Barley seeds miRNome stability during long-term storage and aging

Seed aging is a complex biological process attracting the scientists’ attention for many years. High-throughput small RNA sequencing was applied to examine microRNAs contribution in barley seeds senescence. Unique samples of seeds that despite the same genetic makeup differed in viability after over 45 years of storage in a dry state were investigated. In total, 61 known and 81 novel miRNA were identified in dry seeds. The highest level of expression was found in four conserved miRNA families i.e. miR159, miR156, miR166 and miR168. However, the most astonishing result was the lack of significant differences in the level of almost all miRNAs in seed samples with significantly different viability. This result reveals that miRNAs in dry seeds are extremely stable. This is also the first identified RNA fraction that is not deteriorating along to the loss of seed viability. Moreover, the novel miRNA hvu-new41, with higher expression in seeds with the lowest viability was detected by RT-qPCR, has the potential to become an indicator of the decreasing viability of seeds during storage in a dry state. It might be responsible for the removal of (1-3.1-4)-beta-D-glucanase transcripts and lowering or completely blocking the synthesis of this key enzyme for seed germination. Examiantiopn of 3 barley seeds stocks: Rc - after seed regeneration i.e. non-stored control; Lv - seeds after storage 1972-2018 (germination 2%); Hv - seeds after storage 1972-2018 (germination 86,7%).