TABLE 1.
Summary of dominant approaches to modify biomass polysaccharide composition.
| Engineered species | Transgene expressed | Effects on biomass composition and conversion | References |
| A. thaliana | AtCesA2, AtCesA5, AtCesA6 | (+) 29–37% Cel | Hu et al., 2018 |
| GhCOBL9A | (+) 59% Cel | Niu et al., 2018 | |
| AtGalS1::AtUGE2::AtURGT1 | (+) 80% Gal | Gondolf et al., 2014; Aznar et al., 2018 | |
| pSAG12:OsCSLF6 | (+) non-Cellulosic Glc | Vega-Sánchez et al., 2015 | |
| AtIRX10G283D, AtIRX10E293Q | (−) 39–55% Xyl | Brandon et al., 2019 | |
| AtSBD123 | (+) 76% FW; (+) 50% HC; (+) 30% Pec; (+) 100% non-crystalline Cel; (+) 28% IVD | Grisolia et al., 2017 | |
| pEST:PcPL1 | (+) 90–100% SE, post-induction | Tomassetti et al., 2015 | |
| pSAG12:AnPGA2 | (+) 50–100% SE, post-senescence | Tomassetti et al., 2015 | |
| AtPMEI-2 | (+) 50% SE; (+) 68% DW | Lionetti et al., 2010 | |
| Populus spp. | GhSuSy | (+) 2–6% Cel; (+) CrI | Coleman et al., 2009 |
| PdDUF266A | (+) 17–34% DW; (+) 37% Cel; (+) 13% Cel DP; (+) 38% SE | Yang et al., 2017a | |
| AnAXE1 | (+) 26% SE | Pawar et al., 2016, 2017 | |
| PdDUF231A | (+) 8–21% Cel; (−) 6–8% lignin | Yang et al., 2017b | |
| AaXEG2 | (+) DW; (+) 81% SE | Kaida et al., 2009; Park et al., 2004 | |
| PtPL1 | (+) SE | Biswal et al., 2014 | |
| Tobacco | PsnSuSy1/2 | (+) 18% Cel; (−) 28% lignin | Wei et al., 2015; Li et al., 2019a |
| AcCel5 | (+) 10–15% SE | Brunecky et al., 2011 | |
| TrCel5 | (−) FW; (−) Cel | Klose et al., 2015 | |
| ClEXPA1/2 | (+) FW; (+) 30−50% Cel | Wang et al., 2011 | |
| AnPGA2 | (+) 100% SE; (−) 50−84% FW | Lionetti et al., 2010 | |
| P. virgatum | PvCesA4, PvCesA6 | (−) DW; (−) 6−33% Cel; (+) 2−12% Xyl | Mazarei et al., 2018 |
| OsAT10 | (+) 40% Cel | Li et al., 2018 | |
| O. sativa | OsSuSy3 | (+) 15−26% Cel; (+) 11−13% HC | Fan et al., 2017, 2019 |
| OsGH9B1, OsGH9B3 | (+) 63% SE | Huang et al., 2019 | |
| OsARAF1, OsARAF3 | (−) 19–25% Ara; (−) 28−34% Cel | Sumiyoshi et al., 2013 | |
| OsAT10 | (+) 8−19% Cel; (+) 40% SE | Bartley et al., 2013 | |
| Saccharum spp. | CsCESA | (+) 31% Cel; (+) 28–39% SE; (+) 25% Suc; (+) 56% non-Cel Glc; (+) 22% Gal; (+) 53% GalA | Ndimande, 2013 |
| F. arundinacea | AnFAE | (+) 10–14% IVD | de Buanafina et al., 2008, 2010; Morris et al., 2017 |
Strong, constitutive promoters were used unless otherwise indicated. Cel, cellulose; Ara, arabinose; Glc, glucose; Gal, galactose; GalA, galacturonic acid; Suc, sucrose; Xyl, xylose; HC, hemicellulose; Pec, pectin; FW, fresh weight; DW, dry weight; DP, degree of polymerization; CrI, cellulose crystallinity index; SE, saccharification efficiency; IVD, in vitro digestibility.