Production Of Α-linolenic Acid Research Articles

Functional characterization and expression profile of microsomal FAD2 and FAD3 genes involved in linoleic and α-linolenic acid production in Leucas cephalotes.

The online version contains supplementary material available at 10.1007/s12298-021-01016-z.

Fatty acid desaturases modulated octadecanoid pathway in Sesame

Omega 3 fatty acid desaturases are involved in the production of α-linolenic acid (LNA) an essential omega 3 fatty acid, which is present in only traces in sesame seeds. LNA is the precursor for jasmonic acid which is the end product of octadecanoid pathway. This study was undertaken to analyze the key components of octadecanoid pathway and its relationship with fatty acid content in sesame. Fatty acid desaturation and membrane fluidity are modulated differentially in various stresses. Sesame seedlings were subjected to transient stress to analyse the octadecanoid pathway and its impact on fatty acid desaturation. The mRNA levels of omega 3 desaturases and LNA content were higher in cold stressed sesame seedlings than heat, drought and salinity stresses. The LOX activity and MDA content were higher in heat stressed sesame seedlings. Jasmonic acid content was higher in salinity stressed seedlings while abscisic acid registered the highest in drought stressed seedlings. Chloroplast fatty acid desaturase genes expression was found to increase the LNA content in cold stressed seedlings. The level of membrane damage measured by lipid peroxidation in terms of LOX activity and MDA content were found to be minimal in cold stressed seedling. This suggests a possible role of LNA in membrane fluidity and cold acclimation in sesame. A synergistic role of JA and ABA is also suspected in abiotic stress tolerance in sesame.

Production of α-linolenic Acid by an Oleaginous Green Algae Acutodesmus obliquus Isolated from Malaysia

The main purpose of this study is to provide information on the biochemical composition of the total lipid extract of three different native freshwater microalgae namely Acutodesmus obliquus CN01, Chlorella sp. Carolina-15-2069, and Chlorella vulgaris NIES-1269 at different growth phases, cultured under standardized conditions that will be useful for commercialization purposes due to the content of α-linolenic acid (ALA), a type of omega-3 fatty acids. We monitored growth, biomass accumulation, chlorophyll content, lipid content and fatty acids composition in all three freshwater microalgae. In addition, this study seeks to throw some light on the lipid content of a newly isolated freshwater green alga Acutodesmus obliquus CN01 which have shown to give significant quantities of ALA, an added nutritional value to this microalga oil. Acutodesmus obliquus CN01 exhibited the fastest growth rate among the three microalgae used. Biomass was shown to be enhanced in the nitrogen enrichment medium. The outcomes from this study indicated that newly isolated Acutodesmus obliquus CN01 from Malaysia cultured under normal condition showed fast growth rate with high lipid content and also high ALA content. Therefore, from this study, Acutodesmus obliquus CN01 was identified as species of choice to be further explored for its potential to produce omega-3 fatty acids.

Enhancement of biomass, lipids, and polyunsaturated fatty acid (PUFA) production in Nannochloropsis oceanica with a combination of single wavelength light emitting diodes (LEDs) and low temperature in a three-phase culture system

A three-phase culture system combining blue (465 nm) light-emitting diode (LED) wavelength as the first phase, green (550 nm) as the second phase, and temperature stress as the third phase was applied to a Nannochloropsis oceanica culture in 14-L photobioreactors. Microalgal growth promotion parameters were optimized in the first phase, followed by green LED stress for lipid production in the second phase. Maximum biomass and lipid production values of 0.75 gdcw L−1 and 57.6% (w/w) were obtained at an aeration rate of 0.50 vvm, with a light intensity of 250 µmol m−2 s−1 and 24:0 h light/dark cycle. Culture temperatures of 15, 10 and 5 °C were applied in the third phase, where temperature stress induced the production of monounsaturated and polyunsaturated fatty acid synthesis in N. oceanica. The production of α-linolenic acid, eicosapentaenoic acid and docosahexaenoic acid increased by 52% (w/w), 96% (w/w), and 77% (w/w), respectively, at 5 °C in the third phase.

OeFAD8, OeLIP and OeOSM expression and activity in cold-acclimation of Olea europaea, a perennial dicot without winter-dormancy.

Main conclusionCold-acclimation genes in woody dicots without winter-dormancy, e.g., olive-tree, need investigation. Positive relationships betweenOeFAD8, OeOSM, andOeLIP19and olive-tree cold-acclimation exist, and couple with increased lipid unsaturation and cutinisation.Olive-tree is a woody species with no winter-dormancy and low frost-tolerance. However, cold-tolerant genotypes were empirically selected, highlighting that cold-acclimation might be acquired. Proteins needed for olive-tree cold-acclimation are unknown, even if roles for osmotin (OeOSM) as leaf cryoprotectant, and seed lipid-transfer protein for endosperm cutinisation under cold, were demonstrated. In other species, FAD8, coding a desaturase producing α-linolenic acid, is activated by temperature-lowering, concomitantly with bZIP-LIP19 genes. The research was focussed on finding OeLIP19 gene(s) in olive-tree genome, and analyze it/their expression, and that of OeFAD8 and OeOSM, in drupes and leaves under different cold-conditions/developmental stages/genotypes, in comparison with changes in unsaturated lipids and cell wall cutinisation. Cold-induced cytosolic calcium transients always occurred in leaves/drupes of some genotypes, e.g., Moraiolo, but ceased in others, e.g., Canino, at specific drupe stages/cold-treatments, suggesting cold-acclimation acquisition only in the latter genotypes. Canino and Moraiolo were selected for further analyses. Cold-acclimation in Canino was confirmed by an electrolyte leakage from leaf/drupe membranes highly reduced in comparison with Moraiolo. Strong increases in fruit-epicarp/leaf-epidermis cutinisation characterized cold-acclimated Canino, and positively coupled with OeOSM expression, and immunolocalization of the coded protein. OeFAD8 expression increased with cold-acclimation, as the production of α-linolenic acid, and related compounds. An OeLIP19 gene was isolated. Its levels changed with a trend similar to OeFAD8. All together, results sustain a positive relationship between OeFAD8, OeOSM and OeLIP19 expression in olive-tree cold-acclimation. The parallel changes in unsaturated lipids and cutinisation concur to suggest orchestrated roles of the coded proteins in the process.Electronic supplementary materialThe online version of this article (doi:10.1007/s00425-016-2490-x) contains supplementary material, which is available to authorized users.

α-Linolenic acid concentration and not wounding per se is the key regulator of octadecanoid (oxylipin) pathway activity in rice (Oryza sativa L.) leaves

Using an in vitro system composed of crushed leaf tissues to simulate the wounding response in rice leaves, we established that synthesis of jasmonic acid (JA) and jasmonic acid-isoleucine (JA-Ile) can only occur in unwounded tissue and, in wounded tissue, that only the chloroplast-located section of the octadecanoid pathway is active, resulting in the accumulation of 12-oxo-phytodienoic acid (OPDA). We further showed that OPDA accumulation in vitro was inhibited by 90% using the general lipase inhibitor, tetrahydrolipstatin, indicating that production of α-linolenic acid was the rate-limiting step in octadecanoid pathway activity in rice following wounding and the enzyme capacity for an active pathway was already present. We confirmed this result by showing that added α-linolenic acid stimulated OPDA synthesis in vitro and stimulated OPDA, JA and JA-Ile synthesis in vivo in unwounded tissue. Thus, the response to wounding can be mimicked by the provision of free α-linolenic acid. Our results draw attention to the key importance of lipase activity in initiation of JA and JA-Ile biosynthesis and our lack of knowledge of the cognate lipase(s), lipase substrate identity and mechanism(s) of activation in wounded and unwounded tissue.

Light-induced expression of fatty acid desaturase genes.

In cyanobacterial cells, fatty acid desaturation is one of the crucial steps in the acclimation processes to low-temperature conditions. The expression of all the four acyl lipid desaturase genes of Synechocystis PCC 6803 was studied as a function of temperature and separately as a function of light. We used cells grown at 25 degreesC in light-activated heterotrophic growth conditions. In these cells, the production of alpha-linolenic acid and 18:4 fatty acids was negligible and the synthesis of gamma-linolenic acid was remarkably suppressed compared with those of the cells grown photoautotrophically. The cells grown in the light in the presence of glucose showed no difference in fatty acid composition compared with cells grown photoautotrophically. The level of desC mRNA for delta9 desaturase was not affected by either the temperature or the light. It was constitutively expressed at 25 degreesC with and without illumination. The level of desB transcripts was negligible in the dark-grown cells and was enhanced about 10-fold by exposure of the cells to light. The maximum level of expression occurred within 15 min. The level of desA and desD mRNAs was higher in dark-grown cells than that of desB mRNA for omega3 desaturase. However, the induction of both desA and desD mRNAs for delta12 and delta6 desaturases, respectively, was enhanced by light about 10-fold. Rifampicin, chloramphenicol, and 3-(3, 4-dichlorophenyl)-1,1-dimethylurea completely blocked the induction of the expression of desA, desB, and desD. Consequently, we suggest the regulatory role of light via photosynthetic processes in the induction of the expression of acyl lipid desaturases.