Effects of Monogalactoglycerolipid Deficiency and Diacylglycerol Acyltransferase Overexpression on Oil Accumulation in Transgenic Tobacco
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Engineering accumulation of triacylglycerol (TAG) in vegetative tissues has been recently proposed as a promising strategy for increasing plant oil production. However, little is known about regulatory mechanisms involved in increasing oil production in plant vegetative tissues. In this study, expression of NtMGD1 encoding a major biosynthetic enzyme for the chloroplast membrane lipid was inhibited by RNAi interference in tobacco. Furthermore, AtDGAT1, a rate-regulating gene involved in TAG biosynthesis, was ectopically overexpressed. Results showed that leaf TAG accumulations were significantly increased both by NtMGD1 RNAi and AtDGAT1 overexpression. However, combination of AtDGAT1 overexpression with NtMGD1 RNAi did not result in additive increase in TAG accumulation in leaves than AtDGAT1 overexpression or NtMGD1 RNAi alone. In addition, reduction of monogalactosyldiacylglycerol (MGDG) biosynthesis by NtMGD1 RNAi was relieved by AtDGAT1 overexpression. Expression of lipid transfer protein (LTP) was upregulated both by AtDGAT1 overexpression and NtMGD1 RNAi and correlated with increased oil accumulation in leaves. Our results indicated that fatty acids deesterified from chloroplast membrane galactolipids could be redirected into TAG. TAG is an energy-dense molecule that might act as a storage pool for carbohydrate. This membrane lipid remodeling may represent an adaptive response that enables plant cells to avoid toxic effects of free fatty acids.
KeywordsDiacylglycerol acyltransferase Monogalactosyldiacylglycerol Nicotiana tabacum Oil accumulation Triacylglycerol
Thin layer chromatography
This work was supported by the National Natural Science Foundation of China (Grant Nos. 30870208 and 30770224) and the National Major Special Project of China on New Varieties Cultivation for Transgenic Organisms (Grant No. 2009ZX08004-009B) and the National Key Basic Research Program (Grant No. 2011CBA00900). The authors are grateful to Dr. Zhongping Lin for offering vector pCAMBIA3300.
- Andrianov V, Borisjuk N, Pogrebnyak N, Brinker A, Dixon J, Spitsin S, Flynn J, Matyszczuk P, Andryszak K, Laurelli M, Golovkin M, Koprowski H (2010) Tobacco as a production platform for biofuel: overexpression of Arabidopsis DGAT and LEC2 genes increases accumulation and shifts the composition of lipids in green biomass. Plant Biotechnol J 8:277–287. doi: 10.1111/j.1467-7652.2009.00458.x PubMedCrossRefGoogle Scholar
- El-Hafid L, Pham AT, Zuily-fodil Y, Vieira da Silva JV (1989) Enzymatic breakdown of polar lipids in cotton leaves under water stress: I. Degradation of monogalactosyl-diacylglycerol. Plant Physiol Biochem 27:495–502Google Scholar
- James CN, Horn PJ, Case CR, Gidda SK, Zhang D, Mullen RT, Dyer JM, Anderson RG, Chapman KD (2010) Disruption of the Arabidopsis CGI-58 homologue produces Chanarin-Dorfman-like lipid droplet accumulation in plants. Proc Natl Acad Sci U S A 107:17833–17838. doi: 10.1073/pnas.0911359107 PubMedCrossRefGoogle Scholar
- Luo JJ, Wang GL, Xu YN (2006) Reduction of monogalactosyldiacylglycerol (MGDG) content in tobacco leaves using RNAi in: C. Benning, J. Ohlrogge (Eds.) Current advances in the biochemistry and cell biology of plant lipids. Aardvark Global, Salt Lake City 16:16–20Google Scholar
- Ohlrogge J, Chapman K (2011) Expanding the contribution of plant oils as biofuels: the seeds of green energy. Biochemist 33:34–38Google Scholar
- Sharma N, Anderson M, Kumar A, Zhang Y, Giblin EM, Abrams SR, Zaharia LI, Taylor DC, Fobert PR (2008) Transgenic increases in seed oil content are associated with the differential expression of novel Brassica-specific transcripts. BMC Genomics 9:619. doi: 10.1186/1471-2164-9-619 PubMedCrossRefGoogle Scholar