AI Insight
Researchers studied leaf bacterial communities on four milkweed species throughout a growing season, finding that bacterial diversity increased over time and varied by plant species. Early in the season, bacteria dispersed uniformly across plants making communities similar, but by late season dispersal declined and each plant's bacterial community became distinct. The relationship between bacteria, plant defensive chemicals (cardenolides), and arthropods was species-specific, suggesting that herbivores arriving later in the season encounter different microbial environments depending on the host plant.
Why it matters
This research reveals that plant-bacteria-insect interactions change predictably through seasons, which could inform pest management strategies and our understanding of how plants defend themselves. The findings suggest that timing matters when studying or manipulating plant microbiomes, as the same intervention might have different effects early versus late in the growing season.
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⚠️ Preprint – Noch nicht peer-reviewed
Dieser Artikel wurde noch nicht von unabhängigen Experten begutachtet. Die Ergebnisse sind vorläufig und sollten mit Vorsicht interpretiert werden.
Leaf bacterial communities shape plant defense and interactions with herbivores, yet how host filtering and stochastic processes assemble them remains unclear. We predicted that host identity, chemistry, and arthropods structure them, and that stochastic and deterministic contributions shift seasonally. Across one growing season we sampled leaf bacteria monthly and arthropods weekly on four Asclepias species (Apocynaceae: A. curassavica, A. incarnata, A. syriaca, A. tuberosa) spanning a cardenolide gradient. We sequenced 16S rRNA genes and quantified selection and dispersal contributions to turnover using null models. Host identity shaped bacterial richness and composition, with A. tuberosa hosting the richest communities, and both richness and phylogenetic diversity rose through the season. Early on, homogenizing dispersal made communities more similar among plants; by mid-season no single process dominated turnover, and by late season dispersal limitation prevailed. Homogeneous selection was episodic, not sustained, and arthropod associations were host-specific, negatively so on A. syriaca. Phyllosphere assembly thus shifts from convergence to divergence in one season: young leaves recruit from a shared pool delivered by wind, rain, and arthropods, whereas exchange among ageing plants declines and communities drift apart. Herbivores arriving late meet plant-specific microbial environments, so microbial mediation of herbivory should be host-specific and seasonally contingent.