Characterizing the molecular mechanism of the PmIDD5-PmbHLH130-PmCOL5 transcriptional cascade on flowering in Prunus mume

BACKGROUND: Prunus mume is an important woody ornamental and fruit tree of Rosaceae. Elucidating the molecular regulatory network of its flowering is of great significance for genetic improvement. The basic helix-loop-helix (bHLH) and INDETERMINATE DOMAIN (IDD) transcription factors play vital roles in plant development processes, while their regulatory cascades in Prunus mume remain largely unclear. RESULTS: This study reports a bHLH transcription factor PmbHLH130 in Prunus mume, whose transcription level responds to photoperiod, and which is predominantly expressed in leaves. Subcellular localization and transcriptional activity assays revealed that PmbHLH130 is a nuclear-localized transcriptional activator. Overexpressed PmbHLH130 significantly promotes flowering in transgenic Arabidopsis. PmbHLH130 acts downstream of several central oscillator proteins and PmIDD5, and directly activates the expression of PmCOL5. CONCLUSION: This study reveals that PmIDD5-PmbHLH130-PmCOL5 transcriptional cascade provides a molecular basis for understanding flowering regulation. These findings provide new insights into the molecular mechanisms of flowering control in woody plants and offer a potential framework for molecular breeding of Prunus mume.