Three AtCesA6‐like members enhance biomass production by distinctively promoting cell growth in Arabidopsis

Abstract

SummaryCellulose is an abundant biopolymer and a prominent constituent of plant cell walls. Cellulose is also a central component to plant morphogenesis and contributes the bulk of a plant's biomass. While cellulose synthase (CesA) genes were identified over two decades ago, genetic manipulation of this family to enhance cellulose production has remained difficult. In this study, we show that increasing the expression levels of the three primary cell wall AtCesA6‐like genes (AtCesA2, AtCesA5, AtCesA6), but not AtCesA3, AtCesA9 or secondary cell wall AtCesA7, can promote the expression of major primary wall CesA genes to accelerate primary wall CesA complex (cellulose synthase complexes, CSCs) particle movement for acquiring long microfibrils and consequently increasing cellulose production in Arabidopsis transgenic lines, as compared with wild‐type. The overexpression transgenic lines displayed changes in expression of genes related to cell growth and proliferation, perhaps explaining the enhanced growth of the transgenic seedlings. Notably, overexpression of the three AtCesA6‐like genes also enhanced secondary cell wall deposition that led to improved mechanical strength and higher biomass production in transgenic mature plants. Hence, we propose that overexpression of certain AtCesA genes can provide a biotechnological approach to increase cellulose synthesis and biomass accumulation in transgenic plants.

AtCSLD3 and GhCSLD3 mediate root growth and cell elongation downstream of the ethylene response pathway in Arabidopsis

“…2 ), but the transgenic line overexpressing CSLD3 showed significantly increased cell number and length, confirming that CSLD3 could affect both cell elongation and cell division. In addition, numerous studies have demonstrated that cellulose affects cell elongation and that mutations in primary wall cellulose synthase (CesAs) typically lead to reduced cell elongation and loss of anisotropic growth ( Fagard et al , 2000 ; Cano-Delgado et al , 2003 ; Chen et al , 2010 , 2016 ; Hu et al , 2017 ; Li et al , 2017 ). Here, both AtCSLD3 - and GhCSLD3 -overexpressing lines exhibited significantly enhanced cellulose production and the csld3-1 mutant had decreased cellulose production in both seedlings and mature plants, which might explain the increase in cell elongation.…”

In Arabidopsis hybrids and Hybrid Mimics, up‐regulation of cell wall biogenesis is associated with the increased plant size

“…The observations of different germination times of Arabidopsis hybrids compared with their parents can be due to differences in growth condition, the age of the seeds, or different hybrid genotypes. expressing CesA2, 5, or 6 were taller than the wild type and produced 20% more biomass in 7-week-old mature plants (Hu et al, 2018). UDG genes were up-regulated in each of the hybrids and Mimics.…”

“…Mutation of a single CesA gene does not necessarily result in a new phenotype but some double or triple mutants in different CesA genes have a dwarf or lethal phenotype, emphasizing the critical role of CesA loci in plant growth and biomass (McFarlane et al, ). Transgenic plants overexpressing CesA 2, 5, or 6 were taller than the wild type and produced 20% more biomass in 7‐week‐old mature plants (Hu et al, ). UDG genes were up‐regulated in each of the hybrids and Mimics.…”

Engineering of Bioenergy Crops: Dominant Genetic Approaches to Improve Polysaccharide Properties and Composition in Biomass

“…The study would suggest that careful consideration of promoters may be critical for the success of overexpressing SCW CesAs in crops. Greater success has been demonstrated in Arabidopsis (Arabidopsis thaliana) by overexpression of either of the primary cell wall (PCW) CesAs, CesA2, CesA5 and CesA6 (Hu et al, 2018). CesA2, CesA5, and CesA6 are each functional in a PCW cellulose synthase complex including CesA1 and CesA3.…”