The Mediator complex subunits MED25/PFT1 and MED8 are required for transcriptional responses to changes in cell wall arabinose composition and glucose treatment in Arabidopsis thaliana

Séguéla-Arnaud, Mathilde; Smith, Caroline; Uribe, Marcos Castellanos; May, Sean; Fischl, Harry; McKenzie, Neil; Bevan, Michael W.

doi:10.1186/s12870-015-0592-4

Cited by 23 publications

(23 citation statements)

References 57 publications

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“…Previous studies have shown that mutation of PRL1 , MED25 , or MED8 suppresses the sugar‐hypersensitive hypocotyl elongation phenotype of the mur4‐1 / hsr8‐1 mutant under dark conditions (Li et al ., ; Seguela‐Arnaud et al ., ). Here, we examined the phenotype of med25 hsr8‐1 , med8 hsr8‐1 , and mur4‐1 prl1‐1 on salt medium, and found that the roots of these mutants were only slightly longer than those of mur4‐1 / hsr8‐1 (Fig.…”

Section: Resultsmentioning

confidence: 97%

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Arabinose biosynthesis is critical for salt stress tolerance in Arabidopsis

et al. 2019

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Summary The capability to maintain cell wall integrity is critical for plants to adapt to unfavourable conditions. l‐Arabinose (Ara) is a constituent of several cell wall polysaccharides and many cell wall‐localised glycoproteins, but so far the contribution of Ara metabolism to abiotic stress tolerance is still poorly understood. Here, we report that mutations in the MUR4 (also known as HSR8) gene, which is required for the biosynthesis of UDP‐Arap in Arabidopsis, led to reduced root elongation under high concentrations of NaCl, KCl, NaNO3, or KNO3. The short root phenotype of the mur4/hsr8 mutants under high salinity is rescued by exogenous Ara or gum arabic, a commercial product of arabinogalactan proteins (AGPs) from Acacia senegal. Mutation of the MUR4 gene led to abnormal cell−cell adhesion under salt stress. MUR4 forms either a homodimer or heterodimers with its isoforms. Analysis of the higher order mutants of MUR4 with its three paralogues, MURL, DUR, MEE25, reveals that the paralogues of MUR4 also contribute to the biosynthesis of UDP‐Ara and are critical for root elongation. Taken together, our work revealed the importance of the Ara metabolism in salt stress tolerance and also provides new insights into the enzymes involved in the UDP‐Ara biosynthesis in plants.

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Section: Resultsmentioning

confidence: 97%

“…Previous studies have shown that high sugar response 8 ( hsr8 ), an allele of the mur4 mutant, displays glucose‐hypersensitive hypocotyl elongation and development under dark conditions (Li et al ., ; Seguela‐Arnaud et al ., ). Li et al .…”

Section: Introductionmentioning

confidence: 97%

Arabinose biosynthesis is critical for salt stress tolerance in Arabidopsis

et al. 2019

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“…In an over-expression experiment of BELLRINGER, a homeodomain transcription factor involved in development and growth, only the expression of genes associated with the cell wall were changed including several LTPs (79). Furthermore, the transcriptional regulator MED/PFT1 in Arabidopsis was shown to regulate cell wall gene expression including two LTPs (80). In a meta-analysis of cell wall proteomics data, LTPs were found to be a significant part of the protein population …”

Section: Ltps May Facilitate Cell Expansion and Plant Growthmentioning

confidence: 99%

Plant lipid transfer proteins: are we finally closing in on the roles of these enigmatic proteins?

Edqvist

Blomqvist

Nieuwland

et al. 2018

Journal of Lipid Research

101

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The nonspecific lipid transfer proteins (LTPs) are small, compact proteins folded around a tunnel-like hydrophobic cavity, making them suitable for lipid binding and transport. LTPs are encoded by large gene families in all land plants, but they have not been identified in algae or any other organisms. Thus, LTPs are considered key proteins for plant survival on and colonization of land. LTPs are abundantly expressed in most plant tissues, both above and below ground. They are usually localized to extracellular spaces outside the plasma membrane. Although the in vivo functions of LTPs remain unclear, accumulating evidence suggests a role for LTPs in the transfer and deposition of monomers required for assembly of the water-proof lipid barriers-such as cutin and cuticular wax, suberin, and sporopolleninformed on many plant surfaces. Some LTPs may be involved in other processes, such as signaling during pathogen attacks. Here, we present the current status of LTP research with a focus on the role of these proteins in lipid barrier deposition and cell expansion. We suggest that LTPs facilitate extracellular transfer of barrier materials and adhesion between barriers and extracellular materials. A growing body of research may uncover the true role of LTPs in plants. Overview of plant non-specific lipid transfer proteinsThe plant non-specific lipid transfer proteins (LTPs) are abundant, secreted, soluble, cysteinerich and small proteins with a molecular size usually below 10 kDa (1, 2). In the LTPs four conserved disulfide bridges, formed by an eight-Cys motif (8CM) with the general form CXn-C-Xn-CC-Xn-CXC-Xn-C-Xn-C, stabilize the folding of four or five α-helices into a very compact 3D-structure (3, 4 and Fig. 1). The folding of the helices results in a central hydrophobic cleft suitable for the binding of hydrophobic ligands, such as fatty acids and other lipids (Fig. 2). The compact structure renders the LTPs very insensitive to heat and denaturing agents (5, 6). LTPs are expressed in all investigated land plants, but have not been detected in any other organisms (7). LTPs are encoded by large gene families in seed plants (2,(8)(9)(10)(11). In bryophytes and ferns the gene families are significantly smaller (7,12). LTPs are classified in five major types (LTP1, LTP2, LTPc, LTPd and LTPg) and four minor types (LTPe, LTPf, LTPh, LTPj and LTPk) (7). The classification is based on the spacing between the Cys residues in the 8CM, the polypeptide sequence identity and the position of evolutionary conserved introns. The classification also reflects post-translational modifications, e.g. LTPs with a GPI-anchor belong to LTPg. LTPd and LTPg are encoded in all land plants which suggests that these were possibly the first LTP types that evolved in land plants. The most well-studied LTP types in flowering plants LTP1 and LTP2 probably evolved later since these are not found in liverworts, mosses or other non-seed plants (7). The LTPs are translated with an N-terminal signal peptide that has a potential to localize th...

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“…• Methyl jasmonate and salicylic acid treatment (Xu and Li, 2011), but also in numerous abiotic and biotic stress responses (Kidd et al, 2009;Elfving et al, 2011;Iñigo et al, 2012;Sundaravelpandian et al, 2013;Raya-González et al, 2014;Carvalhais et al, 2015;Seguela-Arnaud et al, 2015).…”

Section: Chapter4mentioning

confidence: 99%

Investigating the role of the Mediator complex in plant defence

Fallath¹

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The Mediator complex is an evolutionarily conserved protein complex involved in transcriptional regulation. In plants, the Mediator complex plays an important role in regulating development as well as the response to abiotic and biotic stress. In this thesis, I investigated three subunits of the Arabidopsis thaliana Mediator complex MEDIATOR25, MEDIATOR18 and MEDIATOR20 (MED25, MED18 and MED20) in plant defence.MED25 has been shown to interact with several transcription factors (TFs) to control jasmonate (JA)-associated transcription. Here, I investigated these interactions further and characterized the minimum protein domains of the TFs needed for interaction and identified new proteins that interact with MED25. The results showed that the protein sequence corresponding to amino acids 138-218 of ETHYLENE RESPONSE FACTOR1 (ERF1) appears to be the minimum protein length for interaction with MED25 and contains the conserved motif (CMIX). Although the protein motif has been found in different proteins in A. thaliana that belong to a variety of families, only members from the IXc AP2/ERF family were found to interact with the MED25 ACID domain.Apart from MED25, I found that the MED18 and MED20 subunits interact within the Mediator complex and infection of the corresponding mutants with Fusarium oxysporum revealed that they display a high level of resistance. RNAseq analysis of F. oxysporum infected med18 and med20 roots showed that salicylic acid (SA)-associated PATHOGENESIS RELATED genes and (ROS) reactive oxygen producing genes were up-regulated while some JA-regulated genes were repressed.We also noticed induction and repression of genes involved in glucosinolate production. This may suggest that ROS and antifungal metabolites are induced in med18 and med20 mutants and could potentially contribute to the reduced colonization of the mutants by F. oxysporum. Overall, the results reveal a new role for MED18 and MED20 in susceptibility to F. oxysporum, most likely via their involvement in JA signalling whose up-regulation would compromise SA and ROS signalling pathways that can confer resistance against this hemibiotrophic pathogen.ii

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The Mediator complex subunits MED25/PFT1 and MED8 are required for transcriptional responses to changes in cell wall arabinose composition and glucose treatment in Arabidopsis thaliana

Cited by 23 publications

References 57 publications

Arabinose biosynthesis is critical for salt stress tolerance in Arabidopsis

Arabinose biosynthesis is critical for salt stress tolerance in Arabidopsis

Plant lipid transfer proteins: are we finally closing in on the roles of these enigmatic proteins?

Investigating the role of the Mediator complex in plant defence

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