Cross talk between Cu excess and Fe deficiency in the roots of rice.

Copper (Cu) and iron (Fe) share similar characteristics and participate as coenzymes in several physiological processes. Both Cu excess and Fe deficiency result in chlorosis, however, the crosstalk between the two is not clear in rice. In this study, we performed transcriptome analysis for Cu excess and Fe deficiency in rice. Some WRKY family members (such as WRKY26) and some bHLH family members (such as late flowering) were selected as novel potential transcription factors involved in the regulation of Cu detoxification and Fe utilization, respectively. These genes were induced under corresponding stress conditions. Many Fe uptake-related genes were induced by Cu excess, while Cu detoxification-related genes were not induced by Fe deficiency. Meanwhile, some genes, such as metallothionein 3a, gibberellin 3beta-dioxygenase 2 and WRKY11, were induced by Cu excess but repressed by Fe deficiency. Concisely, our results highlight the crosstalk between Cu excess and Fe deficiency in rice. Cu excess caused Fe deficiency response, while Fe deficiency did not lead to Cu toxicity response. Metallothionein 3a might be responsible for Cu toxicity-induced chlorosis in rice. The crosstalk between Cu excess and Fe deficiency might be regulated by gibberellic acid.