Leaf fatty acids

Table V. A Comparison of Plant Leaf Fatty Acids...

Figure 7, Scheme for VOC formation from leaf fatty acids following wounding. The enzymatic origins of hexanal and hexenal family VOCs are shown, and the unique or major positive ions detected by PTR-MS are indicated in parentheses for many of these VOCs. Abbreviations ADH, alcohol dehydrogenase AT, acetyl transferase IF, isomerization factor. Reprinted with permission of the American Geophysical Union from Ref. [66]. 

Mongrand, S Badoc, A Patouille, B Lacomblez, C Chavent, M Bessoule, JJ. Chemotaxonomy of the Rubiaceae family based on leaf fatty acid composition. 

Although the number of fatty acids detected in plant tissues approaches 300, most of them only occur in a few plant species (Hitchcock and Nichols, 1971). The major fatty acids are all saturated or unsaturated monocarboxylic acids with an unbranched even-numbered carbon chain. The saturated fatty acids, lauric (dodecanoic), myristic (tetradecanoic), palmitic (hexadeca-noic), and stearic (octadecanoic), and the unsaturated fatty acids, oleic (cis-9-octadecenoic), linoleic (c/5 -9,cw-12-octadecadienoic), and linolenic (all-cij-9,12,15-octadecatrienoic (Table I), together account for almost all of the fatty acid content of higher plants. For example, about 94% of the total fatty acids of commercial oils and 89-97% of leaf fatty acids consist of these seven structures alone. It will be noted that the unsaturated acids all contain a cis-9 double bond and that the polyunsaturated acids contain a methylene-interrupted structure. The four saturated fatty acids differ from each other by two carbons. These structural relationships are due to the principal pathways of fatty acid biosynthesis in plants (see Stumpf, this volume. Chapter 7). 

As mentioned earlier, many seed oils produce a fatty acid that is different from the usual leaf fatty acids and which is characteristic of the plant family (Table II) (Smith, 1970 Hitchcock and Nichols, 1971). In general this makes a useful marker for seed oil development (Fig. 7). Caution is needed, since the characteristic fatty acid is not always exclusive to the oil. Appelqvist (1975) has demonstrated the presence of the monoenoic acid in the hypocotyls and testa ofB. napus, as well as in the cotyledons. It should be noted, however, that the structure of the major C22 monoenoic acid in the testa is not that of erucic acid (cis-13-docosenoic acid) but of an isomer, cis-15-docosenoic acid (Table VIII). Thus, if whole seeds are used in tracer studies of erucic acid biosynthesis or compartmentation, care must be taken in the interpretation of results if anjdysis is made only of the whole C22 monoene fraction (Appelqvist, 1975). Again it is emphasized that, although the subcellular compartmentation of erucic acid may not be exclusive to the major sites of oil storage, the compartmentation within lipid classes is absolutely exclusive to the triacyigiycerols as opposed to the polar lipids (Table III). 

Figure 2. Effect of glycerol feeding to whole JB19 and WT plants on their leaf fatty acid composition.

Table 1. Leaf fatty acid compositions of wild type (WT) Arabidopsis, the fab2 line and the fad3 fad fads triple mutant.

Constitutive expression of California bay medium chain acyl-ACP thioesterase in Brassica napus resulted in medium chain acyl-ACP thioesterase activity in transformed leaf tissue without alteration of leaf fatty acid composition. [ C] Labelling studies of intact leaf discs, chloroplasts and protoplasts were used to evaluate if medium chain acyl moieties are produced in transformed leaves. The possible metabolism of medium chain fatty acids in leaf via P-oxidation is discussed. 

The rate of MCTE activity was also compared to that of oleoyl-ACP thioesterase (OTE) activity. Seed OTE activity was fairly constant in all transformants and the wild type, with a specific activity of approximately 70pmol/min/mg protein. However, leaf OTE activity in the 35S-MCTE transformants was slightly increased, at approximately lOOpmol/min/mg protein, compared to leaf wild type OTE activity at approximately 65pmol/min/mg protein. This may indicate that the total rate of fatty acid synthesis in 35S-MCTE transformed leaves is increased by the introduction of MCTE activity. Since a similar increase in the rate of OTE activity was not observed in the 35S-MCTE tr isformed seeds, any proposed increase in leaf fatty acid synthesis does not appear to have any effect on the total amount of seed oil deposition. 

Light and photosynthetic electron transport convert DPEs into free radicals of undetermined stmcture. The radicals produced in the presence of the bipyridinium and DPE herbicides decrease leaf chlorophyll and carotenoid content and initiate general destmction of chloroplasts with concomitant formation of short-chain hydrocarbons from polyunsaturated fatty acids (37,97). 

After the extraction of lipid and nonlipid components from the leaves of mandarin orange Citrus reticulata, the lipid fraction was further separated by PTLC to determine different lipid classes that affect the chemical deterrence of C. reticulata to the leaf cutting ecat Acromyrmex octopinosus. These lipids seem to be less attractive to the ants [81a]. The metabolism of palmitate in the peripheral nerves of normal and Trembler mice was studied, and the polar lipid fraction purified by PTLC was used to determine the fatty acid composition. It was found that the fatty acid composition of the polar fraction was abnormal, correlating with the decreased overall palmitate elongation and severely decreased synthesis of saturated long-chain fatty acids (in mutant nerves) [81b]. 

Waxes are biosynthesized by plants (e.g., leaf cuticular coatings) and insects (e.g., beeswax). Their chemical constituents vary with plant or animal type, but are mainly esters made from long-chain alcohols (C22-C34) and fatty acids with even carbon numbers dominant (Fig. 7.11). They may also contain alkanes, secondary alcohols, and ketones. The majority of wax components are fully saturated. The ester in waxes is more resistant to hydrolysis than the ester in triacylglycerols, which makes waxes less vulnerable to degradation, and therefore more likely to survive archaeologically. 

Toxicity assessment. Ethanol extract of the leaf, administered intraperitoneally to mice, was active, LDjf, 0.75 g/kg"" " . Ethanol extract of the fresh leaf and stem, administered intraperitoneally to mice at the minimum toxic dose of 1 mL/animal, was active. Water extract of the fresh leaf and stem, administered intraperitoneally to mice at the minimum toxic dose of 1 mL/ animal, was active " . Aqueous extract of the husk fiber, administered orally to mice, was active, LDjf, 2.30 g/kgf" " . Tricarboxylate carrier influence. Oil, administered to rats at a dose of 15% of the diet for 3 weeks, produced a differential mitochondrial fatty acid composition and no appreciable change in phospholipids composition and cholesterol level. Compared with coconut oil-fed rats, the mitochondrial tricarboxylate carrier activity was markedly decreased in liver mitochondria from fish oil-fed rats. No difference in the Arrhenius plot between the two groups was observed "". 

Comus walteri Wangerin Korean Si Zhao Hua (Korean cornel) (leaf, fruit) Fatty acid, loganin, linolenic acid.48-53 An astringent. 

Hippophae rhamnoides L. Sha Ji (Sea buckthorn) (seed, fruit, leaf) Cryptoxanthin, harman, harmol, hemin, isorhamnetin, lycopene, serotonin, isorhamnetin-3-mono-beta-D-glucoside, polyphenols, fatty acids flavonoid, essential oils, tannins, quercitin, vitamin C, vitamin E, beta-carotenoid.50-450 Improve resistance to infection, skin irritation and eruption, treat heart disease, oil for cosmetic use. 

Prunus domestica L. P. glandulosa Thunb. P. japonica Thunb. Yu Lee Ren (Dwarf flowering cherry) (leaf, fruit) Amygdalin, citric acid, fatty acids.53 Diuretic, laxative. 

Prunus padus L. Chou Lee (fruit, leaf) Hyperin, quercetin-3-galacto-xylo-glucoside, nonacosane, beta-sitosterol, lupeol, amygdalin, fatty acids.48 Treat diarrhea, cough. 

Viscum album L. subsp. coloratum Kom. V. album L. subsp. coloratum Kom. f. rubroaurantiacum (Makino) Kitag. V. coloratum (Kom.) Nakai Hu Ji Shang (Asiatic mistletoe) (leaf, stem) Oleanolic acid, beta-amyrin, fatty acids, mesoinositol, flavoyadorinin, homoflavoyadorinin, lupeol, myristic acid, agglutinins, alkaloids, quercitol, querbrachitol, quencetine, acetylcholine, choline, histamine, tyramine, vitamins E and C.33-450 Antihypertensive, prolong the life of patients with late stage stomach cancer. 

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