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Chen G.,Shandong Academy of Agricultural Sciences | Chen G.,Shandong Provincial Key Laboratory of Genetic Improvement | Qu S.,Shandong Academy of Agricultural Sciences | Wang Q.,CAS Wuhan Institute of Hydrobiology | And 16 more authors.
Biotechnology for Biofuels | Year: 2014

Background: Polyunsaturated fatty acids (PUFAs), which contain two or more double bonds in their backbone, are the focus of intensive global research, because of their nutritional value, medicinal applications, and potential use as biofuel. However, the ability to produce these economically important compounds is limited, because it is both expensive and technically challenging to separate omega-3 polyunsaturated fatty acids (ω-3 PUFAs) from natural oils. Although the biosynthetic pathways of some plant and microalgal ω-3 PUFAs have been deciphered, current understanding of the correlation between fatty acid desaturase content and fatty acid synthesis in Synechocystis sp. PCC6803 is incomplete. Results: We constructed a series of homologous vectors for the endogenous and exogenous expression of Δ6 and Δ15 fatty acid desaturases under the control of the photosynthesis psbA2 promoter in transgenic Synechocystis sp. PCC6803. We generated six homologous recombinants, harboring various fatty acid desaturase genes from Synechocystis sp. PCC6803, Gibberella fujikuroi and Mortierella alpina. These lines produced up to 8.9 mg/l of α-linolenic acid (ALA) and 4.1 mg/l of stearidonic acid (SDA), which are more than six times the corresponding wild-type levels, at 20°C and 30°C. Thus, transgenic expression of Δ6 and Δ15 fatty acid desaturases enhances the accumulation of specific ω-3 PUFAs in Synechocystis sp. PCC6803. Conclusions: In the blue-green alga Synechocystis sp. PCC6803, overexpression of endogenous and exogenous genes encoding PUFA desaturases markedly increased accumulation of ALA and SDA and decreased accumulation of linoleic acid and γ-linolenic acid. This study lays the foundation for increasing the fatty acid content of cyanobacteria and, ultimately, for producing nutritional and medicinal products with high levels of essential ω-3 PUFAs. © 2014 Chen et al.; licensee BioMed Central Ltd. Source


Zheng J.,Shandong Normal University | Zheng J.,Shandong Academy of Agricultural Sciences | Zhou J.-J.,Shandong Academy of Agricultural Sciences | Zhou J.-J.,Shandong Provincial Key Laboratory of Genetic Improvement | And 7 more authors.
Rice Science | Year: 2013

Phytochromes have been reported to play important roles in seedling de-etiolation and flowering in rice. To identify the roles of phytochromes in regulating root growth and accumulation of dry substances, the lengths of seminal roots and the dry weights of seedlings were measured in the wild type as well as the phytochrome A (. phyA) and phytochrome B (. phyB) mutants grown under different conditions. When the whole seedlings were exposed to white light, the elongation of the seminal roots was significantly photoinhibited in the wild type, whereas this inhibitory effect was clearly reduced in the phyA and phyB mutants. When the roots of the seedlings were blocked from white light, the phyA and phyB mutants exhibited significantly longer seminal roots than the wild type. These results suggest that both the root-localized and shoot-localized PHYA and PHYB are involved in the photoinhibition of seminal root elongation in rice seedlings. By measuring the dry weights of roots and shoots, it is revealed that PHYB positively regulates the accumulation of dry substances in shoots, however, PHYA exerts the contrary effects on the accumulation of dry substances in roots and shoots of rice seedlings. © 2013 China National Rice Research Institute. Source

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