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Usha R. Palaniswamy, Richard J. McAvoy, and Bernard B. Bible

Purslane (Portulaca oleracea L.) is an excellent source of the essential fatty acid α-linolenic acid (LNA) but little is known of the effects of cultural conditions on LNA concentration. Purslane seedlings were grown under an instantaneous photosynthetic photon flux [PPF (400 to 700 nm)] of 299 or 455 μmol·m-2·s-1 for a daily duration of either 8, 12, 16, or 20 hours. Thus, plants were exposed to a daily PPF of 8.6, 12.9, 17.2, or 21.5 mol·m-2·d-1 in the low PPF treatment (299 μmol.m-2.s-1) and 13.1, 19.7, 26.2, or 32.8 mol·m-2·d-1 in the high PPF treatment (455 μmol·m-2·s-1). Plants in all treatments received a 20-hour photoperiod by providing ≈5 μmol·m-2·s-1 from incandescent lamps starting at the end of the photosynthetic light period. At low PPF, purslane grown under a 16 hour PPF duration produced the highest concentrations of total fatty acids (TFA) and LNA per unit leaf dry weight (DW), but at high PPF, concentrations of these compounds were highest under 8 and 12 hour PPF duration. Trend analysis indicated that maximum TFA and LNA concentrations occurred with a daily PPF of 14.1 and 17.2 mol·m-2·d-1, respectively; and in the thylakoids, protein, chlorophyll, and LNA concentrations peaked at a PPF of 21.8, 19.9, and 16.1 mol·m-2·d-1, respectively. LNA as a percentage of TFA was unaffected by treatment. Shoot DW increased with PPF up to the highest PPF exposure of 32.8 mol·m-2·d-1.

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Usha Rani Palaniswamy, Richard J. McAvoy, and Bernard B. Bible

Purslane (Portulaca oleracea L.) has been identified as an exceptionally rich source of α-linolenic acid (LNA), an essential fatty acid that is beneficial in reducing the incidence of coronary heart disease and certain cancers. In general, about two thirds of the LNA in terrestrial plants is associated with chloroplasts. A green-leafed unnamed cultivar of purslane and a golden-leafed cultivar `Goldberg' were grown hydroponically in a complete nutrient solution with 14.3 mm nitrogen provided as nitrate (NO3 -) and ammonium (NH4 +) forms to yield NO3 --N: NH4 +-N ratios of 1:0, 0.75:0.25, 0.5:0.5, and 0.25:0.75. Young leaves, harvested 18 days after treatment initiation, were analyzed to determine the fatty acid composition and concentrations, and thylakoid protein and chlorophyll concentrations. Although the leaves of plants grown with a NO3 --N: NH4 +-N ratio of 0.5:0.5 contained 239% and 114% more LNA than plants grown with ratios 1:0 and 0.75:0.25, respectively, they contained only 41% and 26% more chlorophyll. The green-leafed cultivar had higher (39%) chlorophyll concentrations than `Goldberg', but both cultivars had similar LNA concentrations [per g dry weight (DW)]. These results suggest that the LNA concentration in the fatty acid-rich species P. oleracea may not be as closely associated with chlorophyll concentration as reported earlier for other plants. Leaves of plants grown in solutions with 0.25:0.75 NO3 --N: NH4 +-N ratio contained 35% less LNA per g leaf DW than the leaves of plants grown in nutrient solutions with a 0.5:0.5 ratio. Although total DW production was not affected by the NO3 --N: NH 4 +-N ratios in the nutrient solutions, the green-leafed cultivar produced higher fresh weight, leaf area, total DW, and number of shoots than `Goldberg'.

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U. Palaniswamy, R. McAvoy, and B. Bible

Omega-3 fatty acids (O3FA) are essential for normal human growth, development, and disease prevention. Purslane (Portulaca oleraceae L.) is an excellent source of alpha-linolenic acid (LNA, an O3FA) and the anti-oxidant alpha-tochopherol. Twenty-one-day-old seedlings of cultivated purslane seedlings were transplanted into greenhouse (≈18-20 °C) and arranged in a randomized complete-blocks design with six replications. Plants were fertilized with nitrogen at 25 mg·mL-1 for the first week, 50 mg·mL-1 for the next week, and 100 mg·mL-1 until harvest using a 20N-4.4P-16.6K water-soluble fertilizer in the irrigation water. The terminal three nodes of shoots were harvested at 6, 10, and 14 trueleaf stage. At each harvest the dry mass (DM), fresh mass (FM), and leaf area were determined. The leaf and stem LNA concentration were determined using gas chromatography. The leaf fatty acid concentrations were 30% to 52% higher at the 6- and 14-leaf stages than at 10-leaf stage. The fatty acid concentrations at the 6- and 14-leaf stages did not differ significantly from each other. FM, DM, and leaf area were the highest at the 14-leaf stage. These data indicate that fatty acid levels do vary with the stage of development in purslane. A more detailed study is necessary to follow the change in LNA concentration in purslane throughout its ontogeny beyond 14 leaves. In another study to determine if the LNA concentration of the upright cultivated type of purslane differed from that of the prostrate wild type, we observed that at 14 to 16 true-leaf stage. the leaves from the cultivated type had 52.5% and 35.2% greater linoleic acid and LNA, respectively, than the wild purslane. In both varieties, leaves were richer in LNA than were the stems. Though the varieties did not differ significantly in the DM yield, the FM and leaf area were higher in the cultivated type than the wild type.

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Xiaozhong Liu and Bingru Huang

Previous studies found that high soil temperature is more detrimental than high air temperature for the growth of creeping bentgrass (Agrostis palustris L.). The objective of the study was to investigate changes in fatty acid composition and saturation levels in leaves and roots for creeping bentgrass exposed to high soil temperature. Shoots and roots of `Penncross' plants were subjected to a differential air/soil temperature of 20/35 °C in a growth chamber. Soil temperature was controlled at 35 °C using an immersion circulating heater in water bath. Shoot injury induced by high soil temperature was evaluated by measuring level of lipid peroxidation expressed as malonyldialdehyde (MDA) content, chlorophyll content, and photochemical efficiency (Fv/Fm) of leaves. MDA content increased while chlorophyll content and Fv/Fm decreased at high soil temperature. The content of total fatty acids and different species of fatty acids were analyzed in both leaves and roots. Total fatty acid content in leaves increased initially at 5 days of high soil temperature and then decreased at 15 days, while total fatty acid content in roots decreased, beginning at 5 days. Linolenic acid was the major fatty acid in leaves and linoleic acid and palmitic acid were the major fatty acids in roots of creeping bentgrass. Leaf content of all fatty acid components except oleic acid increased initially and then decreased at high soil temperature. Root content of all fatty acid components except palmitoleic acid and oleic acid decreased, beginning at 5 d of high soil temperature. Oleic acid in leaves and palmitoleic and oleic acid in roots did not change during the entire experimental period. Leaf content of saturated fatty acids and unsaturated fatty acids increased during the first 5 to 10 days of high soil temperature and decreased at 15 and 25 days, respectively. Root content of saturated fatty acids and unsaturated fatty acids decreased beginning at 5 days of high soil temperature. Double bond index decreased in both leaves and roots. High soil temperature induced changes in fatty acid composition and saturation levels in leaves and roots, and this could be associated with physiological damages in leaves even though only roots were exposed to high temperature.

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Daisuke Sakamoto, Yuri Nakamura, Hiroyoshi Sugiura, Toshihiko Sugiura, Toshikazu Asakura, Mineyuki Yokoyama, and Takaya Moriguchi

fruit industry. α-Ketol linolenic acid [KODA; 9-hydroxy-10-oxo-12( Z ), 15( Z )-octadecadienoic acid] is a signal compound expressed in Lemna paucicostata (Duckweed) after exposure to drought, heat, or osmotic stresses ( Yamaguchi et al., 2001

Open access

Qiuyue Ma, Shushun Li, Jing Wen, Lu Zhu, Kunyuan Yan, Qianzhong Li, Shuxian Li, and Bin Zhang

et al., 2017 ; Liang et al., 2019 ; Wang et al., 2018 ) that contains UFAs, including oleic acid (C18:1), linoleic acid (C18:2), α-linolenic acid (C18:3), and nervonic acid (C24:1) ( Liu et al., 2003 ; Wang et al., 2006 ). In particular, the

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Naoko Nakajima, Yoshinori Ikoma, Hikaru Matsumoto, Keiko Sato, Yuri Nakamura, Mineyuki Yokoyama, Ohji Ifuku, and Shigeo Yoshida

A previous study reported that α-ketol linolenic acid (KODA) was isolated from L. paucicostata as a stress-induced substance ( Yokoyama et al., 2000 ). KODA is an oxylipin, a common compound in green plants ( Vick and Zimmerman, 1987 ). Oxylipins

Open access

Yingchao Lin, Dejun Kong, Zhihong Wang, Yi Chen, Zhixiao Yang, Chun Wu, Hui Yang, and Lili Chen

rates at the two locations. Effects of N application on the fatty acid composition and yield of tobacco seed oil. Increased N application had only a minor effect on the fatty acid composition of the tobacco seed oil except in terms of the linolenic acid

Free access

Desmond G. Mortley, Jun-Hyun Oh, Damicca S. Johnson, Conrad K. Bonsi, and Walter A. Hill

showed that leaves, stems, and seeds of Australian purslane were an excellent source of alpha linolenic acid compared with American varieties harvested at different stages of growth (45, 60, or 70 DAP) regardless of whether plants were grown in the field

Open access

Yuqing Wang, Richard J. Heerema, James L. Walworth, Barry Dungan, Dawn VanLeeuwen, and F. Omar Holguin

‘Wichita’, 2015 ‘Wichita’, and 2015 ‘Western’, respectively ( Table 1 ). In our study, the MUFA oleic acid (C18:1) was the most abundant fatty acid overall. Linoleic acid (C18:2) was the predominant PUFA followed by linolenic acid (C18:3) (data not shown