Abiotic stress-responsive tRNA-derived fragments in pitanga (Eugenia uniflora L.): regulatory roles in drought and salinity adaptation

The tRNA-derived RNA fragments (tRFs) have emerged as pivotal regulators of eukaryotic stress responses. These small non-coding RNAs are implicated in various biological domains. This study investigates the expression and functions of plant tRFs in response to abiotic stress with focus on Eugenia uniflora L. In silico analysis identified a diverse set of small RNAs originating from 73 conserved tRNAs. High-throughput analysis of small RNA (sRNA) libraries revealed a prevalence of 5′tRFs, with 51 947 sRNAs. RT-qPCR analysis unveiled predominant tRFs, such as those derived from tRNA-Arg-CCT. Among the 11 tRFs examined, six displayed notable differences in expression levels under high salt and osmotic stress triggered by NaCl and polyethylene glycol. Notably, 5′tRF ArgTCG and 5′tRF GlyTCC were positively regulated under both saline and water stress conditions. Additionally, we demonstrated that some previously identified targets of these tRFs showed reduced expression following both types of stress. Our findings suggest that abiotic stress-related tRFs interact with various signaling and metabolic pathways. Alterations in the expression of three tRFs and their target genes in both stress conditions highlight the potential significance of tRF changes in E. uniflora adaptation to drought and salinity.