Regulation of secondary cell wall biosynthesis by a NAC transcription factor from Miscanthus

Abstract

Cell wall recalcitrance is a major limitation for the sustainable exploitation of lignocellulosic biomass as a renewable resource. Species and hybrids of the genus Miscanthus have emerged as candidate crops for the production of lignocellulosic feedstock in temperate climates, and dedicated efforts are underway to improve biomass yield. However, nothing is known about the molecular players involved in Miscanthus cell wall biosynthesis to facilitate breeding efforts towards tailored biomass. Here, we identify a Miscanthus sinensis transcription factor related to SEC-ONDARY WALL-ASSOCIATED NAC DOMAIN1 (SND1), which acts as a master switch for the regulation of secondary cell wall formation and lignin biosynthesis.MsSND1 is expressed in growth stages associated with secondary cell wall formation, together with its potential targets. Consistent with this observation, MsSND1 was able to complement the secondary cell wall defects of the Arabidopsis snd1 nst1

Distinct and overlapping functions ofMiscanthus sinensisMYB transcription factors SCM1 and MYB103 in lignin biosynthesis

“…The continued differentiation along the leaf axis from immature leaf sheath towards mature leaf tip results in a linear developmental gradient. Previously, high expression of MsSND1 was found to coincide with vascular differentiation and SCW formation in Miscanthus leaves (Golfier et al ., 2017), implying a role for MsSND1 in those processes. To explore the potential involvement of MsMYB103 and MsSCM1 in secondary cell wall formation in Miscanthus, expression of MsMYB103 and MsSCM1 was determined together with MsSND1 along the leaf gradient and visualized in a heat map (Fig.…”

“…In order to find potential targets in Miscanthus that allows engineering of biomass optimized for bioenergy and biomaterials applications, we searched suitable TFs with the ability to regulate SCW formation with a focus on lignin biosynthesis. In Miscanthus, the NAC TF MsSND1 has been previously characterized as a master regulator orchestrating SCW formation, and MsSCM1, a MYB TF related to MYB20/43/85 (Zhong et al ., 2008), has been proposed as specific regulator of lignin biosynthesis (Golfier et al ., 2017). We identified a putative MsMYB103 in a Miscanthus transcriptome (Barling et al ., 2013) by a homology-based approach with AtMYB103 as query sequence.…”

“…Gene expression analysis was performed according to Golfier et al ., (2017). Briefly, total RNA was extracted from 30 mg ground leaf tissue using GeneMatrix Universal RNA Purification Kit (EURx/Roboklon).…”

“…Thus, while the SCW transcriptional network seems to be conserved to some degree, recent evidence suggests grass-specific nuances exist (Rao and Dixon, 2018), in line with an expansion of the MYB class of TFs in monocots (Rabinowicz et al ., 1999; Zhao and Bartley, 2014). Recently, MsSND1 and MsSCM1 from Miscanthus sinensis have been identified as positive regulators of lignin biosynthesis (Golfier et al ., 2017). However, a detailed analysis of the regulatory properties of MsSND1 and MsSCM1, as well as the impact of these TFs on SCW composition has not been addressed yet.…”

“…Here, we compare two MYB TFs, namely MsSCM1 (Golfier et al ., 2017) and the newly identified MsMYB103 with MsSND1, a master switch of SCW formation. In Miscanthus, MsSCM1 and MsMYB103 were expressed in tissue undergoing lignification.…”