Melatonin confers plant tolerance against cadmium stress via the decrease of cadmium accumulation and reestablishment of microRNA-mediated redox homeostasis
Melatonin confers plant tolerance against cadmium stress via the decrease of cadmium accumulation and reestablishment of microRNA-mediated redox homeostasis
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DOI：
10.1016/j.plantsci.2017.05.001
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发表时间：
2017-08-01
期刊：
影响因子：
5.2
通讯作者：
Shen, Wenbiao
中科院分区：
文献类型：
--
作者：
Gu, Quan;Chen, Ziping;Shen, Wenbiao
尽管褪黑素减轻动物和植物中的镉（Cd）毒性已得到充分研究，但对其在植物中的调节机制知之甚少。在这里，我们发现镉胁迫刺激了苜蓿幼苗根组织中内源褪黑激素的产生。外源褪黑素预处理不仅提高了褪黑素含量，而且减轻了镉对幼苗生长的抑制作用。过度表达苜蓿SNAT（褪黑激素合成基因）的富含褪黑激素的转基因拟南芥植物在镉条件下表现出比野生型植物更高的耐受性。根组织中的镉含量也减少了。与单独的 Cd 胁迫相比，褪黑激素上调了苜蓿幼苗中的 ABC 转运蛋白和 PCR2 转录本，以及拟南芥中的 PDR8 和 HMA4。相比之下，Nramp6 转录本下调。上述转运蛋白的变化与Cd积累的减少相关。此外，褪黑激素还可改善镉引发的氧化还原失衡。这些可能通过 miR398a 和 miR398b 调控的 Cu/Zn 超氧化物歧化酶基因的变化得到支持。组织化学染色、激光扫描共聚焦显微镜和11202含量分析显示出相似的趋势。综上所述，我们清楚地表明褪黑激素通过减少镉积累和重建 microRNA 介导的氧化还原稳态来增强镉耐受性。
Although melatonin-alleviated cadmium (Cd) toxicity both in animals and plants have been well studied, little is known about its regulatory mechanisms in plants. Here, we discovered that Cd stress stimulated the production of endogenous melatonin in alfalfa seedling root tissues. The pretreatment with exogenous melatonin not only increased melatonin content, but also alleviated Cd-induced seedling growth inhibition. The melatonin-rich transgenic Arabidopsis plants overexpressing alfalfa SNAT (a melatonin synthetic gene) exhibited more tolerance than wild-type plants under Cd conditions. Cd content was also reduced in root tissues. In comparison with Cd stress alone, ABC transporter and PCR2 transcripts in alfalfa seedlings, PDR8 and HMA4 in Arabidopsis, were up regulated by melatonin. By contrast, Nramp6 transcripts were down-regulated. Changes in above transporters were correlated with the less accumulation of Cd. Additionally Cd-triggered redox imbalance was improved by melatonin. These could be supported by the changes of the Cu/Zn Superoxide Dismutase gene regulated by miR398a and miR398b. Histochemical staining, laser scanning confocal microscope, and 11202 contents analyses showed the similar tendencies. Taking together, we clearly suggested that melatonin enhanced Cd tolerance via decreasing cadmium accumulation and reestablishing the microRNAs-mediated redox homeostasis.