Uncovering the dormancy code in litchi buds via phosphoproteomics

Among these, kinases such as CDPK and MAPK—along with MYB and zinc finger transcription factors—emerged as key players in controlling bud status. These findings provide the first comprehensive phosphoproteomic map of litchi bud dormancy, laying groundwork for improved management of flowering and yield in tropical fruit crops.

Bud dormancy enables plants to survive unfavorable conditions, but in tropical evergreens like litchi (Litchi chinensis), dormancy can occur even under optimal climates, indicating an intrinsic regulatory mechanism. While dormancy is well studied in temperate species, particularly at the transcriptional level, less is known about post-translational modifications (PTMs)—notably phosphorylation—which can rapidly modulate protein activity. Phosphorylation is orchestrated by kinases and phosphatases, influencing processes like signal transduction, protein transport, and stress responses. Although evidence points to phosphorylation’s role in seed dormancy and bud break in other species, its function in tropical perennials remains underexplored. Due to these knowledge gaps, a deeper understanding of phosphorylation in litchi buds was urgently needed.

A study (DOI: 10.48130/tp-0025-0018) published in Tropical Plants on 04 July 2025 by Ren-Fang Zeng & Xu-Ming Huang’s team, South China Agricultural University, has major implications not only for basic plant biology but also for the practical management of flowering cycles in fruit crops.

In this study, researchers employed label-free quantitative phosphoproteomic analysis using high-resolution LC-MS/MS to investigate phosphorylation dynamics during four developmental stages of litchi terminal buds: dormancy (S1 and S4), bud break (S2), and fast growth (S3). From protein extracts, a total of 7,835 phosphorylated peptide segments corresponding to 6,785 unique phosphorylation sites and 2,795 phosphoproteins were identified. Quality control assessments—including PCA, peptide length distribution, mass accuracy, and protein coverage—confirmed high data reliability and reproducibility. Among the phosphorylation sites, serine was the most commonly modified residue (87.1%), followed by threonine (12.2%) and tyrosine (3%). Differential analysis across developmental stages revealed 492 DRPs between S2 and S1, 284 between S3 and S1, and hundreds more across other comparisons, with higher DRP abundance during growth stages. Functional enrichment (GO and KEGG) showed these DRPs were predominantly involved in phosphorylation, metabolic processes, and signal transduction, and were localized in membranes and nuclei. Six distinct expression patterns of DRPs were identified, with clusters corresponding to dormancy- or growth-specific expression. Key kinases such as CDPK and MAPK, and transcription factors like MYB and zinc finger proteins, showed increased phosphorylation and expression during active growth stages. Correlation analysis revealed specific phosphorylation sites significantly associated with protein expression levels, while qRT-PCR confirmed that many DRP-encoding genes exhibit transcriptional patterns aligned with developmental transitions. Collectively, these findings suggest that phosphorylation-mediated regulation plays a crucial role in the dormancy-to-growth transition in litchi buds, offering new insights into perennial bud regulation mechanisms.

Understanding the phosphorylation dynamics of bud dormancy opens up new possibilities for regulating flowering and optimizing yield in litchi and other tropical fruit trees. By targeting specific kinases or modulating their activity, agronomists could potentially manipulate bud behavior to suit climatic or market demands. Future studies will aim to functionally characterize the most promising DRPs and investigate how environmental.

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References

DOI

10.48130/tp-0025-0018

Original Source URL

https://doi.org/10.48130/tp-0025-0018

Funding Information

This study was supported by the China Litchi and Longan Industry Technology Research System (Project no. CARS-32), the 2023 Special Project for Key Areas of Research and Development of Guangzhou Municipality (2023B01J2002), and the Guangzhou Basic and Applied Basic Research Foundation (No. 2024A04J4919).

About Tropical Plants

Tropical Plants (e-ISSN 2833-9851) is the official journal of Hainan University and published by Maximum Academic Press. Tropical Plants undergoes rigorous peer review and is published in open-access format to enable swift dissemination of research findings, facilitate exchange of academic knowledge and encourage academic discourse on innovative technologies and issues emerging in tropical plant research.