Increasing the energy density of vegetative tissues by diverting carbon from starch to oil biosynthesis in transgenic Arabidopsis
Article first published online: 17 FEB 2011
© 2011 The Authors. Plant Biotechnology Journal © 2011 Society for Experimental Biology, Association of Applied Biologists and Blackwell Publishing Ltd
Plant Biotechnology Journal
Volume 9, Issue 8, pages 874–883, October 2011
How to Cite
Sanjaya, ., Durrett, T. P., Weise, S. E. and Benning, C. (2011), Increasing the energy density of vegetative tissues by diverting carbon from starch to oil biosynthesis in transgenic Arabidopsis. Plant Biotechnology Journal, 9: 874–883. doi: 10.1111/j.1467-7652.2011.00599.x
- Issue published online: 5 SEP 2011
- Article first published online: 17 FEB 2011
- Received 13 October 2010; revised 29 December 2010; accepted 7 January 2011.
- ADP-glucose pyrophosphorylase;
- carbon partitioning;
- primary metabolism;
Increasing the energy density of biomass by engineering the accumulation of triacylglycerols (TAGs) in vegetative tissues is synergistic with efforts to produce biofuels by conversion of lignocellulosic biomass. Typically, TAG accumulates in developing seeds, and little is known about the regulatory mechanisms and control factors preventing oil biosynthesis in vegetative tissues in most plants. Here, we engineered Arabidopsis thaliana to ectopically overproduce the transcription factor WRINKLED1 (WRI1) involved in the regulation of seed oil biosynthesis. Furthermore, we reduced the expression of APS1 encoding a major catalytic isoform of the small subunit of ADP-glucose pyrophosphorylase involved in starch biosynthesis using an RNAi approach. The resulting AGPRNAi-WRI1 lines accumulated less starch and more hexoses. In addition, these lines produced 5.8-fold more oil in vegetative tissues than plants with WRI1 or AGPRNAi alone. Abundant oil droplets were visible in vegetative tissues. TAG molecular species contained long-chain fatty acids, similar to those found in seed oils. In AGPRNAi-WRI1 lines, the relative expression level of sucrose synthase 2 was considerably elevated and correlated with the level of sugars. The relative expression of the genes encoding plastidic proteins involved in de novo fatty acid synthesis, biotin carboxyl carrier protein isoform 2 and acyl carrier protein 1, was also elevated. The relative contribution of TAG compared to starch to the overall energy density increased 9.5-fold in one AGPRNAi-WRI1 transgenic line consistent with altered carbon partitioning from starch to oil.