Expression of highly conserved developmental phase change regulating miR156 and miR172 microRNAs in silver birch using real-time PCR and high-throughput sequencing methodologies

Silver birch (Betula pendula Roth) is the most significant deciduous tree species in Latvia. Efficient vegetative reproduction methods are crucial for shortening breeding cycles. In many woody tree species, success of vegetative propagation sharply decreases as individuals mature. Development of molecular genetic markers related to phase change has the potential to increase the efficiency of vegetative reproduction methods. Studies in annual model plant species have identified evolutionary highly conserved miRNAs that are involved in phase change – miR156 and miR172. This study compared expression levels of these miRNA families using two approaches – real-time PCR (RT‑PCR) and high-throughput sequencing, in silver birch in vitro shoot samples. High expression of miR156 in juvenile samples was identified by both methods, but increased expression of miR172 was only observed by RT‑PCR. Further studies in long-lived perennial species are needed to fully elucidate the miRNAs involved in developmental phase transition processes.