Biology subjects

Marconi, M.

Publications and source records attributed to Marconi, M..

5 recordsLinked to original sources

bioRxiv2026

Cell wall charge gates iron availability in plant roots

Plants acquire essential mineral nutrients from the soil, yet these elements must first traverse the extracellular matrix of the root before reaching the cell surface. How the physical properties of this extracellular compartment influence nutrient distribution and availability remains poorly understood. In plants, this extracellular matrix is formed by the cell wall, which carries a dynamically regulated negative charge that can change during development and in response to environmental cues. Here we demonstrate that cell wall charge functions as a tunable electrostatic gate that determines how iron is partitioned between retention and bioavailability. This decoupling between iron abundance and availability reveals a fundamental tradeoff imposed by extracellular electrostatics. A mechanistic diffusion-binding model shows that increasing wall charge inherently enhances iron sequestration while limiting its mobility at the cell surface. Genetic perturbation of pectin de-methylesterification validates this principle in vivo. Moreover, iron limitation itself triggers active remodeling of cell wall charge, dynamically shifting the balance toward increased iron accessibility. Together, these findings identify the plant cell wall as an active regulator of nutrient homeostasis rather than a passive barrier. By dynamically modulating extracellular electrostatics, roots control iron partitioning and bioavailability, uncovering a new physical layer of regulation in plant mineral nutrition. One-Sentence SummaryThe plant cell wall operates as a tunable electrostatic gate that buffers and releases iron through spatially and environmentally regulated charge dynamics.

plant biology↗

bioRxiv2023

Competing differentiation gradients coordinate fruit morphogenesis

Morphogenesis requires the coordination of cellular behaviors along developmental axes1. In plants, gradients of growth and differentiation are typically established along a single longitudinal primordium axis to control organ shaping2. Here we combine quantitative live-imaging at cellular resolution with genetics, chemical treatments, and modeling to understand the formation of Arabidopsis thaliana female reproductive organ (gynoecium). We show that, contrary to other aerial organs, gynoecium shape is determined by two competing differentiation gradients positioned along two orthogonal axes. An early mediolateral gradient, dependent on meristematic activity in the medial domain, controls the valve morphogenesis while simultaneously restricting an auxin-dependent, longitudinal gradient to the style. This gradient competition serves to finetune the common developmental program governing organ morphogenesis to ensure the specialized function of the gynoecium3,4.

plant biology↗

bioRxiv2022

Stem cell regulators control a G1 duration gradient in the plant root meristem

In meristems, where new plant organs initiate, key stem cell regulators have been identified, but their link to cell cycle progression remains unclear. Here, we show that the root meristem has a positional gradient of G1 duration that ranges from [~]2 h near the meristem boundary to more than 20 h in stem cells and early derivatives. Mutants in the PLETHORA (PLT) genes shortened G1 length and flattened its gradient. Computer modeling of an incoherent feed-forward loop (IFFL) predicted the inference of a negative regulatory pathway. We propose that PLT genes play opposing roles, maintaining meristem and stem cell activity and inhibiting G1 progression through the CDK inhibitor KRP5, a PLT target, and RBR1. This establishes a previously undescribed proximal-distal feature of the root meristem in which a G1 duration gradient is shaped by stem cell and meristem maintenance regulators.

plant biology↗

bioRxiv2021

Design principles of plant root morphogenesis

Plants grow roots to adjust their bodies to dynamic changes in the surrounding environment. How do plant roots emerge from the stem cell reservoir during embryogenesis is however poorly understood. Here, we present a bottom-up strategy to address this challenge by combining empirical observations with advanced computer modeling techniques. We demonstrate that the anisotropy of root growth results from differential growth rates of adjacent tissues, whereas the root meristem development incorporates a multi-level feedback loop between complex transport network of phytohormone auxin, auxin-dependent cell growth and cytoskeleton rearrangements. In silico model predictions are in close agreement with in vivo patterns of anisotropic growth, auxin distribution, and cell polarity, as well as several root phenotypes caused by chemical, mechanical, or genetic perturbations. Our findings reveal a minimal set of design principles connecting tissue mechanics, cell anisotropy, and directional transport that are sufficient for self-organization of the root meristem shape. A mobile auxin signal transported through immobile cells orchestrates polarity and growth mechanics to instruct the morphogenesis of an independent organ.

plant biology↗

bioRxiv2020

Modulation of root growth by nutrient-defined fine-tuning of polar auxin transport

Nitrogen is an essential macronutrient and its availability in soil plays a critical role in plant growth, development and impacts agricultural productivity. Plants have evolved different strategies to sense and respond to heterogeneous nitrogen distribution. Modulating root system architecture, including primary root growth and branching, is among the most essential plant adaptions to ensure adequate nitrogen acquisition. However, the immediate molecular pathways coordinating the adjustment of root growth in response to varying nitrogen sources are poorly understood. Here, using a combination of physiological, live in vivo high- and super resolution imaging, we describe a novel adaptation strategy of root growth on available nitrogen source. We show that growth, i.e. tissue-specific cell division and elongation rates are fine-tuned by modulating auxin flux within and between tissues. Changes in auxin redistribution are achieved by nitrogen source dependent post-translational modification of PIN2, a major auxin efflux carrier, at an uncharacterized, evolutionary conserved phosphosite. Further, we generate a computer model based on our results which successfully recapitulate our experimental observations and creates new predictions that could broaden our understanding of root growth mechanisms in the dynamic environment.

plant biology↗