Berndt, H. | Search bioRxiv

bioRxiv2025

Aphid infestation induces plant-sex-specific changes in floral chemistry and pollinator behaviour in Silene latifolia

Pollinators share the complex information and resource landscape of their host plants with herbivores. Yet, how sap feeders affect floral attractiveness to pollinators remains poorly understood, despite the critical role of this tripartite interaction in natural and agricultural ecosystems. In dioecious plant species, which display pronounced sexual dimorphism, these intricate interactions may vary in magnitude and direction between females and males, with significant implications for plant population dynamics and species co-evolution. In this study, we examined how infestation by the oligophagous aphid Brachycaudus lychnidis affects sex-specific interactions among the dioecious plant Silene latifolia and its specialist moth pollinator Hadena bicruris. We exposed male and female plants to aphid herbivory and evaluated its effects on floral traits (visual cues, floral scent, and nectar chemistry) and pollinator behaviour. While aphid infestation affected some floral traits equally in both sexes and others more strongly in males or in females, we observed stronger declines in female attractiveness to pollinators, which were mainly linked to nectar compounds potentially acting as feeding cues or behavioural modulators. We discuss our results in the light of sexual selection and plant defence theory while emphasizing the complementarity of female and male traits in stabilizing this specialized plant-pollinator-herbivore system. HighlightAphid infestation alters multiple visual and chemical floral traits in a plant sex-specific manner, leading to reduced attractiveness to moth pollinators in female plants, but not in males. Graphical AbstractPlant-sex specific effect of aphid infestation on floral traits (number, size, colour, scent composition, nectar quantity and composition) and pollinator behaviour. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=171 SRC="FIGDIR/small/666187v3_ufig1.gif" ALT="Figure 1"> View larger version (38K): org.highwire.dtl.DTLVardef@14256borg.highwire.dtl.DTLVardef@a49b05org.highwire.dtl.DTLVardef@bd8c92org.highwire.dtl.DTLVardef@57eb93_HPS_FORMAT_FIGEXP M_FIG C_FIG

plant biology↗

bioRxiv2024

An ancient lysozyme in placozoans

Lysozymes are an essential part of immunity and nutrition in metazoans, degrading bacterial cell walls via the hydrolysis of peptidoglycan. Although various lysozymes have been reported for higher animals, the origin of animal lysozymes remains elusive as they seem to be lacking in all early branching phyla. In this study, we investigated a putative goose-type lysozyme (PLys, glycoside hydrolase family 23, GH23) of the placozoan Trichoplax sp. H2. We show that PLys is highly active and produced in gland cells of the ventral epithelium. PLys contains a protective and non-conserved cysteine-rich domain N-terminal of the conserved GH23 lysozyme domain. A truncation of this N-terminal domain in the maturation process of PLys leads to a drastic increase in enzymatic activity at the cost of stability. As the lysozyme is most active under acidic conditions, we investigated the pH trajectories during extracellular digestion in situ. Using a pH-senstive fluorescence reporter, we show that Trichoplax sp. H2 acidifies its temporary feeding grooves pulsatively during digestive events close to the optimum pH for PLys activity. To elucidate the evolutionary origin of the metazoan GH23 lysozyme family, we applied a structure-based phylogenetics approach to show that the metazoan g-type GH23 lysozymes originated from a horizontal gene transfer event from bacteria to an early pre-bilaterian ancestor. GH23 lysozymes have then been retained and expanded in many phyla, including Porifera, Cnidaria, Placozoa and chordates, acting as first animal lysozyme and a key component in the antibacterial arsenal since early animal evolution.

evolutionary biology↗