library_construction_protocol: Total RNA was extracted using mirVanaTM miRNA isolation Kit, small RNA was extracted by gel size selection of 10~40 nt sRNA libraries were constructed using the NEBNext Multiplex Small RNA Library Prep Set for Illumina (E7300). Final libraries were purified from a size selection of bands of about 150bp on a 6% polyacrylamide gel. Two biological replicates were used for anther, pollen, and endosperm samples, three biological replicates were used for root samples