The Influence of pH on Cadmium Accumulation in Seedlings of Rice (Oryza sativa L.)

The growth, development, and quality of rice are inhibited by the presence of cadmium (Cd) in the soil, the uptake of which depends strongly on the pH of the growth medium. Here, a hydroponics-based experiment was conducted to characterize the relationship between Cd accumulation and the pH of the medium in seedlings of the two cultivars, Zhonjiazao17 (ZJZ17) and Xiangzhengyu (XZY). The uptakes of Cd by the roots of both cultivars and its translocation to the shoots were the highest from a medium of pH 6.0. XZY plants accumulated more Cd than ZJZ17 ones. Transcription profiling indicated that the genes, OsNRAMP1 and OsHMA2, were actively involved in Cd uptake and transport, as they were both strongly upregulated at pH 6.0. Both the Cd concentration of the medium and its pH exerted significant effects on the seedling growth. At pH 6.0, zinc was efficiently transported, but the translocation of iron was suppressed in shoot. The genes, OsZIP5 and OsYSL15, are the most likely responsible for the uptake and translocation of both these elements in rice seedlings.