Biology subjects

Jolivet, S.

Publications and source records attributed to Jolivet, S..

6 recordsLinked to original sources

bioRxiv2026

Apoplast multi-omics profiling during fungal infection uncovers new players of basal and early induced immunity

The extracellular space in plant tissues, known as the apoplast, remains one of the least characterized cellular compartments. The apoplastic fluid (APF), akin to mammalian extracellular fluid, serves as the primary interface between pathogens and their host. It allows the exchange of signalling molecules, coordinates host cell responses, and enables the circulation of pathogen effectors that modulate the immune response. We describe here the first multi-omics analysis of the APF content just 6 h after the onset of A. thaliana infection with B. cinerea, a fast-killing necrotrophic fungus. By varying plant nitrogen nutrition, known to affect both plant defenses and pathogen virulence, we identify candidates that do not stand out under optimal conditions. Our analysis uncovers novel nitrogen-dependent mechanisms that regulate both basal and early induced apoplastic immunity, revealing the presence of previously unidentified, potentially protective apoplastic metabolites as well as the intercellular transport of nuclear proteins, thereby offering new insights into early apoplastic immune responses.

plant biology↗

bioRxiv2025

Monopolar orientation of kinetochores at meiosis is enforced by COHESINS and their regulators, CENP-C, and the deSUMOylase SPF2

The first division of meiosis is unique in its capacity to halve the ploidy of the future gametes. To this end, one key innovation compared to mitosis is the monopolar orientation of the pairs of sister kinetochores required for the proper separation of homologs at meiosis I. How monopolar orientation is imposed is unclear and seems to vary in eukaryotes. Here we performed a forward genetic screen in Arabidopsis thaliana, specifically designed to identify the molecular components imposing monopolar orientation, based on mutants ability to restore fertility in spo11 osd1 haploid plants. We show that monopolar orientation involves all four cohesin subunits (REC8, SCC3, SMC1, SMC3), the cohesion establishment factors CTF18 and DCC1, and the cohesin protectors SGO1/2 and PANS1, the inner kinetochore protein CENP-C, and the desumoylase SPF2. The mutants show bipolar orientation of achiasmatic chromosomes, but monopolar orientation is maintained in the presence of crossovers despite splitting of sister kinetochores at metaphase I and reduced levels of cohesin. Taken together, the findings demonstrate that cohesion establishment and protection, kinetochore function, and deSUMOylation, together with crossovers, enforce monopolar orientation in plants and support a cohesion-driven model of kinetochore orientation at meiosis I that is conserved across kingdoms.

cell biology↗

bioRxiv2024

Apoplast metabolomics reveals that plant-pathogen crosstalk is modulated by nitrogen supply

In the present study, we analyzed the role played by the apoplast in the crosstalk between biotic and abiotic stress conditions. In particular, we studied the crosstalk between nitrogen (N) limitation and infection of the model plant Arabidopsis thaliana by E. amylovora, an apoplastic bacterium. Our previous findings indicated that low N (LN) conditions increase E. amylovora in planta titers and expression of virulence factors. In this work, we extracted the apoplast wash fluids (AWF) from plants grown under low N or high N (HN) conditions and applied them to bacteria in vitro. We observed that LN-AWF induced stronger virulence gene expression than HN-AWF. Metabolomic analysis of both apoplast extracts revealed the presence of common metabolites, however, their proportions were distinct, indicating a direct effect of N availability on apoplast content. Interestingly, changes in the apoplast metabolite proportions were also observed early after bacterial infection, but only in plants grown under LN conditions. To evaluate the effect of single metabolites on virulence gene expression, we selected 43 metabolites and observed that 29 of them were activators whereas two, GABA and citrate, acted as repressors. This study shows that environmental constraints, such as N availability, impact plant-pathogen interactions by altering the apoplastic content.

plant biology↗

bioRxiv2024

Unravelling the Interplay of Nitrogen Nutrition and the Botrytis cinerea pectin lyase BcPNL1 in Modulating Arabidopsis thaliana Susceptibility

In this study, we investigated the intricate interplay between nitrogen nutrition, and the dynamics of pectin degradation during plant-pathogen interactions, using Arabidopsis thaliana and Botrytis cinerea as a model pathosystem. Our findings revealed a noteworthy impact of nitrogen availability on the pectin degrading activity of the B. cinerea pectin lyase 1 (PNL) for which the mutant strains presented a reduced pathogenicity restored by complementation. More precisely, infected nitrogen-sufficient (high N) plants exhibited an increased release of PNL-derived oligogalacturonides compared to infected nitrogen-deficient (low N) plants. This correlated with an elevated expression of jasmonic acid repressor genes in high N plants, rendering them more susceptible to B. cinerea. Using{Delta} Bcpnl1 deletion mutants, we demonstrated that the increased production of BcPNL1 -derived oligogalacturonides under high N conditions was responsible for the increased expression of jasmonic acid repressor genes, significantly contributing to the higher susceptibility of high N plantsto B. cinerea. In conclusion, we demonstrated that BcPNL1 is a major pathogenicity factor during B. cinerea interaction that is affected by the plants N nutrition conditions.

plant biology↗

bioRxiv2021

LPMO-oxidized cellulose oligosaccharides evoke immunity in Arabidopsis conferring resistance towards necrotrophic fungus B. cinerea

Lytic Polysaccharide Monooxygenases (LPMOs) are powerful redox enzymes able to oxidatively cleave cellulose polymers. Widely conserved across biological kingdoms, LPMOs of the AA9 family are deployed by phytopathogens during necrotrophic attack of plant cell wall. In response, plants have evolved sophisticated mechanisms to sense cell wall damage and thus self-triggering Damage Triggered Immunity (DTI) responses. Here, we show that Arabidopsis plants exposed to LPMO products responds by activating the innate immunity ultimately leading to increased resistance to pathogenic fungus Botrytis cinerea. We demonstrated with microarray hybridization that plants undergo a deep transcriptional reprogramming upon elicitation with AA9 derived cellulose- or cello-oligosaccharides (AA9_COS). To decipher the specific effects of native and oxidized LPMO-generated cello-oligosaccharides, a pairwise comparison with cellobiose, the smallest non-oxidized unit constituting cellulose, is presented. Moreover, we identified two leucine-rich repeat receptor-like kinases, namely STRESS INDUCED FACTOR 2 and 4, playing a crucial role in signaling the AA9_COS-dependent responses such as camalexin production. We observed an increased production of ethylene, jasmonic and salicylic acid hormones, and finally deposition of callose in cell wall. Collectively, our data reveal that LPMOs might play a crucial role in plant-pathogen interactions.

plant biology↗

bioRxiv2019

Patronus is the elusive plant securin, preventing chromosome separation by antagonizing separase

Chromosome distribution at anaphase of mitosis and meiosis is triggered by separase, an evolutionarily conserved protease. Separase must be tightly regulated to prevent the untimely release of chromatid cohesion and disastrous chromosome distribution defects. Securin is the key inhibitor of separase in animals and fungi, but has not been identified in other eukaryotic lineages. Here, we identified PATRONUS1 and PATRONUS2 (PANS1 and PANS2) as the Arabidopsis homologues of securin. Disruption of PANS1 is known to lead to the premature separation of chromosomes at meiosis, and the simultaneous disruption of PANS1 and PANS2 is lethal. Here, we show that PANS1 targeting by the anaphase-promoting-complex is required to trigger chromosome separation, mirroring the regulation of securin. We showed that PANS1 acts independently from Shugosins. In a genetic screen for pans1 suppressors, we identified SEPARASE mutants, showing that PANS1 and SEPARASE have antagonistic functions in vivo. Finally, we showed that the PANS1 and PANS2 proteins interact directly with SEPARASE. Altogether, our results show that PANS1 and PANS2 act as a plant securin. Remote sequence similarity was identified between the plant patronus family and animal securins, suggesting that they indeed derive from a common ancestor. Identification of patronus as the elusive plant securin illustrates the extreme sequence divergence of this central regulator of mitosis and meiosis.

cell biology↗