Amelioration of aluminum toxicity on OM4900 rice seedlings by sodium silicate

Abstract

Silicon has versatile functions in plant biology, especially in plant defense and tolerance to both biotic and abiotic stressors. In this study, it was investigated if silicon could reduce the toxic effect of aluminum on rice. Aluminum was applied to OM4900 rice seedlings, and then their growth and sugar metabolism were determined. At doses of aluminum chloride of 100 and 200 µM, plant height was significantly enhanced and root elongation was reduced. The accumulation of photosynthetic pigments was tightly correlated with the aluminum concentration showing highest amounts at 400 µM. Sugar levels in roots and endosperm decreased upon aluminum addition. Aluminum toxicity in rice seedlings was relieved by addition of silicon in the form of sodium silicate. In the presence of 200 µM aluminum chloride, the addition of 100 mg/L sodium silicate to the hydroponic solution showed no contribution to plant growth or buildup of photosynthetic pigments. At this concentration, root development was not affected while it was at higher concentrations. Sodium silicate addition did not alter the reduction in sugar levels by aluminum. The presence of 200 µM aluminum chloride with or without sodium silicate in the growing solution significantly decreased silicon content in rice husks.

Aluminum Enhances Growth and Sugar Concentration, Alters Macronutrient Status and Regulates the Expression of NAC Transcription Factors in Rice

“…Likewise, our experiments also demonstrated that chlorophyll concentrations increased in young leaves of Al-treated Cotaxtla, Huimanguillo and Temporalero plants (Figures 3A–C , respectively). These results are also in full agreement with those reported by Nhan and Hai ( 2013 ) in rice plant cultivar OM4900, since both chlorophyll a and b were significantly higher in plants treated with 200, 300, 400, and 500 μM AlCl 3 , as compared with the control.…”

“…For instance, tea plants ( Camellia sinensis ) exposed to 100 μM Al developed better than those grown in Al-free media (Hajiboland et al, 2013a ). In rice cultivar OM4900, Nhan and Hai ( 2013 ) found an increase of 35% in shoot height in plants exposed to 400 μM Al for 8 days. Moreover, Famoso et al ( 2011 ) reported that exposure to 160 μM Al triggered significant root elongation in rice, which is similar to our results.…”

“…In alfalfa ( Medicago sativa ), Al enhances root growth (Zhang et al, 2007 ), whereas in common bean ( Phaseolus vulgaris ) it improves root and shoot growth as well as antioxidant activity (Du et al, 2010 ) and in maize ( Zea mays ) it stimulates leaf growth (Wang et al, 2015 ). In rice ( Oryza sativa ), Al stimulates growth (Osaki et al, 1997 ), root elongation (Famoso et al, 2011 ), shoot height and chlorophylls as well as carotenoids concentrations (Nhan and Hai, 2013 ).…”

Expression patterns and promoter analyses of aluminum-responsive NAC genes suggest a possible growth regulation of rice mediated by aluminum, hormones and NAC transcription factors

“…In rice, the first report indicated that Al stimulates growth [27]; later, in an analysis by the genome-wide association (GWA) on 383 different rice accessions in response to Al, 16 cultivars were reported to show an increase in root growth [12]. Subsequently, Al was reported to have increased the concentration of chlorophylls ( a and b ) and carotenoids [28]. Recently, it was observed that 200 μM Al in 4 cultivars (Cotaxtla, Tres Ríos, Huimanguillo, and Temporalero) stimulated growth, increased the concentrations of chlorophylls and total soluble sugars in the plantlet, and augmented P and K concentrations in the root [1].…”

A contemporary overview of silicon availability in agricultural soils

“…Silicon applications can be effective at alleviating toxicity of metals including Al, Mn, Fe, Cd, Pb, and Zn ( Gu et al, 2012; Maksimović et al, 2012; Bharwana et al, 2013; Dufey et al, 2013; Nhan and Hai , 2013). The responsible mechanisms are complex and can be divided into external ( e.g.…”