Apparent Role of Phosphatidylcholine in the Metabolism of Petroselinic Acid in Developing Umbelliferae Endosperm

Cahoon, Edgar B.; Ohlrogge, John B.

doi:10.1104/pp.104.3.845

Cited by 56 publications

(36 citation statements)

References 28 publications

(38 reference statements)

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“…Yet another role for PLAMs would be an involvement in the trafficking of plastid-synthesized acyl chains to supply substrates for the ERlocalized synthesis of triacylglycerols. A close connection between plastids and ER may be necessary for efficient channeling of acyl groups and is consistent with labeling kinetics observed during lipid metabolic studies of seed and leaf glycerolipid formation (32,33). The recent report that ␣-carbonic anhydrase is imported to the chloroplast after glycosylation in compartments of the secretory pathway (34) opens up speculation that PLAMs and PLAMchloroplast MCSs also partake in protein trafficking.…”

Section: Discussionsupporting

confidence: 73%

Optical Manipulation Reveals Strong Attracting Forces at Membrane Contact Sites between Endoplasmic Reticulum and Chloroplasts

Andersson

Goksör

Sandelius

2007

Journal of Biological Chemistry

194

144

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Here we present the first demonstration of the physical association between membranes involved in MCSs: by using optical imaging and manipulation, strong attracting forces between ER and chloroplasts are revealed. We used Arabidopsis thaliana expressing green fluorescent protein in the ER lumen and observed leaf protoplasts by confocal microscopy. The ER network was evident, with ER branch end points apparently localized at chloroplast surfaces. After rupture of a protoplast using a laser scalpel, the cell content was released. ER fragments remained attached to the released chloroplasts and could be stretched out by optical tweezers. The applied force, 400 pN, could not drag a chloroplast free from its attached ER, which could reflect protein-protein interactions at the ER-chloroplast MCSs. As chloroplasts rely on import of ER-synthesized lipids, we propose that lipid transfer occurs at these MCSs. We suggest that lipid transfer at the MCSs also occurs in the opposite direction, for example to channel plastid-synthesized acyl groups to supply substrates for ER-localized synthesis of membrane and storage lipids.

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Section: Discussionsupporting

confidence: 73%

Optical Manipulation Reveals Strong Attracting Forces at Membrane Contact Sites between Endoplasmic Reticulum and Chloroplasts

Andersson

Goksör

Sandelius

2007

Journal of Biological Chemistry

194

144

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“…To determine the fatty acid composition and the relative amounts of individual lipids, the silica gel from each lipid spot was scraped and transmethylated in a screw-capped tube with an appropriate amount of 17-carbon saturated fatty acid (17:O) to act as an internal standard. For the preparative isolation of individual lipids, total lipids were first separated into neutral lipids, glycolipids, sulfolipids, and phosphatides by column chromatography on silicic acid (Silicar CC4; Mallinckrodt, Chesterfield, MO) following the method described by Lynch and Steponkus (1987) and modified by Cahoon and Ohlrogge (1994). Neutra1 lipids containing free fatty acids were further separated by column chromatography on silicic acid (Kates, 1986) prior to isolation by onedimensional TLC on silica gel G with development in chloroform:acetone (96:4, v / v).…”

Section: Fatty Acid and Lipid Analysesmentioning

confidence: 99%

Intracellular Levels of Free Linolenic and Linoleic Acids Increase in Tomato Leaves in Response to Wounding

et al. 1996

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An intracellular signaling pathway for activating plant defense genes against attacking herbivores and pathogens is mediated by a lipid-based signal transduction cascade. I n this pathway, linolenic acid (18:3) is proposed to be liberated from cell membranes and is converted to cyclopentanones that are involved in transcriptional regulation of defense genes, analogously to prostaglandin synthesis and function in animals. Levels of 18:3 and linoleic acid in tomato (Lycopersicon esculentum) leaves increased within 1 h when the leaves were wounded with a hemostat across the main vein t o simulate herbivore attacks. The increase correlated with the time course of accumulation of jasmonic acid, a cyciopentanone product of 18:3, that had previously been shown t o increase i n leaves in response both to wounding and to elicitors of plant defense genes. One hour after wounding, at least a 15-fold excess of 18:3 was found over that required to account for the levels of newly synthesized jasmonic acid. The free fatty acids in both control and wounded leaves accounted for less than 0.25% of the total fatty acids. However, the total lipid contents of the leaves remained relatively unchanged up to 8 h after wounding, indicating that extensive loss of lipids did not occur, although a gradual decrease in polar lipids was observed, mainly in monogalactosyl diacylglycerol of chloroplast lipids. The data support a role for lipid release as a key step in the signaling events that activate defense genes in tomato leaves in response t o wounding by attacking herbivores. In leaves of tomato (Lycopersicon esculentum) plants, severa1defense genes are activated by herbivore attacks or other mechanical wounds that crush the tissues (Ryan, 1992; Schaller and Ryan, 1996). Among the activated genes are those encoding Ser, aspartyl, and Cys proteinase i h b i t o r s and the enzyme polyphenol oxidase. These genes are activated in leaves both nearby and distant from the wound sites (Ryan, 1992; Schaller and Ryan, 1996). The signals released to local cells have been attributed to (a) oligosaccharide fragments of the plant and/or pathogen cell walls (Bishop et al., 1984;Darvill and Albersheim, 1984), (b) 18:3 (Farmer and Ryan, 1992), a major component of plant membranes, and (c)

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“…Th e argentation TLC allowed a physical separation of the FAMEs by the number and position of double bonds as well as C chain length. Plate preparation, development, and visualization were performed following the methods detailed by Cahoon and Ohlrogge (1994). Th e FAME bands were identifi ed by comparison with known standards (16:1, 18:1, 20:1, and 22:1, Sigma-Aldrich Chemical Co.).…”

Section: Methodsmentioning

confidence: 99%

Carbon Allocation, Belowground Transfers, and Lipid Turnover in a Plant-Microbial Association

Calderón

Schultz

Paul

2012

Soil Science Society of America Journal

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Apparent Role of Phosphatidylcholine in the Metabolism of Petroselinic Acid in Developing Umbelliferae Endosperm

Cited by 56 publications

References 28 publications

Optical Manipulation Reveals Strong Attracting Forces at Membrane Contact Sites between Endoplasmic Reticulum and Chloroplasts

Optical Manipulation Reveals Strong Attracting Forces at Membrane Contact Sites between Endoplasmic Reticulum and Chloroplasts

Intracellular Levels of Free Linolenic and Linoleic Acids Increase in Tomato Leaves in Response to Wounding

Carbon Allocation, Belowground Transfers, and Lipid Turnover in a Plant-Microbial Association

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