Field performance of switchgrass plants engineered for reduced recalcitrance

Aymerick Eudes; Chien-Yuan Lin; Christopher De Ben; Jasmine Ortega; Mi Yeon Lee; Yi-Chun Chen; Guotian Li; Daniel H Putnam; Jenny C Mortimer; Pamela C Ronald; Corinne D Scown; Henrik V Scheller

doi:10.3389/fpls.2023.1181035

Field performance of switchgrass plants engineered for reduced recalcitrance

Front Plant Sci. 2023 May 30:14:1181035. doi: 10.3389/fpls.2023.1181035. eCollection 2023.

Authors

Aymerick Eudes^{1

2}, Chien-Yuan Lin^{1

2}, Christopher De Ben^{1

3}, Jasmine Ortega^{1

2}, Mi Yeon Lee^{1

2}, Yi-Chun Chen^{1

2}, Guotian Li^{1

2

4}, Daniel H Putnam^{1

3}, Jenny C Mortimer^{1

2

5}, Pamela C Ronald^{1

2

4}, Corinne D Scown^{1

6

7}, Henrik V Scheller^{1

2

8}

Affiliations

¹ Feedstocks and Life-Cycle, Economics and Agronomy Divisions, Joint BioEnergy Institute, Emeryville, CA, United States.
² Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
³ Department of Plant Sciences, University of California, Davis, CA, United States.
⁴ Department of Plant Pathology and the Genome Center, University of California, Davis, CA, United States.
⁵ School of Agriculture, Food and Wine & Waite Research Institute, University of Adelaide, Glen Osmond, SA, Australia.
⁶ Energy Analysis and Environmental Impacts Division, Lawrence Berkeley National Laboratory, Berkeley, CA, United States.
⁷ Energy & Biosciences Institute, University of California, Berkeley, CA, United States.
⁸ Department of Plant and Microbial Biology, University of California-Berkeley, Berkeley, CA, United States.

Abstract

Switchgrass (Panicum virgatum L.) is a promising perennial bioenergy crop that achieves high yields with relatively low nutrient and energy inputs. Modification of cell wall composition for reduced recalcitrance can lower the costs of deconstructing biomass to fermentable sugars and other intermediates. We have engineered overexpression of OsAT10, encoding a rice BAHD acyltransferase and QsuB, encoding dehydroshikimate dehydratase from Corynebacterium glutamicum, to enhance saccharification efficiency in switchgrass. These engineering strategies demonstrated low lignin content, low ferulic acid esters, and increased saccharification yield during greenhouse studies in switchgrass and other plant species. In this work, transgenic switchgrass plants overexpressing either OsAT10 or QsuB were tested in the field in Davis, California, USA for three growing seasons. No significant differences in the content of lignin and cell wall-bound p-coumaric acid or ferulic acid were detected in transgenic OsAT10 lines compared with the untransformed Alamo control variety. However, the transgenic overexpressing QsuB lines had increased biomass yield and slightly increased biomass saccharification properties compared to the control plants. This work demonstrates good performance of engineered plants in the field, and also shows that the cell wall changes in the greenhouse were not replicated in the field, emphasizing the need to validate engineered plants under relevant field conditions.

Keywords: BAHD acyltransferase; OsAT10; Panicum virgatum; QsuB; bioenergy; dehydroshikimate dehydratase; field trials; lignin.

Grants and funding

This work was part of the DOE Joint BioEnergy Institute (http://www.jbei.org) supported by the U. S. Department of Energy, Office of Science, Office of Biological and Environmental Research, through contract DE-AC02-05CH11231 between Lawrence Berkeley National Laboratory and the U.S. Department of Energy.