DNA extraction and chloroplast genome determination
Seedlings were raised from seeds in a greenhouse, harvested, and quickly
dried in a convection oven. Total genomic DNA (~30 mg)
was extracted from dry leaves using the mCTAB method ( Li, Wang, Yu,
Wang, & Zhou, 2013). A library was constructed and sequenced for each
sample at Beijing Novogene Bioinformatics Technology Co., Ltd, Beijing,
using an Illumina HiSeq X Ten platform. Chloroplast genome reads were
sorted out and the genomes were assembled de novo using SPAdes
3.9 (Bankevich et al., 2012). The generated contigs were mapped to the
closest references by blastn 2.8.10 (Altschul, Gish, Miller, Myers, &
Lipman, 1990), assembled with Sequencher 5.4 (Corperation)and gaps were
filled by Sanger sequencing using primers reported by Dong, Xu, Cheng,
Lin, and Zhou (2013).