Deletion of Ph1 locus enhances low temperature tolerance via glucosamine metabolism rewiring in wheat

Deletion of the Ph1 locus is known to disrupt chromosome pairing in wheat, but its role in environmental stress adaptation, particularly low temperature tolerance, remains unclear. Low temperature severely impairs wheat productivity by inducing oxidative damage and disrupting photosynthesis. However, the mechanistic links between Ph1 deletion and low temperature tolerance are still poorly understood. This study aimed to investigate the physiological, transcriptomic, and metabolic effects of Ph1 deletion on wheat's response to low temperature stress. Using the ph1b -8 mutant derived from a low-temperature-screened ph1b population and the reference cultivar Chinese Spring, plants were subjected to controlled low temperature treatments (0/4°C, dark/light). Photosynthetic efficiency, membrane integrity, RNA-sequencing, and enzyme activity assays, which focused on glucosamine metabolism and antioxidant pathways, were performed to elucidate molecular adaptations. Transcriptomic profiling revealed DEGs enriched in glucosamine metabolism and photosynthetic pathways, particularly at low temperature, with significant upregulation of glucosamine-metabolizing enzymes (glutamine: fructose-6-phosphate amidotransferase, glucosamine-6-phosphate deaminase, and N-acetylglucosamine kinase) and upstream carbohydrate-processing enzymes (hexokinase), indicating increased flux toward UDP-GlcNAc biosynthesis and accelerated glucose flux. Additionally, the transcriptomic changes suggest a potential mechanism in which the enhanced glucosamine metabolic pathway may synergize with glutathione metabolism to mitigate oxidative damage. Collectively, these findings reveal a previously unrecognized metabolic and transcriptional reprogramming associated with low temperature tolerance in the ph1b -derived mutant line studied ( ph1b -8). This selected mutant line provides new genetic resources and mechanistic insights for improving tolerance to stress conditions.