Decreased Polysaccharide Feruloylation Compromises Plant Cell Wall Integrity and Increases Susceptibility to Necrotrophic Fungal Pathogens.

Nathan T Reem,Lauran Chambers,Daniela Bellincampi,Vincenzo Lionetti,Michael A Held,Gennady Pogorelko,Olga A Zabotina

doi:10.3389/fpls.2016.00630

Nathan T Reem, Lauran Chambers + Show 5 more

Open Access

https://doi.org/10.3389/fpls.2016.00630

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Abstract

The complexity of cell wall composition and structure determines the strength, flexibility, and function of the primary cell wall in plants. However, the contribution of the various components to cell wall integrity (CWI) and function remains unclear. Modifications of cell wall composition can induce plant responses known as CWI control. In this study, we used transgenic expression of the fungal feruloyl esterase AnFAE to examine the effect of post-synthetic modification of Arabidopsis and Brachypodium cell walls. Transgenic Arabidopsis plants expressing AnFAE showed a significant reduction of monomeric ferulic acid, decreased amounts of wall-associated extensins, and increased susceptibility to Botrytis cinerea, compared with wild type. Transgenic Brachypodium showed reductions in monomeric and dimeric ferulic acids and increased susceptibility to Bipolaris sorokiniana. Upon infection, transgenic Arabidopsis and Brachypodium plants also showed increased expression of several defense-related genes compared with wild type. These results demonstrate a role, in both monocot and dicot plants, of polysaccharide feruloylation in plant CWI, which contributes to plant resistance to necrotrophic pathogens.

Highlights

In the heterogeneous, complex, and highly dynamic plant cell wall, structural polysaccharides form a cross-linked macromolecular network consisting of cellulose, hemicellulose, pectin, glycoproteins, and lignin (Albersheim et al, 2010)
To introduce A. nidulans feruloyl esterase (AnFAE), which we previously used to reduce the amount of ferulic acids in Arabidopsis plants (Pogorelko et al, 2011), to Brachypodium plants, a construct harboring Arabidopsis plants expressing the same fungal enzyme (AnFAE) was prepared using the binary vector described by Fursova et al (2012)
Two selected independent transgenic Brachypodium lines were tested for production of AnFAE in the extracellular matrix by assaying enzymatic activity in their apoplastic fluids, with methyl ferulate as a substrate

Summary

Introduction

Complex, and highly dynamic plant cell wall, structural polysaccharides form a cross-linked macromolecular network consisting of cellulose, hemicellulose, pectin, glycoproteins, and (in some specialized tissues) lignin (Albersheim et al, 2010). Cell wall constituents function in regulation of plant growth, development, signal transduction, and responses to environmental stresses (Somerville et al, 2004; Lionetti et al, 2012; Lionetti and Metraux, 2014; Tenhaken, 2015). Many signaling pathways involved in plant stress responses and innate immunity have been identified and characterized (Jones and Dangl, 2006). As the first line of defense for plants, the cell wall must be rigid enough to maintain cell turgor and prevent pathogen invasion, but accommodate cell expansion, division, and organogenesis. Different cell wall components function in controlling cell expansion (Wolf et al, 2012) and defense responses (Nicaise et al, 2009; Tenhaken, 2015)

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