DsGGCT2-1 involved in the detoxification of Cd and Pb through the glutathione catabolism in Dianthus spiculifolius

Toxic heavy metals seriously affect plant growth and human health. Among the heavy metals, cadmium (Cd) and lead (Pb) are serious pollutants. Dianthus spiculifolius has strong tolerance to, and an ability to accumulate, heavy metals. Therefore, it has potential applications as a heavy metal hyperaccumulator. Gamma glutamylcyclotransferase (GGCT) is a key enzyme in maintaining glutathione homeostasis, and it plays a role in plant growth and development and in responses to various stresses. Previously, DsGGCT2-1 was identified as a gene showing significantly increased transcript levels in response to Cd and Pb by transcriptome analysis. In this study, DsGGCT2-1 was confirmed to increase the Cd and Pb tolerance of transgenic yeast, Arabidopsis, and Dianthus, decrease the their accumulation in Dianthus. Overexpression of DsGGCT2-1 in D. spiculifolius plants resulted in increased GGCT activity, higher glutamate (Glu), and glutathione (GSH) content. The results suggest that more Glu is synthesized to maintain GSH homeostasis through the activity of GGCT2-1 in the glutamyl cycle, and the generated GSH is used to chelate with toxic heavy metals, and reduce the toxicity of heavy metals in the cytoplasm. These findings will be useful for devising strategies to remediate heavy metal-polluted soils, and for breeding plants that tolerate heavy metals.