Manipulating cellulose biosynthesis by expression of mutant Arabidopsis proM24::CESA3^ixr1‐2 gene in transgenic tobacco

Abstract

Summary Manipulation of the cellulose biosynthetic machinery in plants has the potential to provide insight into plant growth, morphogenesis and to create modified cellulose for anthropogenic use. Evidence exists that cellulose microfibril structure and its recalcitrance to enzymatic digestion can ameliorated via mis‐sense mutation in the primary cell wall–specific gene AtCELLULOSE SYNTHASE (CESA)3. This mis‐sense mutation has been identified based on conferring drug resistance to the cellulose inhibitory herbicide isoxaben. To examine whether it would be possible to introduce mutant CESA alleles via a transgenic approach, we overexpressed a modified version of CESA3, AtCESA3ixr1‐2 derived from Arabidopsis thaliana L. Heynh into a different plant family, the Solanceae dicotyledon tobacco (Nicotiana tabacum L. variety Samsun NN). Specifically, a chimeric gene construct of CESA3ixr1‐2, codon optimized for tobacco, was placed between the heterologous M24 promoter and the rbcSE9 gene terminator. The results demonstrated that the tobacco plants expressing M24‐CESA3ixr1‐2 displayed isoxaben resistance, consistent with functionality of the mutated AtCESA3ixr1‐2 in tobacco. Secondly, during enzymatic saccharification, transgenic leaf‐ and stem‐derived cellulose is 54%–66% and 40%–51% more efficient, respectively, compared to the wild type, illustrating translational potential of modified CESA loci. Moreover, the introduction of M24‐AtCESA3ixr1‐2 caused aberrant spatial distribution of lignified secondary cell wall tissue and a reduction in the zone occupied by parenchyma cells.

Engineering of plant cell walls for enhanced biofuel production

“…Both mutations cause a decrease in cellulose crystallinity. Expression of a defective cellulose synthase CesA3 (eli1) is correlated with a lignin enrichment in H units [65] suggesting that over-expression of a defective cellulose synthase could be used to enhance the ratio between crystalline and amorphous cellulose as shown in tobacco [66 ] and boost the accumulation of H units to reduce lignin DP and recalcitrance.…”

A Region Containing an as-1 Element of Dahlia Mosaic Virus (DaMV) Subgenomic Transcript Promoter Plays a Key Role in Green Tissue- and Root-Specific Expression in Plants

“…DaMV contains a circular double-stranded DNA of approximately 8 kb, with four single-stranded interruptions (Richins and Shepherd 1983) and six genes (http://dahlia.wsu.edu/ vectorcontrol/whatsknowndmv.htm). Generally, two major transcriptional promoters are present in most of the caulimovirus genome; these two promoters are the fulllength transcript (Flt) and the subgenomic transcript (Sgt) promoters, which have been studied previously in cauliflower mosaic virus (CaMV), figwort mosaic virus (FMV), peanut chlorotic streak virus (PClSV), strawberry vein mosaic virus (SVMV), and mirabilis mosaic virus (MMV) (Bhattacharyya et al 2002;Maiti et al 1997;Maiti and Shepherd 1998;Odell et al 1981;Pattanaik et al 2004;Dey and Maiti 1999;Sahoo et al 2009Sahoo et al , 2013Kroumova et al 2013;. Similarly, our recent data (Sahoo et al 2014b) also revealed that the DaMV genome possesses the Flt and Sgt promoters.…”

Range of cell-wall alterations enhance saccharification in Brachypodium distachyon mutants

“…For example, Penning et al have recently shown that quantitative trait loci (QTLs) for lignin abundance are independent of those for saccharification in a maize recombinant inbred population (14). In particular, altering cellulose production, deposition, or crystallinity can affect saccharification (15)(16)(17) because cellulose typically constitutes around one third of the total mass of plants and the insoluble crystalline cellulose fibers are hard to digest (18). Alterations in matrix polysaccharide content and composition can also affect saccharification (19,20) by changing the extractability and/or architecture of the cell wall.…”