# Identification of miRNAs and Profiling of ROS Metabolism in Response to Saline–Alkali Stress in Wheat (Triticum aestivum L.)

## TL;DR

This study explores how miRNAs and ROS metabolism in wheat respond to saline-alkali stress, identifying key miRNAs and antioxidant mechanisms in tolerant and sensitive wheat varieties.

## Contribution

The study identifies novel miRNA expression patterns and a miRNA-mediated regulatory network linked to ROS metabolism under saline-alkali stress in wheat.

## Key findings

- Four miRNAs showed consistent expression trends across wheat varieties under saline-alkali stress.
- QM wheat maintained higher antioxidant levels and enzyme activities, contributing to stress tolerance.
- A miRNA-mediated regulatory network involving miR408 and miR1135 was predicted to regulate ROS metabolism.

## Abstract

Saline–alkali stress is one of the important abiotic stresses, which affect plant growth and development. However, the understanding of miRNA pathways in different saline–alkali stress is still limited. In order to better understand the salt–alkali stress response mechanism of wheat, we analyzed miRNA transcription levels in two wheat varieties differing in saline–alkali tolerance (Qingmai 6, QM, tolerant; Meisheng 0308, MS, sensitive) under mixed saline–alkali stress (150 mmol·L1 and 300 mmol·L1) for 7 days. High-throughput sequencing identified 11,368 miRNAs (106 conserved, 11,262 non-conserved), among which four miRNAs (miR9653b, miR5384-3p, miR9777, and miR531) exhibited a consistent expression trend across both varieties and all stress concentrations. Additionally, a potential miRNA-mediated regulatory network (including miR408 and miR1135) was predicted to regulate reactive oxygen species (ROS) metabolism via cytochrome P450, plant hormone signal transduction, and MAPK pathways. Saline–alkali-tolerant and sensitive wheat cultivars exhibited distinct miRNA expression patterns under stress. QM maintained higher contents of non-enzymatic antioxidants (ascorbic acid, AsA; reduced glutathione, GSH) and activities of key antioxidant enzymes (ascorbate peroxidase, APX; glutathione reductase, GR), which contributed to balanced ROS homeostasis and enhanced saline–alkali tolerance.