The PNRD (Plant Non-coding RNA Database) database is the updated version of PMRD. Non-coding RNA (ncRNA) is a functional RNA molecule that is not translated into a protein, is highly abundant and functionally important. Since the PMRD is widely used as an important tool for microRNA (miRNA) study, we consider it necessary to renew our background data and integrate as many kinds of RNA as possible to help biologists with their research in the RNA world!