Improving alpha-tocopherol production in plant cell cultures

Istituto di Scienze delle Produzioni Alimentari--Sezione di Lecce, CNR, Via Prov. le Lecce-Monteroni, 73100 Lecce, Italy.
Journal of Plant Physiology (Impact Factor: 2.56). 08/2005; 162(7):782-4. DOI: 10.1016/j.jplph.2015.04.010
Source: PubMed


Suspension cell cultures of Helianthus annuus L. were previously established for the production of the most active component of vitamin E, alpha-tocopherol, by optimizing medium composition and culture conditions. In the present work, the possibility of enhancing alpha-tocopherol production by the addition of jasmonic acid to the culture medium was investigated both in sunflower and Arabidopsis cell cultures. A considerable increase (49% and 66%, respectively) of alpha-tocopherol production was obtained in both, after a 72-h treatment with 5 microM jasmonic acid. The modulation of alpha-tocopherol levels in plant cell cultures can provide useful hints for a regulatory impact on tocopherol metabolism.

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    ABSTRACT: Alpha-tocopherol is the most biologically active component of vitamin E and is synthesized only by photosynthetic organisms. Two heterotrophic cell lines of sunflower (Helianthus annuus L.) of differing alpha-tocopherol biosynthetic capability, three-fold higher in the high synthesizing cell line, HT, than in the low synthesizing one, LT, were previously identified. To investigate the relationship between alpha-tocopherol biosynthesis and photomixotrophic culture conditions, a new photomixotrophic sunflower cell line HS3 was established by selecting HT cells able to grow in the presence of a ten-fold reduced sucrose concentration in the culture medium. The photosynthetic properties of HS3 cells were characterized in comparison with HT and LT cells, revealing an increase in chlorophyll content, chloroplast number, and level of the photosynthesis related enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Furthermore, an enhanced expression of the gene encoding for the tocopherol biosynthetic enzyme geranyl-geranylpyrophosphate synthase (GGPPS) was observed in HS3 cells. HS3 cells also revealed a 25% and a more than three-fold higher tocopherol level than HT and LT, respectively, indicating a positive correlation between alpha-tocopherol biosynthesis of sunflower cell cultures and their photosynthetic properties. These findings can be useful for improving the tocopherol yields of the sunflower in vitro production system.
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    ABSTRACT: Tocopherols, collectively known as vitamin E, are lipophilic antioxidants, essential dietary components for mammals and exclusively synthesized by photosynthetic organisms. Of the four forms (alpha, beta, gamma and delta), alpha-tocopherol is the major vitamin E form present in green plant tissues, and has the highest vitamin E activity. Synthetic alpha-tocopherol, being a racemic mixture of eight different stereoisomers, always results less effective than the natural form (R,R,R) alpha-tocopherol. This raises interest in obtaining this molecule from natural sources, such as plant cell cultures. Plant cell and tissue cultures are able to produce and accumulate valuable metabolites that can be used as food additives, nutraceuticals and pharmaceuticals. Sunflower cell cultures, growing under heterotrophic conditions, were exploited to establish a suitable in vitro production system of natural alpha-tocopherol. Optimization of culture conditions, precursor feeding and elicitor application were used to improve the tocopherol yields of these cultures. Furthermore, these cell cultures were useful to investigate the relationship between alpha-tocopherol biosynthesis and photomixotrophic culture conditions, revealing the possibility to enhance tocopherol production by favouring sunflower cell photosynthetic properties. The modulation of alpha-tocopherol levels in plant cell cultures can provide useful hints for a regulatory impact on tocopherol metabolism.
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