Xyloglucan: The Molecular Muscle of Trees

Mellerowicz, Ewa J.; Immerzeel, Peter; Hayashi, Takahisa

doi:10.1093/aob/mcn170

Cited by 127 publications

(101 citation statements)

References 36 publications

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“…The most recently published models are based on the mechanism of entrapment of material during aggregation (figure 3e) [16,17,73]. These models, by forcing the microfibrils to bend, would generate longitudinal tension inside the G-layer, together with tension in microfibrils, consistent with observations.…”

Section: Entrapment Of Matrix Materials During Cellulose Aggregationsupporting

confidence: 66%

“…These models are designed to explain the molecular function of the chemical constituents found. A first version of this model [73] assumed that xyloglucans, previously considered as the main constituent of the G-layer matrix [10,17], could be entrapped between microfibrils during their aggregation. If the microfibril is initially straight, then the presence of material entrapped during aggregation tends to locally bend the microfibril, and therefore put it in longitudinal tension.…”

Section: Entrapment Of Matrix Materials During Cellulose Aggregationmentioning

confidence: 99%

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Critical review on the mechanisms of maturation stress generation in trees

Alméras

Clair

2016

J. R. Soc. Interface.

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Trees control their posture by generating asymmetric mechanical stress around the periphery of the trunk or branches. This stress is produced in wood during the maturation of the cell wall. When the need for reaction is high, it is accompanied by strong changes in cell organization and composition called reaction wood, namely compression wood in gymnosperms and tension wood in angiosperms. The process by which stress is generated in the cell wall during its formation is not yet known, and various hypothetical mechanisms have been proposed in the literature. Here we aim at discriminating between these models. First, we summarize current knowledge about reaction wood structure, state and behaviour relevant to the understanding of maturation stress generation. Then, the mechanisms proposed in the literature are listed and discussed in order to identify which can be rejected based on their inconsistency with current knowledge at the frontier between plant science and mechanical engineering.

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Section: Entrapment Of Matrix Materials During Cellulose Aggregationsupporting

confidence: 66%

Section: Entrapment Of Matrix Materials During Cellulose Aggregationmentioning

confidence: 99%

Critical review on the mechanisms of maturation stress generation in trees

Alméras

Clair

2016

J. R. Soc. Interface.

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“…Morphological and compositional characterization of the hygroscopic keel revealed the presence of a layer of primarily cellulose (CIL) within the ellipsoid cells, which is capable of absorbing large amounts of water. A similar swellable cellulosic layer termed the 'gelatinous layer' has previously been identified as the active element of stress generation in tension wood fibres of hardwood trees [15][16][17][18] , contractile roots 19,20 and tendrils 21 . It has been recently proposed to induce plant organ movement by exerting an inner pressure on the surrounding cell wall 22 .…”

Section: Discussionmentioning

confidence: 99%

Origami-like unfolding of hydro-actuated ice plant seed capsules

et al. 2011

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Actuated plant materials are a source of inspiration for the design of adaptive materials and structures that are responsive to specific external stimuli. Hydro-responsive, metabolismindependent plant movements are particularly fascinating, because the extracted concepts are more amenable to transfer into engineering than those dependent on cellular activity. Here we investigate the structural and compositional basis of a sophisticated plant movement mechanism-the hydration-dependent unfolding of ice plant seed capsules. This reversible origami-like folding pattern proceeds via a cooperative flexing-and-packing mechanism actuated by a swellable cellulose layer filling specialized plant cells. Swelling is translated into a bidirectional organ movement through simple geometric constraints embedded in the hierarchical architecture of the ice plant valves. Extracted principles from this reliable and reversible actuated movement have relevance to the emerging field of 'programmable matter' with applications as far-reaching as the design of satellites and artificial muscles.

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“…The importance of xyloglucan-cellulose cross links in modulating the strength and extensibility of the primary plant cell wall is a key feature of classical models of this composite structure (Carpita and McCann, 2000;Cosgrove, 2005;Mellerowicz et al, 2008). Although the molecular mechanisms of cell wall extension are largely unknown, a key tenet is transient wall loosening effected by the cleavage and religation of matrix xyloglucan by XET (EC 2.4.1.207).…”

Section: Discussionmentioning

confidence: 99%

Group III-AXTHGenes of Arabidopsis Encode Predominant Xyloglucan Endohydrolases That Are Dispensable for Normal Growth

et al. 2012

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The molecular basis of primary wall extension endures as one of the central enigmas in plant cell morphogenesis. Classical cell wall models suggest that xyloglucan endo-transglycosylase activity is the primary catalyst (together with expansins) of controlled cell wall loosening through the transient cleavage and religation of xyloglucan-cellulose cross links. The genome of Arabidopsis (Arabidopsis thaliana) contains 33 phylogenetically diverse XYLOGLUCAN ENDO-TRANSGLYCOSYLASE/ HYDROLASE (XTH) gene products, two of which were predicted to be predominant xyloglucan endohydrolases due to clustering into group III-A. Enzyme kinetic analysis of recombinant AtXTH31 confirmed this prediction and indicated that this enzyme had similar catalytic properties to the nasturtium (Tropaeolum majus) xyloglucanase1 responsible for storage xyloglucan hydrolysis during germination. Global analysis of Genevestigator data indicated that AtXTH31 and the paralogous AtXTH32 were abundantly expressed in expanding tissues. Microscopy analysis, utilizing the resorufin b-glycoside of the xyloglucan oligosaccharide XXXG as an in situ probe, indicated significant xyloglucan endohydrolase activity in specific regions of both roots and hypocotyls, in good correlation with transcriptomic data. Moreover, this hydrolytic activity was essentially completely eliminated in AtXTH31/AtXTH32 double knockout lines. However, single and double knockout lines, as well as individual overexpressing lines, of AtXTH31 and AtXTH32 did not demonstrate significant growth or developmental phenotypes. These results suggest that although xyloglucan polysaccharide hydrolysis occurs in parallel with primary wall expansion, morphological effects are subtle or may be compensated by other mechanisms. We hypothesize that there is likely to be an interplay between these xyloglucan endohydrolases and recently discovered apoplastic exo-glycosidases in the hydrolytic modification of matrix xyloglucans.

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Xyloglucan: The Molecular Muscle of Trees

Cited by 127 publications

References 36 publications

Critical review on the mechanisms of maturation stress generation in trees

Critical review on the mechanisms of maturation stress generation in trees

Origami-like unfolding of hydro-actuated ice plant seed capsules

Group III-AXTHGenes of Arabidopsis Encode Predominant Xyloglucan Endohydrolases That Are Dispensable for Normal Growth

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