# High-concentration peat drives divergent transcriptomic responses to enhance saline-alkaline tolerance and phytoremediation in two Suaeda species

## TL;DR

Adding high concentrations of peat improves salt tolerance and soil remediation in two halophyte species through distinct genetic responses.

## Contribution

Identifies optimal peat concentration and species-specific genetic mechanisms for saline-alkaline soil remediation.

## Key findings

- High peat concentration (18 g/kg) enhances salt tolerance and biomass in Suaeda species.
- S. glauca activates growth-related pathways, while S. salsa boosts stress-mitigating secondary metabolism.
- Both species downregulate amino acid degradation genes to conserve nitrogen for osmoprotection.

## Abstract

Soil salinization threatens global land use and food security, and halophytes combined with peat amendments are promising for saline-alkali soil remediation.

Here, we integrated transcriptomic and physiological analyses to investigate the adaptive responses of Suaeda glauca and S. salsa grown in saline-alkaline soils amended with peat at 0, 6, or 18 g/kg.

Our results showed that a high peat concentration (18 g/kg) significantly improved salt tolerance and biomass accumulation in both species through distinct species-specific strategies. S. glauca upregulated growth-related pathways (e.g., nitrogen metabolism, and tricarboxylic acid cycle) mediated by bHLH and bZIP transcription factors (TFs), whereas S. salsa activated stress-mitigating secondary metabolism (e.g., flavonoids, phenylpropanoids, anthocyanins) regulated by MYB and NAC TFs. A conserved response across both species was the downregulation of genes involved in amino acid degradation, which helps conserve nitrogen for osmoprotection. RT-qPCR analysis confirmed the reliability of the RNA-seq data. This study identified 18 g/kg as the optimal peat concentration, uncovers species-specific adaptive mechanisms in halophytes, and lays a foundation for the precisely selection of halophyte-peat combinations in saline-alkaline soil remediation.