Biology subjects

Carnol, M.

Publications and source records attributed to Carnol, M..

5 recordsLinked to original sources

bioRxiv2026

Zinc and iron homeostatic interactions in a mutant lacking nicotianamine vacuolar storage and citrate xylem loading

Metal homeostasis in plants relies on coordinated uptake, chelation, and transport mechanisms involving, but not limited to, citrate and nicotianamine (NA). In Arabidopsis (Arabidopsis thaliana), disruption of the citrate exporter FRD3 (FERRIC REDUCTASE DEFECTIVE 3) causes constitutive Fe deficiency responses, altered iron (Fe), manganese (Mn) and zinc (Zn) distribution, with Fe accumulation in the root cell wall. This ultimately results in oxidative and biotic stress responses, and impaired root development, phenotypes that are partially alleviated by Zn excess. In this study, we investigated the consequences of impairing both citrate loading into xylem vessels and NA partitioning within cells. The frd3 zif1 double mutant exhibits enhanced sensitivity to Zn excess, severe defects in root system architecture and meristem maintenance, persistent oxidative stress, and compromised reproductive development. These phenotypes correlate with sustained activation of Fe deficiency signaling and marked defects in root-to-shoot metal translocation. Our findings reveal that coordinated citrate export and NA compartmentation form an integrated buffering strategy required to maintain metal homeostasis and partitioning, as well as redox balance and proper development, including root plasticity and seed yield, under fluctuating metal availability.

plant biology↗

bioRxiv2025

Zinc deficiency induces spatially distinct responses in roots and impacts ZIP12-dependent zinc homeostasis in Arabidopsis

How zinc (Zn) deficiency shapes root development remains unclear, with conflicting reports on its effect on primary root growth in Arabidopsis thaliana (Arabidopsis). The impact of Zn shortage on the root apical meristem (RAM) in particular has not been systematically explored. Using an integrative approach combining cell biology, transcriptomics, and ionomics, we dissected how Zn deficiency alters root zonation and function. We showed that Zn deficiency triggers a striking reorganization of the root tip (RT): the RAM size is reduced, yet meristematic activity and local Zn levels are preserved. This is accompanied by promoted cell elongation and differentiation. Transcriptome profiling revealed a distinct Zn deficiency response in the RAM-enriched RT compared to mature root tissues, with ZIP12 emerging as the most strongly induced gene in the RT. Functional analysis of zip12 mutants uncovered major defects in root growth, RAM structure, expression of Zn-responsive genes, and metal partitioning. Our work unveiled a new layer of root developmental plasticity under Zn deficiency and identified ZIP12 as a central player in maintaining Zn homeostasis and root meristem function in Arabidopsis. These findings provide a framework to better understand how plants adapt root growth to fluctuating micronutrient availability.

plant biology↗

bioRxiv2020

Transcriptional regulation of ZIP genes is independent of local zinc status in Brachypodium shoots upon zinc deficiency and resupply

The biological processes underlying zinc homeostasis are targets for genetic improvement of crops to counter human malnutrition. Detailed phenotyping, ionomic, RNA-Seq analyses and flux measurements with 67Zn isotope revealed whole plant molecular events underlying zinc homeostasis upon varying zinc supply and during zinc resupply to starved Brachypodium distachyon (Brachypodium) plants. Although both zinc deficiency and excess hindered Brachypodium growth, accumulation of biomass and micronutrients into roots and shoots differed depending on zinc supply. The zinc resupply dynamics involved 1893 zinc-responsive genes. Multiple ZIP transporter genes and dozens of other genes were rapidly and transiently down-regulated in early stages of zinc resupply, suggesting a transient zinc shock, sensed locally in roots. Notably genes with identical regulation were observed in shoots without zinc accumulation, pointing to root-to-shoot signals mediating whole plant responses to zinc resupply. Molecular events uncovered in the grass model Brachypodium are useful for the improvement of staple monocots.

plant biology↗

bioRxiv2019

Resolution of the proteome, transcript and ionome dynamics upon Zn re-supply in Zn-deficient Arabidopsis

O_LIRegulation of plant Zn acquisition is poorly understood, while Zn deficiency affects over 2 billion people worldwide. We therefore dissected the dynamic response to changes in Zn supply in Arabidopsis. C_LIO_LIHydroponically-grown Zn starved plants were re-supplied with Zn. Subsequent time-resolved sampling strategy allowed concomitant quantification of the dynamics of Zn uptake, microsomal and soluble proteins, and specific transcripts, in space (roots and shoots) and time. C_LIO_LIZn accumulates in roots within 10min, but 8h are needed before shoot Zn increases. By 8h, root Zn concentration was ~60% of non-starved plants. Overexpressed root Zn transporters further peaked in 10-30min post re-supply, before reaching a minimum in 120min and 200 ppm Zn. Zn-responding signaling/regulatory molecules include receptor and MAP kinases, calcium signaling proteins, phosphoinositides, G-proteins, COP9 signalosome members, as well as multiple transcription factors. C_LIO_LIZn acquisition is a highly controlled dynamic process. Our study identifies novel players in Zn homeostasis and points to cross-talk with other nutrients. It paves the way for directed investigation of so far omitted candidates which dynamically respond to sudden changes in Zn supply but are expressed at similar levels at steady-state Zn deficiency and sufficiency. C_LI

plant biology↗

bioRxiv2017

Assessment Of The Potential Role Of Streptomyces In Cave Moonmilk Formation

Moonmilk is a karstic speleothem mainly composed of fine calcium carbonate crystals (CaCO3) with different textures ranging from pasty to hard, in which the contribution of biotic rock-building processes is presumed to involve indigenous microorganisms. The real bacterial input in the genesis of moonmilk is difficult to assess leading to controversial hypotheses explaining the origins and the mechanisms (biotic versus abiotic) involved. In this work we undertook a comprehensive approach in order to assess the potential role of filamentous bacteria, particularly a collection of moonmilk-originating Streptomyces, in the genesis of this speleothem. Scanning electron microscopy (SEM) confirmed that indigenous filamentous bacteria could indeed participate in moonmilk development by serving as nucleation sites for CaCO3 deposition. The metabolic activities involved in CaCO3 transformation were furthermore assessed in vitro among the collection of moonmilk Streptomyces, which revealed that peptides/amino acids ammonification, and to a lesser extend ureolysis, could be privileged metabolic pathways participating in carbonate precipitation by increasing the pH of the bacterial environment. Additionally, in silico search for the genes involved in biomineralization processes including ureolysis, dissimilatory nitrate reduction to ammonia, active calcium ion transport, and reversible hydration of CO2 allowed to identify genetic predispositions for carbonate precipitation in Streptomyces. Finally, their biomineralization abilities were confirmed by environmental SEM, which allowed to visualize the formation of abundant mineral deposits under laboratory conditions. Overall, our study provides novel evidences that filamentous Actinobacteria could be key protagonists in the genesis of moonmilk through a wide spectrum of biomineralization processes.

microbiology↗