Abstract
BackgroundTo create an ideotype woody bioenergy crop with desirable growth and biomass properties, we utilized the viral 2A-meidated bicistronic expression strategy to express both PtrMYB3 (MYB46 ortholog of Populus trichocarpa, a master regulator of secondary wall biosynthesis) and PdGA20ox1 (a GA20-oxidase from Pinus densiflora that produces gibberellins) in wood-forming tissue (i.e., developing xylem).ResultsTransgenic Arabidopsis plants expressing the gene construct DX15::PdGA20ox1-2A-PtrMYB3 showed a significant increase in both stem fresh weight (threefold) and secondary wall thickening (1.27-fold) relative to wild-type (WT) plants. Transgenic poplars harboring the same gene construct grown in a greenhouse for 60 days had a stem fresh weight up to 2.6-fold greater than that of WT plants. In a living modified organism (LMO) field test conducted for 3 months of active growing season, the stem height and diameter growth of the transgenic poplars were 1.7- and 1.6-fold higher than those of WT plants, respectively, with minimal adverse growth defects. Although no significant changes in secondary wall thickening of the stem tissue of the transgenic poplars were observed, cellulose content was increased up to 14.4 wt% compared to WT, resulting in improved saccharification efficiency of the transgenic poplars. Moreover, enhanced woody biomass production by the transgenic poplars was further validated by re-planting in the same LMO field for additional two growing seasons.ConclusionsTaken together, these results show considerably enhanced wood formation of our transgenic poplars, with improved wood quality for biofuel production.
Highlights
IntroductionTo create an ideotype woody bioenergy crop with desirable growth and biomass properties, we utilized the viral 2A-meidated bicistronic expression strategy to express both PtrMYB3 (MYB46 ortholog of Populus trichocarpa, a master regulator of secondary wall biosynthesis) and PdGA20ox (a GA20-oxidase from Pinus densiflora that produces gibberellins) in wood-forming tissue (i.e., developing xylem)
To create an ideotype woody bioenergy crop with desirable growth and biomass properties, we utilized the viral 2A-meidated bicistronic expression strategy to express both PtrMYB3 (MYB46 ortholog of Populus trichocarpa, a master regulator of secondary wall biosynthesis) and PdGA20ox1 in wood-forming tissue
The results showed that expression of PdGA20ox1 was detected in the stem tissues but not in leaves of the DX15::PdGA20ox1-2A-PtrMYB3 transgenic hybrid poplars (Additional file 1: Fig. S1)
Summary
To create an ideotype woody bioenergy crop with desirable growth and biomass properties, we utilized the viral 2A-meidated bicistronic expression strategy to express both PtrMYB3 (MYB46 ortholog of Populus trichocarpa, a master regulator of secondary wall biosynthesis) and PdGA20ox (a GA20-oxidase from Pinus densiflora that produces gibberellins) in wood-forming tissue (i.e., developing xylem). Woody biomass offers economic and sustainable feedstock for bioenergy production [3,4,5]. While both herbaceous (e.g., grass) and woody biomass are suitable. Cho et al Biotechnol Biofuels (2021) 14:177 forms of plant biomass for biofuel production [6, 7], grass biomass has the advantage of high saccharification efficiency as it is composed of polysaccharides that are converted to bioethanol [8]. Woody biomass (from perennial woody plants or trees) has environmental and economic advantages compared to herbaceous biomass because it can be produced in large quantities at high density even on marginal land and can be harvested at any time during the year [6, 10]. Trees can provide food and raw materials for human [11]
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