From dormancy release to bloom in Prunus mume

Widely cultivated for ornamental and fruit tree purposes in East Asia, Prunus mume Sieb. et Zucc. is best known for its early flowering in late winter to early spring. The timing of flowering is an interesting parameter that affects fruit yield, fruit quality, and ornamental value, but it is strongly influenced by environmental changes. This review brings together recent progress in understanding how flowering time in Prunus mume is controlled by environmental signals, plant hormones, and gene regulation. Bud dormancy, which ensures survival through winter, moves through several stages before flowering, and is primarily regulated by chilling accumulation and subsequent heat requirements, while photoperiod plays a secondary modulatory role. Hormones such as gibberellins (GA) and abscisic acid (ABA) play opposite roles in controlling bud break and dormancy, while cytokinins (CK), auxin (IAA), and ethylene coordinate floral development. At the molecular level, flowering regulation involves several critical genes, including DORMANCY-ASSOCIATED MADS-box (DAM) and SHORT VEGETATIVE PHASE (SVP) genes that maintain dormancy, and FLOWERING LOCUS T (FT), SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1), LEAFY (LFY), and APETALA1 (AP1) genes that promote flowering transition. Recent studies have also identified NAC (NAM, ATAF1/2, and CUC2) transcription factors that fine-tune early flowering in Prunus mume. Advances in genomics, transcriptomics, and phenological models have improved knowledge of flowering time control, although more work is needed to connect molecular mechanisms with field adaptation. This understanding is important for breeding cultivars suited to future climates.