Biology subjects

De Quattro, C.

Publications and source records attributed to De Quattro, C..

6 recordsLinked to original sources

bioRxiv2023

Time-resolved transcriptomics reveal a mechanism of host niche defense: beneficial root endophytes deploy a host-protective antimicrobial GH18-CBM5 chitinase

Associations between plants and beneficial root-endophytic fungi enhance plant performance by improving nutrient uptake, abiotic stress tolerance and disease resistance. To successfully colonize different host plants and defend their host niche against competing microbes, but also to cooperate with beneficial bacterial members of the microbiota, root endophytes such as Sebacinales secrete a multitude of tightly regulated effector-proteins and carbohydrate-active enzymes. However, the functions, specificity, and regulation of these proteins remain poorly understood. In this study, we employ time-resolved transcriptomics to analyse the gene expression profiles of two Sebacinales members interacting with organisms from different kingdoms of life. We identified crucial genes for plant colonization and intermicrobial competition, including a fungal GH18-CBM5 chitinase specifically upregulated in response to the phytopathogenic fungus Bipolaris sorokiniana. This chitinase protects the plant hosts against the pathogen, reducing fungal biomass and disease symptoms in barley and Arabidopsis thaliana. Our findings shed light on interaction partner specific gene expression in Sebacinales endophytes, with potential applications in enhancing plant health and resilience. Bullet pointsO_LIBoth Serendipita indica (Si) and Serendipita vermifera (Sv) show similar transcriptional responses to three host species and the phytopathogen Bipolaris sorokiniana (Bs), indicating common interaction principles between Sebacinales and plant hosts or fungi. C_LIO_LIThese shared mechanisms involve the activation of effector genes like small secreted proteins and carbohydrate-active enzymes. C_LIO_LICooperation with beneficial bacteria elicits only minimal transcriptomic alterations in Sebacinales compared to plants and Bs. C_LIO_LISebacinales respond to Bs by upregulating a specific GH18-CBM5 chitinase unique to Basidiomycota within the fungal kingdom, inhibiting Bs growth and reducing disease symptoms in Arabidopsis thaliana and barley. C_LI

microbiology↗

bioRxiv2023

Nitrogen availability during domestication shaped the divergence of tetraploid wheat

The domestication of crops, with the development of the agroecosystems, is associated with major environmental changes and represent a model to test the role of phenotypic plasticity. Here we investigated 32 genotypes representing key stages of tetraploid wheat domestication. We developed a dedicated pipeline combining RNA-Seq data, estimates of evolvability and QST to characterize the plasticity of gene expression and identify signatures of selection under different nitrogen conditions. The analysis of gene expression diversity showed contrasting results between primary and secondary domestication in relation to nitrogen availability. Indeed, nitrogen triggered the expression of twice the number of genes in durum wheat compared to emmer and wild emmer. QST distributions and QST-FST comparisons revealed distinct selection signatures at each domestication stage. While primary domestication affected the expression of genes involved in biotic interactions, secondary domestication was associated with changes in expression of genes involved in metabolism of amino acids, particularly lysine. Selection signatures were found also in differentially expressed genes, specifically involved in nitrogen metabolism, such as glutamate dehydrogenase. Overall, our findings show that nitrogen availability had a pivotal role during the domestication and adaptive responses of a major food crop, with varying effects across different traits and growth conditions.

genetics↗

bioRxiv2023

Autophagy restricts fungal accommodation in the roots ofArabidopsis thaliana

Endophytic colonization of Arabidopsis thaliana by the beneficial root endophyte Serendipita indica is characterized by an initial biotrophic phase followed by a restricted host cell death-associated phase. This latter phase involves regulated cell death (RCD) for fungal accommodation. However, the host molecular pathways that limit S. indica colonization and govern symbiosis remain largely unknown. Our study demonstrates that autophagy, a major cellular degradation pathway, is activated during S. indica colonization and is required to restrict fungal colonization in Arabidopsis. Independent Arabidopsis knockout (KO) mutants deficient in autophagosome formation are more susceptible to deoxyadenosine (dAdo), a cell death inducer produced by two secreted S. indica effectors at the onset of the cell death-associated phase. In the atg5 autophagy mutant background, impaired dAdo uptake prevents dAdo-induced and symbiosis-mediated cell death. Based on our data, we propose that autophagy-mediated pro-survival responses in the host are crucial for maintaining a balanced symbiotic interaction between S. indica and Arabidopsis. In a NutshellOur study reveals that during colonization of Arabidopsis thaliana roots by the beneficial root endophyte Serendipita indica, autophagy, a key cellular degradation pathway, is activated to limit fungal colonization. Autophagy-deficient Arabidopsis mutants are more susceptible to deoxyadenosine (dAdo), a cell death inducer produced by S. indica. We propose that autophagy-mediated pro-survival responses are essential for maintaining a balanced symbiotic interaction between S. indica and Arabidopsis.

microbiology↗

bioRxiv2023

Mecp2 knock-out astrocytes affect synaptogenesis by IL-6 dependent mechanisms

Synaptic abnormalities represent a hallmark for several neurological diseases and clarification of the underlying mechanisms constitutes a crucial step towards the development of therapeutic strategies. Rett syndrome (RTT) is a rare neurodevelopmental disorder, mainly affecting females, caused by heterozygous mutations in the X-linked Methyl-CpG-Binding Protein 2 (MECP2) gene, leading to a deep derangement of synaptic connectivity. Although initial studies have supported the exclusive involvement of neurons, recent data have highlighted the pivotal contribution of astrocytes in RTT pathogenesis through non-cell autonomous mechanisms. Since astrocytes regulate synaptogenesis by releasing multiple molecules, we investigated the influence of soluble factors secreted by Mecp2 KO astrocytes on synaptic density. We found that Mecp2 deficiency in astrocytes negatively affects their ability to support synapse formation by releasing synaptotoxic molecules, among which we identified interleukin-6 (IL-6). Notably, aberrant IL-6 expression exclusively emerges from a dysfunctional astrocyte-neuron crosstalk, and blocking IL-6 activity prevents synaptic alterations.

neuroscience↗

bioRxiv2023

Root cap cell corpse clearance limits microbial colonization

Programmed cell death occurring during plant development (dPCD) is a fundamental process integral for plant growth and reproduction. Here, we investigate the connection between developmentally controlled PCD and fungal accommodation in Arabidopsis thaliana roots, focusing on the root cap-specific transcription factor ANAC033/SOMBRERO (SMB) and the senescence-associated nuclease BFN1. Mutations of both dPCD regulators increase colonization by the beneficial fungus Serendipita indica, primarily in the differentiation zone. smb-3 mutants additionally exhibit hypercolonization around the meristematic zone and a delay of S. indica-induced root-growth promotion. This demonstrates that root cap dPCD and rapid post-mortem clearance of cellular corpses represent a physical defense mechanism restricting microbial invasion of the root. Additionally, reporter lines and transcriptional analysis revealed that BFN1 expression is downregulated during S. indica colonization in mature root epidermal cells, suggesting a transcriptional control mechanism that facilitates the accommodation of beneficial microbes in the roots. Key findings in bullet pointsO_LIThe process of programmed cell death in root development (dPCD) influences the extent and outcomes of fungal symbiosis C_LIO_LIFungal colonization of the root tip and differentiation zone is restricted by SMB-mediated clearance of dead cells, which preserves the meristem and regulates symbiosis C_LIO_LIExpression of plant nuclease BFN1, which is associated with senescence, is modulated to facilitate root accommodation of beneficial microbes C_LI

plant biology↗

bioRxiv2020

Pod indehiscence in common bean is associated to the fine regulation of PvMYB26 and a non-functional abscission layer

In legumes, pod shattering occurs when mature pods dehisce along the sutures, and detachment of the valves promotes seed dispersal. In Phaseolus vulgaris, the major locus qPD5.1-Pv for pod indehiscence was identified recently. We developed a BC4/F4 introgression line population and narrowed the major locus down to a 22.5-kb region. Here, gene expression and a parallel histological analysis of dehiscent and indehiscent pods identified an AtMYB26 orthologue as the best candidate for loss of pod shattering, on a genomic region ~11 kb downstream of the highest associated peak. Based on mapping and expression data, we propose early and fine up-regulation of PvMYB26 in dehiscent pods. Detailed histological analysis establishes that pod indehiscence is associated to the lack of a functional abscission layer in the ventral sheath, and that the key anatomical modifications associated with pod shattering in common bean occur early during pod development. We finally propose that loss of pod shattering in legumes resulted from histological convergent evolution and that this is the result of selection at orthologous loci. One-sentence summaryA non-functional abscission layer determines the loss of pod shattering; mapping data, and parallel gene expression and histological analysis support PvMYB26 as the candidate gene for pod indehiscence.

genetics↗