Plant Small RNA World Growing Bigger: tRNA-Derived Fragments, Longstanding Players in Regulatory Processes

In the past 2 decades, discovery of a new class small RNAs, known as tRNA-derived fragments (tRFs), shed light on layer regulation implicated in many biological processes. tRFs originate from mature tRNAs and are classified according to tRNA regions that they derive from, namely 3′tRF, 5′tRF, tRF-halves. Additionally, another tRF subgroup deriving precursors has been reported, 3′U tRFs. length ranges 17 26 nt for 3′and 5′tRFs, 30 40 biogenesis is still not yet elucidated, although there strong evidence Dicer (and DICER-LIKE) proteins, well other RNases such Angiogenin mammal RNS proteins family plants, responsible processing specific abundance those molecules varies among tissues, developmental stages, environmental conditions. More recently, several studies have contributed elucidate role these intriguing may play all organisms. Among recent discoveries, were found be involved distinctive regulatory layers, transcription translation regulation, RNA degradation, ribosome biogenesis, stress response, signaling plant nodulation, genome protection against transposable elements. Although biology poorly understood, field blossomed few years, this review summarizes most developments plants.