Cadmium Affect Root Growth in Japonica Rice (Oryza sativa L.) Negatively Interacting with JA at Bud Stage

Abstract To explore the role of jasmonic acid in seed germination of rice under Cd stress, the growth indices of JJ818 and NJ9108 under the bud stage were measured for identifying study the molecular mechanism of variety difference in cadmium tolerance. The tolerant variety JJ818 and the sensitive variety NJ9108 were treated under 150 µmol·L− 1 Cd concentration, methyl jasmonate (MeJA), and Ibuprofen (IBU) alone or in combination. The germination rate, root length, bud length, soluble protein content, soluble sugar content, and sugar components, α-amylase activity, and its related gene expression were measured. The results showed that the root length of the two rice materials were significantly inhibited during germination under the Cd treatment, however, the germination rate and shoot length had little affected. MeJA decreased the germination rate, root length and shoot length, and the contents of soluble sugar and sugar components and α-amylase activity as well. However, IBU treatment showed the opposite trend. Cd treatment also decreased the expression of the αAmy and RL1, and the accompanying changes of up-regulated the gene expression of JIOsPR10, OsLOX1, and OsLOX4 related to synthesizing jasmonic acid(JA). The results showed that JA negatively regulates the cadmium of rice and the genes related to the synthesis and response of JA were related to the variety difference in cadmium tolerance at the bud stage. Compared with the NJ9108, JJ818 was insensitive to jasmonic acid.