Cadmium-induced ammonium ion accumulation of rice seedlings at high temperature is mediated through abscisic acid
2006
Hsu, Yi-Ting | Kuo, Mei Chun | Kao, Ching Huei
In this study, we examined interaction between cadmium (Cd) and temperature in rice seedlings. Effects of CdCl₂ (0.5 mM) simultaneously applied at high (35/30°C day/night), medium (25/20°C) and low (15/13°C) temperatures to rice seedlings were detected by measuring changes in biomass production and NH ₄ ⁺ content. Results indicated that Cd-induced biomass reduction and NH ₄ ⁺ accumulation increased in parallel with temperature increases. On treatment with CdCl₂, the abscisic acid (ABA) content markedly increased in the leaves of seedlings grown at high temperature but not at medium and low temperatures. Exogenous application of ABA at medium temperature increased ABA and NH ₄ ⁺ contents in the leaves of rice seedlings. Fluridone (Flu) treatment, an inhibitor of carotenoid biosynthesis, reduced ABA content, as well as Cd-induced NH ₄ ⁺ accumulation in the leaves of rice seedlings grown at high temperature. These Flu effects can be reversed by application of ABA. Furthermore, Flu treatment did not reduce Cd content in leaves of seedlings grown at high temperature. All these results suggest that Cd-induced NH ₄ ⁺ accumulation at high temperature is mediated through ABA.
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