A robust mechanism for resetting juvenility during each generation in Arabidopsis

In Arabidopsis, microRNAs control the transition from juvenile to adult states. The study, using genomic, genetic and molecular approaches, investigates how miR156 and miR157 are re-activated at each generation. Multicellular organisms undergo several developmental transitions during their life cycles. In contrast to animals, the plant germline is derived from adult somatic cells. As such, the juvenility of a plant must be reset in each generation. Previous studies have demonstrated that the decline in the levels of miR156/7 with age drives plant maturation. Here we show that the resetting of plant juvenility during each generation is mediated by de novo activation of MIR156/7 in Arabidopsis. Blocking this process leads to a shortened juvenile phase and premature flowering in the offspring. In particular, an Arabidopsis plant devoid of miR156/7 flowers even without formation of rosette leaves in long days. Mechanistically, we find that different MIR156/7 genes are reset at different developmental stages through distinct reprogramming routes. Among these genes, MIR156A, B and C are activated de novo during sexual reproduction and embryogenesis, while MIR157A and C are reset upon seed germination. This redundancy generates a robust reset mechanism that ensures accurate restoration of the juvenile phase in each plant generation.

Automated summary

In Arabidopsis, the microRNAs miR156 and miR157 are re-activated through de novo activation of the MIR156/7 genes, which serves as a resetting mechanism for the plant's juvenility in each generation. This ensures accurate restoration of the juvenile phase in each plant generation.