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Evidence is emerging that tRNA-derived fragments (tRFs) are regulatory molecules.Studies of tRFs in plants have been based on conventional small RNA sequencing,and focused on profiling of tRF-5 and tRF-3 species.A more comprehensive and quantitative analysis of the entire tRF population is highly necessary.Here,we employ tRNA-seq and YAMAT-seq,and develop a bioinformaties tool to comprehensively profile the expressions of tRNAs and tRFs in plants.We show that in Arabidopsis,approximately half of tRNA genes are extremely weakly expressed,accounting for only 1％ of total tRNA abundance,while ～12％ of tRNA genes contribute to ～80％ of tRNA abundance.Our tRNA sequencings in various plants reveal that tRNA expression profiles exhibit a cross-species conserved pattern.By characterizing the composition of a highly heterogeneous tRF population,we show that tRNA halves and previously unnoticed 10-16-nt tiny tRFs represent substantial portions.The highly accumulated 13-nt and 16-nt tiny tRFs in Arabidopsis indicate that tiny tRFs are not random tRNA degradation products.Finally,we provide a user-friendly database for displaying the dynamic spatiotemporal expressions of tRNAs and tRFs in the model plants Arabidopsis and rice.