Integrated morphological, physiological, transcriptomic, and metabolomic analyses reveal the stem regeneration mechanism of switchgrass (Panicum virgatum L.) after seedling stage mowing

Switchgrass (Panicum virgatum L.) is a promising bioenergy crop whose productivity under repeated harvesting depends on efficient stem regeneration after injury. However, the systemic regulatory mechanisms underlying this process remain largely unexplored. This investigation combined morphological, physiological, transcriptomic, and metabolomic analyses to elucidate the dynamic recovery responses of switchgrass (cv. Alamo) after mowing at the seedling stage. Within 72 h post-mowing, plants exhibited rapid stem regeneration (0.5 cm/24 h) accompanied by enhanced biomass accumulation, along with the phased activation of antioxidant enzymes (SOD, POD, CAT, APX), changes in osmoregulation substances, MDA levels and lignin deposition. Time-series transcriptomic profiling identified 10,155 differentially expressed genes (DEGs), revealing an early enrichment in phenylpropanoid biosynthesis (4CL, CAD) and glutathione metabolism, followed by a transition to starch/sucrose metabolism and phytohormone signaling (JA, IAA). Metabolomic analysis uncovered a coordinated metabolic shift from stress-responsive compounds (arginine, flavonoids) to growth-promoting intermediates (TCA cycle, JA-Ile). Critically, transgenic switchgrass overexpressing PvERF109 exhibited remarkable compensatory growth, demonstrating its role as a positive regulator of regeneration. Our findings provide a comprehensive framework for understanding wound-induced regeneration in switchgrass and identify potential targets for enhancing the regenerative capacity of bioenergy crops.