Metabolic Engineering of Arabidopsis for Production of Punicic Acid Using Different Promoters

• Author / Creator

  Song, Ziliang

• Fatty acids with conjugated double bonds play a special role in determining both the nutritional and industrial uses of plant oils. Punicic acid (18:3Δ9cis,11trans,13cis), a conjugated fatty acid naturally enriched in the pomegranate (Punica granatum) seeds, has gained increasing attention from the biotechnology community towards its production in metabolically engineered temperate oilseed crops because of its significant health benefits. The present study focused on selecting the best of four heterologous promoters to drive the over-expression of the P.granatum FATTY ACID CONJUGASE (PgFADX) cDNA as a means of producing punicic acid in the seed oil of transgenic Arabidopsis. Among the four promoters for genes encoding seed storage proteins from different oilseed crop species, the linin promoter resulted in the highest level of punicic acid (19.5% of total fatty acids in Arabidopsis seed oil). Analysis of PgFADX in developing seeds further confirmed that the linin promoter was the best choice to achieve a high level of seed-specific expression of the transgene. The native promoter of the PgFADX gene was also investigated. A 2027-bp upstream fragment of the PgFADX gene isolated from the pomegranate genome was fused to the β-GLUCURONIDASE (GUS) reporter gene. GUS activity, however, was not detected in transformed Arabidopsis. A conserved profile of cis-regulatory elements in the four heterologous promoters were identified and discussed in relation to their possible role in regulating gene expression during plant development. The PgFADX promoter was found deficient in several cis-regulatory elements that may be crucial for seed specific gene expression in Arabidopsis. This might indicate that the transcription factors in Arabidopsis could not recognize the special cis-regulatory elements in the PgFADX promoter as those in pomegranate could to achieve a uniquely high expression level.

• Subjects / Keywords

  • Punicic acid
  • Pomegranate
  • Linin
  • Fatty acid conjugase
  • Metabolic engineering
  • Promoter

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3XW48654

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.