Calcium and silicon binding compounds in cell walls of rice shoots

Abstract

Calcium compounds in cell walls of rice shoots were investigated by molecular sieve chromatography and compared with silicon compounds. The phenolcarbohydrate complexes (PCC) obtained by eellulase action, and the lignincarbohydrate complexes (LCC) extracted by dimethylsulfoxide (DMSO) were loaded onto a Sephacryl S-400 column. Then calcium, silicon, phenolic acids, or lignin, and carbohydrate of both complexes were detected in the void volume. These results indicate that calcium and silicon may combine with the phenol-or lignin-earbohydrate complexes in cell walls of rice shoots.Key Words: calcium, cell wall, lignin-earbohydrate complexes, phenolic acids, silicon.Calcium is an essential element and plays an important role in many physiological functions of higher plants. The maintenance of the cell wall structure depends upon calcium cross-linkages, particularly with pectin components of the middle lamella (Bangerth 1979). In a previous paper (Inanaga et al. 1988), we indicated that calcium may play an important role in the stability of the cell wall of the peanut shell through the formation of a calciumcomplex not only with pectin substances but also with the caffeic acid moiety in the LCC or PCC. Ito and Fujiwara (1968) reported that when the cell wall of rice leaf was fractionated, calcium was associated with ligneous substances. In addition to the cell wall of the peanut shell, calcium may also combine with the PCC and LCC of rice.Although silicon is an essential element for the development of rice (Lewin 1969), its physiological role is far from clear. Lewin (1969) reported that silicon is depositted in the form of silica gel in the epidermal cells and cell walls of many plants, and that very often it occurs as special morphological skeletal structure. As silicic acid can be readily formed with polyhydric alcohols and organic acids (Lewin 1969), silicon may also bind with the LCC and PCC of rice plant in a similar way as calcium.Attempts were made to determine whether calcium and silicon combine with the PCC or with the LCC in cell walls of rice shoots. MATERIALS AND METHODSPlant culture. In a greenhouse, rice (Oryza sativa L. cv. Koshijiwase) seedlings transplanted on June 25 were grown for 40 d in tap water with 100 mg L -1 silicon, to which nutrients (40 mg L -1 nitrogen as NH4NO3, 8.7 mg L -1 phosphorus as Na2HPO4, 25 mg L -~ potassium as KC1, 6 mg L -1 magnesium as MgSO4, 7 mg L -~ calcium as CaC12, 3 mg L -~

Silicon deficiency promotes lignin accumulation in rice

“…In rice, silica accumulates mainly on cell walls, forming silicacuticle double layers and silica-cellulose double layers in the surface of leaves, stems and hulls . It was also suggested that silica is combined in some way with phenol-polysaccharide or lignin-polysaccharide compounds (Inanaga and Okasaka 1995). In fact, in vitro simulation experiments showed that silica deposition in aqueous borax solution is induced by the addition of soluble lignin from rice (Fang and Ma 2006).…”

Aqueous Macromolecules with Silicon from Alcoholinsoluble Residues of Rice Seedlings

“…1). Similar silicon-containing high molecular weight compounds were detected in the void volume by molecular sieve open-column chromatography of cellulase digests of rice cell walls 10 . It should be noted that the samples grown without silicic acid also gave the peak at void volume.…”

“…The suspensions were centrifuged and the insoluble residues washed with water. The solubilized material was dialyzed against deionized H 2 O with 10,000 mol wt cut dialysis membrane (Amicon Hollow fiber HIP [10][11][12][13][14][15][16][17][18][19][20]. The retentate was freeze-dried, and then loaded onto a column (1.6 × 90 cm) of Sephadex G-75, equilibrated with 50 mM ammonium formate buffer, pH 5.3, and eluted with the same buffer.…”

“…The complex is considered to be involved in biosilica formation. It was suggested that silicon might be combined with a phenolic acid or aromatic ring moiety of the lignin-carbohydrate complexes in rice cell walls 10,11 . To date, however, there has been no direct evidence that silica binds to organic molecules such as polysaccharides in the cell walls of land plants.…”

Silício no progresso da mancha marrom na folha bandeira do trigo

“…Sabe-se que o ácido monosilícico compete com o Ca pelos sítios de ligações na parede celular devido a sua facilidade em complexar-se com alcoóis polihídricos, ácidos orgânicos, lignina, carboidratos e até mesmo certos compostos fenólicos (Inanaga & Okasaka, 1995). Não houve diferença significativa (P ≥ 0,05) entre as duas cultivares para a concentração foliar de Si e a AACPMM; entretanto a concentração foliar de Ca foi significativamente superior para a cultivar BR-18 do que para a cultivar BRS-208.…”