Melatonin confers plant tolerance against cadmium stress via the decrease of cadmium accumulation and reestablishment of microRNA-mediated redox homeostasis. (August 2017)

• Record Type: Journal Article
• Authors: Gu, Quan; Chen, Ziping; Yu, Xiuli; Cui, Weiti; Pan, Jincheng; Zhao, Gan; Xu, Sheng; Wang, Ren; Shen, Wenbiao
• Is Part Of: Plant science. Volume 261(2017)
• Page Start: 28
• Page End: 37
• Publication Date: 2017-08
• Subjects: ABC transporter ATP-binding cassette transporter -- ASMT N-acetylserotonin methyltransferase -- Cd cadmium -- CSD Cu/Zn superoxide dismutase gene -- DAB 3, 3′-diaminobenzidine -- H2DCFDA 2′7′-dichlorofluorescin diacetate -- H2O2 hydrogen peroxide -- ICP-OES inductively coupled plasma-optical emission spectrometer -- CLSM confocal laser scanning microscope -- Mel melatonin -- miRNAs microRNAs -- NBT nitroblue tetrazolium -- Nramp natural resistance-associated macrophage protein -- O2− superoxide anion -- ROS reactive oxygen specie -- SNAT serotonin N-acetyltransferase -- WT wild-type; Cadmium stress -- Melatonin -- Redox homeostasis -- Transporter -- Medicago sativa -- Transgenic Arabidopsis plants; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2017.05.001
• Languages: English
• ISSNs: 0168-9452

Abstract

Highlights: Cd induced melatonin production in alfalfa and Arabidopsis seedling roots. Transgenic Arabidopsis lines overexpressing alfalfa SNAT ( MsSNAT ) exhibited high-level melatonin and enhanced Cd tolerance. Cd accumulation in plants was decreased via melatonin-modulated heavy metal transporters. Melatonin-reestablished redox homeostasis via miR398. Abstract: 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 H2 O2 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.