Arabidopsis HY1 Confers Cadmium Tolerance by Decreasing Nitric Oxide Production and Improving Iron Homeostasis
Arabidopsis HY1 Confers Cadmium Tolerance by Decreasing Nitric Oxide Production and Improving Iron Homeostasis
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DOI：
10.1093/mp/sst122
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发表时间：
2014-02-01
期刊：
影响因子：
27.5
通讯作者：
Shen, Wenbiao
中科院分区：
文献类型：
--
作者：
Han, Bin;Yang, Zheng;Shen, Wenbiao
编码细胞内血红素加氧酶1(HO1)的基因上调有利于镉(Cd)胁迫下的植物，但其分子机制尚不清楚。在此，我们用遗传和分子方法阐明了拟南芥HY1(AtHO1)在Cd~(2+)耐受性中的作用。对两个HY1缺失突变体、3个HY1过表达系、HO双突变体或三重突变体以及PhyA和PhyB突变体的分析表明，hy1对Cd~(2+)胁迫具有特异性的敏感性。添加HY1的两种酶副产物一氧化碳(CO)和铁(特别是铁)，挽救了Cd~(2+)对Hy1-100初生根伸长的抑制作用。根组织中谷胱甘肽含量低于Col-0的HY1突变能够诱导根组织中一氧化氮(NO)的过量产生和Cd~(2+)的积累，并导致根组织严重缺铁。然而，相反的反应出现在35S：HY1-4。此外，铁还原氧化酶2(FRO2)和铁调节转运蛋白1(IRT1)转录本水平的降低，以及重金属ATPase 2/4(HMA2/4)转录本水平的增加，支持了HY1上调表达可以改善铁缺乏的观点，并可能增加对CD2+的排斥。综上所述，这些结果表明，HY1通过减少拟南芥根组织中NO的产生和改善铁的动态平衡，在耐Cd~(2+)中起着共同的作用。
Up-regulation of the gene that encodes intracellular heme oxygenase 1 (HO1) benefits plants under cadmium (Cd2+) stress; however, the molecular mechanisms remain unclear. Here, we elucidate the role of Arabidopsis HY1 (AtHO1) in Cd2+ tolerance by using genetic and molecular approaches. Analysis of two HY1 null mutants, three HY1 overexpression lines, HO double or triple mutants, as well as phyA and phyB mutants revealed the specific hypersensitivity of hy1 to Cd2+ stress. Supplementation with two enzymatic by-products of HY1, carbon monoxide (CO) and iron (Fe, especially), rescued the Cd2+-induced inhibition of primary root (PR) elongation in hy1-100. The mutation of HY1, which exhibited lower glutathione content than Col-0 in root tissues, was able to induce nitric oxide (NO) overproduction, Cd2+ accumulation, and severe Fe deficiency in root tissues. However, the contrasting responses appeared in 35S:HY1-4. Additionally, reduced levels of Ferric Reduction Oxidase 2 (FRO2) and Iron-Regulated Transporter 1 (IRT1) transcripts, and increased levels of Heavy Metal ATPase 2/4 (HMA2/4) transcripts bolster the notion that HY1 up-regulation ameliorates Fe deficiency, and might increase Cd2+ exclusion. Taken together, these results showed that HY1 plays a common link in Cd2+ tolerance by decreasing NO production and improving Fe homeostasis in Arabidopsis root tissues.