2/16/2024 0 Comments Silicon si element![]() Compelling evidence in the literature shows that specific cell wall components trigger SiO 2 precipitation (reviewed by Guerriero et al., 2016a). However, this passive role is too simplistic and does not explain why plants supplemented with Si are better suited to face exogenous stresses. This difference may be in part due to the different cell wall types ( Yokoyama and Nishitani, 2004) and to the structural importance of Si in type II cell walls (i.e., cell walls characterized by the presence of more phenylpropanoids as compared to type I cell walls in dicots).īy precipitating as SiO 2 and being incorporated into biological structures (e.g., the cell wall, vide infra), Si exerts its protective action via the formation of a physical barrier. It should, however, be noted that in rice, Si(OH) 4 supplementation does trigger major changes, as it induces the upregulation and downregulation of 35 and 121 transcription factors respectively ( Van Bockhaven et al., 2012). This has been observed in the Arabidopsis-powdery mildew pathosystem ( Fauteux et al., 2006). ![]() In (some) plants the provision of Si(OH) 4 has a latent effect in the absence of an external stimulus ( Fauteux et al., 2005, 2006). Tomato is among the excluders, while Urtica dioica (i.e., nettle) is an intermediate type ( Trembath-Reichert et al., 2015). Among the accumulators are Equisetales, Cyperales and Poales: in Graminae, rice is the highest silicifier where Si (in the form of biogenic silica, vide infra) accounts for up to 10% of the shoot dry weight ( Ma et al., 2002). Plants are classified into accumulators, excluders and intermediate type ( Mitani and Ma, 2005), depending on the amount of biogenic silica found in their tissues. A specific 108 amino acid spacing between the conserved NPA domains determines Si(OH) 4 permeability ( Deshmukh et al., 2015). Si is taken up by plants as silicic acid Si(OH) 4 via aquaporin type channels (Nod26-like intrinsic proteins, NIPs) ( Ma et al., 2006 Grégoire et al., 2012 Deshmukh et al., 2013). When supplied to the growth medium (as silicic acid, vide infra), plant vigor and resistance to (a)biotic stresses increase ( Azeem et al., 2015 Coskun et al., 2016 Guerriero et al., 2016a). Plants develop well in its absence, although in some cases, e.g., the silicifier horsetail and rice, the absence of Si triggers increased susceptibility to fungal infection ( Datnoff and Rodrigues, 2005 Law and Exley, 2011). Silicon (Si) is considered non-essential (or quasi-essential, Epstein and Bloom, 2005) for plant growth and development. The study indeed provides perspectives on the use of Si to increase the yield of fiber crops and to improve the thermal stability and tensile strength of natural fibers. The paper also discusses the potential technological aspects linked to the use of Si in agriculture and to modify/improve the physical parameters of plant fibers. A whole section will be devoted to the use of silica (SiO 2) nanoparticles, in the light of the interest that nanotechnology has for agriculture. Emphasis will be given to the protective role of Si during (a)biotic stresses and in this context both priming and the effects of Si on endogenous phytohormones will be discussed. In this study the beneficial role of Si on plants will be discussed, by reviewing the available data in the literature. The protective role of Si was initially attributed to a physical barrier fortifying the cell wall (e.g., against fungal hyphae penetration), however, several studies have shown that the action of this element on plants is far more complex, as it involves a cross-talk with the cell interior and an effect on plant metabolism. Additionally, Si ameliorates the vigor of plants and improves their resistance to exogenous stresses. Biogenic silica is also a deterrent against herbivores. Indeed Si alleviates the toxic effects caused by abiotic stresses, e.g., salt stress, drought, heavy metals, to name a few. Si is not considered essential for plant growth and development, however, increasing evidence in the literature shows that this metalloid is beneficial to plants, especially under stress conditions. 2Environmental Research and Innovation Department, Luxembourg Institute of Science and Technology, Esch-sur-Alzette, LuxembourgĮlemental silicon (Si), after oxygen, is the second most abundant element in the earth’s crust, which is mainly composed of silicates.1Groupe de Recherche en Physiologie Végétale, Earth and Life Institute - Agronomy, Université Catholique de Louvain, Louvain-la-Neuve, Belgium.Marie Luyckx 1 Jean-Francois Hausman 2 Stanley Lutts 1* Gea Guerriero 2*
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