skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Expression of a cyanobacterial {del}{sup 6}-desaturase gene results in {gamma}-linolenic acid production in transgenic plants

Abstract

Gamma-linolenic acid (GLA), a nutritionally important fatty acid in human and animal diets, is not produced in oil seed crops. Many oil seed plants, however, produce significant quantities of linoleic acid, a fatty acid that could be converted to GLA by the enzyme {del}{sup 6}-desaturase if it were present. As a first step to producing GLA in oil seed crops, we have cloned a cyanobacterial {del}{sup 6}-desaturase gene. Expression of this gene in transgenic tobacco resulted in GLA accumulation. Octadecatetraenoic acid, a highly unsaturated, industrially important fatty acid, was also found in transgenic tobacco plants expressing the cyanobacterial {del}{sup 6}-desaturase. This is the first example of engineering the production of `novel` polyunsaturated fatty acids in transgenic plants. 28 refs., 4 figs., 1 tab.

Authors:
;  [1]
  1. Texas A & M Univ., College Station, TX (United States)
Publication Date:
OSTI Identifier:
577023
Resource Type:
Journal Article
Resource Relation:
Journal Name: Bio/Technology; Journal Volume: 14; Journal Issue: 5; Other Information: PBD: May 1996
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; LINOLEIC ACID; LINOLENIC ACID; PRODUCTION; TOBACCO; TRANSGENIC PLANTS; CYANOBACTERIA; GENE REGULATION; GENES; ENZYMES; ENZYME ACTIVITY; DNA-CLONING; BIOLOGICAL ACCUMULATION; GENETIC ENGINEERING; LIPIDS; CARBOXYLIC ACIDS; GAS CHROMATOGRAPHY; CHIMERAS; POLYMERASE CHAIN REACTION

Citation Formats

Reddy, A.S., and Thomas, T.L.. Expression of a cyanobacterial {del}{sup 6}-desaturase gene results in {gamma}-linolenic acid production in transgenic plants. United States: N. p., 1996. Web. doi:10.1038/nbt0596-639.
Reddy, A.S., & Thomas, T.L.. Expression of a cyanobacterial {del}{sup 6}-desaturase gene results in {gamma}-linolenic acid production in transgenic plants. United States. doi:10.1038/nbt0596-639.
Reddy, A.S., and Thomas, T.L.. 1996. "Expression of a cyanobacterial {del}{sup 6}-desaturase gene results in {gamma}-linolenic acid production in transgenic plants". United States. doi:10.1038/nbt0596-639.
@article{osti_577023,
title = {Expression of a cyanobacterial {del}{sup 6}-desaturase gene results in {gamma}-linolenic acid production in transgenic plants},
author = {Reddy, A.S. and Thomas, T.L.},
abstractNote = {Gamma-linolenic acid (GLA), a nutritionally important fatty acid in human and animal diets, is not produced in oil seed crops. Many oil seed plants, however, produce significant quantities of linoleic acid, a fatty acid that could be converted to GLA by the enzyme {del}{sup 6}-desaturase if it were present. As a first step to producing GLA in oil seed crops, we have cloned a cyanobacterial {del}{sup 6}-desaturase gene. Expression of this gene in transgenic tobacco resulted in GLA accumulation. Octadecatetraenoic acid, a highly unsaturated, industrially important fatty acid, was also found in transgenic tobacco plants expressing the cyanobacterial {del}{sup 6}-desaturase. This is the first example of engineering the production of `novel` polyunsaturated fatty acids in transgenic plants. 28 refs., 4 figs., 1 tab.},
doi = {10.1038/nbt0596-639},
journal = {Bio/Technology},
number = 5,
volume = 14,
place = {United States},
year = 1996,
month = 5
}
  • Little is known about the metabolic origin of petroselinic acid (18:1[Delta][sup 6cis]), the principal fatty acid of the seed oil of most Umbelliferae, Araliaceae, and Garryaceae species. To examine the possibility that petroselinic acid is the product of an acyl-acyl carrier protein (ACP) desaturase, Western blots of coriander and other Umbelliferae seed extracts were probed with antibodies against the [Delta][sup 9]-stearoyl-ACP desaturase of avocado. In these extracts, proteins of 39 and 36 kDa were detected. Of these, only the 36-kDa peptide was specific to tissues which synthesize petroselinic acid. A cDNA encoding the 36-kDa peptide was isolated from a coriandermore » endosperm cDNA library, placed under control of the cauliflower mosaic virus 35S promoter, and introduced into tobacco by Agrobacterium tumefaciens-mediated transformation. Expression of this cDNA in transgenic tobacco callus was accompanied by the accumulation of petroselinic acid and [Delta][sup 4]-hexadecenoic acid, both of which were absent from control callus. These results demonstrate the involvement of a 36-kDa putative acyl-ACP desaturase in the biosynthetic pathway of petroselinic acid and the ability to produce fatty acids of unusual structure in transgenic plants by the expression of the gene for this desaturase. 27 refs., 5 figs.« less
  • Human keratinocytes in culture were labelled with /sup 14/C-dihomo-gamma-linolenic acid, /sup 14/C-arachidonic acid or /sup 14/C-eicosapentaenoic acid. All three eicosanoid precursor fatty acids were effectively incorporated into the cells. In phospholipids most of the radioactivity was recovered, in neutral lipids a substantial amount, and as free unesterified fatty acids only a minor amount. Most of the radioactivity was found in phosphatidylethanolamine which was also the major phospholipid as measured by phosphorous assay. The incorporation of dihomo-gamma-linolenic acid and arachidonic acid into lipid subfractions was essentially similar. Eicosapentaenoic acid was, however, much less effectively incorporated into phosphatidylinositol + phosphatidylserine and, correspondingly,more » more effectively into triacylglycerols as compared to the two other precursor fatty acids. Once incorporated, the distribution of all three precursor fatty acids was relatively stable, and only minor amounts of fatty acids were released into the culture medium during short term culture (two days). Our study demonstrates that eicosanoid precursor fatty acids are avidly taken up by human keratinocytes and esterified into membrane lipids. The clinical implication of this finding is that dietary manipulations might be employed to cause changes in the fatty acid composition of keratinocytes.« less
  • There is increasing evidence that derivatives of 20-carbon polyunsaturated fatty acids, the eicosanoids, play an important role in the inflammatory responses of the human skin. To better understand the metabolic fate of fatty acids in the skin, the effect of ultraviolet B (UVB) irradiation (280-320 nm) on the distribution and release of /sup 14/C-labeled arachidonic acid, dihomo-gamma-linolenic acid, and eicosapentaenoic acid in human keratinocytes in culture was investigated. Ultraviolet B irradiation induced the release of all three /sup 14/C-labeled fatty acids from the phospholipids, especially from phosphatidylethanolamine, and this was accompanied by increased labeling of the nonphosphorus lipids. This findingmore » suggests that UVB induces a significant liberation of eicosanoid precursor fatty acids from cellular phospholipids, but the liberated fatty acids are largely reincorporated into the nonphosphorus lipids. In conclusion, the present study suggests that not only arachidonic acid but also dihomo-gamma-linolenic acid, and eicosapentaenoic acid might be involved in the UVB irradiation-induced inflammatory reactions of human skin.« less
  • Methyl gamma -linolenate-1-C/sup 14/ was fed to rats, and the fatty acids of depot and organ lipides of the rats were separated chromatographically and counted. The sole highly active fatty acid was arachidonic, which, after hydrogenation and degradation in three steps, was found to have 97% of the activity in carbon atom 3. These results support the hypothesis that gamma - linolenic acid is an intermediate in the conversion of linoleic acid to arachidonic acid. (auth)