Biology subjects

Molina, D.

Publications and source records attributed to Molina, D..

6 recordsLinked to original sources

bioRxiv2024

An AINTEGUMENTA phospho-switch controls bilateral stem cell activity during secondary growth

Plant stem cells have the remarkable ability to give rise to distinct tissues and organs throughout development. Two concentric cylinders of actively dividing stem cells are the main drivers of radial thickening during secondary growth, each producing distinct vascular cell types towards the inside and the outside. While the molecular mechanisms underlying their initiation have been well studied, it remains unclear how these stem cell layers determine which cell type is generated. Here, we demonstrate that the cross-talk between the ERECTA (ER) receptor pathway and auxin signalling controls the amount and choice of output tissue in these two stem cell regions. Mechanistically, we show that the ER pathway phosphorylates the transcription factor AINTEGUMENTA, thereby modulating bilateral stem cell activity and favouring the differentiation of only one type of cell. Our results thus show that the phosphorylation status of ANT regulates root girth and biomass accumulation by influencing bilateral stem cell production. This highlights the critical role of post-translational modifications in plant growth and development. SignificanceThis study uncovers a critical regulatory mechanism governing bilateral stem cell activity during plant radial growth. Stem cells in the cambia proliferate and differentiate into specialized tissues like wood and cork, key sites of biomass accumulation. By exploring the interplay between the ERECTA (ER) receptor and auxin signalling, we reveal how these pathways modulate stem cell differentiation and radial thickening through the phosphorylation of the transcription factor AINTEGUMENTA (ANT). Phosphorylation status of ANT modulates stem cell activity, dictating the production of specific vascular cell types like wood thus controlling root girth. This research underscores the importance of post-translational modifications in plant development and provides a novel regulation underpinning stem cell differentiation, with significant implications for enhancing biomass accumulation as wood.

plant biology↗

bioRxiv2024

MYB68 regulates suberin patterning and radially distinct endodermal differentiation

Roots are composed of concentric tissue layers that embrace the centrally localized vasculature. Of these layers, particularly the endodermis stands out as it contains barriers that facilitate selective uptake across the plasma membrane. In mature root regions, endodermal cells undergo additional differentiation and become coated with suberin, a hydrophobic polymer that blocks membrane transport and seals off the inner root parts. Intriguingly, individual cells adjacent to the water-conducting xylem remain unsuberized. These are termed "passage cells", based on the assumption that they facilitate radial vascular access in a zone which is otherwise impenetrable. The identity of passage cells remain unknown, but their existence suggests that distinct identities and developmental trajectories exist within the second differentiation of the endodermis. In this study, we investigate this in the model plant Arabidopsis thaliana. Our work identifies a genetic regulator that controls pole-specific endodermal differentiation and tissue-forming divisions connected to passage cells. Through a number of analyses, we provide spatiotemporal insights into suberization, establish a framework for radial organization of the endodermis and highlight putative function(s) of passage cells. Combined our findings illustrate how multi-dimensional developmental proceses integrate with environmental inputs in order to provide distinct cellular functions within root tissues.

plant biology↗

bioRxiv2024

MYB68 orchestrates cork differentiation by regulating stem cell proliferation and suberin deposition

Plants have developed specialized barriers to protect and isolate the inner tissues from the environment while maintaining homeostasis. Different barriers are present in various organs and at different growth stages. During secondary growth, the periderm acts as the protective tissue, covering roots, stems, and branches as they become thick. The periderm is a dynamic barrier comprising a stem cell niche known as the cork cambium, which bifacially divides to generate the phelloderm inward and the cork outward. Cork cells have a unique cell wall impregnated with suberin and lignin polymers, essential for the barrier function. Despite its importance, the differentiation process that forms new cork cells from the stem cell is largely unknown. In this work, we identify members of the MYB36-subclade transcription factors as key regulators of cork differentiation. On the one hand, this set of transcription factors promotes suberin deposition by inducing the expression of enzymes involved in all steps of suberin biosynthesis, including the recently discovered suberin-polymerizing enzymes GDS Lipases; on the other hand, it represses cork cambium proliferation. Furthermore, we demonstrated that suberin deposition in the cork is a robust process regulated by a complex network of transcription factors, including other MYB transcription factors that activate suberin deposition in the endodermis. However, only members of the MYB36 subclade can repress cell proliferation in different developmental contexts, highlighting general and specific functions for MYB transcription factors. These findings have broad applicability, as tissue-specific manipulation of MYB activity has the potential for improving traits of biotechnological interest, such as thicker periderms and more suberized cork layers, and for assessing how these traits affect plant performance in response to stresses.

plant biology↗

bioRxiv2023

β-carotene accelerates resolution of atherosclerosis by promoting regulatory T cell expansion in the atherosclerotic lesion

{beta}-carotene oxygenase 1 (BCO1) catalyzes the cleavage of {beta}-carotene to form vitamin A. Besides its role in vision, vitamin A regulates the expression of genes involved in lipid metabolism and immune cell differentiation. BCO1 activity is associated with the reduction of plasma cholesterol in humans and mice, while dietary {beta}-carotene reduces hepatic lipid secretion and delays atherosclerosis progression in various experimental models. Here we show that {beta}-carotene also accelerates atherosclerosis resolution in two independent murine models, independently of changes in body weight gain or plasma lipid profile. Experiments in Bco1-/- mice implicate vitamin A production in the effects of {beta}-carotene on atherosclerosis resolution. To explore the direct implication of dietary {beta}-carotene on regulatory T cells (Tregs) differentiation, we utilized anti-CD25 monoclonal antibody infusions. Our data show that {beta}-carotene favors Treg expansion in the plaque, and that the partial inhibition of Tregs mitigates the effect of {beta}-carotene on atherosclerosis resolution. Our data highlight the potential of {beta}-carotene and BCO1 activity in the resolution of atherosclerotic cardiovascular disease.

immunology↗

bioRxiv2020

Tissue-autonomous phenylpropanoid production is essential for establishment of root barriers

Plants deposit polymeric barriers in their root cell walls to protect against external stress and facilitate selective nutrient uptake. The compounds that make up these barriers originate from the fatty acid- and phenylpropanoid biosynthetic pathways. Although the machinery responsible for production of the barrier constituents is well-char-acterized, our pathway models lack spatiotemporal resolution - especially in roots - and the source tissue is often not clear due to the apoplastic nature of barriers. Insights into how the individual root tissues or cells contribute to forming apoplastic barriers is important for elucidation of their ultrastructure, function and development. Manipulation of the associated biosynthesis is delicate, as mutants often display pleiotropic phenotypes due to the broad role of the underlying metabolites. Here, we address these issues by creating a genetic tool that allows in vivo repression of the phenylpropanoid pathway with both spatial and temporal control. We provide strong evidence that tissue-auton-omous production of phenylpropanoids is essential for establishment of the endodermal Casparian strip. Moreover, we find that in order to maintain deposition and attachment of a coherent suberin matrix to the cell wall, cells require continuous production of aromatic constituents. This process is especially crucial in the suberized endodermis where we find that repression of phenylpropanoid production leads to active removal of suberin.

plant biology↗

bioRxiv2019

Genome sequencing and functional characterization of a Dictyopanus pusillus fungal extract offers a promising alternative for lignocellulose pretreatment of oil palm residues

The pretreatment of biomass is a critical requirement of bio-renewable fuel production from lignocellulose. Although current processes primarily involve chemical and physical approaches, the biological breakdown of lignin using enzymes and microorganisms is quickly becoming an interesting eco-friendly alternative to classical processes. As a result, bioprospection of wild fungi from naturally occurring lignin-rich sources remains a suitable method to uncover and isolate new species exhibiting ligninolytic activity. In this study, wild species of white rot fungi were collected from Colombian forests based on their natural wood decay ability and high capacity to secrete oxidoreductases with high affinity for phenolic polymers such as lignin. Based on high activity obtained from solid-state fermentation using a lignocellulose source from oil palm as matrix, we describe the isolation and whole-genome sequencing of Dictyopanus pusillus, a wild basidiomycete fungus exhibiting ABTS oxidation as an indication of laccase activity. Functional characterization of a crude enzymatic extract identified laccase activity as the main enzymatic contributor to fungal extracts, an observation supported by the identification of 13 putative genes encoding for homologous laccases in the genome. To the best of our knowledge, this represents the first report of an enzymatic extract exhibiting laccase activity in the Dictyopanus genera, offering means to exploit this species and its enzymes for the delignification process of lignocellulosic by-products from oil palm.

bioengineering↗