Endo-1,4-[beta]-Glucanase, Xyloglucanase, and Xyloglucan Endo-Transglycosylase Activities Versus Potential Substrates in Ripening Tomatoes

Maclachlan, Gordon; Brady, Colin J.

doi:10.1104/pp.105.3.965

Cited by 157 publications

(112 citation statements)

References 28 publications

Supporting

Mentioning

107

Contrasting

Order By: Relevance

“…In sycamore suspension-cultured cells, half of the XG polymer is composed of the subunits XXFG and XXXG; however, the rest of the molecules is composed of subunits with more extensive sidechain substitution (York etal., 1995). In another example, XG from the growing tissues of tobacco and tomato does not possess subunits with fucosylated trisaccharide sidechains (Maclachlan and Brady, 1994;Seymour et aL, 1990;York et aL, 1996). However, it appears that the sidechain chemistry in these XGs is appreciably different from the forms discussed in this study (York et aL, 1996) and it is therefore possible that different conformational preferences dictate the formation of the cellulose binding conformation.…”

Section: Mechanisms Of Xg Binding To Cellulosementioning

confidence: 65%

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

1997

View full text Add to dashboard Cite

SummaryCross-links between cellulose microfibrils and xyloglucan (XG) molecules play a major role in defining the structural properties of plant cell walls and the regulation of growth and development of dicotyledonous plants. How these cross-links are established and how they are regulated has yet to be determined. In a previous study, preliminary data were presented which suggested that the different sidechains of XG may play a role in controlling cellulose microfibriI-XG interactions. In this study, this question is addressed directly by analyzing to what extent the different sidechains of pea cell wall XG and nasturtium seed storage XG affect their binding to cellulose microfibrils. Of particular importance to this study are the chemical data indicating that pea XG possesses a trisaccharide sidechain, which is not found in nasturtium XG. To this end, conformational dynamic simulations have been used to predict whether oligosaccharides representative of pea and nasturtium XG can adopt a hypothesized cellulosebinding conformation and which of these XGs exhibits a preferential ability to bind cellulose. Extensive analysis of the conformational forms populated during 300 K and high-temperature Monte Carlo simulations established that a planar, sterically accessible, glucan backbone is essential for optimal cellulose-binding. For the trisaccharide sidechain-containing oligosaccharide as found in pea XG, sidechain orientation appeared to regulate the gradual acquisition of this hypothesized cellulose binding conformation. Thus, conformational forms were identified that included the twisted backbone (non-planar) putative solution form of XG, forms in which the trisaccharide sidechain orientation enables increased backbone planarity and steric accessibility, and finally a planar, sterically accessible, backbone. By applying these conformational requirements for cellulose binding, it has been Received 25 May 1996; revised 11 October 1996; accepted 12 November 1996. *For correspondence (fax +1 303 492 7744; e-mail levy@spot.colorado.edu).determined that pea XG possesses a two-to threefold occurrence of the cellulose binding conformation than nasturtium XG. Based on this finding, it was predicted that pea XG would bind to cellulose at a higher rate than nasturtium XG. In vitro binding assays showed that pea XG-avicel binding does indeed occur at a twofold higher rate than nasturtium XG-avicel binding. The enhanced ability of pea cell wall XG over nasturtium seed storage XG to associate with cellulose is consistent with a structural role of the former during epicotyl growth where efficient association with cellulose is a requirement. In contrast, the relatively low ability of nasturtium XG to bind cellulose is consistent with the need to enhance the accessibility of this polymer to glycanases during germination. These findings suggest potential roles for XG sidechain substitution, enabling XG to function in a variety of different biological contexts.

show abstract

Section: Mechanisms Of Xg Binding To Cellulosementioning

confidence: 65%

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

1997

View full text Add to dashboard Cite

show abstract

“…Tomato fruit ripening includes the progressive and extensive loss of firmness that is largely a result of metabolism of the cell wall polysaccharides (Brummell, 2006;Cantu et al, 2007Cantu et al, , 2008a. The ripeningassociated disassembly of hemicellulosic and pectic cell wall polysaccharides is known to be severely reduced in rin fruit and apparently is diminished in nor and 1-MCP-treated fruit, since they also have only limited softening (Seymour et al, 1987;Giovannoni et al, 1989;DellaPenna et al, 1990;Maclachlan and Brady, 1994). We have previously shown that fruit susceptibility to B. cinerea depends on LePG and LeExp1, two proteins that participate in the disassembly of the cell wall, which are expressed in ripe fruit even though B. cinerea secretes its own polysaccharidehydrolyzing enzymes (van Kan, 2006;Cantu et al, 2008a).…”

Section: Discussionmentioning

confidence: 99%

Ripening-Regulated Susceptibility of Tomato Fruit toBotrytis cinereaRequiresNORBut NotRINor Ethylene

Cantu

Blanco‐Ulate

Long³

et al. 2009

Plant Physiology

148

163

View full text Add to dashboard Cite

Fruit ripening is a developmental process that is associated with increased susceptibility to the necrotrophic pathogen Botrytis cinerea. Histochemical observations demonstrate that unripe tomato (Solanum lycopersicum) fruit activate pathogen defense responses, but these responses are attenuated in ripe fruit infected by B. cinerea. Tomato fruit ripening is regulated independently and cooperatively by ethylene and transcription factors, including NON-RIPENING (NOR) and RIPENING-INHIBITOR (RIN). Mutations in NOR or RIN or interference with ethylene perception prevent fruit from ripening and, thereby, would be expected to influence susceptibility. We show, however, that the susceptibility of ripe fruit is dependent on NOR but not on RIN and only partially on ethylene perception, leading to the conclusion that not all of the pathways and events that constitute ripening render fruit susceptible. Additionally, on unripe fruit, B. cinerea induces the expression of genes also expressed as uninfected fruit ripen. Among the ripening-associated genes induced by B. cinerea are LePG (for polygalacturonase) and LeExp1 (for expansin), which encode cell wall-modifying proteins and have been shown to facilitate susceptibility. LePG and LeExp1 are induced only in susceptible rin fruit and not in resistant nor fruit. Thus, to infect fruit, B. cinerea relies on some of the processes and events that occur during ripening, and the fungus induces these pathways in unripe fruit, suggesting that the pathogen itself can initiate the induction of susceptibility by exploiting endogenous developmental programs. These results demonstrate the developmental plasticity of plant responses to the fungus and indicate how known regulators of fruit ripening participate in regulating ripening-associated pathogen susceptibility.

show abstract

“…[In ripening fruits of tomato (Lycopersicon esculentum L. var 83-G-38), the amounts of cellulose and xyloglucan remained constant during tissue softening, but the relative molecular weight of xyloglucan decreased markedly and the Mr of cellulose declined slightly] (Maclachlan and Brady, 1994). Xyloglucan is the principal hemicellulose and present in both dicot and monocot cell walls, although it is present in far larger amounts in the walls of dicots (about 20 %) relative to those of monocots (about 2 %) (Darvill et al, 1980).…”

Section: Cell Wall Structure and Softening -Associated Changesmentioning

confidence: 99%

Biochemistry of fruit softening: an overview

Payasi¹,

Mishra

Chaves

et al. 2009

Physiol Mol Biol Plants

200

125

View full text Add to dashboard Cite

Softening is a developmentally programmed ripening process, associated with biochemical changes in cell wall fractions involving hydrolytic processes resulting in breakdown of cell-wall polymers such as cellulose, hemicelluloses and pectin etc. Various hydrolytic reactions are brought about by polygalacturonase, pectin methyl esterase, pectate lyase, rhamnogalacturonase, cellulase and β-galactosidase etc. Besides these enzymes, expansin protein also plays an important role in softening. Textural changes during ripening help in determining the shelf life of a fruit. An understanding of these changes would help in formulating procedures for controlling fruit softening vis-à-vis enhancing shelf life of fruits. In the present review an attempt has been made to coalesce recent findings on biochemistry of fruit softening.

show abstract

Endo-1,4-[beta]-Glucanase, Xyloglucanase, and Xyloglucan Endo-Transglycosylase Activities Versus Potential Substrates in Ripening Tomatoes

Cited by 157 publications

References 28 publications

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

Xyloglucan sidechains modulate binding to cellulose during in vitro binding assays as predicted by conformational dynamics simulations

Ripening-Regulated Susceptibility of Tomato Fruit toBotrytis cinereaRequiresNORBut NotRINor Ethylene

Biochemistry of fruit softening: an overview

Contact Info

Product

Resources

About