Immunocytochemical characterization of tension wood: Gelatinous fibers contain more than just cellulose

Abstract

Gelatinous fibers (G-fibers) are the active component of tension wood. G-fibers are unlike traditional fiber cells in that they possess a thick, nonlignified gelatinous layer (G-layer) internal to the normal secondary cell wall layers. For the past several decades, the G-layer has generally been presumed to be composed nearly entirely of crystalline cellulose, although several reports have appeared that disagreed with this hypothesis. In this report, immunocytochemical techniques were used to investigate the polysaccharide composition of G-fibers in sweetgum (Liquidambar styraciflua; Hamamelidaceae) and hackberry (Celtis occidentalis; Ulmaceae) tension wood. Surprisingly, a number of antibodies that recognize arabinogalactan proteins and RG I-type pectin molecules bound to the G-layer. Because AGPs and pectic mucilages are found in other plant tissues where swelling reactions occur, we propose that these polymers may be the source of the contractile forces that act on the cellulose microfibrils to provide the tension force necessary to bend the tree trunk.

Maturation Stress Generation in Poplar Tension Wood Studied by Synchrotron Radiation Microdiffraction

“…This conclusion is in sharp contrast with current conceptions of maturation stress generation as exclusively based on the action of the G-layer (Bowling and Vaughn, 2008;Goswami et al, 2008;. There is evidence that cell walls without G-layers can produce significant axial tensile stress, for example in normal wood or in the tension wood of many tropical species (Onaka, 1949;Clair et al, 2006b;Ruelle et al, 2007).…”

“…www.plantphysiol.org/cgi/doi/10.1104/pp.109.149542 1994Yamamoto, 1998Yamamoto, , 2004Alméras et al, 2005Alméras et al, , 2006Bowling and Vaughn, 2008;Goswami et al, 2008;. The specific organization of the G-layer suggests a tensile force induced in the microfibrils during the maturation process.…”

“…The specific organization of the G-layer suggests a tensile force induced in the microfibrils during the maturation process. Different hypotheses have been proposed to explain this mechanism, such as the contraction of amorphous zones within the cellulose microfibrils (Yamamoto, 2004), the action of xyloglucans during the formation of microfibril aggregates (Nishikubo et al, 2007;, and the effect of changes in moisture content stimulated by pectin-like substances (Bowling and Vaughn, 2008). A recent work (Goswami et al, 2008) argued an alternative model, initially proposed by Mü nch (1938), which proposed that the maturation stress originates in the swelling of the G-layer during cell maturation and is transmitted to the adjacent secondary layers, where the larger MFAs allow an efficient conversion of lateral stress into axial tensile stress.…”

Quantitative Evaluation of Hybrid Aspen Xylem and Immunolabeling Patterns Using Image Analysis and Multivariate Statistics

“…It has been used extensively over the last decade to study the development and topochemistry of primary and secondary cell walls in plant and xylem tissues, including in genetically modified trees (e.g. Awano et al 2000;Willats et al 2000;Grunwald et al 2001Grunwald et al , 2002aZhang et al 2003;Joseleau et al 2004;Knox et al 2005;Hosoo et al 2006;Ruel et al 2006;Altaner et al 2007a, b;Daniel et al 2006;Nishikubo et al 2007;Bowling and Vaughn 2008;Mast et al 2009;Sandquist et al 2010;Kim and Daniel 2013). It is an outstanding observational aid to highlight the presence and availability of epitopes, within limits of the specificity determined for each antibody.…”

Nanospherical arabinogalactan proteins are a key component of the high-strength adhesive secreted by English ivy

“…These substances presumably arise from the encapsulation of partial components of the plant cell wall within the cured adhesive, a phenomenon that has been detailed in the previous studies (15,18). Given that AGs and pectic substances have been identified to be two of the predominant components in the majority of botanic adhesives, including those obtained from the climbing organs of Virginia creeper, Boston ivy, and Ficus pumila, as shown in the previous cytochemical analyses ( [14][15][16][17][48][49][50], it is logical to expect that these two acidic polysaccharides possess exceptional capacity to effectively support the adhesive function of the sticky exudates at the interface. In particular, for the mucilage secreted by the root hairs of English ivy, the pectic acids may exist alone and/or be covalently bonded to the AGPs within the ivy nanoparticles as interpreted above.…”