Transcriptome analysis of wheat (Triticum aestivum) reveals regulatory mechanisms of adaptation to water deficit stress induced by arbuscular mycorrhizal fungi

RNA sequencing (RNA-Seq) is a powerful tool for exploring transcriptional responses to environmental cues and elucidating gene regulatory networks. This study investigates how arbuscular mycorrhizal fungi (AMF) alleviate water deficit (WD) stress in Triticum aestivum seedlings through transcriptomic analysis. A comparative transcriptome analysis was performed on wheat roots under two irrigation regimes, well-watered (WW) and WD, and/or AMF inoculation, to identify differentially expressed genes (DEGs). AMF inoculation modulated the expression of genes involved in osmotic adjustment and protective metabolite biosynthesis. While genes such as P5CS, ARG, OAT, and TaPROT2 were downregulated in AMF-treated plants under WD, asparagine synthase (ASNS) was notably upregulated. Furthermore, AMF symbiosis enhanced the expression of genes related to polyamine and GABA metabolism under WD stress. A significant upregulation of antioxidant-related genes, particularly GSTU1, indicated an AMF-induced strengthening of the antioxidant defense system. Additionally, AMF treatment upregulated multiple nutrient transporter genes, including PHT, AMT, NPF, NRT, HAK/AKT, aquaporins, sugar transporters, and ABC transporters, thereby contributing to improved nutritional status. AMF also influenced carbohydrate metabolism to promote cell wall (CW) biosynthesis and remodelling, highlighting its role in structural adaptation to drought. These findings offer key molecular insights into the mechanisms by which AMF symbiosis modulates gene expression to improve wheat drought tolerance under varying irrigation conditions.