Genetic, transcriptional, and regulatory landscape of monolignol biosynthesis pathway in Miscanthus × giganteus

Xiaofei Zeng; Jiajing Sheng; Fenglin Zhu; Tianzi Wei; Lingling Zhao; Xiaohu Hu; Xingfei Zheng; Fasong Zhou; Zhongli Hu; Ying Diao; Surong Jin

doi:10.1186/s13068-020-01819-4

Genetic, transcriptional, and regulatory landscape of monolignol biosynthesis pathway in Miscanthus × giganteus

Biotechnol Biofuels. 2020 Oct 27:13:179. doi: 10.1186/s13068-020-01819-4. eCollection 2020.

Authors

Xiaofei Zeng^{1

2}, Jiajing Sheng^{3

4}, Fenglin Zhu⁴, Tianzi Wei², Lingling Zhao⁴, Xiaohu Hu⁴, Xingfei Zheng⁴, Fasong Zhou⁴, Zhongli Hu⁴, Ying Diao¹, Surong Jin⁵

Affiliations

¹ School of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, 430023 People's Republic of China.
² School of Medicine, Southern University of Science and Technology, Shenzhen, 518055 People's Republic of China.
³ School of Life Sciences, Nantong University, Nantong, 226019 People's Republic of China.
⁴ State Key Laboratory of Hybrid Rice, College of Life Sciences, Hubei Lotus Engineering Center, Wuhan University, Wuhan, 430072 People's Republic of China.
⁵ School of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan, 430070 People's Republic of China.

Abstract

Background: Miscanthus × giganteus is widely recognized as a promising lignocellulosic biomass crop due to its advantages of high biomass production, low environmental impacts, and the potential to be cultivated on marginal land. However, the high costs of bioethanol production still limit the current commercialization of lignocellulosic bioethanol. The lignin in the cell wall and its by-products released in the pretreatment step is the main component inhibiting the enzymatic reactions in the saccharification and fermentation processes. Hence, genetic modification of the genes involved in lignin biosynthesis could be a feasible strategy to overcome this barrier by manipulating the lignin content and composition of M. × giganteus. For this purpose, the essential knowledge of these genes and understanding the underlying regulatory mechanisms in M. × giganteus is required.

Results: In this study, MgPAL1, MgPAL5, Mg4CL1, Mg4CL3, MgHCT1, MgHCT2, MgC3'H1, MgCCoAOMT1, MgCCoAOMT3, MgCCR1, MgCCR2, MgF5H, MgCOMT, and MgCAD were identified as the major monolignol biosynthetic genes in M. × giganteus based on genetic and transcriptional evidence. Among them, 12 genes were cloned and sequenced. By combining transcription factor binding site prediction and expression correlation analysis, MYB46, MYB61, MYB63, WRKY24, WRKY35, WRKY12, ERF021, ERF058, and ERF017 were inferred to regulate the expression of these genes directly. On the basis of these results, an integrated model was summarized to depict the monolignol biosynthesis pathway and the underlying regulatory mechanism in M. × giganteus.

Conclusions: This study provides a list of potential gene targets for genetic improvement of lignocellulosic biomass quality of M. × giganteus, and reveals the genetic, transcriptional, and regulatory landscape of the monolignol biosynthesis pathway in M. × giganteus.

Keywords: Bioethanol; Genetic engineering; Lignin; Miscanthus × giganteus; Monolignol biosynthesis pathway; Monolignol biosynthetic genes; Regulatory mechanism; Transcription factors; Transcriptome analysis.