Biology subjects

Flors, V.

Publications and source records attributed to Flors, V..

6 recordsLinked to original sources

bioRxiv2026

Insect REPAT proteins mediate cross-kingdom communication in microbe-insect-plant interactions

Plant-herbivore interactions are embedded within complex ecological networks in which microorganisms associated with either partner can reshape interactions across trophic levels. Yet how microbial infections of herbivorous insects alter the molecular signals they deliver to plants remains largely unexplored. Here, we identify REPAT proteins as key molecular mediators linking microbial infection in caterpillars to plant defense responses. Comparative genomic analyses revealed that REPATs comprise an insect protein family that has expanded in Lepidoptera, with a conserved {beta}-REPAT lineage and rapidly diversifying - and {gamma}-REPAT lineages, the latter encompassing most REPATs previously implicated in plant interactions. Proteomic analyses of caterpillar oral secretions revealed that viruses with contrasting infection strategies exerted opposite effects on REPAT abundance. Infection with the lethal baculovirus Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) increased the abundance of multiple REPAT proteins, whereas infection with the persistent, covert iflavirus Spodoptera exigua iflavirus 1 (SeIV1) consistently reduced REPAT abundance across dietary conditions. These changes were associated with reciprocal effects on plant defense: herbivory by SeMNPV-infected larvae attenuated jasmonate-associated responses in tomato, whereas SeIV1-infected larvae enhanced defense activation in pepper. Together, our findings reveal that viral infection of the herbivore can propagate across trophic levels and reshape plant responses to herbivory by altering the repertoire of effectors delivered during feeding, uncovering a mechanism through which insect-microbe interactions can influence plant defense.

ecology↗

bioRxiv2026

Reduced benzoxazinoid defences favour maize beneficial colonisation by Colletotrichum tofieldiae

O_LISpecialised defence metabolites mediate plant-microbe interactions, but their regulation during beneficial associations in cereals remains poorly understood. Here we investigate how maize (Zea mays) chemical defences are modulated during interaction with the beneficial fungal endophyte Colletotrichum tofieldiae (strain Ct0861) to promote host growth. C_LIO_LITo elucidate the molecular basis of this interaction, we combined transcriptomics, metabolite analyses and functional assays. To assess benzoxazinoids (BXs) roles at the plant-fungus interface, we compared Ct0861 colonisation and growth-promotion in wild-type maize and the BX-deficient bx1::DS mutant, using the pathogen Colletotrichum graminicola (CgM1.001) as reference. C_LIO_LITranscriptomic analyses revealed coordinated regulation of specialised defence pathways during the initial stages of Ct0861 colonisation, featuring systemic induction of terpenoid phytoalexin biosynthesis alongside localised suppression of roots BXs. Metabolomic analyses showed reduced apoplastic MBOA in Ct0861-colonised roots. Toxicity assays evidenced that Ct0861, unlike CgM1.001, is highly sensitive to MBOA. Accordingly, Ct0861 accumulation and growth-promoting effects were significantly enhanced in the bx1::DS mutant without causing disease symptoms. C_LIO_LIOur findings indicate that BXs restrict Ct0861 maize colonisation, where BX deficiency increases fungal biomass and enhances growth promotion. Understanding how crops fine tune specialised metabolism to balance microbial restriction with beneficial accommodation provides valuable insights for sustainable agriculture. C_LI

plant biology↗

bioRxiv2024

Ethylene signaling is essential for mycorrhiza-induced resistance against chewing herbivores in tomato

Root colonization by certain beneficial microbes can prime plant defenses aboveground, modifying plant responses to potential attackers. Arbuscular mycorrhizal (AM) fungi establish mutualistic symbiosis with most plant species, usually enhancing plant resistance to biotic stresses, leading to Mycorrhiza-Induced Resistance (MIR). Still, our knowledge of the complex molecular regulation leading to MIR is very limited. Here we show that the AM fungus Funneliformis mosseae protects tomato plants against two different chewing herbivores, Spodoptera exigua and Manduca sexta, and we explore the underlying molecular mechanism. We explore the impact of AM symbiosis on the plant response to the herbivores through genome-wide transcriptional profiling, followed by bioinformatics network analyses and functional bioassays. Herbivore-triggered JA-regulated defenses were primed in leaves of mycorrhizal plants, while ET biosynthesis and signaling was also higher both before and after herbivory. We hypothesized that fine-tuned ET signaling is required for the primed defensive response leading to MIR in mycorrhizal plants. We followed analytical, functional, and genetic approaches to test this hypothesis and get mechanistic insights into the ET signaling in MIR. ET is a complex regulator of plant responses to stress, and although ET is generally considered a negative regulator of plant defenses against herbivory, tomato lines deficient in ET synthesis or perception could not develop MIR against either herbivore. Thus, we demonstrate that hormone crosstalk is central to the priming of plant immunity by beneficial microbes, with ET fine-tuning being essential for the primed JA biosynthesis and boosted defenses leading to MIR in tomato.

plant biology↗

bioRxiv2021

NITROGEN LIMITATION ADAPTATION functions as a negative regulator of Arabidopsis immunity

BackgroundPhosphorus is an important macronutrient required for plant growth and development. It is absorbed through the roots in the form of inorganic phosphate (Pi). To cope with Pi limitation, plants have evolved an array of adaptive mechanisms to facilitate Pi acquisition and protect them from stress caused by Pi starvation. The NITROGEN LIMITATION ADAPTION (NLA) gene plays a key role in the regulation of phosphate starvation responses (PSR), its expression being regulated by the microRNA miR827. Stress caused by Pi limiting conditions might also affect the plants response to pathogen infection. However, cross-talk between phosphate signaling pathways and immune responses remains unclear. ResultsIn this study, we investigated whether NLA plays a role in Arabidopsis immunity. We show that loss-of-function of NLA and MIR827 overexpression causes an increase in phosphate (Pi) content which results in resistance to infection by the fungal pathogen Plectosphaerella cucumerina. The nla mutant plants accumulated callose in their leaves, a response that is also observed in wild-type plants that have been treated with high Pi. We also show that pathogen infection and treatment with fungal elicitors is accompanied by transcriptional activation of MIR827 and down-regulation of NLA. Upon pathogen challenge, nla plants exhibited higher levels of the phytoalexin camalexin compared to wild type plants. Camalexin level also increases in wild type plants treated with high Pi. Furthermore, the nla mutant plants accumulated salicylic acid (SA) and jasmonic acid (JA) in the absence of pathogen infection whose levels further increased upon pathogen. ConclusionsThis study shows that NLA acts as a negative regulator of Arabidopsis immunity. Overaccumulation of Pi in nla plants positively affects resistance to infection by fungal pathogens. This piece of information reinforces the idea of signaling convergence between Pi and immune responses for the regulation of disease resistance in Arabidopsis.

plant biology↗

bioRxiv2021

Phosphate-induced resistance to pathogen infection in Arabidopsis

In nature, plants are concurrently exposed to a number of abiotic and biotic stresses. Our understanding of convergence points between responses to combined biotic/abiotic stress pathways remains, however, rudimentary. Here we show that MIR399 overexpression, loss-of-function of PHO2 (PHOSPHATE2), or treatment with high Pi, is accompanied by an increase in phosphate (Pi) content and accumulation of reactive oxygen species (ROS) in Arabidopsis thaliana. High Pi plants (e.g. miR399 overexpressor, pho2 mutant, and plants grown under high Pi supply) exhibited resistance to infection by necrotrophic and hemibiotrophic fungal pathogens. In the absence of pathogen infection, the expression level of genes in the salicylic acid (SA)- and jasmonic acid (JA)-dependent signaling pathways was higher in high Pi plants compared to wild type plants, which is consistent with increased levels of SA and JA in non-infected high Pi plants. During infection, an opposite regulation in the two branches of the JA pathway (ERF1/PDF1.2 and MYC2/VSP2) occurs in high Pi plants. Thus, while the ERF1-PDF1 branch positively responds to fungal infection, the MYC2/VSP2 branch is negatively regulated during pathogen infection in high Pi plants. This study supports that Pi accumulation promotes resistance to infection by fungal pathogens in Arabidopsis, while providing a basis to better understand crosstalk between Pi signaling and hormonal signalling pathways for modulation of plant immune responses. Significance statementThis study highlights the importance of phosphate (Pi) in regulating immune responses, hence, disease resistance in Arabidopsis thaliana. Increasing Pi content either by MIR399 overexpression (or loss-of-function of PHOSPHATE2), as well as by Pi treatment enhances resistance to infection by necrotrophic and hemibiotrophic fungal pathogens through modulation of SA- and JA-dependent signaling pathways. These results also support that miR399 functions as a regulator of Arabidopsis immunity.

plant biology↗

bioRxiv2021

Custom-made design of metabolite composition in N. benthamiana leaves using CRISPR activators.

Transcriptional regulators based on CRISPR architecture expand our ability of reprogramming endogenous gene expression in plants. One of their potential applications is the customization of plant metabolome through the activation of selected enzymes in a given metabolic pathway. Using the previously described multiplexable CRISPR activator dCasEV2.1, we assayed the selective enrichment in Nicotiana benthamiana leaves of four different flavonoids, namely naringenin, eriodictyol, kaempferol and quercetin. After careful selection of target genes and guide RNAs combinations, we created successful activation programs for each of the four metabolites, each program activating between three and seven genes, and with individual gene activation levels ranging from 4- to 1500-fold. Metabolic analysis of the flavonoid profiles of each multigene activation program showed a sharp and selective enrichment of the intended metabolites and their glycosylated derivatives. Remarkably, principal component analysis of untargeted metabolic profiles clearly separated samples according to their activation treatment, and hierarchical clustering separated the samples in five groups, corresponding to the expected four highly enriched metabolite groups, plus an un-activated control. These results demonstrate that dCasEV2.1 is a powerful tool for re-routing metabolic fluxes towards the accumulation of metabolites of interest, opening the door for custom-made design of metabolic contents in plants.

synthetic biology↗