Fatty Acid Alteration of Plastidic and Extra-Plastidic Membrane Lipids in Metribuzin-Resistant Photoautotrophic Chenopodium rubrum Cells as Compared to Wild-Type Cells

Abstract

The fatty acid compositions of plastidic and extra-plastidic membrane lipids of two metri-buzin-resistant cell lines L4 and L7 of C henopodium rubrum were determined after growth in the absence and in the presence of the herbicide and compared with those o f wild type cells. Fatty acid biosynthesis was markedly affected in all cell lines by metribuzin treatment. In the absence and in the presence of metribuzin alterations of the fatty acid com position of the various lipid classes were, as compared to wild type cells, generally lower in the highly resistant L4 cells than in the less resistant L7 cells. The two resistant cell lines demonstrated a higher degree of unsaturation within the plastidic monogalactosyldiacylglycerols (L4 cells also within plastidic digalactosyldiacylglycerols) and, particularly, within the predominantly extra-plastidic phosphatidylcholines (L7 cells also within the predominantly extra-plastidic phosphatidylethanolamines), whereas the degree of unsaturation was slightly altered in the plastidic phosphatidylglycerols. Within the two metribuzin-resistant cell lines, the highly resis­ tant L4 cells differed from the less resistant L7 cells by increased a-linolenic acid/palmitic acid ratios in both the plastidic and extra-plastidic membrane lipids suggesting that particu­ larly in L4 cells higher proportions of linolenate are formed as a result o f selection pressure. On the other hand, the proportion of linoleate was increased predominantly in extra-plastidic membrane lipids of both L4 and L7 cells which explains a raise in linoleic acid/palmitic acid ratios in both cell lines as compared to wild-type cells. Moreover, in the absence of metri­ buzin decreased proportions o f fram-3-hexadecenoic acid were found in phosphatidylglycer­ ols of L4 and, particularly, of L7 cells as compared to the wild type cells. It is suggested that L4 and L7 cells -having multiple mutations in the psbA gene as observed earlier -are additionally characterized by increased degree of unsaturation of acyl moieties in various polar lipids, e.g. linoleoyl moieties in L4 and L7 cells as well as linolenoyl moieties particularly in highly resistant L4 cells. This increase gives rise to a change in membrane fluidity and may finally lead to increased metribuzin resistance.

Changes in photosynthetic electron transfer and state transitions in an herbicide-resistant D1 mutant from soybean cell cultures

“…This mutant strain showed an unusually high content of saturated (and reduced levels of unsaturated) fatty acids in comparison with WT and, consequently, a more rigid thylakoid membrane matrix [14,16]. Changes in fatty acids unsaturation have also been reported for 14/02/2007 many other plant atrazine-resistant mutants, however, on the contrary, these mutants displayed higher levels of unsaturated lipids [17][18][19][20].…”

Stress Response Monitoring of Photoautotrophic Higher Plant Suspension Cultures by Fluorescence Imaging for High-Throughput Toxic Compound Screening

“…These features circumvent the challenges associated with the analyses of a multi-factorial plant composed of multiple tissues and cell types exposed to diverse endogenous signals and external factors and/or stimuli. Plant suspension cultures are also valuable in the study of the effects of chemicals and environmental stresses, defense response, secondary metabolite formation, ion transport, gene regulation, and signal transduction, biopharmaceutical production, uptake, metabolism, phytoremediation of toxic compounds and plant resistance to herbicides [9]- [15].…”

Photoinhibition and recovery in a herbicide-resistant mutant from Glycine max (L.) Merr. cell cultures deficient in fatty acid unsaturation

“…In addition to this, the chloroplast membrane of STR7 accumulated an unusually high content (20%) of saturated C16:0 and reduced levels of C16:1 and C18:3 unsaturated fatty acids compared to the WT . Changes in fatty acid unsaturation have also been reported in many other atrazine-resistant mutants from plants (Pillai and St. John 1981;Lemoine et al 1986;De Prado et al 1992;Schwenger-Erger et al 2002). The relationship between the psbA mutation and fatty acid unsaturation remains unclear, but it could be related to the influence of photosynthetic electron transport on the activity of fatty acid desaturases (Kis et al 1998).…”