library_construction_protocol: Agarose electrophoresis was used to check the integrality of total RNA samples, and then the samples werequantified on the NanoDrop ND-1000 instrument. Total RNA samples were first pretreated as following to remove some RNA  modifications that interfere with small RNA-seq library construction: 3-aminoacyl (charged) deacylation to 3-OHfor 3-adaptor ligation, 3-cP (2 ,3-cyclic phosphate) removal to 3-OH for 3-adaptor ligation,5-OH(hydroxyl group) phosphorylation to 5-P for 5-adaptor ligation, m1A and m3C demethylation for efficient reverse transcription. Then pretreated total RNA was used to prepare the sequencing library in the following steps: 1) 3-adapter ligation; 2) 5-adapter ligation; 3) cDNA synthesis; 4) PCR amplification; 5)  size selection of 134～160bp PCR amplified fragments (corresponding to 14～40nt small RNA size range). The libraries were denatured as single-stranded DNA molecules, captured on Illumina flow cells, amplified in situ as sequencing clusters and sequenced for 50 cycles on Illumina NextSeq 500 system per the manufacturers instructions