Plants facing the seasonal variations always need a growth restraining mechanism when temperatures turn down. C-repeat binding factor (CBF) genes work essentially in the cold perception. Despite lots of researches on CBFs, the multiple crosstalk is still interesting on their interaction with hormones and dormancy-associated MADS (DAM) genes in the growth and dormancy control. Therefore, this study highlights roles of PmCBFs in cold-induced dormancy from different orgens. And a sense-response relationship between PmCBFs and PmDAMs is exhibited in this process, jointly regulated by six PmCBFs and PmDAM4–6. Meantime, GA3 and ABA showed negative and positive correlation with PmCBFs expression levels, respectively. We also find a high correlation between IAA and PmDAM1–3. Finally, we display the interaction mode of PmCBFs and PmDAMs, especially PmCBF1-PmDAM1. These results can disclose another view of molecular mechanism in plant growth between cold-response pathway and dormancy regulation together with genes and hormones.

TCP proteins, belonging to a plant-specific transcription factors family, are known to have great functions in plant development, especially flower and leaf development. However, there is little information about this gene family in Prunus mume, which is widely cultivated in China as an ornamental and fruit tree. Here a genome-wide analysis of TCP genes were performed to explore their evolution in P. mume. Nineteen PmTCPs were identified and three of them contained putative miR319 target sites. Phylogenetic and comprehensive bioinformatics analyses of these genes revealed that different types of TCP genes had undergone different evolutionary processes and the genes in the same clade had similar chromosomal location, gene structure, and conserved domains. Expression analysis of these PmTCPs indicated that there were diverse expression patterns among different clades. Most TCP genes were predominantly expressed in flower, leaf, and stem, and showed high expression levels in the different stages of flower bud differentiation, especially in petal formation stage and gametophyte development. Genes in TCP-P subfamily had main roles in both flower development and gametophyte development. The CIN genes in double petal cultivars might have key roles in the formation of petal, while they were correlated with gametophyte development in the single petal cultivar. The CYC/TB1 type genes were highly detected in the formation of petal and pistil. The less-complex flower types of P. mume might result from the fact that there were only two CYC type genes present in P. mume and a lack of CYC2 genes to control the identity of flower types. These results lays the foundation for further study on the functions of TCP genes during flower development.

Flower phylogenetics and genetically controlled development have been revolutionised during the last two decades. However, some of these evolutionary aspects are still debatable. MADS-box genes are known to play essential role in specifying the floral organogenesis and differentiation in numerous model plants like Petunia hybrida, Arabidopsis thaliana and Antirrhinum majus. SEPALLATA (SEP) genes, belonging to the MADS-box gene family, are members of the ABCDE and quartet models of floral organ development and play a vital role in flower development. However, few studies of the genes in Prunus mume have yet been conducted. In this study, we cloned four PmSEPs and investigated their phylogenetic relationship with other species. Expression pattern analyses and yeast two-hybrid assays of these four genes indicated their involvement in the floral organogenesis with PmSEP4 specifically related to specification of the prolificated flowers in P. mume. It was observed that the flower meristem was specified by PmSEP1 and PmSEP4, the sepal by PmSEP1 and PmSEP4, petals by PmSEP2 and PmSEP3, stamens by PmSEP2 and PmSEP3 and pistils by PmSEP2 and PmSEP3. With the above in mind, flower development in P. mume might be due to an expression of SEP genes. Our findings can provide a foundation for further investigations of the transcriptional factors governing flower development, their molecular mechanisms and genetic basis.

Dormancy Associated MADS-box genes are SVP/MADs-box members and supposed to play crucial roles in plant dormancy of perennial species. In Prunus mume, PmDAM6 has been previously identified to induce plant dormancy. In the current study, six PmDAMs were cloned in P. mume and functionally analyzed in yeast and tobacco to detect the roles of the genes paralogous to PmDAM6. The expression patterns together with sequence similarities indicate that PmDAMs are divided into two sub-clades within SVP group. Moreover, PmDAMs are verified to take part in the development of different plant organs, specifically the flower buds, in some intricate patterns. Furthermore, the PmDAM proteins are found to have special functions by forming corresponding protein complex during the development of flower bud and induction of dormancy. In particular, when PmDAM1 dominating in flower bud in the warm months, the protein complexes are consisted of PmDAM1 itself or with PmDAM2. With the decrease temperatures in the following months, PmDAM6 was found to be highly expressed and gradually changed the complex structure to PmDAM6-protein complex due to strong binding tendencies with PmDAM1 and PmDAM3. Finally, the homodimers of PmDAM6 prevailed to induce the dormancy. The results obtained in the current study highlight the functions of PmDAMs in the tissue development and dormancy, which provide available suggestions for further explorations of protein-complex functions in association with bud growth and dormancy.

The survival in freezing temperature for woody plants is exclusively dependent on the perception of coldness and induction of dormancy. CBF/DREB1 transcriptional factors join cold-response conduits and the DAM genes, especially PmDAM6, are well-known regulators of dormancy. Despite the immense importance, little is documented on the association between CBF proteins and the complexity of the promoter region in PmDAM6 with the function of bud dormancy in P. mume. Therefore, this study was based on the cloning of PmDAM6 and six PmCBFs to evaluate their integral roles in the process of bud development. The consistency of expressions in either vegetative or reproductive buds provided a negative control from PmCBFs to PmDAM6 during the onset of dormancy. Besides, PmCBF5 could form heteromeric complexes with PmDAM1 and PmDAM6. PmCBF1, PmCBF3, and PmDAM4 recognized the promoter of PmDAM6 by the alternative binding sites. Therefore, the interactions of these genes formulated the base of an obvious model to respond to the coldness and engendered dormancy release. Findings of this study will further help the unveil the genetic control of bud dormancy and its augmentation in P. mume and may offer an explanation for the vernalization.