# Physiological and Transcriptomic Responses of Rice Cultivars to Combined Cadmium and Elevated Temperature Stress

## TL;DR

This study explores how two rice varieties respond to cadmium contamination and higher temperatures, revealing different strategies for growth and stress tolerance.

## Contribution

The study identifies genotype-specific physiological and transcriptomic responses to combined cadmium and temperature stress in rice.

## Key findings

- YZX showed greater growth increases at higher temperatures but accumulated more cadmium in roots.
- XWX12 exhibited stronger antioxidant enzyme activity and reduced cadmium accumulation in shoots.
- Transcriptomic analysis revealed distinct strategies for Cd sequestration and stress response between the two cultivars.

## Abstract

Cadmium (Cd) contamination and rising temperatures pose significant challenges to rice growth and food safety. Here, we investigated growth responses, Cd accumulation, physiological adaptations, and transcriptomic profiles of two rice cultivars, Yuzhenxiang (YZX) and Xiangwanxian 12 (XWX12), under combined Cd (0, 5, 20 μmol L−1) and temperature (25 °C, 30 °C) stress. Moderate warming (30 °C) generally promoted seedling growth and enhanced Cd uptake, with YZX showing greater increases in plant height and biomass, whereas XWX12 developed longer roots. At maturity, the temperature-induced growth advantage persisted in YZX, accompanied by a 60% increase in root Cd concentration, compared with 36% in XWX12. Antioxidant enzyme activities (POD, SOD, CAT) were significantly induced under combined stress, with XWX12 exhibiting stronger enzymatic responses and broader activation of ABC transporter genes, supporting reduced Cd accumulation in shoots. Malondialdehyde content indicated milder oxidative damage in YZX despite higher Cd accumulation. Transcriptomic analyses revealed extensive early transcriptional reprogramming, with enrichment of antioxidant metabolism, ABC transporters, MAPK signaling, and Cd transport-related genes, demonstrating coordinated physiological and molecular responses. XWX12 favored intracellular Cd sequestration and sustained antioxidant activation, whereas YZX relied more on uptake and translocation processes. Overall, these results highlight genotype-specific strategies in coping with combined Cd and temperature stress, providing mechanistic insights for improving rice tolerance and safety under warming and contaminated environments.