Polyunsaturated fatty acids (PUFAs) content of the fungus Mortierella alpina isolated from soil

Twenty-five isolates of Mortierella spcies were prepared, which can be used for the production of polyunsaturated fatty acids (PUFAs)-rich oil for nutritional supplements. The fatty acid contents were determined after heterotrophic fermentation. The content of total fatty acids (TFAs) in the cell dry weight of all isolates including two commercially purchased Mortierella alpina strains ranged from 207.51 to 370.11 mg/g, whereas PUFAs were the dominant fatty acid type. The highest PUFA-containing strain, M. alpina SC9, was identified and confirmed as a new strain of M. alpina through comparison analysis of the sequences of internal transcribed spacers 1 and 2 (ITS1 and ITS2) and the 5.8S rDNA region. During a 7-day fermentation, the PUFAs content of M. alpina SC9 varied between 189.83 and 240.00 mg/g, with a remarkable correlation between the oleic acid (C18:1, OA) and arachidonic acid (C20:4n-6, AA) contents and between the linoleic acid (C18:2n-6, LA) and AA contents, suggesting the PUFA content in the fungus is tightly regulated. This study provides a framework of isolation, identification, and characterization of an important PUFA-producing species, M. alpina.     

Changes of folate and other potential health-promoting phytochemicals in legume seeds as affected by germination

Folate deficiency associated with low dietary intake is a well-documented public health problem, resulting in serious health and socioeconomic burdens. Therefore, optimization of the germination process of different cultivars of legume seeds in relation to the content and composition of folate, vitamin C, and total phenolics and total antioxidant capacity was carried out to maximize the health-promoting properties. The content and composition of folate, vitamin C, and total phenolic and total antioxidant capacities varied between species, among cultivars, and with germination time. During germination, total folate content was maximum at 815.2 μg/100 g fresh weight in soybean sprout and at 675.4 μg/100 g fresh weight in mungbean sprout on the fourth day, which were equivalent to, respectively, 3.5- and 3.9-fold increases in the seed's content, and total folate content strongly decreased thereafter. 5-CH(3)-H(4)folate was the most abundant folate species in legume sprouts and reached a maximum on the fourth day. Vitamin C was not detected in raw seeds, and its content increased sharply in soybean and mungbean sprouts and reached a maximum at the fourth day of germination (29 and 27.7 mg/100 g fresh weight, respectively). Germination of soybean and mungbean for 4 days provided the largest amount of total folate as well as the more stable species 5-CH(3)-H(4)folate and also brought about large amounts of vitamin C and total phenolics and substantial antioxidant capacities.     

Compositional characteristics and antioxidant properties of fresh and processed sea cucumber (Cucumaria frondosa)

The antioxidant activity of fresh and rehydrated sea cucumber (Cucumaria frondosa) samples with/without internal organs was evaluated for the first time. In addition, their proximate, amino acid, and fatty acid compositions were examined. Rehydrated sea cucumber samples in distilled water were prepared from oven-dried products. All samples contained 83-90% moisture, but showed a significant difference among groups in their protein and lipid contents. Glutamic acid was the predominant amino acid in sea cucumber, followed by glycine and aspartic acid. Essential amino acids such as leucine and lysine were also present at high levels. The trend for free amino acid was different from that of total amino acids and varied among groups. Lipids in sea cucumber were dominated by eicosapentaenoic acid (EPA, C20:5n-3), ranging from 43.2 to 56.7% of the total fatty acids. Docosahexaenoic acid (DHA, C22:6n-3) was present at a much lower concentration of 2.0-5.8%. All sea cucumber samples exhibited radical scavenging property against 2,2'-azobis(2-aminopropane) dihydrochloride (AAPH) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, with rehydrated samples, especially those with internal organs, possessing higher antioxidant activity than their fresh counterparts. No correlation existed between radical scavenging capacity and total phenolics content, suggesting that other components, in addition to phenolic compounds, contribute to the antioxidant activity of sea cucumber.     

Fatty acid composition of lipids in sea buckthorn (Hippophaë rhamnoides L.) berries of different origins

The oil content and fatty acid composition of berries from two subspecies of sea buckthorn (Hippopha? rhamnoides L.) were investigated. The berries of subsp. rhamnoides contained a higher proportion of oil in seeds (11.3% vs 7.3%, p < 0.01), berries (3.5% vs 2.1%, p < 0.001), and seedless parts (2.8% vs 1.7%, p < 0.01) than the berries of subsp. sinensis. Linoleic (18:2n-6) and alpha-linolenic acids (18:3n-3) comprised about 70% of seed oil fatty acids. Palmitoleic acid (16:1n-7), practically absent in the seed oil, comprised 12.1--39.0% of oil in pulp/peel and 8.9--31.0% of that in the whole berries. More linoleic acid (40.9% vs 39.1%) and less alpha-linolenic acid (26.6% vs 30.6%) was found in the seed oil of subsp. sinensis than in the seed oil of subsp. rhamnoides (p < 0.05). The proportion of palmitoleic acid was higher in the oil of berries of subsp. rhamnoides than the berries of subsp. sinensis (26.0% vs 21.5%, 0.05 < p < 0.1), but was vice versa with alpha-linolenic acid (8.8% vs 11.2%, 0.05 < p < 0.1). The proportions of alpha-linolenic acid correlated inversely with oleic and linoleic acids in the seed oil. In the oil of whole berries, the proportion of palmitoleic acid correlated negatively with the proportions of linoleic and alpha-linolenic acids.     

Fatty acid profiles, tocopherol contents, and antioxidant activities of heartnut (Juglans ailanthifolia Var. cordiformis) and Persian walnut (Juglans regia L.)

The fatty acid and tocopherol compositions of three heartnut (Juglans ailanthifolia var. cordiformis) varieties (Imshu, Campbell CW1, and Campbell CW3) were examined and compared with those of two Persian walnut (Juglans regia L.) varieties (Combe and Lake). The major fatty acids found in heartnuts and walnuts were identified by gas chromatography as linoleic (18:2n-6), alpha-linolenic (18:3n-3), oleic (18:1n-9), palmitic (16:0), and stearic acid (18:0). Polyunsaturated fatty acids were the main group of fatty acids found in both heartnut and walnut, ranging from 73.07 to 80.98%, and were significantly higher in heartnut than in Persian walnuts (P < 0.001). In addition, heartnuts had significantly higher levels of 18:2n-6 and lower levels of 18:3n-3 compared to the Persian walnuts. gamma-Tocopherol was the main tocopherol homologue present in both types of nuts, followed by delta- and alpha-tocopherol. The highest concentration of gamma-tocopherol was found in Combe Persian walnut at 267.87 mug/g, followed by Lake Persian walnut and Imshu, Campbell CW1, and CW3 heartnut at 205.45, 187.33, 161.84, and 126.46 mug/g, respectively. Tocopherols, particularly the gamma-tocopherol, were found to contribute the most to the strong total antioxidant activities of both walnut and heartnut oils using either the free radical 2,2-diphenyl-1-picrylhydrazyl assay or the photochemiluminescence method.     

Influence of harvest date and crop yield on the fatty acid composition of virgin olive oils from cv. Picual

In this study was analyzed the effect of crop year and harvesting time on the fatty acid composition of cv. Picual virgin olive oil. The study was carried out during the fruit ripening period for three crop seasons. The mean fatty acid composition of Picual oils was determined. The oils contained palmitic acid (11.9%), oleic acid (79.3%), and linoleic acid (2.95%). The content of palmitic acid and saturated fatty acids decreased during fruit ripening while oleic and linoleic acids increased. The amount of stearic and linolenic acids decreased. The amount of saturated acids, palmitic and stearic, and the polyunsaturated acids linoleic and linolenic was dependent on the time of harvest, whereas the amount of oleic acid varied with the crop year. The differences observed between crop years for both palmitic and linoleic acid may be explained by the differences in the temperature during oil biosynthesis and by the amount of summer rainfall for oleic acid content. A significant relationship was observed between the MUFA/PUFA ratio and the oxidative stability measured by the Rancimat method.     

Phenolic compounds and fatty acids from acorns (Quercus spp.), the main dietary constituent of free-ranged Iberian pigs

The aim of the present work was to identify and quantify the phenolic compounds and fatty acids in acorns from Quercus ilex, Quercus rotundifolia, and Quercus suber. The concentration of oleic acid was >63% of total fatty acids in all cases, followed by palmitic and linoleic acids at similar concentrations (12-20%). The concentrations of alpha-tocopherol in Q. rotundifolia, Q. ilex, and Q. suber were 19, 31, and 38 mg/kg of dry matter (DM), respectively, whereas the concentrations of gamma-tocopherol were 113, 66, and 74 mg/kg of DM, respectively. Thirty-two different phenolic compounds were distinguished. All of them were gallic acid derivatives, in the form of either galloyl esters of glucose, combinations of galloyl and hexahydroxydiphenoyl esters of glucose, tergallic O- or C-glucosides, or ellagic acid derivatives. Several tergallic acid C-glucosides were also present in the extracts obtained from Q. suber. Acorns from Q. ilex and Q. rotundifolia showed similar polyphenol patterns mainly with gallic acid-like spectra. Chromatograms of Q. suber showed mainly polyphenols with ellagic acid-like spectra. Valoneic acid dilactone was especially abundant in Q. suber skin. The contribution of skin to the total phenolics of the acorn was relatively small in Q. rotundifolia and Q. ilex but relatively high in Q. suber. Skin extracts from Q. suber, Q. rotundifolia, and Q. ilex showed 1.3, 1.4, and 1.0 antioxidant efficiencies, respectively (compared to that of butylhydroxyanisole). Endosperm extracts showed lower capacity to prevent lipid peroxidation than skin extracts.     

Bioactive compounds in legumes and their germinated products

Nineteen domestic legume varieties, including 6 soybeans, 7 black soybeans, 4 azuki beans, and 2 mung beans, were evaluated for contents of dietary fiber, total phenolics, and flavonoids. Nine varieties of legumes (black soybean TN6, TN3, BM, and WY; soybean KS1, KS2, and KS8; azuki bean AKS5 and AKS6) were good sources of bioactive compounds and were selected for germination tests. After short- and long-term germinations, the bioactive compounds were determined and compared with compositions of isoflavones in soybeans. The reducing power of legumes correlated well with their total flavonoid contents (r (2) = 0.9414), whereas less correlation was found between reducing power and total phenolics contents (r (2) = 0.6885). The dark-coat seeds, such as azuki beans and black soybeans, contained high amounts of phenolic compounds and contributed to high antioxidative ability, whereas their phenolics content and antioxidative abilities significantly decreased after short-term germination due to losses of pigments in the seed coats. After long-term germination, the contents of bioactive compounds (total phenolics and flavonoids) increased again and the ratio of aglycones to total isoflavones significantly increased in black soybeans. TN3 and TN6 seeds and their long-term germinated seeds and AKS5 seeds were identified as the legume samples that might have the highest antioxidant ability according to the results of chemometric analysis. Selection of the right legume varieties combined with a suitable germination process could provide good sources of bioactive compounds from legumes and their germinated products for neutraceutical applications.     

Chemical composition of selected edible nut seeds

Commercially important edible nut seeds were analyzed for chemical composition and moisture sorption. Moisture (1.47-9.51%), protein (7.50-21.56%), lipid (42.88-66.71%), ash (1.16-3.28%), total soluble sugars (0.55-3.96%), tannins (0.01-0.88%), and phytate (0.15-0.35%) contents varied considerably. Regardless of the seed type, lipids were mainly composed of mono- and polyunsaturated fatty acids (>75% of the total lipids). Fatty acid composition analysis indicated that oleic acid (C18:1) was the main constituent of monounsaturated lipids in all seed samples. With the exception of macadamia, linoleic acid (C18:2) was the major polyunsaturated fatty acid. In the case of walnuts, in addition to linoleic acid (59.79%) linolenic acid (C18:3) also significantly contributed toward the total polyunsaturated lipids. Amino acid composition analyses indicated lysine (Brazil nut, cashew nut, hazelnut, pine nut, and walnut), sulfur amino acids methionine and cysteine (almond), tryptophan (macadamia, pecan), and threonine (peanut) to be the first limiting amino acid as compared to human (2-5 year old) amino acid requirements. The amino acid composition of the seeds was characterized by the dominance of hydrophobic (range = 37.16-44.54%) and acidic (27.95-33.17%) amino acids followed by basic (16.16-21.17%) and hydrophilic (8.48-11.74%) amino acids. Trypsin inhibitory activity, hemagglutinating activity, and proteolytic activity were not detected in the nut seed samples analyzed. Sorption isotherms (Aw range = 0.08-0.97) indicated a narrow range for monolayer water content (11-29 mg/g of dry matter). No visible mold growth was evident on any of the samples stored at Aw < 0.53 and 25 degrees C for 6 months.     

苦杏仁去皮热风干燥适宜温度提高油脂品质

为探索适宜的杏仁热风干燥温度,以热烫去皮处理后的湿杏仁为试验材料,研究了热风干燥不同温度对杏仁及其油脂的感官、理化和营养品质的影响。结果表明,经热烫去皮、干燥处理后可以得到颜色较浅的杏仁油,有利于提高杏仁油的感官品质,但会造成杏仁油过氧化值显著升高(P0.05),油酸、亚油酸、十七碳烯酸、二十碳一烯酸等不饱和脂肪酸的比例和甾醇含量降低,棕榈酸、棕榈油酸、硬脂酸、十七碳烷酸、二十碳烷酸、二十碳一烯酸的比例和总生育酚含量升高,对杏仁油的理化特性和营养品质产生影响。但不同脂肪酸及其伴随物种类、不同温度处理变化幅度不同。随着干燥温度的提高,干燥速率逐渐加快,杏仁及杏仁油的颜色逐渐加深,杏仁油亮度下降,酸价略有升高,但不同干燥温度之间差异不显著(P0.05);过氧化值呈上升趋势,且80℃以上干燥处理显著高于40℃和60℃干燥处理(P0.05);总不饱和脂肪酸、油酸、亚油酸、十七碳烯酸、二十碳烷酸的比例及β-生育酚、δ-生育酚及总生育酚含量总体呈下降趋势,棕榈油酸、棕榈酸、硬脂酸的比例和β-谷甾醇、总甾醇含量总体呈升高趋势。低温干燥有利于提高杏仁油中生育酚含量,而提高干燥温度则有利于杏仁油中植物甾醇含量的提高。尤其是干燥温度为80℃以上时,杏仁油的品质变化加快。因此,为提高杏仁油理化与营养品质,杏仁脱皮后的干燥宜在80℃以下的较低温度条件下进行。研究结果可为杏仁干燥和高品质杏仁油加工提供参考。     

Evaluation of the antioxidant activity of capsiate analogues in polar, nonpolar, and micellar media

Synthesis of 10 capsiate analogues was conducted by lipase-mediated (Novozyme 435) esterification of vanillyl alcohol with different fatty acids. The antioxidant activity of the synthesized capsiates was evaluated using three in vitro assays: DPPH radical scavenging assay (polar medium), Rancimat assay (nonpolar medium), and autoxidation of linoleic acid (micellar medium). The objective of this study is to find the influence of structural characteristics of the alkyl chain of capsiate analogues on their antioxidant activity. In these assays, BHT and α-tocopherol were used as reference compounds. Both DPPH and Rancimat assays did not show any specific trend of antioxidant activity with the increase in lipophilicity and also with the type of fatty acids grafted to the phenolic moiety. In the Tween 20 micellar system for the inhibition of autoxidation of linoleic acid, vanillyl ester attached to a C18 alkyl chain (vanillyl stearate, oleate, and ricinoleate) exhibited maximum inhibition of autoxidation of linoleic acid.     

Oil and squalene in amaranthus grain and leaf

Amaranthus grain of 104 genotypes from 30 species was investigated for oil and squalene contents and fatty acid profiles. The overall average oil content in Amaranthus grain was 5.0%, ranging from 1.9 to 8.7%. Squalene concentration in extracted oils ranged from trace to 7.3%, with an average concentration of 4.2%. The average contents of three major fatty acids in Amaranthus grain were 22.2, 29.1, and 44.6% for palmitic, oleic, and linoleic, respectively. The average fat content in dried mature leaves of 45 Amaranthus genotypes was 1.63%, ranging from 1.08 to 2.18%. The squalene concentration in leaf lipid extracts averaged 0.26%, ranging from trace to 0.77%, which is much lower than that from seeds. The major fatty acids of leaf extracts were linolenic, linoleic, and palmitic. Linolenic ranged from 56.5 to 62.0% of total fatty acids; linoleic, from 15.5 to 24.7%; and palmitic acid, from 13.5 to 15.5%. As for the fatty acid compositions at different growth stages, fatty acid content in leaf lipid was lower in mature leaves than in young leaves. The saturated/unsaturated ratio decreased when the leaf grew to maturity. Principal component analysis (PCA) was carried out on compositional characteristics of grain. The first two components accounted for 70% of the total variance (38.3 and 21.7%, respectively). There was a positive correlation between oil content and squalene yield, and a negative correlations were found between linoleic and either of the other two major fatty acids, palmitic and oleic. The taxonomic relationship among the species was also elucidated by PCA.     

Impact of dietary conjugated linoleic acid on the oxidative stability of rat liver microsomes and skeletal muscle homogenates

Dietary conjugated linoleic acid (CLA; 0-2.0%) increased CLA concentrations in liver microsomes and skeletal muscle homogenates from rats. Dietary CLA decreased oleic and arachadonic acid concentrations in both liver microsomes and skeletal muscle. The presence of CLA in liver microsomes had no impact on linoleic acid, arachadonic acid, and alpha-tocopherol oxidation rates. Dietary CLA (2.0%) also did not alter alpha-tocopherol oxidation rates in liver microsomes or muscle homogenates. Formation of malonaldehyde (MDA) in oxidizing liver microsomes decreased with increasing CLA concentration as determined by measurement of thiobarbituric acid-MDA complexes by HPLC. The ability of CLA to decrease MDA formation without impacting other lipid oxidation markers such as the disappearance of fatty acid and alpha-tocopherol suggests that decreased MDA concentration was the result of CLA's ability to lower polyenoic fatty acids such as arachadonic acid. While CLA does not appear to act as an antioxidant, its ability to decrease polyenoic fatty acid concentrations could decrease the formation of highly cytotoxic lipid oxidation products such as MDA.     

Chemical composition of caneberry (Rubus spp.) seeds and oils and their antioxidant potential

Caneberries (Rubus spp. L.) are grown primarily throughout the Pacific Northwestern United States and Canada. Processing of caneberry fruit typically removes the seed, and the development of a value-added use of seeds could expand the market for caneberries and the profit margins for growers. An initial step toward the use of the seeds is a characterization of seed and oil. Our investigation has described compositional characteristics for seeds of five commonly grown caneberry species: red raspberry, black raspberry, boysenberry, Marion blackberry, and evergreen blackberry. Seeds from all five species had 6-7% protein and 11-18% oil. The oils contained 53-63% linoleic acid, 15-31% linolenic acid, and 3-8% saturated fatty acids. The two smaller seeded raspberry species had higher percentages of oil, the lowest amounts of saturated fatty acid, and the highest amounts of linolenic acid. Antioxidant capacities were detected both for whole seeds and for cold-pressed oils but did not correlate to total phenolics or tocopherols. Ellagitannins and free ellagic acid were the main phenolics detected in all five caneberry species and were approximately 3-fold more abundant in the blackberries and the boysenberry than in the raspberries.     

Effect of diet on the deposition of n-3 fatty acids, conjugated linoleic and C18:1trans fatty acid isomers in muscle lipids of German Holstein bulls

This study examined the effects of feeding diets rich in either n-3 or n-6 polyunsaturated fatty acids (PUFA) on the fatty acid composition of longissimus muscle in beef bulls. Thirty-three German Holstein bulls were randomly allocated to either an indoor concentrate system or periods of pasture feeding (160 days) followed by a finishing period on a concentrate containing linseed to enhance the contents of n-3 PUFA and conjugated linoleic acids (CLA) in beef muscle. The relative proportion and concentration (mg/100 g fresh muscle) of n-3 fatty acids in the phospholipid and triglyceride fractions were significantly increased (p < or = 0.05) in muscle lipids of pasture-fed bulls. The pasture feeding affected the distribution of individual CLA isomers in the muscle lipids. The proportion of the most prominent isomer, CLA cis-9,trans-11, was decreased from 73.5 to 65.0% of total CLA in bulls fed on concentrate as compared to pasture. The second most abundant CLA isomers were CLA trans-7,cis-9 and CLA trans-11,cis-13 in bulls fed on concentrate and pasture, respectively. Diet had no effect on the concentration of C18:1 trans-11. In contrast, the concentration of the C18:1 trans-13/14, trans-15, and trans-16 isomers in the muscle lipids was up to two times higher in pasture-fed as compared to concentrate-fed bulls. Pasture feeding enhanced the concentration of n-3 fatty acids, but the diet had no effect on the concentration of CLA cis-9,trans-11.     

褐藻糖胶对黄颡鱼幼鱼中脂肪酸的影响

为研究褐藻糖胶作为饲料添加剂对黄颡鱼幼鱼脂肪酸的影响,选取大小、体重相近的黄颡鱼幼鱼,随机分为对照组和试验组,对照组饲喂不添加褐藻糖胶的基础饲料,试验组饲喂添加0.1%褐藻糖胶的饲料,采用气相色谱质谱联用技术(GC-MS)分析不同喂养时间(1、2、4、8周)下试验组和对照组黄颡鱼幼鱼脂肪酸含量的变化。结果表明,黄颡鱼幼鱼体内共检测出15个总脂肪酸(TFA)和17个游离脂肪酸(FFA)。方差分析结果表明,黄颡鱼幼鱼TFA中C18:1 (n-9)、C20:4(n-5)和C22:6 (n-3)具有交互作用,而大部分FFA间都存在交互作用。喂养时间对黄颡鱼幼鱼脂肪酸有显著影响(P<0.05),随着喂养时间的延长,游离的单不饱和脂肪酸(MUFA)含量呈先减少后增加趋势,而总MUFA含量呈先增加后减少趋势;黄颡鱼幼鱼游离脂肪酸和总脂肪酸中饱和脂肪酸(SFA)均呈先增加后减少趋势,而多不饱和脂肪酸(PUFA)呈先下降后升高趋势。0.1%褐藻糖胶对黄颡鱼幼鱼TFA中C18:1 (n-9)、C20:4(n-5)和C22:6 (n-3)含量影响显著(P<0.05),对FFA组分含量的影响均显著(P<0.05),试验组黄颡鱼幼鱼SFA含量高于对照组,MUFA含量低于对照组,PUFA在喂养第2周时高于对照组,喂养第8周时低于对照组。此外,黄颡鱼幼鱼C20:3(n-3)/C22:6(n-3)的比值小于0.4,且喂养0.1%褐藻糖胶第8周时,黄颡鱼幼鱼C22:6(n-3)和C20:4(n-5)含量明显高于对照组,说明褐藻糖胶有益于黄颡鱼产卵和孵化,有助于黄颡鱼幼鱼的发育生长。本研究结果为黄颡鱼的健康养殖提供了基础数据。     

Nondestructive determination of oil content and fatty acid composition in perilla seeds by near-infrared spectroscopy

Near-infrared reflectance spectroscopy (NIRS) was used as a rapid and nondestructive method to determine the oil content and fatty acid composition in intact seeds of perilla [Perilla frutescens var. japonica (Hassk.) Hara] germplasms in Korea. A total of 397 samples (about 2 g of intact seeds) were scanned in the reflectance mode of a scanning monochromator, and the reference values for the oil content and fatty acid composition were measured by gravimetric method and gas-liquid chromatography, respectively. Calibration equations for oil and individual fatty acids were developed using modified partial least-squares regression with internal cross validation (n = 297). The equations for oil and oleic and linolenic acid had lower standard errors of cross-validation (SECV), higher R2 (coefficient of determination in calibration), and higher ratio of unexplained variance divided by variance (1-VR) values than those for palmitic, stearic, and linoleic acid. Prediction of an external validation set (n = 100) showed significant correlation between reference values and NIRS estimated values based on the standard error of prediction (SEP), r2 (coefficient of determination in prediction), and the ratio of standard deviation (SD) of reference data to SEP. The models for oil content and major fatty acids, oleic and linolenic acid, had relatively higher values of SD/SEP(C) and r2 (more than 3.0 and 0.9, respectively), thereby characterizing those equations as having good quantitative information, whereas those of palmitic, stearic, and linoleic acid had lower values (below 2.0 and 0.7, respectively), unsuitable for screening purposes. The results indicated that NIRS could be used to rapidly determine oil content and fatty acid composition (oleic and linolenic acid) in perilla seeds in the breeding programs for development of high-quality perilla oil.     

FeSO4引发提高秦艽种子萌发的生理机制

为探讨FeSO4引发提高秦艽种子萌发抗性的生理机制,同时设置水引发处理,以未作任何处理的种子为对照(CK),研究了0.6%FeSO4引发处理24 h对种子膜透性、储藏性物质、能量、激素及抗性相关酶等方面的影响。结果表明:FeSO4引发降低了种子膜透性,提高种子活力,在吸水12 h和24 h时,电导率分别较CK降低了6.61%和11.67%;调动了种子内部储藏物质的代谢,蔗糖含量减少9.57%,可溶性蛋白增加49.63%,饱和脂肪酸中的豆蔻酸和木焦油酸甲酯含量分别增加4.93%和9.03%,不饱和脂肪酸中的山嵛酸、油酸、亚油酸和亚麻酸分别减少6.73%、8.18%、8.40%和6.70%;改变了种子激素平衡,其中脱落酸的含量下降64.78%,赤霉素含量增加近22倍;加速了种子能量代谢, ATP含量增加2.16倍,细胞色素C氧化酶活性增加67.91%。此外,FeSO4引发使线粒体非酶促系统中谷胱甘肽含量和抗坏血酸的含量分别增加74.08%和10.89%,使细胞内酶促系统超氧化物歧化酶、过氧化氢酶和抗坏血酸过氧化物酶活性分别增加285%、179%以及19.6%。因此,FeSO4引发对种子萌发是一个综合过程,一方面可促进种子物质代谢和提高能荷水平,一方面可改善种子内部生理状态和提高胁迫响应能力,从而提高种子活力,促进种子快速和整齐萌发。     

Metabolism of triacylglycerol species during seed germination in fatty acid sunflower (Helianthus annuus) mutants

Sunflower mutant lines with high saturated fatty acid content (palmitic or stearic) in the oil have a completely different set of triacylglycerols (TAG), some of which were not found in standard sunflowers. For optimum seed germination, all of these new TAG species must be effectively catabolized. The behavior of the TAG composition during germination in cotyledons of all these mutant lines showed two different phases: an initial phase (between 0 and 2 days after sowing) with a higher catalytic activity and a preference for TAG containing at least two oleic acid molecules and a second phase with lower TAG degradation rate and a low preference for TAG containing two saturated fatty acids usually accompanied by linoleic acid. Despite the elevated content of saturated fatty acids in some TAG species, the total TAG degradation rate and germination process were similar in these lines, suggesting that sunflower seed lipases do not show a marked preference for any TAG species.     

Assessment of oil content and fatty acid composition variability in two economically important Hibiscus species

The Hibiscus genus encompasses more than 300 species, but kenaf (Hibiscus cannabinus L.) and roselle (Hibiscus sabdariffa L.) are the two most economically important species within the genus. Seeds from these two Hibiscus species contain a relatively high amount of oil with two unusual fatty acids: dihydrosterculic and vernolic acids. The fatty acid composition in the oil can directly affect oil quality and its utilization. However, the variability in oil content and fatty acid composition for these two species is unclear. For these two species, 329 available accessions were acquired from the USDA germplasm collection. Their oil content and fatty acid composition were determined by nuclear magnetic resonance (NMR) and gas chromatography (GC), respectively. Using NMR and GC analyses, we found that Hibiscus seeds on average contained 18% oil and seed oil was composed of six major fatty acids (each >1%) and seven minor fatty acids (each <1%). Hibiscus cannabinus seeds contained significantly higher amounts of oil (18.14%), palmitic (20.75%), oleic (28.91%), vernolic acids (VA, 4.16%), and significantly lower amounts of stearic (3.96%), linoleic (39.49%), and dihydrosterculic acids (DHSA, 1.08%) than H. sabdariffa seeds (17.35%, 18.52%, 25.16%, 3.52%, 4.31%, 44.72%, and 1.57%, respectively). For edible oils, a higher oleic/linoleic (O/L) ratio and lower level of DHSA are preferred, and for industrial oils a high level of VA is preferred. Our results indicate that seeds from H. cannabinus may be of higher quality than H. sabdariffa seeds for these reasons. Significant variability in oil content and major fatty acids was also detected within both species. The variability in oil content and fatty acid composition revealed from this study will be useful for exploring seed utilization and developing new cultivars in these Hibiscus species.