Decoding chilling temperature adaptation in bermudagrass: Temporal transcriptomic and metabolomic dynamics in tolerant and sensitive genotypes

Abstract

Chilling tolerance, expressed as late‐season green color retention, is a critical trait for extending the utility of bermudagrass ( Cynodon spp.) into the southern states. While previous studies have focused on rapid responses within 12–24 h of cold exposure, the temporal progression of molecular and metabolic adjustments over several days remains poorly understood. Here, we conducted integrated transcriptomic and metabolomic analyses of two contrasting hybrids—TifTuf (tolerant) and OSU2074 (susceptible)—after 1, 2, and 4 days of chilling (4°C). TifTuf exhibited extensive, phased transcriptional reprogramming involving transcription factors, abscisic acid signaling genes, protective proteins, and carbohydrate metabolism pathways. In contrast, OSU2074 showed markedly fewer differentially expressed genes, reflecting attenuated transcriptional plasticity. Metabolomic profiling revealed that TifTuf consistently accumulated osmoprotective and stress‐associated amino acids (e.g., proline, valine, and lysine) and sugars (e.g., sucrose, raffinose, galactinol, and myo‐inositol), with progressive increases over time, whereas OSU2074 predominantly accumulated soluble sugars and tricarboxylic acid intermediates in a less coordinated pattern. Importantly, coordinated increases in valine, sucrose, and raffinose in TifTuf paralleled the upregulation of valyl‐tRNA synthetase , sucrose synthase , sucrose phosphate synthase , and sucrose‐phosphate phosphatase , linking gene regulation with metabolite accumulation. These findings reveal that chilling tolerance in bermudagrass arises from dynamic, stage‐specific coordination between transcriptional networks and metabolite adjustments, whereas susceptibility reflects weaker transcriptional responses coupled with reactive metabolic shifts. This study provides the first integrated temporal multi‐omics framework of bermudagrass chilling adaptation, identifying candidate genes and metabolites to guide breeding strategies for improved late‐season green retention in warm‐season turfgrasses.