# LcSHMT4 from Sheepgrass Improves Tolerance to Cadmium and Manganese and Enhances Cd and Mn Accumulation in Grains

## TL;DR

A gene from sheepgrass helps plants tolerate and accumulate cadmium and manganese, offering potential for cleaning up heavy metal pollution.

## Contribution

LcSHMT4 from sheepgrass is shown to improve heavy metal tolerance and accumulation in transgenic plants.

## Key findings

- LcSHMT4 overexpression in yeast and rice increases tolerance to cadmium and manganese.
- Transgenic rice accumulates more cadmium and manganese in grains when overexpressing LcSHMT4.
- LcSHMT4 may enhance heavy metal tolerance through antioxidant enzymes and transporter gene activation.

## Abstract

Heavy metal contamination is a serious environmental problem worldwide, with substantial negative ecological and economic effects. Serine hydroxymethyltransferase (SHMT) is a key metabolic and photorespiratory enzyme in plant cells, and it is also involved in stress responses. In this study, LcSHMT4 was isolated from sheepgrass (Leymus chinensis (Trin.) Tzvel) after transcriptome sequence analysis. The transcript levels of LcSHMT4 in sheepgrass seedlings increased under Cd and Mn stresses, and subcellular localization analysis in tobacco leaves revealed that its encoded protein localizes at the mitochondria. Transgenic yeast and rice lines overexpressing LcSHMT4 showed increased tolerance to Cd and Mn, compared with that of their controls. In addition, compared with the control, transgenic rice overexpressing LcSHMT4 accumulated more Cd and Mn in brown rice grains. The transcript levels of genes encoding Cd or Mn transporters were increased in the LcSHMT4-overexpressing transgenic rice lines. We speculate that LcSHMT4 may enhance Cd and Mn tolerance by increasing the activities of antioxidant enzymes and the glutathione content and increase heavy metal accumulation by inducing the expression of genes encoding transporters. These results highlight useful genetic resources and provide a theoretical basis for further research on heavy metal tolerance and the phytoremediation of heavy-metal-contaminated soil.