Biology subjects

Leon, P.

Publications and source records attributed to Leon, P..

3 recordsLinked to original sources

bioRxiv2025

ATG8i Autophagy activation is mediated by cytosolic Ca2+ under osmotic stress in Arabidopsis thaliana

Autophagy is a highly conserved catabolic process in eukaryotic cells that enables the degradation and recycling of damaged or unnecessary cytoplasmic components. It plays essential roles in both development and responses to environmental stress. In this study, we investigated the regulation of autophagy in response to osmotic stress, focusing on the dynamics of the RFP-tagged ATG8i protein and the potential involvement of cytosolic calcium ion (Ca{superscript 2}) in this process. Our findings indicate that both osmotic stress and Ca{superscript 2} signaling modulate the accumulation of RFP-ATG8i-labeled autophagosomes in a plant organ-specific manner. Furthermore, the observed colocalization of RFP-ATG8i with the endoplasmic reticulum (ER) marker HDEL suggests a significant role for ATG8i in ER-phagy, highlighting its potential contribution to ER turnover under stress conditions.

plant biology↗

bioRxiv2024

Apocarotenoid signaling regulates meristem activity and shapes shoot and root lateral organ formation in Arabidopsis

Plant carotenoids are precursors to phytohormones and signaling molecules, playing critical roles in plant development, an emerging area of research. This study investigates the function of the undefined apocarotenoid ACS1 signal in modulating plant development, particularly its impact on the morphologenesis of lateral organs and apical meristems. By modulating ACS1 levels under varying light conditions, we demonstrate its dynamic role in leaf and root development. Notably the characteristic radial leaf morphology of the clb5 mutant reverts to normal even days post-germination, demonstrating that ACS1 is not a toxic signal but rather a key component of a biogenic retrograde signaling pathway. Transcriptomic analysis of clb5 seedlings at different post-germination stages underscores the critical role of ACS1 during specific developmental window. The expression profile of this mutant correlates with a proplastid stage, where even the expression of most of the genes involved in plastid biogenesis are downregulated. Furthermore, ACS1 disrupts the expression of diverse developmentally important genes, including those participating in auxin transport and signaling, leading to impaired meristem maintenance and inhibiting leaf expansion. The effects of ACS1 extends beyond photosynthetic tissues, impacting shoot and apical root meristem organization. In particular, ACS1 affects columella cell pattering, disrupting normal gravitropic responses. These findings demonstrate that ACS1 dynamically regulates both leaf and root development, as well as meristem activity. This study provides new insights into the role of cis-carotenoids as retrograde signals, functioning very early in the plastid differentiation and emphasizes the significance of plastid retrograde signaling in plant growth and development.

plant biology↗

bioRxiv2021

Interplay between positive and negative regulation by B3-type transcription factors is critical for the accurate expression of the ABA INSENSITIVE 4 gene.

The ABA-INSENSITIVE 4 transcription factor is key for the regulation of diverse aspects of plant development and environmental responses, including proper perception of hormonal and nutritional signals. ABI4 activity is highly regulated at the transcriptional and post-transcriptional levels leading to precise expression mainly in the developing seed and early seedling development. Based on genetic and molecular approaches in the current study we provide new insights into the central mechanism underpinning the transcriptional regulation of ABI4 during both seed and vegetative development. We identified a complex interplay between the LEC2 and ABI3 transcriptional activators and the HSI/VAL repressors that is critical for proper ABI4 expression. Interestingly, the regulation by these proteins relies on the two RY cis-acting motifs present two kb upstream of the ABI4 gene. Our analysis also shows that the chromatin landscape of the ABI4 loci is highly dependent on the LEC2 and HSI2/VAL proteins. LEC2 regulation extends to the vegetative development and the absence of this factor results in ABA- and sugar-insensitive signaling in the developing plant. This regulatory circuit functions as a major control module for the correct spatial-temporal expression of ABI4 and prevents its ectopic accumulation that is harmful to the plant.

developmental biology↗