Wall Structure and Wall Loosening. A Look Backwards and Forwards

Cosgrove, Daniel J.

doi:10.1104/pp.125.1.131

Cited by 277 publications

(216 citation statements)

References 25 publications

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“…PCWs are sophisticated assemblies of cellulose, hemicellulose, pectin and glycoproteins. Even though the components of PCWs have been well studied, there is still limited understanding of the 3D architecture (Cosgrove 2001(Cosgrove , 2014Wang and Hong 2016). This lack of understanding is largely attributed to the complex nature of the interactions between cellulose and other PCW components.…”

Section: Introductionmentioning

confidence: 99%

Structural factors affecting 13C NMR chemical shifts of cellulose: a computational study

et al. 2017

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The doublet C4 peaks at * 85 and * 89 ppm in solid-state 13 C NMR spectra of native cellulose have been attributed to signals of C4 atoms on the surface (solvent-exposed) and in the interior of microfibrils, designated as sC4 and iC4, respectively. The relative intensity ratios of sC4 and iC4 observed in NMR spectra of cellulose have been used to estimate the degree of crystallinity of cellulose and the number of glucan chains in cellulose microfibrils. However, the molecular structures of cellulose responsible for the specific surface and interior C4 peaks have not been positively confirmed. Using density functional theory (DFT) methods and structures produced from classical molecular dynamics simulations, we investigated how the following four factors affect 13 C NMR chemical shifts in cellulose: conformations of exocyclic groups at C6 (tg, gt and gg), H 2 O molecules H-bonded on the surface of the microfibril, glycosidic bond angles (U, W) and the distances between H4 and HO3 atoms. We focus on changes in the d 13 C4 value because it is the most significant observable for the same C atom within the cellulose structure. DFT results indicate that different conformations of the exocyclic groups at C6 have the greatest influence on d 13 C4 peak separation, while the other three factors have secondary effects that increase the spread of the calculated C4 interior and surface peaks.

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Section: Introductionmentioning

confidence: 99%

Structural factors affecting 13C NMR chemical shifts of cellulose: a computational study

et al. 2017

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“…With the application of cyanide acid, there was a reduction of MG deposition on the cellular walls of cells of the radicular meristem of Echinochloa crusgalli (Tresch & Grossmann, 2003). Alternatively, it may be due to a secondary effect common to auxinic herbicides, possibly associated to the quick auxinic activity on β-glucans (1→3, 1→4) on the hydrolysis of the cellular wall matrix (Cosgrove, 2001). …”

Section: Effect On the Formation Of The Cellular Wallmentioning

confidence: 99%

Integrative Theory of the Mode of Action of Quinclorac: Literature Review1

Fipke

Vidal

2016

Planta daninha

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-Quinclorac is a systemic herbicide absorbed by germinating seeds, roots and leaves of seedlings. It is a selective compound for crops such as rice, canola, barley, corn, sorghum, and pasture. Quinclorac can be used to control various monocots and dicotyledonous weed species. The biochemical function of this herbicide in the plant has intrigued scientists for nearly four decades. The objectives of this review are to present evidence of three hypotheses on the biochemical functioning of quinclorac and to propose an integrative mode of action. The first theory on the mode of action of quinclorac is supported by evidence of inhibition of incorporation of C 14 -glucose into cellulose and hemicellulose, thus, affecting the cell wall synthesis. The second hypothesis suggests that quinclorac acts as an auxin in broadleaved weed species. In grass species, however, this herbicide appears to stimulate the activity of the 1-aminocyclopropane-1-carboxylate synthase enzyme and, subsequently, to increase the ethylene production; also, it seems to increase the cyanide acid content to phytotoxic levels. A third hypothesis to explain the harmful effect in some plant species is the formation of reactive oxygen species (ROS). Apparently, these processes are not mutually exclusive; therefore, an integrative theory for the action of quinclorac is suggested. It is theorized that the aforementioned biochemical activities are interconnected and can be the phytotoxic backbone to explain the herbicidal effect depending on the plant species and the plant growth stage, among other factors.Keywords: cellulose biosynthesis-inhibitor, cyanide, auxinic herbicide, reactive oxygen species. Palavras-chave: inibidor da síntese de celulose, herbicida auxínico, cianeto, espécies reativas de oxigênio. RESUMO

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“…where  and  are interpreted as the bulk modulus and shear modulus of cell wall matrix, respectively, and 1  and 2  are parameters of the elastic response of cellulose microfibrils. The first and second terms on the right side of eqn.…”

Section: Viscoelastic Responsementioning

confidence: 99%

“…It must be strong enough to resist the mechanical stress (which may exceed 10 8 Nm -2 (100 MPa)) generated by the cell turgor pressure and at the same time it must be sufficiently compliant to permit irreversible wall expansion. The cell wall accommodates these requirements through its composite structure, having stiff microfibrils with high mechanical strength embedded in a viscoplastic amorphous matrix that moves in a controlled fashion [2]. Fig.…”

Section: Introductionmentioning

confidence: 99%