Raw images were transformed into raw reads by base calling using CASAVA (Version 1.8.2). Clean reads were obtained by removing reads with adapters, reads in which unknown bases were more than 5%, and low-quality reads (the percentage of low-quality bases was over 50% in a read, and we defined the low-quality base to be the base whose sequencing quality was no more than 10). At the same time, Q20, Q30, and GC content of the clean data were calculated.