An miR156-regulated nucleobase-ascorbate transporter 2 confers cadmium tolerance via enhanced anti-oxidative capacity in barley

• Published in: Journal of advanced research 2023-02, Vol.44, p.23-37
• Main Authors: Wang, Nian-Hong, Zhou, Xue-Yi, Shi, Shou-Heng, Zhang, Shuo, Chen, Zhong-Hua, Ali, Mohamed Abdelalim, Ahmed, Imrul Mosaddek, Wang, Yizhou, Wu, Feibo
• Format: Article
• Language: English
• Subjects: Animals; Antioxidants - metabolism; Antioxidants - pharmacology; Ascorbic Acid - pharmacology; Cadmium - metabolism; Cadmium - pharmacology; Cadmium toxicity; Ecosystem; Hordeum - genetics; Hordeum vulgare L; Humans; Metals, Heavy - pharmacology; MicroRNAs - genetics; miRNA; Original; Oxidative signaling; Phylogeny; Plants, Genetically Modified - genetics; Plants, Genetically Modified - metabolism; RNA sequencing
• ISSN: 2090-1232; 2090-1224; 2090-1224
• DOI: 10.1016/j.jare.2022.04.001

[Display omitted] •microRNA expression compared in Cd-tolerant/sensitive barley Zhenong8 vs W6nk2.•First report a novel gene HvNAT2 targeted by miR156g-3p_3 vital in barley Cd tolerance.•HvNAT2 evolved from the Zygnematales in Streptophyte algae and positively regulates Cd tolerance.•Overexpression of HvNAT2 enhances the expression of genes for ROS scavenging and antoxidative enzyme activity. Cadmium (Cd) is one of the most detrimental heavy metal pollutants, seriously affecting crop production and human health. Nucleobase-ascorbic acid transporters (NAT) are widely present in many living organisms including plants, animals and microbes; however, the role of NAT in plant Cd tolerance remains unknown. To identify Cd-induced miRNAs that target HvNAT2 and to determine the role of this gene and its product in Cd tolerance. High-throughput-sequencing was used to identify the miRNA expression profile of barley roots in response to Cd stress. Overexpression (OX) and RNAi lines were then constructed for HvNAT2 and comparative transcriptomic analysis was performed to determine the function of this transporter examining its effects on traits such as Cd uptake/flux and translocation, morphology and antioxidant capacity in relation to Cd tolerance. In addition, phylogenetic analysis was performed to obtain insights into the evolution of HvNAT2. Cd stress-induced genome-wide expression profiles of miRNAs identified a Cd-induced miRNA, miR156g-3p_3, that had HvNAT2 as its target. HvNAT2 was negatively regulated in the high-Cd-accumulating and Cd-tolerant genotype Zhenong8. Evolutionary analysis indicated that orthologues of the plasma membrane localized, HvNAT2, can be traced back to the sister group of land plants, the streptophyte algae. Overexpression of HvNAT2 increases Cd tolerance with higher tissue Cd accumulation but less oxidative damage in transgenic barley plants. RNAi of HvNAT2 leads to a significant reduction of Cd tolerance. The higher Cd accumulation in roots of the OX3 line was also demonstrated by confocal microscopy and electrophysiology. Transcriptome analysis showed that the enhancement of antioxidant capacity by HvNAT2 was related to stress signaling pathways. Furthermore, oxidative stress tolerance in HvNAT2-OX plants was regulated by the synthesis of phytochelatins and the glutathione metabolism cycle. Our study reveals a key molecular mechanism of NAT in Cd tolerance in plants that is useful for sustainable agricultural production and management