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ABSTRACT Plants require water and nutrients for survival, although the effects of their availabilities on plant fitness differ amongst species. Genome size variation, within and across species, is suspected to influence plant water and nutrient requirements, but little is known about how variations in these resources concurrently affect plant fitness based on genome size. We examined how genome size variation between autopolyploid cytotypes influences plant morphological and physiological traits, and whether cytotype‐specific trait responses differ based on water and/or nutrient availability.Diploid and autotetraploidSolidago gigantea(Giant Goldenrod) were grown in a greenhouse under four soil water:N+P treatments (L:L, L:H, H:L, H:H), and stomata characteristics (size, density), growth (above‐ and belowground biomass, R/S), and physiological (Anet,E,WUE) responses were measured.Resource availabilities and cytotype identity influenced some plant responses but their effects were independent of each other. Plants grown in high‐water and nutrient treatments were larger, plants grown in low‐water or high‐nutrient treatments had higherWUEbut lowerE, andAnetandErates decreased as plants aged. Autotetraploids also had larger and fewer stomata, higher biomass and largerAnetthan diploids.Nutrient and water availability could influence intra‐ and interspecific competitive outcomes. AlthoughS. giganteacytotypes were not differentially affected by resource treatments, genome size may influence cytogeographic range patterning and population establishment likelihood. For instance, the larger size of autotetraploidS. giganteamight render them more competitive for resources and niche space than diploids.
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Mechanistic insights into plant community responses to environmental variables: genome size, cellular nutrient investments, and metabolic tradeoffs
Summary Affecting biodiversity, plants with larger genome sizes (GS) may be restricted in nutrient‐poor conditions. This pattern has been attributed to their greater cellular nitrogen (N) and phosphorus (P) investments and hypothesized nutrient–investment tradeoffs between cell synthesis and physiological attributes associated with growth. However, the influence of GS on cell size and functioning may also contribute to GS‐dependent growth responses to nutrients.To test whether and how GS is associated with cellular nutrient, stomata, and/or physiological attributes, we examined > 500 forbs and grasses from seven grassland sites conducting a long‐term N and P fertilization experiment.Larger GS plants had increased cellular nutrient contents and larger, but fewer stomata than smaller GS plants. Larger GS grasses (but not forbs) also had lower photosynthetic rates and water‐use efficiencies. However, nutrients had no direct effect on GS‐dependent physiological attributes and GS‐dependent physiological changes likely arise from how GS influences cells. At the driest sites, large GS grasses displayed high water‐use efficiency mostly because transpiration was reduced relative to photosynthesis in these conditions.We suggest that climatic conditions and GS‐associated cell traits that modify physiological responses, rather than resource–investment tradeoffs, largely explain GS‐dependent growth responses to nutrients (especially for grasses).
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- PAR ID:
- 10571240
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 245
- Issue:
- 5
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 2336-2349
- Size(s):
- p. 2336-2349
- Sponsoring Org:
- National Science Foundation
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