Influence of Rare Earth Elements on Metabolism and Related Enzyme Activity and Isozyme Expression in Tetrastigma hemsleyanum Cell Suspension Cultures

Abstract

The effects of rare earth elements (REEs) not only on cell growth and flavonoid accumulation of Tetrastigma hemsleyanum suspension cells but also on the isoenzyme patterns and activities of related enzymes were studied in this paper. There were no significant differences in enhancement of flavonoid accumulation in T. hemsleyanum suspension cells among La(3+), Ce(3+), and Nd(3+). Whereas their inductive effects on cell proliferation varied greatly. The most significant effects were achieved with 100 μM Ce(3+)and Nd(3+). Under treatment over a 25-day culture period, the maximal biomass levels reached 1.92- and 1.74-fold and the total flavonoid contents are 1.45- and 1.49-fold, than that of control, respectively. Catalase, phenylalanine ammonia-lyase (PAL), and peroxidase (POD) activity was activated significantly when the REE concentration range from 0 to 300 μM, whereas no significant changes were found in superoxide dismutase activity. Differences of esterase isozymes under REE treatment only laid in expression level, and there were no specific bands. The expression level of some POD isozymes strengthened with increasing concentration of REEs within the range of 50-200 μM. When REE concentration was higher than 300 μM, the expression of some POD isozymes was inhibited; meanwhile, some other new POD isozymes were induced. Our results also showed REEs did not directly influence PAL activity. So, we speculated that 50-200 μM REEs could activate some of antioxidant enzymes, adjust some isozymes expression, trigger the defense responses of T. hemsleyanum suspension cells, and stimulate flavonoid accumulation by inducing PAL activity.

Transcriptome profiling reveals candidate flavonol-related genes of Tetrastigma hemsleyanum under cold stress

“…POD activity was measured according to our previous report [24]. POD activity was determined based on the linear increase in absorbance at 460 nm during incubation of the extracts at 25 °C with 10 mM guaiacol and 1 mM H 2 O 2 in 0.05 M sodiumacetate buffer (pH 5.4) in a total volume of 3 ml.…”

Rare earth elements in plants

“…Similar to heavy metals, REE inhibit the enzyme activities when their concentrations exceed a critical value. For example, esterase activity increases by adding 50 -100 μM of REE but decreases by 200 μM REE (Xin et al 2013). Under an acid rain, REE can significantly reduce the sensitivity of antioxidant enzymes to acid stress (Yan et al 1999).…”

Geochemical behaviour of rare earths in Vitis vinifera grafted onto different rootstocks and growing on several soils

“…REEs have been studied due to their progressively increasing exploitation in industrial practices, leading to their potential accumulation as pollutants. Particularly in China, REEs have often been added as fertiliser during agricultural activities to increase the growth rates of several vegetal species, which stimulate the production of secondary metabolites in several plants (d'Aquino et al, 2009;Hu et al, 2004;Liang et al, 2005;Xin et al, 2013), whereas their affinity for phosphates can lead to their enrichment in fertilisers worldwide.…”