Trade-offs between arbuscular mycorrhizal fungal competitive ability and host growth promotion in Plantago lanceolata

Oecologia ◽  
2009 ◽  
Vol 160 (4) ◽  
pp. 807-816 ◽  
Author(s):  
Alison Elizabeth Bennett ◽  
James D. Bever
2019 ◽  
Vol 286 (1900) ◽  
pp. 20190236 ◽  
Author(s):  
Andrew C. Matthews ◽  
Lauri Mikonranta ◽  
Ben Raymond

Theory suggests that symbionts can readily evolve more parasitic or mutualistic strategies with respect to hosts. However, many symbionts have stable interactions with hosts that improve nutrient assimilation or confer protection from pathogens. We explored the potential for evolution of increased parasitism or decreased parasitism and mutualism in a natural gut symbiosis between larvae of Plutella xylostella and the microbe Enterobacter cloacae. We focused on interactions with the pathogen, Bacillus thuringiensis : selecting for parasitism in terms of facilitating pathogen infection, or increased mutualism in terms of host protection. Selection for parasitism led to symbionts increasing pathogen-induced mortality but reduced their competitive ability with pathogens and their in vitro growth rates. Symbionts did not evolve to confer protection from pathogens. However, several lineages evolved reduced parasitism, primarily in terms of moderating impacts on host growth, potentially because prudence pays dividends through increased host size. Overall, the evolution of increased parasitism was achievable but was opposed by trade-offs likely to reduce fitness. The evolution of protection may not have occurred because suppressing growth of B. thuringiensis in the gut might provide only weak protection or because evolution towards protective interactions was opposed by the loss of competitive fitness in symbionts.


2014 ◽  
Vol 70 (2) ◽  
pp. 97-101 ◽  
Author(s):  
Janusz Błaszkowski ◽  
Mariusz Tadych ◽  
Tadeusz Madej

A new ectocarpic arbuscular mycorrhizal fungal species, <em>Glomus arenarium</em> (<em>Glomales</em>, <em>Zygomycetes</em>), was recovered from maritime sand dunes of northern Poland. <em>Glomus arenarium</em> forms spores with a narrow and hyaline subtending hypha. Spores are orange to raw umber, globose to subglobose, (55-)97(-120) µm diam or ovoid, 65-105 x 95-140 µm. Their wall consists of three layers: a hyaline outermost layer present only in very young spores, a semiflexible, hyaline middle layer rarely present in mature spores, and a permanent, laminate, orange to raw umber innermost layer. No spore wall layers of <em>G. arenarium</em> reagent. This fungus formed spores and arbuscular mycorrhizae in single-species pot cultures with Plantago lanceolata.


2020 ◽  
Author(s):  
Bence Gáspár ◽  
Oliver Bossdorf ◽  
Madalin Parepa

AbstractBackground and aimsIntraspecific variation in functional traits is essential for the evolutionary success of organisms. The co-variation between trait variation and environment, as well as between different traits, can help us to understand which ecological factors drive habitat adaptation, and to what extent adaptation may be constrained by trait correlations and trade-offs. In managed grasslands, plants experience a combination of competition, recurrent biomass removal and nutrient pulses. Each of these ecological challenges requires specific plant tolerances, and populations should locally adapt if intraspecific variation exists in these traits.MethodsWe studied variation in land use-related traits in the common grassland plant Plantago lanceolata. In a common environment, we quantified the competitive ability (R*), clipping tolerance and responses to a nitrogen pulse of plants from 54 populations with different land use intensities across Germany.Key resultsWe found significant population differentiation in competitive ability but there was little evidence that trait variation was related to land use intensity. There was a positive relationship between competitive ability and clipping tolerance at the population level, indicating a genetic, and possibly functional, link between these two traits. In contrast, clipping tolerance and nitrogen responses were negatively correlated at the levels of plant individuals, indicating a physiological trade-off between plant responses to these two land-use processes.ConclusionsOur results show that there is substantial intraspecific variation in some of the key functional traits for plant success in managed grasslands, and that rapid evolution and adaptation is therefore possible in these traits.


2020 ◽  
Author(s):  
Peter G. Kennedy ◽  
Joe Gagne ◽  
Eduardo Perez-Pazos ◽  
Lotus A. Lofgren ◽  
Nhu H. Nguyen

AbstractTwo common ecological assumptions are that host generalist and rare species are poorer competitors relative to host specialist and more abundant counterparts. While these assumptions have received considerable study in both plant and animals, how they apply to ectomycorrhizal fungi remains largely unknown. To investigate how interspecific competition may influence the anomalous host associations of the rare ectomycorrhizal generalist fungus, Suillus subaureus, we conducted a seedling bioassay. Pinus strobus seedlings were inoculated in single- or two-species treatments of three Suillus species: S. subaureus, S. americanus, and S. spraguei. After 4 and 8 months of growth, seedlings were harvested and scored for mycorrhizal colonization as well as dry biomass. At both time points, we found a clear competitive hierarchy among these species: S. americanus > S. subaureus > S. spraguei, with the competitive inferior, S. spraguei, having significantly delayed colonization relative to S. americanus and S. subaureus. In the single-species treatments, we found no significant differences in the dry biomasses of seedlings colonized by each Suillus species, suggesting none of these species was a more effective plant symbiont relative to each other. Taken together, these results indicate that the rarity and anomalous host associations exhibited by S. subaureus in natural settings are not driven by inherently poor competitive ability or host growth promotion, but that the timing of colonization is a key factor determining the outcome of ectomycorrhizal fungal competitive interactions.


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