Expression of a bacterial 3-dehydroshikimate dehydratase (QsuB) reduces lignin and improves biomass saccharification efficiency in switchgrass (Panicum virgatum L.)

BMC Plant Biology

George Wang¹  Edward E. K. Baidoo¹  Aymerick Eudes²  Dominique Loqué²  Veronica Teixeira Benites²  Sasha Yogiswara²  Zhangying Hao²  Anagh Sinha²  Pamela C. Ronald³  Tong Wei⁴  Henrik V. Scheller⁵ 

[1] Joint BioEnergy Institute, 94608, Emeryville, CA, USA;Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA;Joint BioEnergy Institute, 94608, Emeryville, CA, USA;Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA;Joint BioEnergy Institute, 94608, Emeryville, CA, USA;Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA;Department of Plant Pathology and the Genome Center, University of California, 95616, Davis, CA, USA;Joint BioEnergy Institute, 94608, Emeryville, CA, USA;Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA;Department of Plant Pathology and the Genome Center, University of California, 95616, Davis, CA, USA;Present address: State Key Laboratory of Agricultural Genomics, BGI-Shenzhen, 518000, Shenzhen, China;Joint BioEnergy Institute, 94608, Emeryville, CA, USA;Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, 94720, Berkeley, CA, USA;Department of Plant and Microbial Biology, University of California-Berkeley, 94720, Berkeley, CA, USA;

关键词: Switchgrass;    Lignin;    Shikimate;    Protocatechuate;    Saccharification;    Bioenergy;   

DOI  :  10.1186/s12870-021-02842-9

来源: Springer

【 摘 要 】

BackgroundLignin deposited in plant cell walls negatively affects biomass conversion into advanced bioproducts. There is therefore a strong interest in developing bioenergy crops with reduced lignin content or altered lignin structures. Another desired trait for bioenergy crops is the ability to accumulate novel bioproducts, which would enhance the development of economically sustainable biorefineries. As previously demonstrated in the model plant Arabidopsis, expression of a 3-dehydroshikimate dehydratase in plants offers the potential for decreasing lignin content and overproducing a value-added metabolic coproduct (i.e., protocatechuate) suitable for biological upgrading.ResultsThe 3-dehydroshikimate dehydratase QsuB from Corynebacterium glutamicum was expressed in the bioenergy crop switchgrass (Panicum virgatum L.) using the stem-specific promoter of an O-methyltransferase gene (pShOMT) from sugarcane. The activity of pShOMT was validated in switchgrass after observation in-situ of beta-glucuronidase (GUS) activity in stem nodes of plants carrying a pShOMT::GUS fusion construct. Under controlled growth conditions, engineered switchgrass lines containing a pShOMT::QsuB construct showed reductions of lignin content, improvements of biomass saccharification efficiency, and accumulated higher amount of protocatechuate compared to control plants. Attempts to generate transgenic switchgrass lines carrying the QsuB gene under the control of the constitutive promoter pZmUbi-1 were unsuccessful, suggesting possible toxicity issues associated with ectopic QsuB expression during the plant regeneration process.ConclusionThis study validates the transfer of the QsuB engineering approach from a model plant to switchgrass. We have demonstrated altered expression of two important traits: lignin content and accumulation of a co-product. We found that the choice of promoter to drive QsuB expression should be carefully considered when deploying this strategy to other bioenergy crops. Field-testing of engineered QsuB switchgrass are in progress to assess the performance of the introduced traits and agronomic performances of the transgenic plants.

【 授权许可】

CC BY