Current Models for Transcriptional Regulation of Secondary Cell Wall Biosynthesis in Grasses

Xiaolan Rao,Richard A. Dixon

doi:10.3389/fpls.2018.00399

Xiaolan Rao, Richard A. Dixon

Open Access

https://doi.org/10.3389/fpls.2018.00399

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Abstract

Secondary cell walls mediate many crucial biological processes in plants including mechanical support, water and nutrient transport and stress management. They also provide an abundant resource of renewable feed, fiber, and fuel. The grass family contains the most important food, forage, and biofuel crops. Understanding the regulatory mechanism of secondary wall formation in grasses is necessary for exploiting these plants for agriculture and industry. Previous research has established a detailed model of the secondary wall regulatory network in the dicot model species Arabidopsis thaliana. Grasses, branching off from the dicot ancestor 140–150 million years ago, display distinct cell wall morphology and composition, suggesting potential for a different secondary wall regulation program from that established for dicots. Recently, combined application of molecular, genetic and bioinformatics approaches have revealed more transcription factors involved in secondary cell wall biosynthesis in grasses. Compared with the dicots, grasses exhibit a relatively conserved but nevertheless divergent transcriptional regulatory program to activate their secondary cell wall development and to coordinate secondary wall biosynthesis with other physiological processes.

Highlights

The plant cell wall is a structural layer located outside of the cell membrane that provides the physical strength to maintain cell shape against gravity (Taiz and Zeiger, 1998)
This review focuses on current advances in secondary cell wall regulation in grasses, and discusses the commonalities and the differences between grasses and dicots
AtMYB46 and its ortholog PvMYB46 share a high similarity in activation efficiency on eight cis-acting elements [named the secondary wall MYB-responsive element (SMRE)] to induce the expression of target genes involved in secondary wall-related cellulose, xylan, and lignin biosynthesis (Ko et al, 2012; Zhong and Ye, 2012; Kim et al, 2013; Zhong et al, 2015), indicating the conservation of MYB46 function in grasses and Arabidopsis

Summary

Introduction

The plant cell wall is a structural layer located outside of the cell membrane that provides the physical strength to maintain cell shape against gravity (Taiz and Zeiger, 1998). SWNs from rice, maize, Brachypodium, and switchgrass are capable of directly inducing the expression of secondary wall biosynthesis genes in Arabidopsis through binding to the SNBE (secondary wall NAC binding element) motif in the target gene’s promoters (Zhong et al, 2006, 2011, 2015; Valdivia et al, 2013).

Results

Conclusion