Genome-Wide Identification of the Nramp Gene Family in Spirodela polyrhiza and Expression Analysis under Cadmium Stress

Abstract

Natural resistance-associated macrophage proteins (Nramps) are specific metal transporters in plants with different functions among various species. The evolutionary and functional information of the <i>Nramp</i> gene family in <i>Spirodela polyrhiza</i> has not been previously reported in detail. To identify the <i>Nramp</i> genes in <i>S. polyrhiza</i>, we performed genome-wide identification, characterization, classification, and cis-elements analysis among 22 species with 138 amino acid sequences. We also conducted chromosomal localization and analyzed the synteny relationship, promoter, subcellular localization, and expression patterns in <i>S. polyrhiza</i>. β-Glucuronidase staining indicated that <i>SpNramp</i><i>1</i> and <i>SpNramp3</i> mainly accumulated in the root and joint between mother and daughter frond. Moreover, <i>SpNramp1</i> was also widely displayed in the frond. <i>SpNramp2</i> was intensively distributed in the root and frond. Quantitative real-time PCR results proved that the <i>SpNramp</i> gene expression level was influenced by Cd stress, especially in response to Fe or Mn deficiency. The study provides detailed information on the <i>SpNramp</i> gene family and their distribution and expression, laying a beneficial foundation for functional research.