This study identifies LdCDF2 as a hub linking GA signaling and biosynthesis and elucidates how the DELLA-LdCDF2 dual switch mediates GA self-amplification.
Abstract
The dormancy release and initiation of germination in underground storage organs are critical for plant adaptation and agriculture. Gibberellin (GA) promotes germination, but how GA signaling achieves self-amplification at the early stage of germination to drive rapid germination remains unknown. In particular, the molecular hub that connects GA perception and biosynthesis has yet to be identified. Here, we identified CYCLING DOF FACTOR 2 (LdCDF2) from Lilium davidii var. unicolor as a novel positive regulator of germination. Using stable genetic transformation, protein‒protein interaction assays, and cell-free degradation assays, we revealed a germination module wherein LdCDF2 directly couples GA signaling with biosynthesis. Mechanistically, LdCDF2 directly activates the transcription of LdGA3ox2/3, thereby promoting GA biosynthesis. Moreover, the DELLA protein LdSLR1 interacts with LdCDF2, inhibiting the transcriptional activity of LdCDF2 and accelerating its degradation via the 26S proteasome, thereby exerting a dual inhibitory effect on germination. When GA signaling degrades LdSLR1, LdCDF2 is released, reactivating GA synthesis and enabling GA signal self-amplification. Genetic evidence revealed that stable silencing of LdCDF2 reduced the germination rate by 76.0% and endogenous GA3 level to 57.69% of that of the control, while overexpression increased the rate by 2.7-fold and the GA3 level by 6.29-fold. In summary, this study identifies LdCDF2 as a hub linking GA signaling and biosynthesis and elucidates how the DELLA-LdCDF2 dual switch mediates GA self-amplification. This discovery advances our understanding of underground organ germination mechanisms and provides new molecular targets for studying plant hormone signaling cascades and precisely controlling bulbous plant germination timing.
A review of WD40 repeat proteins strengthens current findings relating their structural properties, molecular mechanisms, and functional diversity, underscoring their potential as targets for developing stress-resilient, high-yield crops in a changing climate.
A positive feedback loop between CLV3 and WUS that is mediated by multiple hormone interactions, which is critical for plants to adapt to harsh environments is revealed.
Mengchu Xu, Haijun Wu, Chengwu Liu et al.· Molecular Plant· 0 citations
This review synthesizes recent progress in how BBX activity is modulated through chromatin remodeling, alternative splicing and E3-ligase-mediated protein stability, among other mechanisms, and proposes that understanding BBX function requires a shift from identifying isolated target genes to decoding the combinatorial logic of their interactions.
J. Botto, G. Gómez-Ocampo, C. Barraza· Plant physiology and biochem...· 0 citations
Seed dormancy and germination represent a critical developmental transition that determines plant fitness, ecological adaptation, and agricultural productivity. This switch is governed by the integration of environmental cues with endogenous hormonal networks, most notably the antagonistic balance between abscisic acid (ABA), which enforces dormancy, and gibberellins (GA), which promote germination. Among environmental signals, light acts as a central informational cue regulating germination timing through phytochrome-mediated pathways. A key component of this network is PHYTOCHROME-INTERACTING FACTOR 1 (PIF1), a transcriptional regulator that maintains dormancy in darkness by promoting ABA biosynthesis and signaling while suppressing GA accumulation. Light perception through phytochromes triggers rapid degradation of PIF1, leading to a hormonal reprogramming that shifts the balance toward GA dominance and initiates germination. Crucially, this light-hormone signaling module is strongly integrated with epigenetic regulation, where chromatin remodeling, DNA methylation, histone modifications, and small RNAs dynamically regulate the accessibility of key dormancy- and germination-related genes. This multilayered regulatory architecture enables environmental inputs to be converted into stable or reversible developmental states during the dormancy-to-growth transition. In this review, we synthesize current advances in understanding how light signaling interfaces with hormonal and epigenetic pathways to control seed fate decisions. We further highlight how additional environmental cues, including temperature, nitrate availability, and smoke-derived signals, converge on the ABA–GA regulatory axis to fine-tune germination responses. Additionally, we discuss emerging mechanistic gaps and translational opportunities for improving seed performance, reducing pre-harvest sprouting (PHS), and enhancing crop resilience under changing climatic conditions. Collectively, we propose an integrated framework in which light, hormonal, and epigenetic networks function as a coordinated regulatory system ensuring germination occurs only under favorable environmental conditions.
Seed dormancy is a complex developmental and agronomic trait requiring a delicate balance: insufficient dormancy leads to pre-harvest sprouting (PHS), while excessive dormancy causes uneven germination. Understanding the intrinsic mechanisms resolving this trade-off is vital for crop improvement. In this study, our findings indicate that the heat shock transcription factor OsHsfA2a acts as a negative regulator of seed dormancy. The hsfa2a knockout mutants exhibited enhanced PHS resistance while maintaining yield potential and post-harvest germination rates, offering a potential strategy to uncouple PHS resistance from agronomic penalties. Mechanistically, our data suggest that OsHsfA2a self-associates and can activate the ABA catabolic gene OsABA8ox3, thereby promoting dormancy release. Furthermore, genetic analysis using the sd6 hsfa2a double mutant supports the hypothesis that the bHLH transcription factor OsSD6 is epistatic to OsHsfA2a, acting as an upstream initiator. Biochemically, OsSD6 transcriptionally activates OsHsfA2a. Once expressed, OsHsfA2a likely amplifies the signal via a self-activation loop. However, the accumulating OsSD6 protein physically interacts with OsHsfA2a, which we propose competitively attenuates its DNA-binding capacity. These results support a multi-tiered regulatory module operating across both transcriptional and post-translational levels. Collectively, our findings provide insights into an intrinsic physiological mechanism by which this module fine-tunes ABA catabolism to govern primary seed dormancy, providing precise genetic targets for mitigating PHS.
Zhang Dong, Xiaobo Zhu, Haoyuan Chen et al.· Plant, Cell and Environment· 0 citations
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