Characterization of during flower development in early- and late-flowering tree peonies cultivars.

The flowering period is the most important ornamental trait of tree peony, while industrial development of tree peony has been limited by short flowering period. miR319 plays an important regulatory role in plant flowering. In the current study, the expression characteristics and evolution of in tree peony flowering was explored using 'Feng Dan' and 'Lian He', which are early-flowering and late-flowering varieties of tree peony, respectively. The structure, evolution, and target(s) of were analyzed by bioinformatics. Evolution analysis showed that pre- was distributed in 41 plant species, among which the length of the precursor sequence exhibited marked differences (between 52 and 308 bp). Pre- of tree peony was located close to the corresponding sequences of and in the phylogenetic tree, and in addition, could form a typical hairpin structure including a mature body with a length of 20 bp located on the 3p arm and part of the loop sequence. The mature sequence of miR319 was highly conserved among different species. Target genes of include MYB-related transcription factor in tree peony. Expression of , assayed by qRT-PCR, differed between 'Feng Dan' and 'Lian He' during different flower development periods. and its target gene showed a negative expression regulation relationship during the periods of CE (color exposure), BS (blooming stage), IF (initial flowering), and HO (half opening) in the early-flowering 'Feng Dan', and the same in FB (Full blooming) periods of late-flowering 'Lian He'. Findings from this study provide a reference for further investigation into the mechanism of miR319 in the development of different varieties of tree peony.