Abstract
BackgroundMiscanthus × 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.ResultsIn 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.ConclusionsThis 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.
Highlights
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
This study provides a list of potential gene targets for genetic improvement of lignocellulosic biomass quality of M. × giganteus
Our study indicates that ERF may be another important Transcription factor (TF) family involved in monolignol biosynthesis in M. × giganteus
Summary
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. 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. Zeng et al Biotechnol Biofuels (2020) 13:179 nature of lignocellulosic feedstocks leads to the high costs of pretreatment, saccharification, and fermentation processes, limiting the current commercialization of lignocellulosic bioethanol [5, 6]. Its by-products released in the pretreatment step are the primary inhibitors of enzymatic reactions in the saccharification and fermentation processes [8, 9] To overcome this barrier, researchers have focused on manipulating the lignin content and composition of the lignocellulosic feedstocks via genetic engineering approaches. × giganteus enhances the environmental safety of genetic engineering These results suggest the potential utilization of genetic manipulation of lignin biosynthesis in M. Basic knowledge of the genes involved in lignin biosynthesis and how these genes are regulated in M. × giganteus is essential
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