Ghent University. Faculty of Bioscience Engineering
Abstract
The objective of our research was to use the flexibility of the cell wall to its extremes by modifying its composition while avoiding deleterious effects on plant physiology. One of the strategies to achieve this is the heterologous expression of genes coding for cell wall degrading (CWD) enzymes in plants. These can alter the cell wall structure during plant growth and might improve saccharification yield of the lignocellulosic biomass. In this PhD study 29 genes coding for cell wall degrading enzymes (66 different constructs) were introduced in Arabidopsis and one of the enzymes (a galactanase) was studied in detail. Interestingly, galactanase expression improved the saccharification efficiency without causing a dramatic yield penalty. In parallel, an attempt was made to modify cell wall properties by the expression of the A. caulinodans NodC gene in Arabidopsis. The obtained transgenic lines accumulated GlcNAc mono- and oligosaccharides in their apoplast, which influenced the overall cell wall architecture and modified the cell wall properties. Furthermore, since lignin is major limiting factor that affect saccharification yield, reducing lignin content became a potential strategy to improve the saccharification yield. Here, we have generated Arabidopsis lines with an altered PIRIN2 and PIRIN4 expression. The lines had an altered lignin composition, reduced lignin content and an improved saccharification yield. Despite their modified cell wall, no dramatic effect on plant growth and development was detected
