Molecular Regulatory Networks Underlying Root Growth and Development in Crested Wheatgrass (Agropyron cristatum L.)

Crested wheatgrass (Agropyron cristatum) is a perennial forage species characterized by extensive root systems that contribute to ecological restoration and stress resilience. This study aimed to elucidate the regulatory mechanisms of root growth and development through transcriptome analysis at three developmental stages (20, 28, and 42 days after germination). Morphological analyses revealed progressive increases in root length, biomass, and surface area over time. Transcriptomic profiling identified 28,518 differentially expressed genes (DEGs) between R-28 and R-20, 35,581 DEGs between R-42 and R-20, and 24,418 DEGs between R-42 and R-28, indicating extensive transcriptional reprogramming during root development. Functional enrichment analyses highlighted pathways involved in ribosome biogenesis, phenylpropanoid metabolism, and energy regulation. Notably, 45 bHLH, 57 NAC, 56 WRKY, and 6 GRAS genes were differentially expressed and well-annotated, underscoring their regulatory roles in root system development. Furthermore, 65 nitrogen metabolism-related genes and multiple hormone signaling pathways, including auxin, abscisic acid, and ethylene, exhibited dynamic expression patterns coordinating developmental and stress-responsive processes. Collectively, these findings provide novel insights into the regulatory networks governing A. cristatum root development and offer valuable genetic resources for functional genomics studies, ecological restoration efforts, and breeding programs.