Screening shade-tolerant centipedegrass genotypes: Physiological and transcriptomic insights into shade adaptation mechanisms

Shade stress is a major constraint for the growth and performance of turfgrass in urban environments. To investigate shade tolerance mechanisms in centipedegrass (Eremochloa ophiuroides), we evaluated 16 genotypes under 66% and 99% shading for 18 d. CP11 was identified as shade-tolerant; CP2 was shade-sensitive. Both were subjected to detailed physiological and transcriptomic analyses. CP11 exhibited significantly reduced leaf wilting, higher relative water content, greater membrane stability, and enhanced chlorophyll retention compared with CP2. In addition, CP11 maintained higher antioxidant enzyme activities and osmolyte accumulation, supporting superior oxidative stress mitigation and osmotic adjustment. Transcriptome analysis identified 259 upregulated and 278 downregulated differentially expressed genes (DEGs) in CP11 leaves, and 108 upregulated and 104 downregulated DEGs in roots, consistently regulated at 6 and 12 d under 99% shading compared with CP2, revealing candidate genes like psbB, PP2C, and CRF2 for CP11's enhanced shade adaptability, which highlight molecular mechanisms involving chlorophyll biosynthesis, stress signaling, and ethylene regulation. Gene Ontology (GO) enrichment analysis showed that CP11 upregulates leaf pathways for nuclear division, water transport, and plasma membrane integrity, and root pathways for energy metabolism and membrane functions, while downregulating energy-intensive processes like DNA repair and ion transport, indicating a resource-conserving strategy that, together with coordinated physiological protection and transcriptomic reprogramming, underscores CP11's multifaceted adaptations to prolonged shading stress. This work provides mechanistic insights into shade adaptation and establishes a genetic foundation for breeding shade-resilient centipedegrass cultivars to support sustainable urban landscaping.