An official website of the United States government
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.
more »
« less
Polyploid plants obtain greater fitness benefits from a nutrient acquisition mutualism
Summary Polyploidy is a key driver of ecological and evolutionary processes in plants, yet little is known about its effects on biotic interactions. This gap in knowledge is especially profound for nutrient acquisition mutualisms, despite the fact that they regulate global nutrient cycles and structure ecosystems. Generalism in mutualistic interactions depends on the range of potential partners (niche breadth), the benefits obtained and ability to maintain benefits across a variety of partners (fitness plasticity). Here, we determine how each of these is influenced by polyploidy in the legume–rhizobium mutualism.We inoculated a broad geographic sample of natural diploid and autotetraploid alfalfa (Medicago sativa) lineages with a diverse panel ofSinorhizobiumbacterial symbionts. To analyze the extent and mechanism of generalism, we measured host growth benefits and functional traits.Autotetraploid plants obtained greater fitness enhancement from mutualistic interactions and were better able to maintain this across diverse rhizobial partners (i.e. low plasticity in fitness) relative to diploids. These benefits were not attributed to increases in niche breadth, but instead reflect increased rewards from investment in the mutualism.Polyploid plants displayed greater generalization in bacterial mutualisms relative to diploids, illustrating another axis of advantage for polyploids over diploids.
more »
« less
- Award ID(s):
- 1738009
- PAR ID:
- 10456999
- Publisher / Repository:
- Wiley-Blackwell
- Date Published:
- Journal Name:
- New Phytologist
- Volume:
- 227
- Issue:
- 3
- ISSN:
- 0028-646X
- Format(s):
- Medium: X Size: p. 944-954
- Size(s):
- p. 944-954
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Summary Ecological theory predicts that early generation polyploids (‘neopolyploids’) should quickly go extinct owing to the disadvantages of rarity and competition with their diploid progenitors. However, polyploids persist in natural habitats globally. This paradox has been addressed theoretically by recognizing that reproductive assurance of neopolyploids and niche differentiation can promote establishment. Despite this, the direct effects of polyploidy at the population level remain largely untested despite establishment being an intrinsically population‐level process.We conducted population‐level experiments where life‐history investment in current and future growth was tracked in four lineage pairs of diploids and synthetic autotetraploids of the aquatic plantSpirodela polyrhiza. Population growth was evaluated with and without competition between diploids and neopolyploids across a range of nutrient treatments.Although neopolyploid populations produce more biomass, they reach lower population sizes and have reduced carrying capacities when growing alone or in competition across all nutrient treatments. Thus, contrary to individual‐level studies, our population‐level data suggest that neopolyploids are competitively inferior to diploids. Conversely, neopolyploid populations have greater investment in dormant propagule production than diploids.Our results show that neopolyploid populations should not persist based on current growth dynamics, but high potential future growth may allow polyploids to establish in subsequent seasons.more » « less
-
PremisePolyploidy is known to cause physiological changes in plants which, in turn, can affect species interactions. One major physiological change predicted in polyploid plants is a heightened demand for growth‐limiting nutrients. Consequently, we expect polyploidy to cause an increased reliance on the belowground mutualists that supply these growth‐limiting nutrients. An important first step in investigating how polyploidy affects nutritional mutualisms in plants, then, is to characterize differences in the rate at which diploids and polyploids interact with belowground mutualists. MethodsWe usedHeuchera cylindrica(Saxifragaceae) to test how polyploidy influences interactions with arbuscular mycorrhizal fungi (AMF). Here we first confirmed the presence ofAMFinH. cylindrica, and then we used field‐collected specimens to quantify and compare the presence ofAMFstructures while controlling for site‐specific variation. ResultsTetraploids had higher colonization rates as measured by total, hyphal, and nutritional‐exchange structures; however, we found that diploids and tetraploids did not differ in vesicle colonization rates. ConclusionsThe results suggest that polyploidy may alter belowground nutritional mutualisms with plants. Because colonization by nutritional‐exchange structures was higher in polyploids but vesicle colonization was not, polyploids might form stronger associations with theirAMFpartners. Controlled experiments are necessary to test whether this pattern is driven by the direct effect of polyploidy onAMFcolonization.more » « less
-
Abstract Whole‐genome duplication has long been appreciated for its role in driving phenotypic novelty in plants, often altering the way organisms interface with the abiotic environment. Only recently, however, have we begun to investigate how polyploidy influences interactions of plants with other species, despite the biotic niche being predicted as one of the main determinants of polyploid establishment. Nevertheless, we lack information about how polyploidy affects the diversity and composition of the microbial taxa that colonize plants, and whether this is genotype‐dependent and repeatable across natural environments. This information is a first step towards understanding whether the microbiome contributes to polyploid establishment. We, thus, tested the immediate effect of polyploidy on the diversity and composition of the bacterial microbiome of the aquatic plantSpirodela polyrhizausing four pairs of diploids and synthetic autotetraploids. Under controlled conditions, axenic plants were inoculated with pond waters collected from 10 field sites across a broad environmental gradient. Autotetraploids hosted 4%–11% greater bacterial taxonomic and phylogenetic diversity than their diploid progenitors. Polyploidy, along with its interactions with the inoculum source and genetic lineage, collectively explained 7% of the total variation in microbiome composition. Furthermore, polyploidy broadened the core microbiome, with autotetraploids having 15 unique bacterial taxa in addition to the 55 they shared with diploids. Our results show that whole‐genome duplication directly leads to novelty in the plant microbiome and importantly that the effect is dependent on the genetic ancestry of the polyploid and generalizable over many environmental contexts.more » « less
-
Premise of research. Polyploidy, a major evolutionary process in flowering plants, is expected to 19 impact floral traits which can have cascading effects on pollination interactions, but this may 20 depend on selfing propensity. In a novel use of herbarium specimens, we assessed the effects of 21 polyploidy and mating system on floral traits and the pollination niche of 40 Brassicaceae 22 species. 23 Methodology. We combined data on mating system (self-compatible or self-incompatible) with 24 inferred ploidy level (polyploid or diploid) and use phylogenetically controlled analyses to 25 investigate their influence on floral traits (size and shape) and the degree of pollination 26 generalism based on the frequency and the richness of heterospecific pollen morphospecies 27 captured by stigmas. 28 Pivotal Results. Flower size (but not shape) depended on the interaction between ploidy and 29 mating system. Self-incompatible polyploid species had larger flowers than self-incompatible 30 diploids but there was no difference for self-compatible species. The breadth of pollination niche 31 (degree of generalism) was not affected by ploidy but rather strongly by mating system only. 32 Self-incompatible species had more stigmas with heterospecific pollen and higher heterospecific 33 pollen morphospecies richness per stigma than self-compatible species, regardless of their 34 ploidy. 35 Conclusions. Our results demonstrate that mating system moderated the influence of ploidy on 36 morphological features associated with pollination generalism but that response in terms of 37 heterospecific pollen captured as a proxy of pollination generalism was more variable.more » « less
