (DAG); DVDAG, divernoyl-DAG.

Seed Development Stages

FIGURE 3.5 Relative abundance of DGAT1, DGAT2, and PDAT transcripts during castor (Ricinus communis) seed development.

The expression patterns of DGAT1s and DGAT2s in high-vernolic acid accumulators indicate that DGAT2 is of key importance in ricinoleic acid and vernolic acid accumulation (Figure 3.5).

Shockey et al. (2005, 2006) similarly reported that DGAT2 rather than DGAT1 is the main enzyme responsible for selective accumulation of the unusual conjugated fatty acid, eleostearic acid, in tung oil. A 370-bp DGAT2 fragment from Vernonia was cloned, and RACE (rapid amplification of cDNA ends) procedures were performed to clone the full-length cDNA. Southern analyses indicated that there likely are more than one DGAT2 in Vernonia. Vernonia DGAT2 groups with castor and tung DGAT2 based on sequence homology (Figure 3.6).

-CeDGAT2A

-CeDGAT2B

-MmDGAT2

-MrDGAT2A

-MrDGAT2B

-ScDGAT2

-AtDGAT2

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