Present address: Australian Institute for Bioengineering and Nanotechnology, The University of Queensland, c/o BSES Limited, PO Box 86, Indooroopilly, Qld 4068, Australia
Spatio-temporal characterization of polyhydroxybutyrate accumulation in sugarcane
Article first published online: 28 NOV 2006
Plant Biotechnology Journal
Volume 5, Issue 1, pages 173–184, January 2007
How to Cite
Purnell, M. P., Petrasovits, L. A., Nielsen, L. K. and Brumbley, S. M. (2007), Spatio-temporal characterization of polyhydroxybutyrate accumulation in sugarcane. Plant Biotechnology Journal, 5: 173–184. doi: 10.1111/j.1467-7652.2006.00230.x
- Issue published online: 28 NOV 2006
- Article first published online: 28 NOV 2006
- Received 4 August 2006; revised 26 September 2006; accepted 29 September 2006.
- real-time polymerase chain reaction;
- transgenic sugarcane
We report here the results from a glasshouse trial of several transgenic sugarcane (Saccharum spp. hybrids) lines accumulating the bacterial polyester polyhydroxybutyrate (PHB) in plastids. The aims of the trial were to characterize the spatio-temporal pattern of PHB accumulation at a whole-plant level, to identify factors limiting PHB production and to determine whether agronomic performance was affected adversely by PHB accumulation. Statistical analysis showed that a vertical PHB concentration gradient existed throughout the plant, the polymer concentration being lowest in the youngest leaves and increasing with leaf age. In addition, there was a horizontal gradient along the length of a leaf, with the PHB concentration increasing from the youngest part of the leaf (the base) to the oldest (the tip). The rank order of the lines did not change over time. Moreover, there was a uniform spatio-temporal pattern of relative PHB accumulation among the lines, despite the fact that they showed marked differences in absolute PHB concentration. Molecular analysis revealed that the expression of the transgenes encoding the PHB biosynthesis enzymes was apparently coordinated, and that there were good correlations between PHB concentration and the abundance of the PHB biosynthesis enzymes. The maximum recorded PHB concentration, 1.77% of leaf dry weight, did not confer an agronomic penalty. The plant height, total aerial biomass and culm-internode sugar content were not affected relative to controls. Although moderate PHB concentrations were achieved in leaves, the maximum total-plant PHB yield was only 0.79% (11.9 g PHB in 1.51 kg dry weight). We combine the insights from our statistical and molecular analyses to discuss possible strategies for increasing the yield of PHB in sugarcane.