Sympatric diploid and tetraploid cytotypes of Centaurea stoebe s.l. do not differ in arbuscular mycorrhizal communities and mycorrhizal growth response

Genome duplication is associated with multiple changes at different levels, including interactions with pollinators and herbivores. Yet little is known whether polyploidy may also shape belowground interactions.Methods: To elucidate potential ploidy‐specific interactions with arbuscular mycorrhizal fungi (AMF), we compared mycorrhizal colonization and assembly of AMF communities in roots of diploid and tetraploid Centaurea stoebe s.l. (Asteraceae) co‐occurring in a Central European population. In a follow‐up greenhouse experiment, we tested inter‐cytotype differences in mycorrhizal growth response by combining ploidy, substrate, and inoculation with native AMF in a full‐factorial design.Key Results: All sampled plants were highly colonized by AMF, with the Glomeraceae predominating. AMF‐community composition revealed by 454‐pyrosequencing reflected the spatial distribution of the hosts, but not their ploidy level or soil characteristics. In the greenhouse experiment, the tetraploids produced more shoot biomass than the diploids did when grown in a more fertile substrate, while no inter‐cytotype differences were found in a less fertile substrate. AMF inoculation significantly reduced plant growth and improved P uptake, but its effects did not differ between the cytotypes.Conclusions: The results do not support our hypotheses that the cytotype structure in a mixed‐ploidy population of C. stoebe is mirrored in AMF‐community composition and that ploidy‐specific fungal communities contribute to cytotype co‐existence. Causes and implications of the observed negative growth response to AMF are discussed

Plant Communities Rather than Soil Properties Structure Arbuscular Mycorrhizal Fungal Communities along Primary Succession on a Mine Spoil

Arbuscular mycorrhizal fungal (AMF) community assembly during primary succession has so far received little attention. It remains therefore unclear, which of the factors, driving AMF community composition, are important during ecosystem development. We addressed this question on a large spoil heap, which provides a mosaic of sites in different successional stages under different managements. We selected 24 sites of c. 12, 20, 30, or 50 years in age, including sites with spontaneously developing vegetation and sites reclaimed by alder plantations. On each site, we sampled twice a year roots of the perennial rhizomatous grass Calamagrostis epigejos (Poaceae) to determine AMF root colonization and diversity (using 454-sequencing), determined the soil chemical properties and composition of plant communities. AMF taxa richness was unaffected by site age, but AMF composition variation increased along the chronosequences. AMF communities were unaffected by soil chemistry, but related to the composition of neighboring plant communities of the sampled C. epigejos plants. In contrast, the plant communities of the sites were more distinctively structured than the AMF communities along the four successional stages. We conclude that AMF and plant community successions respond to different factors. AMF communities seem to be influenced by biotic rather than by abiotic factors and to diverge with successional age

Data-Frouz et al., 2019

Codes and relevant data are described separately in each excel sheet

Earthworms affect growth and competition between ectomycorrhizal and arbuscular mycorrhizal plants

Abstract Previous research showed that during intermediate stages of primary succession, when vegetation is dominated by ectomycorrhizal (EcM) shrubs and trees, site colonization by earthworms substantially alters plant communities. Research has also shown that EcM shrubs and trees suppress arbuscular mycorrhizal (AM) plants in the understory. To determine whether earthworm activity reduces this asymmetric competition, we conducted a full factorial laboratory experiment in which we grew EcM Betula pendula and AM Tripleurospermum inodorum, together or apart, in soils affected or not affected by earthworms. When both plants were grown together in soil unaffected by earthworms, growth of T. inodorum was significantly reduced by competition with B. pendula, but B. pendula growth was not reduced by T. inodorum. In soil affected by earthworms, the growth of both species was increased, and the negative effect of B. pendula on T. inodorum was no longer statistically significant (P < 0.05). These data indicate that earthworms weaken the asymmetric competition between EcM and AM plants. Consistent with this inference, EcM colonization of B. pendula was decreased and AM fungal bioassay in soil was increased by earthworms

Respiratory muscle strength in children with mild bronchial asthma disease

Background: Respiratory muscle strength can be decreased in patients with asthma; however, it is not well-documented whether a mild bronchial asthma disease can affect respiratory muscle strength in children and can be associated with higher presence of breathing difficulties. Objective: The main aim of the present study was to compare respiratory muscle strength between children with asthma and age-matched healthy children. The next aim of this study was to assess the incidence of decreased respiratory muscle strength in children with asthma and healthy children and assess the effect of decreased respiratory muscle strength on the incidence of breathing difficulties. Methods: Children with mild bronchial asthma (n&#8239;=&#8239;167) and age-matched, healthy children (n&#8239;=&#8239;100) were recruited into this study. Pulmonary function tests, maximal inspiratory (PImax) and expiratory (PEmax) mouth pressures and the incidence of breathing difficulty were evaluated in children with asthma and healthy controls. Results: The inspiratory muscle strength was similar between children with asthma and healthy children. Conversely, the expiratory muscle strength was lower in asthmatic children. There was a statistically significant difference between girls with asthma and healthy girls (PEmax&#8239;=&#8239;81.7&#8239;&#177;&#8239;29.8% vs. 100.1&#8239;&#177;&#8239;23.7% of predicted, p&#8239;&lt;&#8239;.001). PEmax was significantly higher in boys with asthma than in girls with asthma (PEmax&#8239;=&#8239;92.9&#8239;&#177;&#8239;26.4 % vs. 81.7&#8239;&#177;&#8239;29.8% of predicted, p&#8239;=&#8239;.03). A higher incidence of breathing difficulties during physical activity (uphill walking, running, swimming) was confirmed in children with asthma with lower respiratory muscle strength. Conclusions: There was a higher prevalence of decreased expiratory muscle strength in children with asthma; therefore, respiratory muscle strength should be tested in these children, especially in those who are symptomatic

Species most positively and negatively affected by fungicide application.

<p>Graph shows change in the absolute cover of particular species after 3 years of fungicide application, averaged over 10 plots. Asterisks indicate significant (P ≤ 0.05) differences in species cover in the last year of the experiment between plots with and without fungicide application tested with a factorial ANOVA with block used as a covariate.</p

Number of plant species in plots with fungicide application and in control plots.

<p>The graph shows means and standard errors (n = 10). Columns marked by the same letter are not significantly different (P > 0.05). Tests were performed using a GLM with a Poisson distribution, with block as a covariate.</p

Effect of fungicide treatment on plant growth.

<p>Comparison of cover of <i>Aster amellus</i> (A), cover of <i>Brachypodium pinnatum</i> (B), cover of graminoids (C) and cover of perennial forbs (D) in plots with fungicide application and in control plots during the 3 years of the experiment. The graph shows means and standard errors (n = 10). Columns marked by the same letter are not significantly different (P > 0.05) in a factorial ANOVA. Data from 2007 were collected before fungicide application.</p

Effect of cover of graminoids on species richness.

<p>Significant negative correlation between change in cover of graminoids and change in species richness in plots with and without 3 years of fungicide application (F_1,18 = 19.51; P < 0.001; linear regression).</p