Complete chloroplast genome sequence of a vegetative Bermudagrass cultivar Tifeagle (Cynodon dactylon × Cynodon transvaalensis)

Hybrid (Cynodonn dactylon × C. transvaalensis) is a widely distributed turfgrass and shows a great value of environment, horticulture and economic. Though, the chloroplast genome of C. dactylon has been reported, it might be helpful finding reasons that triploid bermudagrass shows a better drought and trampling tolerance than common bermudagrass through comparing chloroplast genome analysis. The present results showed the complete chloroplast genome of the C. dactylon × C. transvaalensis is 134655 bp in length. The tetramerous genome contained a large single copy (LSC) region (79,998 bp), a small single copy (SSC) region (12,517 bp), and a pair of inverted repeat (IR) regions (42,140 bp). In the chloroplast genome, 116 genes were predicted, including 83 protein-coding, 29 tRNA and 4 rRNA genes. Furthermore, a total of 80 repeat sequences were identified. Only 0.23% intergenicnon-collinear sequences were found between the chloroplast genome of Cynodon dactylon × C. transvaalensis and Cynodon dactylon. Introduction Cynodon dactylon × Cynodon transvaalensis is widely used in sports fields, lawns, parks, golf courses (Harlan et al. 1970). The triploid hybrid bermudagrass showed higher turf quality with limited irrigation than common bermudagrass (Hanna 1998). Hu et al. (2009, 2010) reported that the better ability of drought tolerance due to the hybrid bermudagrass had more active ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO) enzyme, RuBisCO activase and more stable proteins for carbon assimilation which made a greater capability of photosynthesis. By comparative proteomic analyzing the difference between triploid and common bermudagrass under water-deficit stress, Zhao et al. (2011) found a inhibition of expression of Chl a-b binding proteins, oxygen-evolving enhancer protein, ATP synthase and RuBisCO large subunit in common bermudagrass under drought stress. These results demonstrate there exist a differential gene expression and enzymatic activity in chloroplast under drought stress between triploid and common bermudagrass. It is speculated that chloroplast sequence variation happened in the process of triploid bermudagrass formation. If so, the genomic resources of the sequence of C. dactylon (Genbank accession number KY024482.1) (Huang et al. 2017) and hybrid (C. dactylon × C. transvaalensis) will be of great value for new bermudagrass germplasm generation and genetic conservation. Author for correspondence: . Faculty of Agricultural Science, Guangdong Ocean University, Zhanjiang, P. R. China. State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources; Guangdong Engineering Research Center for Grassland Science; College of Life Sciences, South China Agricultural University, Guangzhou, Guangdong, China. Guilin Medical University,Guilin, Guangxi, China. College of Life Sciences, South China Agricultural University, Guangzhou, China.