Biology subjects

Dubrovsky, J. G.

Publications and source records attributed to Dubrovsky, J. G..

6 recordsLinked to original sources

bioRxiv2026

The transcription factor ESR2/DRNL/BOL differentially regulates de novo organogenesis, regeneration, and lateral root development in Arabidopsis thaliana

Plant regeneration requires coordinated transcriptional and hormonal regulation to re-establish organ identity. The AP2/ERF transcription factor ENHANCER OF SHOOT REGENERATION 2 /DORNROESCHEN-LIKE / BOLITA (ESR2/DRNL/BOL) expressed in aerial organ founder cells promotes shoot formation, but its broader role across organogenic contexts remains unclear. Here, using loss-of-function and inducible overexpression lines of Arabidopsis thaliana, we demonstrate that ESR2 exerts context-dependent and antagonistic effects on shoot and root development. ESR2 activation promotes shoot and aerial-like tissue formation and enhances callus proliferation, particularly under cytokinin-rich conditions. Conversely, ESR2 suppresses or delays multiple de novo root formation programs, including adventitious, basal, and regenerated roots, while its loss enhances root initiation and growth. Expression analyses reveal that ESR2 promoter activity is found at de novo formed basal and adventitious root primordia and emerged root apical meristems, suggesting a role in conferring regenerative competence while restricting their developmental progression. Moreover, it is expressed in newly established quiescent centers of lateral roots in intact plants and the loss of ESR2 function strongly and negatively affects lateral root initiation, revealing an unanticipated developmental role of ESR2 and its requirement for lateral root formation. Together, these findings identify ESR2 as a shared molecular regulator governing early organogenesis in intact plants and plant explants; it establishes an aerial organ fate bias while maintaining the competence for -and limiting the progression of- de novo root development in explants.

plant biology↗

bioRxiv2025

Spatiotemporal Dynamics of Anionic Phospholipids Orchestrate Lateral Root Initiation and Morphogenesis in Arabidopsis thaliana

Lateral root (LR) development in Arabidopsis thaliana requires precise coordination of pericycle founder cell (FC) specification, patterning, and morphogenesis. While auxin signalling is well established in this process, the role of membrane lipid signalling--particularly phosphoinositides--remains less understood. Here, we investigate the contribution of the anionic phospholipids PI4P, PI(4,5)P2, and phosphatidylserine (PS) to LR formation using live-cell biosensors, genetic mutants, and inducible lipid depletion tools. We show that PI4P is uniformly distributed throughout lateral root primordia (LRPs), whereas PI(4,5)P2 is specifically depleted in the proliferative core during early LRP development. Time-lapse imaging revealed stable PI4P and PI(4,5)P2 levels before and after FC activation, while PS increased rapidly post-activation. In xylem-pole pericycle (XPP) cells, PI(4,5)P2 decreased and PS increased following LR initiation, with both changes occurring in a membrane-domain-specific manner. Genetic analysis of the pip5k1pip5k2 double mutant, deficient in PI(4,5)P2 synthesis, revealed impaired LR initiation and emergence. Conversely, inducible depletion of PI(4,5)P2 using the iDePP system enhanced LRP initiation and accelerated development when activated after FC specification. These results suggest that PI4P functions as a stable basal lipid, while PI(4,5)P2 and PS undergo dynamic, spatially regulated changes critical for LR progression. Notably, PI(4,5)P2 acts as a negative regulator of LRP initiation and morphogenesis. Our findings highlight how lipid signalling, in coordination with hormonal cues, provides spatial and temporal control over pericycle cell behaviour and lateral root organogenesis. SIGNIFICANCE STATEMENTThis study reveals how specific membrane lipids help control where and when new lateral roots form in plants. While plant hormones like auxin are known to guide root branching, this work shows that lipids such as PI(4,5)P2 and phosphatidylserine also play key roles. Using live imaging and genetic tools, we found that reducing PI(4,5)P2 in certain root cells promotes root growth by triggering cell division and development. In contrast, phosphatidylserine level increases right when root-forming cells become active. These discoveries highlight a new layer of control in plant development and suggest that lipids help fine-tune the formation of roots, which is essential for how plants take up water and nutrients.

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↗

bioRxiv2022

Aromatic amino acid biosynthesis by a Lotus Aldolase impacts root hair development and symbiotic associations

O_LILegume roots can be symbiotically colonized by arbuscular mycorrhizal (AM) fungi and nitrogen-fixing bacteria. In Lotus japonicus, the latter occurs intracellularly by the cognate rhizobial partner Mesorhizobium loti or intercellularly with the Agrobacterium pusense IRBG74 strain. Although these symbiotic programs show distinctive cellular and transcriptome signatures, some molecular components are shared. C_LIO_LIIn this study, we demonstrate that Aldolase1, the first enzyme in the biosynthetic pathway of aromatic amino acids (AAA), plays a critical role in root hair development and for AM and rhizobial symbioses in Lotus. C_LIO_LITwo homozygous mutants affected in Aldolase1 (ald1-1 and ald1-2) show drastic alterations in the root hair morphology, associated with a progressive disruption of the actin cytoskeleton. The altered root hair structure was prevented by chemical and genetic complementation. C_LIO_LIBoth ald1-1 and ald1-2 show significant reductions in rhizobial infection (intracellular and intercellular), nodule organogenesis and AM colonization. RNAseq analysis of ald1-2 roots suggested that these phenotypes are associated with downregulation of several cell wall related genes, and with an attenuated symbiotic signalling. This work provides robust evidence that links AAA metabolism to root hair development and successful symbiotic associations. C_LI

plant biology↗

bioRxiv2021

Nanoscopic resolution within a single imaging frame

Mean-Shift Super Resolution (MSSR) is a principle based on the Mean Shift theory that extends spatial resolution in fluorescence images, beyond the diffraction limit. MSSR works on low- and high-density fluorophore images, is not limited by the architecture of the detector (EM-CCD, sCMOS, or photomultiplier-based laser scanning systems) and is applicable to single images as well as temporal series. The theoretical limit of spatial resolution, based on optimized real-world imaging conditions and analysis of temporal image series, has been measured to be 40 nm. Furthermore, MSSR has denoising capabilities that outperform other analytical super resolution image approaches. Altogether, MSSR is a powerful, flexible, and generic tool for multidimensional and live cell imaging applications.

bioinformatics↗

bioRxiv2020

The Arabidopsis TTL3 protein interconnects brassinosteroid signalling and cytoskeleton during lateral root development

Lateral roots are essential components of the plant edaphic interface, contributing to water and nutrient uptake, biotic and abiotic interactions, stress survival, and plant anchorage. We have identified the TETRATRICOPEPTIDE-REPEAT THIOREDOXIN-LIKE 3 (TTL3) being related to lateral root emergence and later development. TTL3 interacts with microtubules and potentially interconnects cytoskeletal function with the brassinosteroid signalling pathway. Loss of function of TTL3 leads to a reduced number of emerged lateral roots due to delayed development of lateral root primordia. Lateral root growth of the ttl3 mutant is less sensitive to BR treatment. Timing and spatial distribution of TTL3 expression is consistent with its role in development of lateral root primordia before their emergence and subsequent development into lateral roots. TTL3 is a novel component of the root system morphogenesis regulatory network.

developmental biology↗