Mechanistic insights into plant community responses to environmental variables: genome size, cellular nutrient investments, and metabolic trade-offs

Authors: HERSCH-GREEN, ERIKA - Michigan Technological University; PETOSKY, HAILEE - Michigan Technological University; SMITH, NICHOLAS - Texas Tech University; Fay, Philip

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2024
Publication Date: 12/25/2024
Citation: Hersch-Green, E.I., Petosky, H., Smith, N.G., Fay, P.A. 2024. Mechanistic insights into plant community responses to environmental variables: genome size, cellular nutrient investments, and metabolic trade-offs. New Phytologist. https://doi.org/10.1111/nph.20374.

Interpretive Summary: Eutrophication, the presence of excess nutrients in the environment, is a widespread global change phenomenon that can greatly reduce ecosystem health, biodiversity, and ecosystem services provision in natural and managed ecosystems including grasslands. Understanding the underlying genetic mechanisms by which eutrophication may affect plant diversity in grasslands is basic information necessary to effectively mitigate negative effects of eutrophication. This study examined the effects of fertilization with nitrogen and phosphorus, individually and together, on the nutrient content and physiological efficiency of over 500 grassland plant species across seven locations in the U.S. spanning a broad range of mean precipitation and mean temperature, and related changes in physiological efficiency to the size of plant genomes and traits of leaf stomata. These stomatal traits and genome size-related changes in physiological efficiency explained changes in growth responses and were augmented by site mean precipitation and temperature. These findings illustrate a mechanism through which eutrophication may influence grassland biodiversity.

Technical Abstract: Eutrophication is altering biodiversity worldwide and data suggests that plants with larger genome sizes (GS) may be restricted in nutrient-poor conditions, presumably owing to their greater cellular nitrogen (N) and phosphorus (P) investments and associated stronger cell synthesis versus growth investment trade-offs. However, differential growth responses of plants with varying GS may also be influenced by differences in cell sizes and functioning, which can also vary dependent upon GS. We examined >500 plants from seven grassland sites in which nothing, N and/or P had been annually added to test whether GS is associated with increases in cellular nutrients, stomata cell sizes, and/or physiological attributes. Larger GS plants had greater cellular nutrients and larger, but fewer stomata than smaller GS plants. However, only GS of grasses, not forbs, was associated with physiological attributes. Specifically, larger GS grasses tended to be less photosynthetically active and water-use efficient, although at the driest sites, large GS grasses also exhibited high water-use efficiency. We suggest that cell morphological and functional changes associated with GS, rather than investment trade-offs, largely explain GS-dependent growth responses (especially for grasses) and that plant GS may influence biodiversity responses to eutrophication dependent upon climate conditions.