Plant microbiomes have a greater effect than plant size on flowering and growth in Asclepias syriaca
Year: 2026
Type: preprint
Abstract: Plants strike a delicate balance between growth and defense. The calculus of how to defend against herbivores, and maximize growth and reproduction, can differ between annuals and perennials. Annuals have a live fast, reproduce young strategy; while perennials may maximize fecundity over years. Milkweed, a herbaceous perennial, is a mix of these two strategies. On one hand, a single individual milkweed ramet is functionally a herbaceous annual and vulnerable to herbivory. On the other hand, below ground connections allow plants to share resources and persist for multiple years, perhaps lowering the cost of localized herbivory. Here, we study the impact herbivory on the leaf and soil microbiome on milkweed growth and flowering in a naturally occurring population. Specifically, using milkweed populations at three different sites in Virginia, following individual ramets throughout the growth and flowering season, we quantified the soil and leaf microbiome through metagenomic shotgun sequencing. After controlling for plant size and plant genotype, we asked how the microbiome composition was related to flowering time and growth. We find that the leaf microbiome is a strong predictor of plant growth rate, but not flowering. Conversely, we find that the soil microbiome and plant size predict flowering probability. We found no evidence that herbivory altered the leaf or soil microbiome composition. Together these results provide evidence that plant microbiomes also influence growth and fecundity in natural populations of milkweed. These results also provide evidence that the leaf microbiome in milkweed is robust and stable in the face of significant herbivory. This study expands our knowledge of the contribution of plant microbiomes to plant demography in a clonal perennial plant.
Institution: William & Mary
Language: English
Subfield: Plant Science
Domain: Life Sciences
SDGs: Zero hunger, Life on land
Open Access status: green
OpenAlex ID: W7223140706