Heterologous Expression of a Glycine soja C2H2 Zinc Finger Gene Improves Aluminum Tolerance in Arabidopsis

Abstract

Aluminum (Al) toxicity limits plant growth and has a major impact on the agricultural productivity in acidic soils. The zinc-finger protein (ZFP) family plays multiple roles in plant development and abiotic stresses. Although previous reports have confirmed the function of these genes, their transcriptional mechanisms in wild soybean (<i>Glycine soja</i>) are unclear. In this study, <i>GsGIS3</i> was isolated from Al-tolerant wild soybean gene expression profiles to be functionally characterized in <i>Arabidopsis</i>. Laser confocal microscopic observations demonstrated that GsGIS3 is a nuclear protein, containing one C2H2 zinc-finger structure. Our results show that the expression of <i>GsGIS3</i> was of a much higher level in the stem than in the leaf and root and was upregulated under AlCl₃, NaCl or GA3 treatment. Compared to the control, overexpression of <i>GsGIS3</i> in <i>Arabidopsis</i> improved Al tolerance in transgenic lines with more root growth, higher proline and lower Malondialdehyde (MDA) accumulation under concentrations of AlCl₃. Analysis of hematoxylin staining indicated that <i>GsGIS3</i> enhanced the resistance of transgenic plants to Al toxicity by reducing Al accumulation in <i>Arabidopsis</i> roots. Moreover, <i>GsGIS3</i> expression in <i>Arabidopsis</i> enhanced the expression of Al-tolerance-related genes. Taken together, our findings indicate that <i>GsGIS3</i>, as a C2H2 ZFP, may enhance tolerance to Al toxicity through positive regulation of Al-tolerance-related genes.