Nonlegumes, legumes, and root nodules harbor different arbuscular mycorrhizal fungal communities.

Legumes are an important plant functional group since they can form a tripartite symbiosis with nitrogen-fixing Rhizobium bacteria and phosphorus-acquiring arbuscular mycorrhizal fungi (AMF). However, not much is known about AMF community composition in legumes and their root nodules. In this study, we analyzed the AMF community composition in the roots of three nonlegumes and in the roots and root nodules of three legumes growing in a natural dune grassland. We amplified a portion of the small-subunit ribosomal DNA and analyzed it by using restriction fragment length polymorphism and direct sequencing. We found differences in AMF communities between legumes and nonlegumes and between legume roots and root nodules. Different plant species also contained different AMF communities, with different AMF diversity. One AMF sequence type was much more abundant in legumes than in nonlegumes (39 and 13%, respectively). Root nodules contained characteristic AMF communities that were different from those in legume roots, even though the communities were similar in nodules from different legume species. One AMF sequence type was found almost exclusively in root nodules. Legumes and root nodules have relatively high nitrogen concentrations and high phosphorus demands. Accordingly, the presence of legume- and nodule-related AMF can be explained by the specific nutritional requirements of legumes or by host-specific interactions among legumes, root nodules, and AMF. In summary, we found that AMF communities vary between plant functional groups (legumes and nonlegumes), between plant species, and between parts of a root system (roots and root nodules)

«Через край із серця рідне слово ллється…» (про мову поезій П. Куліша)

Several studies have shown that soil biotic communities from organically managed fields are more diverse and exhibit higher activity levels compared to conventionally managed fields. The impact of these different soil communities on plant productivity and the provision of soil ecosystem services are, however, still unclear. Here, we test the effects of soil inoculation from each of three organic and three conventional maize fields on maize productivity and nutrient loss during leaching events induced by simulated rain. In particular, we examine whether differences in productivity and nutrient loss are related to the abundance and species composition of arbuscular mycorrhizal (AM) fungi. We hypothesized that soil biota from organically managed fields would improve maize growth and reduce nutrient leaching significantly more than those from conventionally managed fields. In contrast to our hypothesis, we found that plant productivity was negatively affected by soil inoculation, and this effect was stronger with inoculum from organic fields. Plant productivity was inversely correlated with AMF abundance, suggesting that enhanced carbon allocation to AMF is at least in part responsible for plant growth reduction under our experimental conditions. However, soil inoculation did alter the ecological functioning of the system by reducing phosphorus leaching losses after simulated rain. Moreover, these leaching losses were lower with increased hyphal density and were related with abundance of particular AMF types, suggesting that abundance of AMF and their community composition may be useful indicators of phosphorus leaching losses. The results demonstrate that soil communities from different agricultural fields vary in their impact on plant productivity and nutrient leaching losses. The results further indicate that there is a potential tradeoff between positive effects of soil communities on sustainability and negative effects on crop productivity. © 2011 The Author(s)

Ігор Степанович Флюнт - доктор медичних наук

23 грудня 2003 року на засіданні спеціалізованої вченої Д 26.198.01 при Інституті фізіології ім. О.О. Богомольця НАН України успішно захистив докторську дисертацію за спеціальністю 14.03.04 - патологічна фізіологія провідний бальнеолог України, лауреат премії ім. Т. Торосєвича в галузі бальнеології, член Нью-Йоркської АН, член Ради Асоціації учених міста Трускавця, керівник трускавецької групи клінічної бальнеології та фітотерапії Інституту фізіології ім. О.О. Богомольця, начмед санаторію “Весна” ЗАТ ЛОЗ “Трускавецькурорт” Ігор Степанович ФЛЮНТ

Does conversion to reduced tillage really increase soil organic carbon stocks in organic arable farming?

Aggravation of weather extremes increases awareness of climate change consequences. Mitigation options are in demand that aim to reduce the atmospheric concentration of greenhouse gases. Amongst others, the conversion from ploughing to reduced tillage is argued to increase soil organic carbon (SOC) stocks as an accumulation of SOC in topsoil layers is commonly reported. Yet, reviews and meta-analyses describe various results from significant increases to just a redistribution of SOC in the soil profile. Reasons can be found in different sampling depths, SOC and bulk density measurement procedure, and stock calculation (equivalent soil mass vs. equal sampling depth). Furthermore, few studies evaluated the impact of organic farming systems. In nine long-term experiments on tillage systems in temperate Europe (France, Germany, Netherlands, and Switzerland), a common soil sampling campaign took place in spring and autumn 2017, and spring 2018. All trials represent common mixed organic farming systems of the respective region and contain plots with conventional and reduced tillage practices. While climatic conditions are similar, soil types vary from sandy to clayey soils. We took three undisturbed soil cores with driving hammer probes (8 cm in diameter) in each plot (minimum 3 plots per treatment) to a maximum depth of 100 cm and divided the cores in the increments 0-30, 30-50, 50-70, and 70-100 cm. The topsoil (0-30 cm) was further divided into the different tillage depths of the respective trial. We determined bulk density and organic carbon concentration as main variables and soil texture and pH as co-variates for each sample and collected C-inputs for each plot in all trails on a yearly basis. Multivariate statistics will enable the comprehensive evaluation of tillage effects on SOC stocks up to a depth of 100 cm in organic long-term trials. Texture, trial age, and the co-variate C-input will be decisive for the development of SOC stocks and enable the evaluation of carbon sequestration potentials of agricultural soils through improved tillage practices

Selectivity and functional diversity in arbuscular mycorrhizas of co-occurring fungi and plants from a temperate deciduous woodland

1 The arbuscular mycorrhizal (AM) fungi colonizing plants at a woodland site in North Yorkshire (UK) have been characterized from the roots of five plant species (Rubus fruticosus agg. L., Epilobium angustifolium L., Acer pseudoplatanus L., Ajuga reptans L. and Glechoma hederacea L.), and identified using small-subunit rRNA (SSUrRNA) gene amplification and sequencing. 2 Interactions between five plant species from the site and four co-occurring glomalean fungi were investigated in artificial one-to-one AM symbioses. Three of the fungi were isolated from the site; the fourth was a culture genetically similar to a taxon found at the site. Phosphorus uptake and growth responses were compared with non-mycorrhizal controls. 3 Individual fungi colonized each plant with different spatial distribution and intensity. Some did not colonize at all, indicating incompatibility under the conditions used in the experiments. 4 Glomus hoi consistently occupied a large proportion of root systems and outperformed the other fungi, improving P uptake and enhancing the growth of four out of the five plant species. Only G. hoi colonized and increased P uptake in Acer pseudoplatanus, the host plant with which it associates almost exclusively under field conditions. Colonization of all plant species by Scutellospora dipurpurescens was sparse, and beneficial to only one of the host plants (Teucrium scorodonia). Archaeospora trappei and Glomus sp. UY1225 had variable effects on the host plants, conferring a range of P uptake and growth benefits on Lysimachia nummularia and T. scorodonia, increasing P uptake whilst not affecting biomass in Ajuga reptans and Glechoma hederacea, and failing to form mycorrhizas with A. pseudoplatanus. 5 These experimental mycorrhizas show that root colonization, symbiont compatibility and plant performance vary with each fungus-plant combination, even when the plants and fungi naturally co-exist. 6 We provide evidence of physical and functional selectivity in AM. The small number of described AM fungal species (154) has been ascribed to their supposed lack of host specificity, but if the selectivity we have observed is the general rule, then we may predict that many more, probably hard-to-culture glomalean species await discovery, or that members of species as currently perceived may be physiologically or functionally distinct

Darkness visible: reflections on underground ecology

1 Soil science and ecology have developed independently, making it difficult for ecologists to contribute to urgent current debates on the destruction of the global soil resource and its key role in the global carbon cycle. Soils are believed to be exceptionally biodiverse parts of ecosystems, a view confirmed by recent data from the UK Soil Biodiversity Programme at Sourhope, Scotland, where high diversity was a characteristic of small organisms, but not of larger ones. Explaining this difference requires knowledge that we currently lack about the basic biology and biogeography of micro-organisms. 2 It seems inherently plausible that the high levels of biological diversity in soil play some part in determining the ability of soils to undertake ecosystem-level processes, such as carbon and mineral cycling. However, we lack conceptual models to address this issue, and debate about the role of biodiversity in ecosystem processes has centred around the concept of functional redundancy, and has consequently been largely semantic. More precise construction of our experimental questions is needed to advance understanding. 3 These issues are well illustrated by the fungi that form arbuscular mycorrhizas, the Glomeromycota. This ancient symbiosis of plants and fungi is responsible for phosphate uptake in most land plants, and the phylum is generally held to be species-poor and non-specific, with most members readily colonizing any plant species. Molecular techniques have shown both those assumptions to be unsafe, raising questions about what factors have promoted diversification in these fungi. One source of this genetic diversity may be functional diversity. 4 Specificity of the mycorrhizal interaction between plants and fungi would have important ecosystem consequences. One example would be in the control of invasiveness in introduced plant species: surprisingly, naturalized plant species in Britain are disproportionately from mycorrhizal families, suggesting that these fungi may play a role in assisting invasion. 5 What emerges from an attempt to relate biodiversity and ecosystem processes in soil is our extraordinary ignorance about the organisms involved. There are fundamental questions that are now answerable with new techniques and sufficient will, such as how biodiverse are natural soils? Do microbes have biogeography? Are there rare or even endangered microbes