A model of crosslink kinetics in the expanding plant cell wall: Yield stress and enzyme action

JOURNAL OF THEORETICAL BIOLOGY

卷:307

Article

Dyson, R. J.²  Band, L. R.³  Jensen, O. E.^1,3 

[1] Univ Nottingham, Sch Math Sci, Nottingham NG7 2RD, England

[2] Univ Birmingham, Sch Math, Birmingham B15 2TT, W Midlands, England

[3] Univ Nottingham, Ctr Plant Integrat Biol, Loughborough LE12 5RD, England

关键词: Cellulose microfibril;    Hemicellulose;    Cross link;    Yield stress;   

DOI  :  10.1016/j.jtbi.2012.04.035

来源: Elsevier

【 摘 要 】

The plant primary cell wall is a composite material containing stiff cellulose microfibrils that are embedded within a pectin matrix and crosslinked through a network of hemicellulose polymers. This microstructure endows the wall with nonlinear anisotropic mechanical properties and allows enzymatic regulation of expansive cell growth. We present a mathematical model of hemicellulose crosslink dynamics in an expanding cell wall incorporating strain-enhanced breakage and enzyme-mediated crosslink kinetics. The model predicts the characteristic yielding behaviour in the relationship between stress and strain-rate seen experimentally, and suggests how the effective yield and extensibility of the wall depend on microstructural parameters and on the action of enzymes of the XTH and expansin families. The model suggests that the yielding behaviour encapsulated in the classical Lockhart equation can be explained by the strongly nonlinear dependence of crosslink breakage rate on crosslink elongation. The model also demonstrates how enzymes that target crosslink binding can be effective in softening the wall in its pre-yield state, whereas its post-yield extensibility is determined primarily by the pectin matrix. (C) 2012 Elsevier Ltd. All rights reserved.

【 授权许可】

Free