Levels of polyunsaturated fatty acids correlate with growth rate in plant cell cultures

Abstract

In higher plants, fatty acids (FAs) with 18 carbons (18C) represent about 70% of total FAs, the most abundant species being 18:2 and 18:3. These two polyunsaturated FAs (PUFAs) represent about 55% of total FAs in Arabidopsis cell suspension cultures, whereas 18:1 represents about 10%. The level of PUFAs may vary, depending on ill-defined factors. Here, we compared various sets of plant cell cultures and noticed a correlation between the growth rate of a cell population and the level of unsaturation of 18C FAs. These observations suggest that the final level of PUFAs might depend in part on the rate of cell division, and that FAD2 and FAD3 desaturases, which are respectively responsible for the formation of 18:2 and 18:3 on phospholipids, have limiting activities in fast-growing cultures. In plant cell culture, phosphate (Pi) deprivation is known to impair cell division and to trigger lipid remodeling. We observed that Pi starvation had no effect on the expression of FAD genes, and that the level of PUFAs in this situation was also correlated with the growth rate. Thus, the level of PUFAs appears as a hallmark in determining cell maturity and aging.

LYSOPHOSPHATIDIC ACID ACYLTRANSFERASES 4 and 5 are involved in glycerolipid metabolism and nitrogen starvation response in Arabidopsis

“…This finding does not necessarily imply less incorporation of 18:1, because PA produced by LPAT activity may contain a large amount of polyunsaturated fatty acids according to the established model of acyl editing (Bates et al ., ). In plant cell culture, levels of polyunsaturated fatty acids correlate with growth rate (Meï et al ., ); however, lpat4‐1 lpat5‐1 showed an altered ratio even under the N+ condition with no significant growth retardation. Possibly, the change may be associated with increased desaturation of 18:1 that was invested in PC biosynthesis, whose mechanism awaits further investigation.…”

C1 Metabolism Inhibition and Nitrogen Deprivation Trigger Triacylglycerol Accumulation in Arabidopsis thaliana Cell Cultures and Highlight a Role of NPC in Phosphatidylcholine-to-Triacylglycerol Pathway

“…It must be noted that, even if the glycerolipid composition (distribution) is relatively robust in these cells, variations in the total amount of lipids can be observed from one culture to another (Meï et al, 2015). Thus, data from each assay were always compared to a control originating from the same culture batch as the treated cells (see Materials and Methods section).…”

“…To correct inherent variations from one culture to another (Meï et al, 2015), a control was systematically run for each experiment and data were analyzed as fold change versus the corresponding controls. Quantifications were normalized by multiplying the experiment/control ratio by the average value of the control.…”

Reorganization of Acyl Flux through the Lipid Metabolic Network in Oil-Accumulating Tobacco Leaves

“…3C) is also consistent with an increased rate of acyl flux through PC, because membrane lipid desaturation is dependent on both the rate of desaturation and the rate of acyl flux through the membrane lipid. Increases in the fatty acid synthesis rate have been demonstrated to increase 18:1 and decrease PUFA content of membrane lipids (Maatta et al, 2012;Meï et al, 2015;Botella et al, 2016). Considering that the engineering of a very large pull of acyl chains into TAG in the HO line only increases PC acyl editing instead of drawing acyl chains away from it, PC acyl editing may be considered a key part of fatty acid export from the plastid into the eukaryotic pathway.…”