design: Total genomic DNA was extracted by using the cetyltrimethylammonium bromide (CTAB) method . The integrity and quality of the genomic DNA was evaluated by electrophoresis, and the nucleic acid concentration of each sample was determined using a Qubit Fluorometer  and NanoDrop 2000 . The genomic DNAs were then sheared into 500 bp fragments using an Ultrasonicator . The sequencing libraries were constructed from these samples and sequenced on the Illumina HiSeq 2500 platform according to the manufacturers instructions.