Abscisic acid–induced transcription factor PsMYB306 negatively regulates tree peony bud dormancy release

Abstract

Bud dormancy is a crucial strategy for perennial plants to withstand adverse winter conditions. However, the regulatory mechanism of bud dormancy in tree peony (Paeonia suffruticosa) remains largely unknown. Here, we observed dramatically reduced and increased accumulation of abscisic acid (ABA) and bioactive gibberellins (GAs) GA1 and GA3, respectively, during bud endo-dormancy release of tree peony under prolonged chilling treatment. An Illumina RNA sequencing study was performed to identify potential genes involved in the bud endo-dormancy regulation in tree peony. Correlation matrix, principal component, and interaction network analyses identified a down-regulated MYB transcription factor gene, PsMYB306, the expression of which positively correlated with 9-CIS-EPOXYCAROTENOID DIOXYGENASE 3 (PsNCED3) expression. Protein modeling analysis revealed four residues within the R2R3 domain of PsMYB306 to possess DNA binding capability. Transcription of PsMYB306 was increased by ABA treatment. Overexpression of PsMYB306 in petunia (Petunia hybrida) inhibited seed germination and plant growth, concomitant with elevated ABA and decreased GA contents. Silencing of PsMYB306 accelerated cold-triggered tree peony bud burst, and influenced the production of ABA and GAs and the expression of their biosynthetic genes. ABA application reduced bud dormancy release and transcription of ENT-KAURENOIC ACID OXIDASE 1 (PsKAO1), GA20-OXIDASE 1 (PsGA20ox1), and GA3-OXIDASE 1 (PsGA3ox1) associated with GA biosynthesis in PsMYB306-silenced buds. In vivo and in vitro binding assays confirmed that PsMYB306 specifically transactivated the promoter of PsNCED3. Silencing of PsNCED3 also promoted bud break and growth. Altogether, our findings suggest that PsMYB306 negatively modulates cold-induced bud endo-dormancy release by regulating ABA production.

A tree peony RING-H2 finger protein, PsATL33, plays an essential role in cold-induced bud dormancy release by regulating gibberellin content

“…To investigate the molecular mechanisms of bud dormancy break in tree peony, a 783-bp transcript encoding a putative RING-H2 finger protein, designated PsATL33 , was identified from transcriptome data of chilling-treated tree peony buds ( Yuan et al., 2024 ). Sequence analysis revealed that its cDNA contains a complete coding region of 483 bp, encoding a polypeptide of 161 amino acids ( Supplementary Figure S1 ).…”

“…Bud dormancy is an effective strategy for woody perennial plants to resist cold weather in winter ( Yuan et al., 2024 ). The timely bud dormancy and release are important for perennial plants to overwinter and grow normally in the next year.…”

“…The recombinant plasmid was transformed into A. tumefaciens GV3101. The leaf disc method was used for stable genetic transformation of petunia plants ( Yuan et al., 2024 ). Briefly, young leaves from petunia ‘Mitchell Diploid’ plants were collected and cut into 1 cm × 1 cm leaf discs, which were infected with Agrobacteria harboring the recombinant plasmids.…”

“…In previous studies, we performed RNA sequencing (RNA-Seq) analysis of tree peony buds during chilling-induced dormancy release ( Yuan et al., 2024 ). A large number of differentially expressed genes were identified from RNA-Seq data.…”