Plant viruses represent a risk to agricultural production and as only a few treatments exist, it is urgent to identify resistance mechanisms and factors. In plant immunity, plasma membrane (PM)-localized proteins play an essential role in sensing the extracellular threat presented by bacteria, fungi, or herbivores. Viruses are intracellular pathogens and as such the role of the plant PM in detection and resistance against viruses is often overlooked. We investigated the role of the partially PM-bound Calcium-dependent protein kinase 3 (CPK3) in viral infection and we discovered that it displayed a specific ability to hamper viral propagation over CPK isoforms that are involved in immune response to extracellular pathogens. More and more evidence supports that the lateral organization of PM proteins and lipids underlies signal transduction in plants. We showed here that CPK3 diffusion in the PM is reduced upon activation as well as upon viral infection and that such immobilization depended on its substrate, Remorin (REM1.2), a scaffold protein. Furthermore, we discovered that the viral infection induced a CPK3-dependent increase of REM1.2 PM diffusion. Such interdependence was also observable regarding viral propagation. This study unveils a complex relationship between a kinase and its substrate that contrasts with the commonly described co-stabilisation upon activation while it proposes a PM-based mechanism involved in decreased sensitivity to viral infection in plants.
Legumes and rhizobia establish a nitrogen-fixing symbiosis that involves the formation of a lateral root organ, the nodule, and the infection process that allows intracellular accommodation of rhizobia within nodule cells. This process involves significant gene expression changes regulated at the transcriptional and post-transcriptional levels. We have previously shown that a transcript encoding the subunit 3 of the Superkiller Complex (SKI), which guides mRNAs to the exosome for 3′-to-5′ degradation, is required for nodule formation and bacterial persistence within the nodule, as well as the induction of early nodulation genes (e.g. MtENOD40) during the Medicago truncatula-Sinorhizobium meliloti symbiosis. Here, we reveal through transcript degradome analysis that knockdown of MtSKI3 impairs the miR172-directed endonucleolytic cleavage of the mRNA encoding Nodule Number Control 1 (MtNNC1), an APETALA2 transcription factor that negatively modulates nodulation. Specific silencing of MtNNC1 enhances nodule number, bacterial infection, and the induction of MtENOD40 upon inoculation with S. meliloti whereas overexpression of a miR172-resistant form of MtNNC1 significantly reduces nodule formation. This work identifies miR172 cleavage of MtNNC1 and its control by MtSKI3, a component of the 3′-to-5′ mRNA degradation pathway, as a new regulatory hub controlling indeterminate nodulation.
In the context of the dynGENIE3 [13] approach for inferring regulatory network interactions from time-series data, we show that it is possible to modify that algorithm to significantly enhance its prediction reliability. To quantify the level of reliability, we used ground-zero truths based on simulated datasets generated by the GeneNetWeaver [22] tool. Our work introduces novel methods leveraging time-lagged correlations and estimators of mRNA decay rates, leading to significantly improved driver-target inference. Additionally, a temperature-based rescaling of priors was developed to further enhance prediction reliability. Results demonstrate substantial improvements in performance with a particularly notable increase in AUPRC scores. These advances underscore the possible gains resulting from incorporating priors into gene regulatory network inference. ### Competing Interest Statement The authors have declared no competing interest.
HIR2 is a plant-specific protein belonging to the superfamily of SPFH domain-containing proteins that were proposed to play scaffolding functions in membranes. HIR2 organizes in plasma membrane (PM) nanodomains that correspond to nanometric scale structures enriched in specific lipids and proteins acting as signaling/regulation hubs. So far, how PM nanodomains are formed and maintained in plant cells remains largely unknown. Combining state of the art microscopy techniques, we investigated the mechanisms governing the trafficking and the organization into nanodomains of Arabidopsis HIR2 protein. We revealed that the mono S-acylation of HIR2 either on C6 or on C7 was required for HIR2 targeting to the PM of Arabidopsis cells, independently of the conventional secretory pathway. Investigating the mechanisms implicated in the arrangement of HIR2 into nanodomains, we provided evidences that the lipid composition in sterols and very long chain fatty acids of the PM influenced HIR2 organization. HIR2 forms oligomers and we demonstrated here that the C-terminal part of HIR2 is required for self-assembly, similarly to animal SPFH proteins. Interestingly, we highlighted that the oligomerization of HIR2 is essential for its organization in nanodomains and to ensure HIR2 lateral stability in the PM. Overall, we propose that HIR2 nanodomain organization is a complex mechanism relying on different parameters including PM lipid composition and oligomerization. HIR proteins are involved in plant immunity. Here, we revealed that HIR2 nanodomain organization is required to boost the apoplastic ROS burst induced by the bacterial peptide flg22. One sentence summary S-acylation and oligomerization control the plasma membrane targeting and the organization into nanodomains of the Arabidopsis SPFH-domain containing protein HIR2, respectively. ### Competing Interest Statement The authors have declared no competing interest.
Dans la perspective d’une acculturation scientifique citoyenne de tous les élèves et d’un regain d’intérêt pour les métiers scientifiques, il est attendu plus ou moins explicitement des enseignants de sciences de l’enseignement secondaire français qu’ils aident les élèves à saisir la spécificité des sciences ainsi que l’existence de régimes de vérité différents. Nous présentons l’approche théorique adoptée consistant à caractériser les sciences en articulant pratiques sociales, psychologie et anthropologie puis les résultats d’une partie d’un questionnaire visant à explorer les représentations des sciences de 601 primo-entrants dans une université scientifique selon différentes entrées. L’une des trois questions retenues est centrée sur le scientifique considéré comme individu générique (quelles sont les quatre qualités les plus importantes pour être un scientifique ?). Les deux autres abordent les sciences comparativement à d’autres pratiques, l’une sous l’angle des savoirs (les connaissances scientifiques sont-elles de même nature que les connaissances artistiques et philosophiques ?), l’autre sous l’angle du sujet (un scientifique peut-il être croyant ?). Nous analysons les verbatims fournis aux questions comparatives et examinons l’impact du positionnement. Nous discutons de l’intérêt d’une approche centrée sur le sujet en termes de possibles.
