Effects of Lanthanum on the Change of Calcium Level in the Root Cells of Rice

Rare-earth elements (REEs) have been widely used in agriculture for the growth of crops in China since the 1980s. As a secondary messenger, calcium ion (Ca2+) participates in physiological and biochemical reactions in plants via cellular or intercellular signal transduction networks. The aim of this study was to investigate the effects of trivalent lanthanum (La3+) on the change of Ca2+ in the root cells of rice (Oryza sativa L. cv. Shengdao 16) with laser-scanning confocal microscopy. The results indicated that Ca2+ level in the root cells was affected by the concentrations of La3+. The level of Ca2+ slightly decreased in the root of rice treated with 0.2 mmol L–1 La3+, and Ca2+ oscillation was induced in the root of rice treated with 1.0 mmol L–1 La3+. However, Ca2+ level increased in the root of rice treated with 2.0 mmol L–1 La3+. In addition, the results indicated that Ca2+ level in the rice roots slightly decreased after Ca2+ inhibitors verapamil (VP), ruthenium red (RR), trifluperazine (TFP), and e...