The adventitious rooting−related oxygenase (ARRO−1) gene is specifically expressed in the early rooting stage and is considered a molecular marker of rooting. In this study, a PsARRO−1 gene (GenBank accession number KJ620008) was identified from a pre−constructed transcriptome database of root development of Paeonia suffruticosa under sandy loam cultivation. The expression was verified by RT−qPCR, and it was found that the expression trend was consistent with the expression in the transcriptome database. The PsARRO−1 gene was specifically highly expressed during the root primordium germination phase. In addition, the RT−qPCR analysis indicated that the expression of PsARRO−1 in roots was significantly higher than in stems and leaves, its peak expression in vitro was 5 days earlier than in soil, and its expression was higher than that of tree peony in soil. Subcellular localization analysis showed that PsARRO−1 was localized in the plasma membrane. Moreover, the transient silent expression of the PsARRO−1 gene was found in the roots of peony seedlings grown using VIGS technology. The root activity was significantly reduced after transient silencing of the expression of the PsARRO−1 gene. These results indicate that PsARRO−1 has a positive regulatory effect on tree peony root development.
