Cellulose synthesis in Arabidopsis by heterologous expression of lower plants CESA proteins

Cellulose is the most abundant component of plant cell walls where it plays a pivotal role in regulating plant cell size and shape. In addition, as a component of the woody secondary cell walls, cellulose represents an abundant renewable resource to produce materials and chemicals. In higher plants, cellulose is synthesised at the plasma membrane by a hexameric protein complex, known as the rosette, that is able to synthesise 18 glucose chains that bond together to form a microfibril. While this rosette structure is highly conserved, significant variation exists in the structure and physical properties of cellulose found in different cell types and synthesised by different species. In this study, we surveyed the ability of the catalytic subunits of the cellulose synthase complex (CESA proteins) from a range of lower plant species to synthesise cellulose in the Arabidopsis secondary cell walls. Several lower plant CESA proteins are able to function in higher plants in conjunction Arabidopsis CESAs. Additionally, two moss CESA proteins synthesised cellulose in absence of Arabidopsis CESAs but with reduced crystallinity, indicating that it is the structure of CESA proteins themselves and not the cellular environment that determines the properties of the cellulose synthesised.