Hitting the Wall—Sensing and Signaling Pathways Involved in Plant Cell Wall Remodeling in Response to Abiotic Stress

Abstract

Plant cells are surrounded by highly dynamic cell walls that play important roles regulating aspects of plant development. Recent advances in visualization and measurement of cell wall properties have enabled accumulation of new data about wall architecture and biomechanics. This has resulted in greater understanding of the dynamics of cell wall deposition and remodeling. The cell wall is the first line of defense against different adverse abiotic and biotic environmental influences. Different abiotic stress conditions such as salinity, drought, and frost trigger production of Reactive Oxygen Species (ROS) which act as important signaling molecules in stress activated cellular responses. Detection of ROS by still-elusive receptors triggers numerous signaling events that result in production of different protective compounds or even cell death, but most notably in stress-induced cell wall remodeling. This is mediated by different plant hormones, of which the most studied are jasmonic acid and brassinosteroids. In this review we highlight key factors involved in sensing, signal transduction, and response(s) to abiotic stress and how these mechanisms are related to cell wall-associated stress acclimatization. ROS, plant hormones, cell wall remodeling enzymes and different wall mechanosensors act coordinately during abiotic stress, resulting in abiotic stress wall acclimatization, enabling plants to survive adverse environmental conditions.

A wall with integrity: surveillance and maintenance of the plant cell wall under stress

“…HG-containing stretches of demethylesterified GalA can be crosslinked by Ca 2+ , promoting wall stiffening (Hocq et al, 2017). Abiotic stress causes changes to cell wall structure (Tenhaken, 2014;Novakovi c et al, 2018), which can be sensed by CWI sensors. In addition to HG crosslinking, borate-crosslinking of RG-II also contributes to the mechanical strength of the wall and is required for growth under both normal and stress conditions (O'Neill et al, 2001;Sechet et al, 2018).…”

“…Both abiotic and biotic stresses challenge CWI, but plant cells are capable of correcting detrimental changes to the wall to allow for growth (Hamann, 2012;Tenhaken, 2014;Novakovi c et al, 2018). Both abiotic and biotic stresses challenge CWI, but plant cells are capable of correcting detrimental changes to the wall to allow for growth (Hamann, 2012;Tenhaken, 2014;Novakovi c et al, 2018).…”

“…Growth rate in Arabidopsis roots falls sharply in the first 4-5 h of salt treatment, and is restored to a new steady state level by 12-13 h post-treatment (Geng et al, 2013;Feng et al, 2018). One avenue that is worth exploring is to test whether wall crosslinking is re-established and whether there is an increase in ROS formation and peroxidase activity, both of which potentially strengthen the wall (Tenhaken, 2014;Novakovi c et al, 2018). AFM measurements reveal that the outermost layer of the wall in epidermal cells undergoes a softening-stiffening transition before growth rate recovery .…”

“…Both abiotic and biotic stresses challenge CWI, but plant cells are capable of correcting detrimental changes to the wall to allow for growth (Hamann, 2012;Tenhaken, 2014;Novakovi c et al, 2018). A significant amount of our knowledge on how the cell wall responds to stressors has been generated through transcriptomic and proteomic analyses of the genes and enzymes that synthesize and modify the wall (Tenhaken, 2014;Le Gall et al, 2015;Novakovi c et al, 2018). The precise nature of the alterations that are made to the wall, including changes in its composition, structure and mechanical properties, are largely unknown.…”

“…The stiffening process, on the other hand, is thought to be critical for the maintenance of CWI before growth resumes under salt stress , but it remains to be established what compositional and organizational changes occur to stiffen the wall. One avenue that is worth exploring is to test whether wall crosslinking is re-established and whether there is an increase in ROS formation and peroxidase activity, both of which potentially strengthen the wall (Tenhaken, 2014;Novakovi c et al, 2018).…”