Co-overexpression FIT with AtbHLH38 or AtbHLH39 in Arabidopsis enhanced cadmium tolerance via increased cadmium sequestration in roots and improved iron homeostasis of shoots
| 作者： |
Huilan Wu,Chunlin Chen,Juan Du,Hongfei Liu,Yan Cui,Yue Zhang,Yujing He,Junming Li,Zongyun Feng,Yiqing Wang,Chengcai Chu and Honq-Qing Ling |
| 刊物名称： |
Plant Physiology |
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| 发表年度： |
2011-12-20 |
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| 摘要： |
Cadmium (Cd) is toxic to plant cells. Under Cd exposure, the plant displayed leaf chlorosis which is a typical symptom as iron deficiency. Interactions of cadmium with iron have been reported. However, the molecular mechanisms of cadmium-iron interactions are not well understood. Here, we showed that FIT, AtbHLH38 and AtbHLH39, three basic helix-loop-helix transcription factors involved in iron homeostasis in plants, also play important roles in Cd tolerance. The gene expression analysis showed that the expression of FIT, AtbHLH38 and AtbHLH39 was up-regulated in the roots of plants treated with Cd. The plants overexpressing AtbHLH39, double-overexpressing FIT/AtbHLH38 and FIT/AtbHLH39 exhibited more tolerance to Cd exposure than wild type, whereas no Cd tolerance was observed in plants overexpressing either AtbHLH38 or FIT. Further analysis revealed that co-overexpression of FIT with AtbHLH38 or AtbHLH39 constitutively activated the expression of HMA3, MTP3, IRT2 and IREG2, which are involved in the heavy metal detoxification in Arabidopsis. Moreover, co-overexpression of FIT with AtbHLH38 or AtbHLH39 also enhanced the expression of NAS1 and NAS2, resulting in the accumulation of nicotiananamine, a crucial chelator for iron transportation and homeostasis. Finally, we showed that maintaining high iron content in shoot under Cd exposure could alleviate the Cd toxicity. Our results provide a new insight to understand the molecular mechanisms of Cd tolerance in plants. |
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