Manganese Treatment Alleviates Zinc Deficiency Symptoms in Arabidopsis Seedlings

Plant phenotypes caused by mineral deficiencies differ depending on growth conditions. We recently reported that the growth of Arabidopsis thaliana was severely inhibited on MGRL-based zinc (Zn)-deficient medium but not on MS-based Zn-deficient medium. Here, we explored the underlying reason for the phenotypic differences in Arabidopsis grown on different media. The root growth and chlorophyll contents reduced by Zn deficiency were rescued by the addition of extra manganese (Mn) during short-term growth (10 or 14 d). However, this treatment did not affect the growth recovery after long-term growth (38 d). To investigate the reason for plant recovery from Zn deficiency, we performed an RNA-seq analysis of the roots grown on Zn-basal medium and Zn-depleted medium with/without additional Mn. Principal component analysis of the RNA-seq data showed that the gene expression patterns of plants on Zn-basal medium were similar to those on Zn-depleted medium with Mn, whereas those on Zn-depleted medium without Mn were different from the others. The expression of several transcription factors and reactive oxygen species (ROS)-related genes was upregulated in only plants on Zn-depleted medium without Mn. Consistent with the gene expression, ROS accumulation in the roots grown on Zn-depleted medium without Mn was higher than those on the other conditions. These results suggest that plants accumulate ROS and reduce their biomass under undesirable growth conditions, such as Zn-depletion. Taken together, this study shows that the addition of extra Mn to Zn-depleted medium induces transcriptional changes in ROS-related genes, thereby alleviating short-term growth inhibition due to Zn deficiency.

Keywords: Arabidopsis; Manganese; ROS; Zinc.