Integrated analyses of phenotype, phytohormone, and transcriptome to elucidate the mechanism governing internode elongation in two contrasting elephant grass (Cenchrus purpureus) cultivars

•Internode length is an important factor that affects the plant height of elephant grass.•Cenchrus purpureus cv. Mott is a gibberellin-sensitive dwarf cultivar.•The endogenous gibberellin A1 concentrations and lignin content were markedly decreased in the Cenchrus purpureus cv. Mott.•Some of representative gibberellin and lignin biosynthetic enzymes were downregulated in the Cenchrus purpureus cv. Mott.