Fangyun Cheng

Bud dormancy poses a major constraint for tree peony growth and flowering, especially in off‐season cultivation. While GATA transcription factors regulate ABA‐mediated seed dormancy, their role in bud dormancy remains unclear. In this study, we characterized the GATA family in tree peony and identified two key transcription regulators, PlGATA1 and PlGATA6 , that displayed antagonistic expression patterns in dormant and non‐dormant buds of Paeonia × lemoinei ‘High Noon’. Exogenous ABA treatment induced PlGATA1 expression while suppressing PlGATA6 , indicating divergent roles in ABA signalling. Heterologous expression in Arabidopsis revealed that PlGATA1 enhanced seed dormancy, whereas PlGATA6 suppressed it. Transient transformation assays in tree peony showed that PlGATA1 overexpression or PlGATA6 silencing induced bud dormancy and altered the expression of the ABA metabolism gene. Critically, in vivo and in vitro binding assays confirmed that PlGATA1 activates the PlABI5 promoter, while PlGATA6 activates the PlCYP707A2‐1 promoter. Collectively, our results establish PlGATA1 and PlGATA6 as an antagonistic transcriptional module that fine‐tunes ABA homoeostasis, thereby acting as a molecular switch controlling bud dormancy in tree peony. This study provides novel insights into the transcriptional regulation of bud dormancy and suggests potential targets for improving off‐season cultivation in woody plants.

Plant quantitative trait allelic variation stems from complex regulatory networks. Tree peony, which is native to China, is a unique woody plant with ornamental, medicinal, and oil-producing value. Paeonia ostii, as an important species of tree peony, has emerged as a novel woody oil crop in recent years. However, research on functional genes associated with yield traits in P. ostii remains relatively limited. To gain deeper insights into the genetic architecture underlying one of the three key yield components—grain weight—in this study, a genome-wide association map for 123 unrelated P. ostii was constructed by integrating short-read and long-read sequencing. From 959 screened yield-related candidate transcription factors, 57 polymorphic expressed sequence tag-simple sequence repeats (EST-SSRs) were identified. In combination with 24 previously reported polymorphic EST-SSRs linked to tree peony seed yield, 81 markers were utilized for genotyping 123 P. ostii materials. These EST-SSRs showed high genetic diversity and low linkage disequilibrium. Additionally, population structure analysis revealed two distinct subgroups within the mapping population. Furthermore, 21 EST-SSRs were significantly associated with hundred-grain weight according to mixed linear model (MLM) association analysis. These loci primarily originated from the AP2, TCP, YAB, WRKY, WD, BHLH, and MADS-box gene families, contributing to phenotypic variation at rates ranging from 9.15% to 35.94%. Through sequence alignment analysis, we determined that WRI1, ERF7, NGAL3, and YAB1 might serve as key candidate genes regulating seed weight in P. ostii, highlighting their significant research value and warranting further investigation. The findings of this study provide valuable resources for elucidating allelic variation in the quantitative traits of oil-producing woody perennials.

Flower color is an essential biological and ornamental trait in plants. Paeonia rockii (flare tree peony, FTP) exhibits diverse flower colors, characterized by a distinctive basal flare in petals, which enhances its ornamental and ecological value. However, while previous research has mainly focused on flare formation, the regulatory mechanisms controlling the background color of petals remain unclear. This study identifies a novel regulatory module governing petal background coloration in FTP. Within this module, PrMYB75a acts as the central regulator to promote anthocyanin accumulation, as evidenced by stable transformation in Arabidopsis thaliana and tobacco (Nicotiana tabacum), as well as virus-induced gene silencing in FTP. Furthermore, yeast one-hybrid, dual-luciferase reporter, and electrophoretic mobility shift assays collectively demonstrated that PrMYB75a directly activates two key anthocyanin structural genes, PrCHS1 and PrANS, by interacting with MYB-binding sites nearest to the ATG start codon in their promoters. Additionally, we identified an upstream regulator, PrFRS2, which activates both PrMYB75a and PrANS by binding to the FAR1/FHY3-binding sites in their promoters. Modulation of PrFRS2 expression levels through gene silencing and overexpression resulted in alterations in flower pigmentation in both FTP and tobacco. In summary, within the PrFRS2-PrMYB75a module, PrFRS2 indirectly activates PrCHS1 and PrANS by regulating PrMYB75a, or directly activates PrANS, leading to anthocyanin accumulation in FTP purple petals. This module represents a novel regulatory mechanism of petal background coloration in FTP, providing new perspectives on color variation in flowering plants and offering genetic resources for the improvement of the flower color trait in tree peonies.

Bud dormancy critically affects tree peony growth and flowering, particularly for off-season forcing cultivation. GATA transcription factors are known regulators of ABA-mediated seed dormancy in plants. However, their potential role in bud dormancy remains unexplored. In this study, we systematic identified GATA family in tree peony genome and revealed key regulators PlGATA1 and PlGATA6 . Comparing the gene expressions in dormant and non-dormant buds in Paeonia × lemoinei ’High Noon’, we observed starkly contrasting expression patterns for PlGATA1 and PlGATA6 . Exogenous ABA treatment induced PlGATA1 expression while suppressing PlGATA6 , indicating the functional divergence in their regulatory pathways. Overexpression in Arabidopsis demonstrated that PlGATA1 induced seed dormancy, while PlGATA6 inhibits its. In tree peony, overexpression of PlGATA1 or silencing of PlGATA6 induced bud dormancy and modulated ABA metabolism-related gene expression. Critically, in vivo and in vitro binding assays confirmed that PlGATA1 activates the PlABI5 promoter, while PlGATA6 activates PlCYP707A1 promoter. Collectively, our findings demonstrate that PlGATA1 and PlGATA6 serve as a ’molecular switch’ governing bud dormancy induction in tree peony through antagonistically regulating ABA homeostasis. These results provide novel insights into the transcriptional regulatory mechanisms of bud dormancy and identify potential target genes to improve off-season cultivation in woody plants.