Biology subjects

Meteignier, L.-V.

Publications and source records attributed to Meteignier, L.-V..

6 recordsLinked to original sources

bioRxiv2026

Interspecific transfer of specialized metabolites in root exudates coincides with root chromatin regulation and systemic chemical defenses in rice

O_LIBenzoxazinoids are indole-derived specialized metabolites released into the soil through root exudates. Initially studied for their allelopathic and toxic effects, they are now recognized as broad regulators of plant-organism interactions, including microbiome-mediated pathogen resistance. However, whether benzoxazinoid-containing root exudates can directly influence disease susceptibility in neighboring plants remains unclear. C_LIO_LIUsing an agriculturally relevant rice-maize co-culture system, we show that benzoxazinoids naturally exuded by maize roots are taken up by rice roots and are associated with reduced rice blast disease in leaves. C_LIO_LIThis protection occurs without detectable benzoxazinoid accumulation in rice leaves, constitutive immune activation or decreased plant height. Instead, benzoxazinoid uptake by rice roots is associated with chromatin hyperacetylation, increased expression of key phenylpropanoid biosynthetic genes and broad metabolic reprogramming. C_LIO_LIThese responses extend systemically to leaves, where rice establishes a defense-related chemical state distinct from the systemic acquired resistance previously observed in benzoxazinoid-dependent, microbiome-mediated plant-soil feedbacks. C_LIO_LIOur findings support a model in which specialized metabolites exuded by one crop species are acquired by a neighbouring species and trigger chromatin-associated metabolic reprogramming linked to systemic chemical defence. This study provides a molecular framework connecting plant-plant chemical interactions, root exudation, chromatin regulation and disease susceptibility. C_LI

plant biology↗

bioRxiv2026

Root phenolics as potential drivers of preformed defenses and reduced disease susceptibility in a paradigm bread wheat mixture

Plant-plant interactions modulate foliar disease susceptibility in intraspecific mixtures. However, the molecular events including signals and responses underlying the reduction in disease susceptibility remain largely unexplored. Here, we developed an experimental system that can abolish root-mediated interactions between plants in a model of bread wheat varietal mixture. We then performed transcriptomic and metabolomic analyses to uncover the molecular responses linked to decreased susceptibility to Septoria tritici blotch in plant-plant interactions. Our analysis revealed that disrupting root chemical interactions impaired the reduction in susceptibility to Septoria and identified phenolic compounds as potential key mediators. The plant-plant interactions under study triggered significant molecular changes in specialized metabolism, biotic interactions, transporters, and responses to resources. Disrupting root interactions canceled both the macroscopic and molecular responses, thus providing a strong link between them. These insights provide a deeper understanding of the molecular basis of plant-plant interactions and the processes involved in reducing disease susceptibility in intraspecific mixtures. Significance statementNeighboring plants mediate resistance to leaf fungal pathogens by releasing root-derived molecules. These interactions trigger multi-omic reprogramming of defenses in both leaves and roots. Enhanced resistance in varietal mixtures is associated with the early activation of defense pathways. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=186 SRC="FIGDIR/small/699261v1_ufig1.gif" ALT="Figure 1"> View larger version (27K): org.highwire.dtl.DTLVardef@16f02a9org.highwire.dtl.DTLVardef@117b872org.highwire.dtl.DTLVardef@4e5243org.highwire.dtl.DTLVardef@1fac682_HPS_FORMAT_FIGEXP M_FIG O_FLOATNOGraphical abstractC_FLOATNO C_FIG

plant biology↗

bioRxiv2025

Evolution of CYP71D as a driving force of the diversification of monoterpene indole alkaloid biosynthesis

Monoterpene indole alkaloids (MIAs) constitute a vast group of plant natural products synthesized within the Gentianales order. MIAs possess outstanding pharmacological properties that explain their wide use in the treatment of human diseases. These biological activities result from the complex structure of MIAs that originate from intricated biosynthetic pathways involving several enzyme families and notably cytochrome P450s. The early steps of MIA synthesis involve several P450s from the 71 clade, which catalyse the conversion of various reduced strictosidine aglycones into MIAs from the mavacurane, strychnane, akuammilane, sarpagane, and heteroyohimane groups. An extensive study of these P450 distribution in genomic resources reveals that they all belong to a single evolutionary lineage named GAS clade, restricted to the MIA producing Gentianales (Gelsemiaceae and Rauvolfioideae). A related but distinct P450 lineage (named sister GAS clade) was found in non-MIA producing Gentianales and species producing structurally distinct MIAs (Rubiaceae). Functional characterization of 36 members of the GAS clade revealed that these enzymes felt into four main groups of activity depending on substrate acceptance (ex: tetrahydroalstonine, geissoschizine, ajmalicine...) and the nature of the catalyzed reaction (aromatization, cyclisation). These characterizations also lead to the identification of a yohimbane aromatization activity for several of these P450s, increasing the number of MIA scaffolds associated with GAS activity to six. Lastly, the chronology of emergence of these GAS activities was assessed by using ancestral sequence reconstitution, establishing that the initial ancestor of the whole GAS clade exhibits a main alstonine synthase activity. Subsequent gene duplication events, combined with neofunctionalization, facilitated the progressive emergence of eight additional activities, variably distributed among the four GAS subgroups. This comprehensive enzyme characterization establishes the evolutionary trajectory of the GAS clade, demonstrating how its diversification has progressively shaped the chemical diversity of MIAs in Gentianales.

biochemistry↗

bioRxiv2020

In vivo stabilization of endogenous chloroplast RNAs by customized artificial pentatricopeptide repeat proteins

Pentatricopeptide repeat (PPR) proteins are helical repeat-proteins that bind RNA in a modular fashion with a sequence-specificity that can be manipulated by the use of an amino acid code. As such, PPR repeats are promising scaffolds for the design of RNA binding proteins for synthetic biology applications. However, the in vivo functional capabilities of artificial PPR proteins built from consensus PPR motifs are just starting to be explored. Here, we report in vivo functions of an artificial PPR protein, dPPRrbcL, made of consensus PPR motifs that were designed to bind a sequence near the 5 end of rbcL transcripts in Arabidopsis chloroplasts. We used a functional complementation assay to demonstrate that this protein bound its intended RNA target with specificity in vivo and that it substituted for a natural PPR protein by stabilizing processed rbcL mRNA. We targeted a second protein of analogous design to the petL 5 UTR, where it substituted for the native stabilizing PPR protein PGR3, albeit inefficiently. These results showed that artificial PPRs can be engineered to functionally mimic the class of native PPR proteins that serve as physical barriers against exoribonucleases.

plant biology↗

bioRxiv2020

Arabidopsis mTERF9 protein promotes chloroplast ribosomal assembly and translation by establishing ribonucleoprotein interactions in vivo.

The mitochondrial transcription termination factor proteins are nuclear-encoded nucleic acid binders defined by degenerate tandem helical-repeats of ~30 amino acids. They are found in metazoans and plants where they localize to mitochondria or chloroplasts. In higher plants, the mTERF family comprises ~30 members and several of these have been linked to plant development and response to abiotic stress. However, knowledge of the molecular basis underlying these physiological effects is scarce. We show that the Arabidopsis mTERF9 protein promotes the accumulation of the 16S and 23S rRNAs in chloroplasts, and interacts predominantly with the 16S rRNA in vivo and in vitro. Furthermore, mTERF9 is found in large complexes containing ribosomes and polysomes in chloroplasts. The comprehensive analysis of mTERF9 in vivo protein interactome identified many subunits of the 70S ribosome whose assembly is compromised in the null mterf9 mutant, putative ribosome biogenesis factors and CPN60 chaperonins. Protein interaction assays in yeast revealed that mTERF9 directly interact with these proteins. Our data demonstrate that mTERF9 integrates protein-protein and protein-RNA interactions to promote chloroplast ribosomal assembly and translation. Besides extending our knowledge of mTERF functional repertoire in plants, these findings provide an important insight into the chloroplast ribosome biogenesis.

plant biology↗

bioRxiv2019

Topoisomerase VI participates in an insulator-like function that prevents H3K9me2 spreading into euchromatic islands

The organization of the genome into transcriptionally active and inactive chromatin domains requires well-delineated chromatin boundaries and insulator functions in order to maintain the identity of adjacent genomic loci with antagonistic chromatin marks and functionality. In plants that lack known chromatin insulators, the mechanisms that prevent heterochromatin spreading into euchromatin remain to be identified. Here, we show that DNA Topoisomerase VI participates in a chromatin boundary function that safeguards the expression of genes in euchromatin islands within silenced heterochromatin regions. While some transposable elements are reactivated in mutants of the Topoisomerase VI complex, genes insulated in euchromatin islands within heterochromatic regions of the Arabidopsis thaliana genome are specifically downregulated. H3K9me2 levels consistently increase at euchromatin island loci and decrease at some TE loci. We further show that Topoisomerase VI physically interacts with S-adenosylmethionine (SAM) synthase MAT3, which is required for H3K9me2 deposition. Topoisomerase VI promotes MAT3 occupancy on heterochromatic elements and its exclusion from euchromatic islands, thereby providing a mechanistic insight into the essential role of Topoisomerase VI in the delimitation of chromatin domains.

plant biology↗