Cell Wall Signalling in Arabidopsis thaliana
Final Report Abstract
Communication between the extracellular matrix and the cell interior is essential for all organisms as intrinsic and extrinsic cues have to be integrated to coordinate development, morphogenesis, and behaviour. This applies in particular to plants, the growth and shape of which is governed by deposition and remodelling of the cell wall, a rigid, yet dynamic, extracellular network. To control growth, but also to respond to extrinsic perturbations, cell wall state is constantly monitored and information must be conveyed to the cell interior in order to fine-tune the physico-chemical properties of the wall for optimal responses. However, very little is known about this cell wall-mediated signalling in plants. We therefore aimed to understand role of cell wall perception and cell wall-mediated feedback signalling in plant development. Using targeted modification of the major cell wall component pectin, we have identified a novel feedback signalling pathway connecting cell wall surveillance with brassinosteroid (BR) hormone signalling. The brassinosteroid (BR) signalling module is a central regulator of plant growth and one of the best characterized signalling pathways in plants. As a central factor in conveying information about the state of the wall to the BR signalling pathway we could identify a receptor-like protein in the plasma membrane, called RLP44, which is highly conserved throughout the plant kingdom. RLP44 is able to interact with both cell wall pectins and the receptors for the brassinosteroid hormones. Presence of RLP44 affects the protein dynamics and interaction within the BR receptor complex to promote its activity. However, RLP44 also interacts with other plasma membrane receptors and the rlp44 mutants show a diverse array of defects associated with development. Among those defects is the ectopic development of xylem cells in the place of other cell types, indicating that RLP44 is required for the maintenance of cell fate. In this context, RLP44 requires the presence of the BR receptor for functionality, but the control of vascular development is independent of BR target genes. Instead, RLP44 activates another receptor (PSKR1), which is responsive to signalling peptides and in turn ensures proper vascular development and cell fate. These results demonstrate how development relies on complex and dynamic interactions between the different plasma membrane receptors to integrate various cues from the environment. We could show that these interactions are controlled by post-translational modifications which are responsive to the state of the cell wall. Moreover, cell wall signalling affects the cell division orientation in root and shoot stem cells. These and other findings from our lab support the hypothesis that signalling form the cell wall has important consequences not only as a feedback control mechanism to maintain cell wall homeostasis, but also has a role in guiding cell fate decisions and thus plays an important role in the coordination of plant development.
Publications
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(2014). A receptor-like protein mediates the response to pectin modification by activating brassinosteroid signaling. PNAS 111:15261-6
Wolf S, van der Does D, Ladwig F, Sticht C, Kolbeck A, Schurholz AK, Augustin S, Keinath N, Rausch T, Greiner S, Schumacher K, Harter K, Zipfel C, Hofte H
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2014. Growth Control: A Saga of Cell Walls, ROS, and Peptide Receptors. Plant Cell 26:1848-56
Wolf S, Hofte H
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2016. Reassessment of an Arabidopsis cell wall invertase inhibitor AtCIF1 reveals its role in seed germination and early seedling growth. Plant Mol Biol 90:137-55
Su T, Wolf S, Han M, Zhao H, Wei H, Greiner S, Rausch T
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The Effects of High Steady State Auxin Levels on Root Cell Elongation in Brachypodium. Plant Cell 28: 1009-1024
Pacheco-Villalobos D, Diaz-Moreno SM, van der Schuren A, Tamaki T, Kang YH, Gujas B, Novak O, Jaspert N, Li Z, Wolf S, Oecking C, Ljung K, Bulone V, Hardtke CS
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(2017) . Regulation of secondary cell wall biosynthesis by a NAC transcription factor from Miscanthus. Plant Direct 1 (5), e00024
Golfier P, Volkert C, He F, Rausch T, Wolf S
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(2017). Plant cell wall signalling and receptor-like kinases. Biochem J. 474, 471-492
Wolf S
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(2018) BRI1 Controls Vascular Cell Fate in the Arabidopsis Root through RLP44 and Phytosulfokine Signalling. PNAS 115 (46): 11838-11843
Holzwart E, Huerta AI, Glöckner N, Garnelo Gómez B, Wanke F, Augustin S, Askani J, Schürholz A-K, Harter K, Wolf S
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(2018). A comprehensive toolkit for inducible, cell type-specific gene expression in Arabidopsis. Plant Physiol 178: 40-53
Schürholz A-K, López-Salmerón V, Li Z, Forner J, Wenzl C, Gaillochet C, Augustin S, Vilches Barro A, Fuchs M, Gebert M, Lohmann JU, Greb T, Wolf S
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(2019) A mutant allele uncouples the brassinosteroid-dependent and independent functions of BRASSINOSTEROID INSENSITIVE 1. Plant Physiology 182, pp. 669–678
Holzwart, E., Wanke, F., Glöckner, N., Höfte, H., Harter, K., Wolf., S.
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(2019). Distinct and overlapping functions of Miscanthus sinensis MYB transcription factors SCM1 and MYB103 in lignin biosynthesis
Golfier P, Unda F, Murphy EK, Xie J, He F, Zhang W, Mansfield SD, Rausch T, and Wolf S
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(2019). Phosphorylation-dependent routing of RLP44 towards brassinosteroid or phytosulfokine signalling
Garnelo Gómez B, Lozano-Duran R, and Wolf S
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(2019). The in vivo impact of MsLAC1, a Miscanthus laccase isoform, on lignification and lignin composition contrasts with its in vitro substrate preference. BMC Plant Biology 19, 552
He F, Machemer-Noonan K, Golfier P, Unda F, Dechert J, Zhang W, Hoffmann N, Samuels L, Mansfield SD, Rausch T, Wolf S
