Engineering Plants for Improved Biofuel Properties

Scientists from the Lawrence Berkeley National Laboratory were able to manipulate genes of plants to develop varieties that can be easily converted to biofuel. This was achieved through engineering plants with smaller amounts of xylan, the major non-cellulosic polysaccharide which is present in plant's secondary cell walls.

To develop plant varieties with low xylan content and improved properties for easier saccharification, scientists used three mutant strains of Arabidopsis deficient in xylan --irregular xylem (irx) mutants irx7, irx8 and irx9. The irx mutants normally exhibit severe dwarf phenotypes that result from xylem vessel collapse and consequent impaired transport of water and nutrients. The team hypothesized that restoring xylan biosynthesis in the plants would complement the mutations.

To reintroduce xylan biosynthesis into the xylem of irx7, 8 and 9, scientists manipulated the promoter regions of vessel-specific transcription factor genes. This revealed that the ensuing phenotypes completely restored wild-type growth patterns in some cases, resulting in stronger plants with restored mechanical properties, while at the same time maintaining a low overall xylan content and improved saccharification properties that allowed for better breakdown into biofuels. Plants with up to 23% reduction in xylose levels and 18% reduction in lignin content were obtained, while normal xylem function was restored. The plants also showed a 42% increase in saccharification yield after pretreatment.

Access the pdf copy of the study at http://www.biotechnologyforbiofuels.com/content/pdf/1754-6834-5-84.pdf.