Identification of miRNAs and their targets in tea (Camellia sinensis).

MicroRNAs (miRNAs) are endogenous small RNAs playing a crucial role in plant growth and development, as well as stress responses. Among them, some are highly evolutionally conserved in the plant kingdom, this provide a powerful strategy for identifying miRNAs in a new species. Tea (Camellia sinensis) is one of the most important commercial beverage crops in the world, but only a limited number of miRNAs have been identified. In the present study, a total of 14 new C. sinensis miRNAs were identified by expressed sequence tag (EST) analysis from 47452 available C. sinensis ESTs. These miRNAs potentially target 51 mRNAs, which can act as transcription factors, and participate in stress response, transmembrane transport, and signal transduction. Analysis of gene ontology (GO), based on these targets, suggested that 37 biological processes were involved, such as oxidation-reduction process, stress response, and transport. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis inferred that the identified miRNAs took part in 13 metabolic networks. Our study will help further understanding of the essential roles of miRNAs in C. sinensis growth and development, and stress response.