design: In brief, after we extracted the DNA samples, the following methods were used for detecting DNA samples: (1) The degree of DNA degradation and RNA contamination were analysed by agarose gel electrophoresis; (2) DNA purity (OD260/280 ratio) was detected by using Nanodrop; (3) DNA concentration was accurately quantified using Qubit, in which DNA samples had OD values between 1.8 and 2.0. The content above 1.5 g was used for library construction.