Mitochondria were isolated from all G. elata tissues except the rhizome using previously described centrifugation methods72. A modified CTAB method was used to extract mt-DNAs19. The purified mt-DNAs were sequenced on an Illumina Hiseq 2500 to generate 100 bp paired-end reads at the State Key Lab of Systematic and Evolutionary Botany, Chinese Academy of Sciences (Beijing).