Plant Secondary Metabolites—Missing Pieces in the Soil Organic Matter Puzzle of Boreal Forests

Processes underlying soil organic matter (SOM) transformations are meeting growing interest as SOM contains more carbon (C) than global vegetation and the atmosphere combined. Therefore, SOM is a crucial element of the C cycle, especially in ecosystems rich in organic matter, such as boreal forests. However, climate change may shift the fate of this SOM from C sink into C source, accelerating global warming. These processes require a better understanding of the involved mechanisms driving both the C cycle and the interlinked nitrogen (N) cycle. SOM transformations are balanced by a network of interactions between biological, chemical and physical factors. In this review, we discuss the findings of the most recent studies to the current state of knowledge about the main drivers in SOM transformations. We focus on plant-derived secondary metabolites, as their biochemical traits, especially interactions with soil microbial communities, organic N compounds and enzymes make them potential regulators of SOM decomposition. However, these regulatory abilities of plant-derived compounds are not fully explored.Peer reviewe

Tannins and Their Complex Interaction with Different Organic Nitrogen Compounds and Enzymes : Old Paradigms versus Recent Advances

Tannins, an abundant group of plant secondary compounds, raise interest in different fields of science, owing to their unique chemical characteristics. In chemical ecology, tannins play a crucial role in plant defense against pathogens, herbivores, and changing environmental conditions. In the food industry and in medicine, tannins are important because of their proven positive effect on human health and disease treatment, Such wide interests fueled studies on tannin chemistry, especially on their flagship ability to precipitate proteins. In this Review, we expand the basic knowledge on tannin chemistry to the newest insights from the field. We focus especially on tannin reactions with different non-protein organic N compounds, as well as the complex interactions of tannins with enzymes, resulting in either an increase or decrease in enzyme activity.Peer reviewe

Fast and reliable method to estimate global DNA methylation in plants and fungi with high-pressure liquid chromatography (HPLC)-ultraviolet detection and even more sensitive one with HPLC-mass spectrometry

Abstract: DNA (Deoxyribonucleic acid) methylation is one of the epigenetic modifications of DNA, acting as a bridge between genotype and phenotype. Thus, disruption of DNA methylation pattern has tremendous consequences for organism development. Current methods to determine DNA methylation suffer from methodological drawbacks like high requirement of DNA and poor reproducibility of chromatograms. Here we provide a fast and reliable method using high-pressure liquid chromatography (HPLC)-ultraviolet (UV) detector and even more sensitive one with HPLC- mass spectrometry (MS) and we test this method with various plant and fungal DNA isolates. We optimized the preparation of the DNA degradation step to decrease background noise, we improved separation conditions to provide reliable and reproducible chromatograms and conditions to measure nucleotides in HPLC-MS. We showed that global DNA methylation level can be accurately and reproducibly measured with as little as 0.2 µM for HPLC-UV and 0.02 µM for HPLC-MS of methylated cytosine

Precise method to measure fungal and bacterial necromass using high pressure liquid chromatography with fluorescence detector adjusted to inorganic, organic and peat soils

Soil organic matter is the dominant pool of carbon (C) in terrestrial ecosystems. Recent advances in understanding of the mechanisms of C stabilization in the soil emphasize microbes as the main drivers. Special attention is placed on the accumulation of bacterial and fungal necromasses. This calls for development of fast and reliable methods to estimate microbial necromass in a various type of soils, including peat soils. Here we provide precise method to measure fungal and bacterial necromasses with high-pressure liquid chromatography-fluorescence detector (HPLC-FLD) and its comparison with gas chromatography method. Purity of the chromatographic peaks was confirmed with mass spectrometry. The HPLC-FLD method provides reliable results for mineral, organic and highly organic peat soils

Uniqueness of tree stand composition and soil microbial communities are related across urban spruce-dominated forests

Context: Urban forest soils represent significant reservoirs of biodiversity in cities. Retaining this diversity under urban land-use change requires understanding on how species richness, community assembly and uniqueness of species assemblages are related to local forest characteristics and surrounding landscape structure. Objectives: Our aim was to assess the significance and relative importance of logging history, tree species composition and urbanization in shaping soil microbial communities across urban spruce-dominated forest landscapes. We investigated responses of microbial diversity from three complementary viewpoints: local diversity, community assembly patterns and community uniqueness. Methods: We collected soil bacterial and fungal metabarcoding data from 73 spruce-dominated forest sites distributed in three urban centers across southern Finland. We related these data to measurements of logging intensity, tree species composition and degree of urbanization. Results: Logging intensity, tree species composition and urbanization affected site-scale microbial diversity, but the effects varied between microbial groups. Only logging intensity had a significant imprint on microbial assembly, and this effect was restricted to bacteria. Relative uniqueness of microbial assemblages at the landscape-scale was coupled with the uniqueness of tree species composition in all microbial groups, and further affected by tree diversity in saprotrophic fungi and urbanization in ectomycorrhizal fungi. Conclusions: In the context of urban spruce-dominated forests, locally diverse tree stands are not necessarily the same as those that contribute the most to landscape-scale diversity. Identifying and preserving contrasting tree stand structures, which support distinctive soil microbial assemblages, may be the winning strategy in maintaining a wide range of soil microbial diversity

Species-dependent responses of crop plants to polystyrene microplastics

Abstract: Only recently there has been a strong focus on the impacts of microplastics on terrestrial crop plants. This study aims to examine and compare the effects of microplastics on two monocotyledonous (barley, Hordeum vulgare and wheat, Triticum aestivum), and two dicotyledonous (carrot, Daucus carota and lettuce, Lactuca sativa) plant species through two complimentary experiments. First, we investigated the effects of low, medium, and high (103, 105, 107 particles per mL) concentrations of 500 nm polystyrene microplastics (PS-MPs) on seed germination and early development. We found species-dependent effects on the early development, with microplastics only significantly affecting lettuce and carrot. When acutely exposed during germination, PS-MPs significantly delayed the germination of lettuce by 24%, as well as promoted the shoot growth of carrot by 71% and decreased its biomass by 26%. No effect was recorded on monocot species. Secondly, we performed a chronic (21 d) hydroponic experiment on lettuce and wheat. We observed that PS-MPs significantly reduced the shoot growth of lettuce by up to 35% and increased its biomass by up to 64%, while no record was reported on wheat. In addition, stress level indicators and defence mechanisms were significantly up-regulated in both lettuce and wheat seedlings. Overall, this study shows that PS-MPs affect plant development: impacts were recorded on both germination and growth for dicots, and responses identified by biochemical markers of stress were increased in both lettuce and wheat. This highlights species-dependent effects as the four crops were grown under identical conditions to allow direct comparison. For future research, our study emphasizes the need to focus on crop specific effects, while also working towards knowledge of plastic-induced impacts at environmentally relevant conditions

Expectations of disabled persons and physiotherapists towards sexual rehabilitation

Wstęp. Kluczowym elementem w prowadzeniu skutecznej rehabilitacji seksualnej jest nie tylko odpowiednia wiedza, ale również zrozumienie potrzeb i oczekiwań pacjentów. Celem pracy było porównanie oczekiwań osób z uszkodzeniem narządu ruchu i fizjoterapeutów wobec rehabilitacji seksualnej. Materiał i metody. W badaniach ankietowych wzięło udział 100 fizjoterapeutów (77 K i 23 M) oraz 66 osób niepełnosprawnych (39 K i 27 M) z uszkodzeniem narządu ruchu. W ankiecie zadano pytania dotyczące roli rehabilitacji seksualnej w kompleksowym modelu rehabilitacji oraz oczekiwanego zakresu działań, jakie powinna obejmować. Wyniki. Obydwie grupy doceniają rolę kontaktów seksualnych w życiu codziennym. U większości (67%) niepełnosprawnych inicjacja miała miejsce po zaistnieniu niepełnosprawności, co przełamuje stereotypowy obraz możliwości seksualnych osób niepełnosprawnych. Zarówno niepełnosprawni, jak i fizjoterapeuci nadają wysoką rangę rehabilitacji seksualnej w holistycznym modelu rehabilitacji. Za podstawowe jej cele badani uznali przełamywanie mitów, lęków i stereotypów poprzez informowanie społeczeństwa oraz indywidualne dostosowanie odpowiednich pozycji seksualnych. Wykazano istotną zależność (p < 0,05) między wskazywaniem na ważną rolę rehabilitacji seksualnej a samodzielnym poszukiwaniem wiedzy na ten temat. Znaczna część niepełnosprawnych nigdy w procesie usprawniania nie spotkała się z problematyką rehabilitacji seksualnej. Informacji oczekuje się przede wszystkim od lekarzy, psychologów i fizjoterapeutów. Wnioski: 1. Wśród niepełnosprawnych rosną oczekiwania wobec rehabilitacji seksualnej, jednak mają oni problemy ze znalezieniem odpowiedniej wiedzy w tym zakresie. Należy więc rozszerzyć zakres szkoleń dla osób, od których oczekują oni pomocy w pierwszej kolejności (lekarzy, fizjoterapeutów). 2. Powszechna wiedza dotycząca seksualności osób niepełnosprawnych oparta jest w znacznej mierze na stereotypach, dlatego ich przełamywanie powinno być jednym z głównych celów rehabilitacji seksualnej.Introduction. Key element in conducting the effective sexual rehabilitation (SR) is not only an adequate knowledge, but also understanding needs and expectations of patients. Comparing expectations of persons with motor disability and physiotherapists towards the sexual rehabilitation was a purpose of the work. Material and method. One hundred physiotherapists took part in the questionnaire examination (77 female and 23 male) and 66 persons with motor disability (39 female and 27 male). In questionnaire form questions about role of the SR in the comprehensive model of the rehabilitation were asked as well as expected range of activities it should contain. Results. Both groups appreciate the role of sexual contacts in the everyday life. At the majority (67%) of disabled the initiation took place after becoming disable, what is breaking the stereotyped image of their sexual possibilities. Both disabled persons and physiotherapists are giving the sexual rehabilitation high rank in the holistic model of rehabilitation. For SR basic aims examined persons recognized firstly breaking myths, fears and stereotypes by informing the society and secondly individual adapting appropriate sexual positions. An essential relation was demonstrated (p < 0.05) between pointing at the important role of the sexual rehabilitation and independent seeking the knowledge onto this subject. The considerable part of disabled persons never met with issues of the SR. The proper information should be available mainly from doctors, psychologists and physiotherapists. Conclusions. 1. In group of disabled persons expectations towards the sexual rehabilitation are growing, but they have problems with finding adequate knowledge in this subject. Special courses should be led for persons, from which they expect the help at first (doctors, physiotherapists). 2. The common knowledge about the sexuality of disabled is mostly based on stereotypes, that&#8217;s why breaking them should be one of the main aims of the sexual rehabilitation

Restriction of plant roots in boreal forest organic soils affects the microbial community but does not change the dominance from ectomycorrhizal to saprotrophic fungi

Boreal forest soils store significant amounts of carbon and are cohabited by saprotrophic and ectomycorrhizal fungi (ECM). The 'Gadgil effect' implies antagonistic interactions between saprotrophic fungi and ECM. Plant photosynthates support the competitive fitness of the ECM, and may also shape the soil bacterial communities. Many 'Gadgil effect' experiments have focused on litter layer (O-L) or have litter and root-fragments present, and thus possibly favor the saprotrophs. We compared how the restriction of plant roots and exudates affect soil microbial community structures in organic soil (mixed O-F and O-H). For this, we established a 3-yr field experiment with 3 different mesh treatments affecting the penetration of plant roots and external fungal hyphae. Exclusion of plant photosynthates induced modest changes in both fungal and bacterial community structures, but not to potential functionality of the microbial community. The microbial community was resilient towards rather short-term disturbances. Contrary to the 'Gadgil effect', mesh treatments restricting the entrance of plant roots and external fungal hyphae did not favor saprotrophs that originally inhabited the soil. Thus, we propose that different substrate preferences (fresh litter vs. fermented or humified soil), rather than antagonism, maintain the spatial separation of saprotrophs and mycorrhizal fungi in boreal forest soils.Peer reviewe

Interaction between ectomycorrhizal and ericoid mycorrhizal plants decelerates stable soil organic matter decomposition

Boreal forests are N-limited ecosystems storing globally significant amounts of carbon (C) belowground as soil organic matter (SOM). The significant role of mycorrhizal fungi, both ericoid (ERM) and ectomycorrhizal (ECM) in decomposition and building up SOM has been proposed, but it is still largely unknown how these two types of mycorrhiza interact in terms of SOM changes. Here we try to elucidate the combined effect of these mycorrhizal types on the SOM decomposition and accumulation in a pot study with ECM-pine (Pinus sylvestris L.) and ERM-heather (Calluna vulgaris L.). Experimental design included plants growing alone or in a mixture, and a non-planted control. In contrast to the mixture, heather growing alone exerted higher biomass, higher uptake of N from stable SOM pool, slightly higher microbial biomass C and fungal biomass. Moreover, heather soil had the highest dissolved organic carbon and nitrogen. On the contrary, mixed cultures showed lower growth of heather and stable SOM decomposition. Our results suggest that interaction between ERM and ECM plants may lead to stable SOM accumulation in boreal forest soils

Site fertility and soil water-table level affect fungal biomass production and community composition in boreal peatland forests

A substantial amount of below-ground carbon (C) is suggested to be associated with fungi, which may significantly affect the soil C balance in forested ecosystems. Ergosterol from in-growth mesh bags and litterbags was used to estimate fungal biomass production and community composition in drained peatland forests with differing fertility. Extramatrical mycelia (EMM) biomass production was generally higher in the nutrient-poor site, increased with deeper water table level and decreased along the length of the recovery time. EMM biomass production was of the same magnitude as in mineral-soil forests. Saprotrophic fungal biomass production was higher in the nutrient-rich site. Both ectomycorrhizal (ECM) and saprotrophic fungal community composition changed according to site fertility and water table level. ECM fungal community composition with different exploration types may explain the differences in fungal biomass production between peatland forests. Melanin-rich Hyaloscypha may indicate decreased turnover of biomass in nutrient-rich young peatland forest. Genera Lactarius and Laccaria may be important in nutrient rich and Piloderma in the nutrient-poor conditions, respectively. Furthermore, Paxillus involutus and Cortinarius sp. may be important generalists in all sites and responsible for EMM biomass production during the first summer months. Saprotrophs showed a functionally more diverse fungal community in the nutrient-rich site.Peer reviewe