Length distribution of small RNAs from various tissues of wheat plants. (A) Distinct reads (only one occurrence per library). (B) Total reads. (C) Abundance of 21 and 22 nt sRNAs from various tissues of wheat plants. *means abundance of 21 nt miRNA is significantly higher than that of 22 nt in non-seed tissues (P < 0.05). **means abundance of 22 nt miRNA is significantly higher than that of 21 nt in seed related tissues (P < 0.01). DG: dry grain; GSE: germinating seed embryos; SH: shoots; SL: seedling leaves; SR: seedling roots; SJ: stems in the jointing stage; YS5: 0–5 mm young spikes; YS15: 10–15 mm young spikes; FL: flag leaves; GRA8: grains 8 days after pollination; GRA15: grains 15 days after pollination.