Gene Expression Profiling of African Bermudagrass under Cold Acclimation

African bermudagrass (Cynodon transvaalensis Burtt Davy) is a fine-texture warm-season grass that often crosses with common bermudagrass [C. dactylon (L.) Pers] to create turf-type hybrid bermudagrass. African bermudagrass can adapt to colder climates than its origin in the southwestern Transvaal in South Africa, which has been used to improve winter hardiness of interspecific hybrid bermudagrass cultivars. However, the underlying genomic mechanisms that respond to cold temperatures are not fully elucidated in the species. Accordingly, the objective of this study was to identify differentially expressed genes (DEGs) in African bermudagrass genotype 'OKC1163' during different stages of cold acclimation. Plants were exposed to 8/2 degrees C day and night (12/12 hour) light cycles as cold acclimation treatment, while the control group was 24/20 degrees C with 12/12 hour day and night light cycles. Leaf tissues from three replications were collected at 12, 24, and 48 hours of treatment and from the control to identify DEGs. Compared with the untreated control, a total of 1707 genes were differentially expressed at 12 hours, including 967 upregulated and 740 downregulated genes, respectively. At 24 hours, a total of 2277 genes were differentially expressed, including 1140 upregulated and 1137 downregulated genes. At 48 hours, a total of 2691 genes were differentially expressed, including 1429 upregulated and 1262 downregulated genes. The most significant Gene Ontology enrichments were phosphorus metabolic process and response to abscisic acid, crucial biological functions that play significant roles in the adaptive response of plants to cold temperature stress. Integrating this information with previous winter hardiness quantitative trait loci, several candidate genes were consistently identified to be associated with cold acclimation, such as multiple cytochrome P450 and several ethylene-responsive transcription factors. This study offers insights into the transcriptional changes occurring during cold acclimation in African bermudagrass that can be used in designing molecular markers for selecting winter-hardy bermudagrass genotypes.