Biology subjects

Zarattini, M.

Publications and source records attributed to Zarattini, M..

3 recordsLinked to original sources

bioRxiv2026

Bacillus adaptation to Pseudomonas secondary metabolites enhances its root competitiveness

Bacillus velezensis is a widely used plant growth-promoting rhizobacterium whose effectiveness under natural conditions is strongly influenced by interactions with surrounding microorganisms. While bacterial secondary metabolites are known to shape these interactions, little is known about their long-term evolutionary consequences. Here, we show that repeated exposure of B. velezensis GA1 to secondary metabolites produced by the competing rhizobacterium Pseudomonas sessilinigenes CMR12a drives the emergence of an adapted subpopulation with enhanced ecological fitness. Multi-omics analyses revealed extensive metabolomic and transcriptional changes associated with altered growth dynamics, sporulation, motility, and biofilm formation. Importantly, the evolved variant exhibited improved tomato root colonization and reduced the abundance of the competing Pseudomonas strain in planta. Together, our results demonstrate that prolonged exposure to diffusible bacterial metabolites can drive rapid adaptive diversification in rhizosphere-associated bacteria and highlight the importance of long-term interbacterial interactions in shaping the outcome of plant microbiome assembly and biocontrol performance.

microbiology↗

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↗

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↗