Bosanquet, J. L. | bioRxiv Science

bioRxiv2025

Epigenomic Landscape of Oak (Quercus robur) across Seasons and Generations

O_LISeasonal fluctuations strongly shape the physiology of long-lived trees by coordinating growth, dormancy, and stress responses. Increasing evidence points to epigenetic mechanisms, particularly DNA methylation, as regulators of these processes, yet their role in long-lived trees across seasons and generations remains poorly understood. C_LIO_LIWe generated single-base resolution maps of cytosine methylation exploring the epigenetic landscape of 180 year-old mature oak (Quercus robur) trees (genetically homogeneous) along spring, summer and autumn, and in their progeny. C_LIO_LIGenome-wide DNA-methylation revealed a progressive increase in the CHH context (H = A, T or C) from Spring to Summer and Autumn, suggesting epigenetic reprogramming is happening over season. Differentially Methylated Regions (DMRs) were concentrated in promoter regions and terminal inverted repeat (TIR). Differentially methylated transposable elements (TEs) and genes were involved in leaf development and hormonal signalling. By contrast, generational differences (parents versus offspring) were most prominent in CG and CHG contexts and were concentrated in genic regions. C_LIO_LIOaks exhibit distinct seasonal and generational DNA methylation signatures, highlighting the plasticity and developmental specificity of epigenetic regulation. These findings provide a genomic foundation for understanding how epigenetic memory contributes to phenology, developmental programming and long-term adaptation in long-lived plants. C_LI

genetics↗

bioRxiv2024

Elicitor specific mechanisms of defence priming in oak seedlings against powdery mildew

Defence priming sensitises plant defences to enable a faster and/or stronger response to subsequent stress. Various chemicals can trigger priming; however, the response remains unexplored in oak. Here, we characterise salicylic acid (SA)-, jasmonic acid (JA)-, and {beta}-aminobutyric acid (BABA)-induced priming of oak seedlings against the causal agent of powdery mildew (Erysiphe alphitoides, PM). Whilst JA had no effects, BABA and SA enhanced resistance by priming callose deposition and SA-dependent gene expression, respectively. Untargeted transcriptome and metabolome analyses revealed genes and metabolites uniquely primed by BABA, SA, and JA. Enrichment analyses demonstrated a limited number of pathways differentiating the three treatments or the resistance-inducing elicitors BABA and SA. However, a similar mode of action between BABA and JA was identified. Moreover, our analyses revealed a lack of crosstalk between SA and JA. Interestingly, priming by BABA was linked to alkaloid, lignan, phenylpropanoid, and indolitic compounds biosynthesis. Moreover, integration of the omics analyses revealed the role of ubiquitination and protein degradation in priming by BABA. Our results confirm the existence of chemical-induced priming in oak and has identified specific molecular markers associated with well-characterised elicitor.

plant biology↗