MIKC-Type MADS-Box Gene Analysis Reveals the Role of in Bud Dormancy Transition in Herbaceous Peony.

The MIKC-type MADS-box (MIKC) gene family is essential for controlling various plant developmental processes, including flowering time and dormancy transitions. Although the MIKC gene family has been widely studied across different plants, its characterization and functional study in herbaceous peony remain limited. In this study, 19 Pall. MIKC-type (PlMIKC) genes were identified from the transcriptome of a low-chilling requirement Pall. cultivar 'Hang Baishao'. These MIKC genes were categorized into seven clades: six were classified as MIKC-type, including FUL/AP1, DAM, PI, AGL18, AGL12, AG, and SOC1, and one, AGL30, was classified as MIKC*-type. Notably, the FLC clade genes were absent in Pall. The PlMIKC genes were predominantly localized to the nucleus, and their sequences contained highly conserved MADS and K-domains. Phylogenetic analysis demonstrated that PlMIKC genes share a strong evolutionary affinity with the MIKC genes from grapevine () and poplar (). A low-temperature-induced bud dormancy transition (BDT) experiment revealed that PlMIKC genes, such as and , were highly expressed during dormancy maintenance, while , , and were upregulated during BDT. Additionally, the transient overexpression of in 'Hang Baishao' significantly accelerated BDT and promoted bud break, suggesting that , traditionally linked to flowering regulation, also plays a key role in dormancy transition. Since limited literature on the MIKC gene family is currently available in herbaceous peony, this study expands the knowledge of the MIKC genes in Pall. and offers valuable insights into the molecular regulation of bud dormancy in response to low temperatures.