Tree peonies are an economically important crop with flowers of high ornamental value. Most tree peony cultivars in gardens are once-flowering, and the continuous flowering (CF) trait has been revealed only in a few tree peony cultivars, such as ‘High Noon’ (‘HN’). However, the molecular mechanism underlying its CF remains unclear. Here, we demonstrated that PsTFL1 functions as a floral inhibitor via the ectopic expression of PsTFL1 in transgenic Arabidopsis thaliana plants. Our findings suggest that PsFT and PsTFL1 interact with PsFD, and the detected interactions may occur in the nucleus. Compared with the non-CF variety, the gene expression patterns of PsFT, PsTFL1, and PsFD during the flower development indicate that these three genes may be related to the CF habit in tree peony ‘HN’. These findings will aid future investigations of CF behavior and promote the breeding of tree peonies and other perennial woody plants.

Background: Kinesins are ATP-dependent molecular motors that mediate intracellular transport, cytoskeleton remodeling, and abiotic stress responses in plants. The KIN gene family remains poorly characterized in Prunus mume. This study aimed to explore the evolutionary features and cold-responsive functions of the PmKIN gene family. Methods: A systematic genome‑wide analysis was performed in P. mume. We performed phylogenetic classification, conserved domain detection, gene duplication and selection pressure analysis, cis-element prediction, tissue expression profiling, cold stress expression assay, and protein interaction network prediction. Results: Fifty PmKIN family members were defined and grouped into 10 subfamilies. K14 subfamily contained the largest number of members. All members harbor conserved motor domains, and segmental duplication drove the expansion of this gene family, which was overall constrained by purifying selection. The PmKIN homologous genes were highly conserved among Rosaceae species, including Prunus persica, Prunus armeniaca, Prunus avium, and Malus domestica. Our promoter analysis detected abundant cis-elements for light, hormone, cold, and drought signals in PmKIN genes, especially in the K14 and K7 subfamilies. These genes displayed tissue-biased expression, with roots and stems showing much higher transcript levels than fruits. Under low-temperature stress, the tolerant cultivar appeared to mount a relatively rapid PmKIN upregulation, whereas the sensitive one seemed to show a sluggish response and poor recovery. Three members (PmKIN22/27/35) were suggested to be potentially critical in low-temperature-response regulation. A 285-pair interaction network predicted PmKIN45 as the central hub, and functional predictions imply that PmKIN proteins may be linked to microtubules, hormone pathways, and stress signaling, possibly coordinating growth and low-temperature responses. Conclusions: This work screens candidate genes associated with low-temperature responses in P. mume, providing genetic resources for the molecular breeding of cold-resistant cultivars and expanded cultivation of P. mume and other ornamental horticultural species.