Transfer RNA and ribosomal RNA fragments – emerging players in plant–microbe interactions

Abstract

SummaryAccording to current textbooks, the principal task of transfer and ribosomal RNAs (tRNAs and rRNAs, respectively) is synthesizing proteins. During the last decade, additional cellular roles for precisely processed tRNA and rRNAs fragments have become evident in all kingdoms of life. These RNA fragments were originally overlooked in transcriptome datasets or regarded as unspecific degradation products. Upon closer inspection, they were found to engage in a variety of cellular processes, in particular the modulation of translation and the regulation of gene expression by sequence complementarity‐ and Argonaute protein‐dependent gene silencing. More recently, the presence of tRNA and rRNA fragments has also been recognized in the context of plant–microbe interactions, both on the plant and the microbial side. While most of these fragments are likely to affect endogenous processes, there is increasing evidence for their transfer across kingdoms in the course of such interactions; these processes may involve mutual exchange in association with extracellular vesicles. Here, we summarize the state‐of‐the‐art understanding of tRNA and rRNA fragment's roles in the context of plant–microbe interactions, their potential biogenesis, presumed delivery routes, and presumptive modes of action.

Barley powdery mildew invasion coincides with the dynamic accumulation of leaf apoplastic extracellular vesicles that are associated with host stress response proteins

“…Small RNAs of 18-25 nucleotides in size are frequently described as associated with EVs and are thought to mediate mutual cross-kingdom gene silencing in pathogenic (Cai et al 2019) and mutualistic (Qiao et al 2023) plant-microbe encounters. Apart from canonical small RNAs, circular RNAs (Zand Karimi et al 2022), rRNA fragments (Kusch et al 2023;Panstruga & Spanu 2024) and mRNAs (Kwon et al 2021;Ruf et al 2022;Wang et al 2024) have been linked to these vesicles. Proteins associated with plant EVs are often enriched in stress-and immunity-related proteins, but also RNA-binding proteins possibly involved in RNA-loading onto EVs Regente et al 2017;He et al 2021).…”

“…2022), rRNA fragments (Kusch et al . 2023; Panstruga & Spanu 2024) and mRNAs (Kwon et al . 2021; Ruf et al .…”