Biology subjects

Crava, C. M.

Publications and source records attributed to Crava, C. M..

5 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↗

bioRxiv2025

A Grapholita molesta (Lepidoptera: Tortricidae) cadherin in the 99C cadherin clade binds to Bacillus thuringiensis Cry1A proteins

Bt-cadherins, a particular type of midgut cadherins, act as receptors for Bacillus thuringiensis Cry1A pesticidal proteins. The aim of this work was to identify and validate the Cry1A cadherin receptor in Grapholita molesta (GmCad1). The GmCad1 gene was annotated by Blast genome mining using lepidopteran Bt-related cadherins. The phylogenetic analyses grouped GmCad1 with other Torticidae cadherins, in a different clade than the lepidopteran Bt-related cadherins. The in silico analysis of the GmCad1 showed a structure similar to that of the Bt-related cadherins, with 11 cadherin repeats (CRs), a transmembrane region, and an intracellular domain. The full-length mRNA sequencing confirmed GmCad1 expression in vivo in G. molesta guts. To validate the binding ability of Cry1A proteins to GmCad1, a cadherin fragment (CR7-CR11) was expressed and in vitro binding was studied demonstrating that Cry1Aa, Cry1Ab, and Cry1Ac bind to this region in a dose-dependent manner. In silico molecular docking analysis suggested that the interaction may involve mainly the Domains II of Cry1Ab and Cry1Ac, and the Domain III of Cry1Aa. This study provides the first evidence of a 99-C cadherin serving as a receptor for Cry1A in G. molesta.

molecular biology↗

bioRxiv2023

Heterologous expression of insect IRs in transgenic Drosophila melanogaster

Among insect chemosensory receptors, the broadly conserved Ionotropic Receptors (IRs) remain some of the least investigated. Several studies have documented IR activation by recording insects neuronal activity in situ, some demonstrated their activation when expressed in oocytes from Xenopus, others made use of the Drosophila "ionotropic receptor decoders" to functionally mis-express IRs from the same species or from the closely related D. sechellia. Here we demonstrated that both substituting tuning IRs of D. melanogaster and expressing heterologous IRs from other insects alongside the Drosophila native ones result in functional heteromeric complexes. By these methods, we functionally characterized the IR41a1 subunit of the codling moth Cydia pomonella, which demonstrated binding to polyamines with different pharmacological characteristics and the IR75d subunit of the spotted wing drosophila Drosophila suzukii, which binds hexanoic acid. Then we expressed the D. suzukii acid sensor IR64a into the D. melanogaster "ionotropic receptor decoder" neuron, which resulted in the inhibition to the main activators of other neurons housed in the same sensillum of D. melanogaster, as an evidence of its possible functional expression, but it did not show response to acids. In situ hybridization on the antennae of D. suzukii unveiled a wide expression of this subunit in neurons proximal to the sacculus. Structural analysis did not explain absence of IR64a binding to acids, but it identified key amino acid features that may justify possible hexanoic acid binding for IR75d. While our findings add to the derophanization efforts conducted on the chemosensors of the aforementioned pests, they demonstrated potential for the use of neurons of transgenic Drosophila as a tool to functionally characterize IRs from different insect species.

molecular biology↗

bioRxiv2020

Coupling transcriptomics and behaviour to unveil the olfactory system of Spodoptera exigua larvae

Chemoreception in insects is crucial for many aspects related to food seeking, enemy avoidance, and reproduction. Different families of receptors and binding proteins interact with chemical stimuli, including odorant receptors (ORs), ionotropic receptors (IRs), gustatory receptors (GRs), odorant binding proteins (OBPs) and chemosensory proteins (CSPs). In this work, we describe the chemosensory-related gene repertoire of the worldwide spread pest Spodoptera exigua (Lepidoptera: Noctuide) focusing on the transcripts expressed in larvae, which feed on many horticultural crops producing yield losses. A comprehensive de novo assembly that includes reads from chemosensory organs of larvae and adults, and other larval tissues, enabled us to annotate 200 candidate chemosensory-related genes encoding 63 ORs, 28 IRs, 38 GRs, 48 OBPs and 23 CSPs. Of them, 51 transcripts are new annotations. RNA-seq and reverse transcription PCR analyses show that 50 ORs are expressed in larval heads, and 15 OBPs are larva-specific. To identify candidate ecologically-relevant odours for S. exigua larvae, we set up behavioural experiments with different volatile organic compounds (VOCs). 1-hexanol triggers attraction at the three timepoints tested and linalool repels larvae at any timepoints. Other five VOCs elicit behavioural response at single timepoint. Lastly, we tested if pre-exposure to single VOCs influence the expression patterns of selected ORs and pheromone binding proteins (PBPs), showing a massive and general up-regulation of some ORs after 24h exposure. This work sets the basis for the study of chemosensation in S. exigua larvae, boosting further studies aimed to characterize chemosensory-related genes that underlie ecologically-relevant behaviours of larval stage.

ecology↗

bioRxiv2019

Exploring multiple sensory systems in ovipositors of Drosophila suzukii and related species with different egg-laying behaviour

Drosophila suzukii is an invasive agricultural pest species that lays eggs in fruit during ripening, while most closely related Drosophila species use rotten matter as oviposition substrates. This behaviour is allowed by an enlarged and serrated ovipositor that can pierce intact fruit skin. D. suzukii combines multiple sensory systems (mechanosensation, olfaction, and taste) to select oviposition sites. Here, we test the hypothesis that the D. suzukii ovipositor is involved in these sensory modalities. We first investigate the ovipositor gene expression using a comparative framework of four Drosophila species with gradual changes in ovipositor morphology to identify evolutionary adaptations specific to D. suzukii. Results show transcription of chemoreceptors and mechanoreceptors in the four species, with a common core of sensory receptors expressed in all of them. Then, we demonstrate that sensory structures present in the distal tip of the D. suzukii ovipositor are mechanosensory-like sensilla, and that the degenerin/epithelial sodium channel ppk is expressed in homologous structures in Drosophila melanogaster. Our results suggest the D. suzukii ovipositor playing a role in mechanosensation, which might be shared with other Drosophila species.

zoology↗