Intensity Of Colonization Research Articles

Pedoclimatic conditions impact the mycorrhizal potential of the rhizospheric soil, essential oil yield, chemical profile, and biological activities in Lavandula dentata

Lavandula dentata produces a wide range of products, essential oils (EO) and bioactive molecules, extensively used for their various cosmetic and medicinal properties. However, in Morocco, L. dentata has been classified among vulnerable species experiencing a noticeable decline due to several biotic and abiotic stresses. This study aims to better understand the relationship between the ability of L. dentata, to produce bioactive molecules and pedoclimatic conditions. The study was carried out in two semi-arid regions: Asni (altitude: 1400 m) and Had Draa (altitude: 120 m). The results showed that the pedoclimatic conditions did not affect significantly the natural mycorrhization of Lavender expressed in terms of mycorrhizal frequency and colonization intensity. However, the mycorrhizal potential of the soil was 3 to 4 times higher in Asni than in Had Draa. Asni pedoclimatic conditions favored higher EO yield (14 μL/g DM) which was 2 times higher than in Had Draa. However, EO of Had Draa exhibited greater effectiveness in terms of antimicrobial, and herbicidal activities. While the EO of Had Draa was characterized by a high abundance of endo-borneol (36%) and fenchol (20%), the EO chemical profile of the EO of Asni showed high abundance of camphor (28%) and terpinene-4-ol (12%). Taken together, the findings pointed out that the pedoclimatic conditions prevailing in Asni such as high altitude, high precipitation, low nutrient levels, and low organic matter could improve the mycorrhizal potential of the soil, increase L. dentata EO yield, but have a negative impact on its biological activities.

Domestication of rice may have changed its arbuscular mycorrhizal properties by modifying phosphorus nutrition-related traits and decreasing symbiotic compatibility.

Modern cultivated rice (Oryza sativa) typically experiences limited growth benefits from arbuscular mycorrhizal (AM) symbiosis. This could be due to the long-term domestication of rice under favorable phosphorus conditions. However, there is limited understanding of whether and how the rice domestication has modified AM properties. This study compared AM properties between a collection of wild (Oryza rufipogon) and domesticated rice genotypes and investigated the mechanisms underlying their differences by analyzing physiological, genomic, transcriptomic, and metabolomic traits critical for AM symbiosis. The results revealed significantly lower mycorrhizal growth responses and colonization intensity in domesticated rice compared to wild rice, and this change of AM properties may be associated with the domestication modifications of plant phosphorus utilization efficiency at physiological and genomic levels. Domestication also resulted in a decrease in the activity of the mycorrhizal phosphorus acquisition pathway, which may be attributed to reduced mycorrhizal compatibility of rice roots by enhancing defense responses like root lignification and reducing carbon supply to AM fungi. In conclusion, rice domestication may have changed its AM properties by modifying P nutrition-related traits and reducing symbiotic compatibility. This study offers new insights for improving AM properties in future rice breeding programs to enhance sustainable agricultural production.

Soil microenvironmental variation drives below‐ground trait variation and interacts with macroclimate to structure above‐ground trait variation of arctic shrubs

Abstract Intraspecific trait variation can influence plant performance in different environments and may thereby determine the ability of individual plants to respond to climate change. However, our understanding of its patterns and environmental drivers across different spatial scales is incomplete, especially in understudied regions like the Arctic. To fill this knowledge gap, we examined above‐ground and below‐ground traits from three shrub taxa expanding across the tundra biome and evaluated their relationships with multiple microenvironmental and macroclimatic factors. The traits reflected plant size and structure (plant height, leaf area and root to shoot ratio), leaf economics (specific leaf area, nitrogen content), and root economics and collaboration with mycorrhizal fungi (specific root length, root tissue density, nitrogen content, and ectomycorrhizal colonisation intensity). We also measured leaf and root δ15N and leaf δ13C to characterise nitrogen source and acquisition pathways and plant water stress. Traits were measured in replicated plots (N = 135) varying in soil microclimate, thaw depth and organic layer thickness established across five sites spanning a macroclimate gradient in northern Alaska. This hierarchical design allowed us to disentangle the independent and combined effects of fine‐scale and broad‐scale factors on intraspecific trait variation. We found substantial intraspecific variation at fine spatial scales for most traits and less variation along the macroclimate gradient and between shrub taxa. Consistent with these patterns, microenvironmental factors, mainly soil moisture and thaw depth, interacted with macroclimate, mainly climatic water deficit, to structure size‐structural and leaf trait variation. In contrast, most root traits responded additively to thaw depth and macroclimate. Synthesis. Our results demonstrate that above‐ground and below‐ground tundra shrub traits respond differently to microenvironmental and macroclimatic variation. These differing responses contribute to substantial trait variation at fine spatial scales and may decouple above‐ground and below‐ground trait responses to climate change.

The role of the gut microbiota in the genesis of gallstone formation in childhood

Cholelithiasis has been and remains a frequent socially significant public health problem worldwide. The pathomorphosis of the disease has also undergone significant changes, which has significantly rejuvenated, occurring not only at a young age, but also in childhood. More than 175,000 cholecystectomies are performed annually for cholelithiasis. Cholelithiasis affects 10-20% of the adult population in our country. At the same time, cholecystectomy came in second place after appendectomy. There are no official statistics on the prevalence of GCD in the general population of children in Russia. In the Krasnodar Territory, the incidence of cholelithiasis in childhood, according to the data of circulation, is 1.8-3.3%. Over the past decade, a number of studies have been conducted confirming the role of the microbiota in various parts of the gastrointestinal tract as a new link in the etiopathogenesis of GI. Intestinal bacteria (Clostridium, Bifidobacterium, Peptostreptococcus, Bacteroides, Eubacterium, Escherichia coli), involved in the oxidation and epimerization of bile acids, can disrupt enterohepatic circulation and lead to the formation of gallstones. At the same time, cholecystectomy leads to further transformation of the microbiota composition in various parts of the gastrointestinal tract, increasing the risk of developing stomach cancer and colorectal cancer. Further research is needed to determine the possibility of using the assessment of the composition of the gastrointestinal microbiota as a marker for the early diagnosis of various gastroenterological diseases of cholelithiasis in particular. The purpose of the study: To determine the role of the intestinal microbiota in the development of metabolic disorders in children with cholelithiasis in order to predict the complicated course of the disease. Material and methods. The work was carried out on the basis of the children’s city polyclinic No. 122 Moscow`s Health Department (chief physician - A.I. Bragin), 194 children with housing and communal services were under supervision. The control group consisted of 78 practically healthy children of the I Health group. The study groups were comparable in gender and age. Criteria for inclusion in the study: children with an established diagnosis of cholelithiasis, asymptomatic course at the age of 3 to 15 years. Exclusion criteria from the study: refusal of the child’s legal representative from the study, the presence of diagnosed acute diseases in the child during the last month, chronic somatic diseases, taking antibiotics and probiotics in the last 6 months, catamnestic observation for less than 12 months. General clinical studies were conducted: questionnaires, health assessment, anthropometry, biochemical examination of blood serum, including lipidogram, ultrasound examination of the abdominal cavity and gallbladder. To assess the intestinal microbiome, the following methods were used: standard bacteriological analysis of feces (method of sowing feces on liquid agarized nutrient media); complex coprological examination with the determination of pancreatic elastase (ELISA method) and fecal carbohydrates (Benedict method); biochemical examination of feces with the determination of short-chain fatty acids (SCFCS) (gas-liquid chromatography method); The Shannon index was adopted as a measure of intestinal dysbiosis. Statistical analysis was performed using the software package Statistica8.0 and MS OfficeExcel 2010/ The results of the study and the conclusion. The biotransformation of the bile acid pool mediated by the gut microbiota regulates the metabolism of bile, glucose and lipids. In children with GI, the number of bacteria representing the indigenous microbiota is generally lower, the intensity of colonization of the intestinal mucosa by them is significantly less, the species diversity of opportunistic and pathogenic bacteria is significantly higher compared with those in practically healthy children. There is an unstable and poor-quality system of interrelation with the macroorganism, disparate metabolic pathways. MK is not able to qualitatively maintain homeostasis within its own consortium. All this creates conditions for disruption of bile acid metabolism and the formation of lithogenic bile. The presence of intestinal dysbiosis in children with GI can cause not only the formation of gallstones, but also negatively affect the further growth and development of children, including the formation of metabolic complications and inflammatory processes.

Soil Properties and Forest Decline in the North-Western Part of Romania

The paper presents the study of the soil quality and health expressed by the chemical and biological properties in a research field placed at Varciorog, Bihor County, Romania. The soil samples were collected from 3 soil variants in March 2023. In each soil variant, some soil chemical parameters and the abundance of bacteria were determined. The frequency and intensity of colonization, along with arbuscules and vesicles, were scored to determine the mycorrhizal potential of each soil. The community-level physiological profile was used to determine the functional microbiome and its ability to decompose a specific set of substrates. In the control variant (CTRL), which is a functional forest cultivated with beech in a proportion of 90%, the soil properties were compared with those determined from Site 1 (a declined mixed forest) and from Site 2 (chestnut forest in a stage of complete drying). The data were statistically processed with a one-way ANOVA test, followed by the Duncan post-hoc test, which revealed significant variation in the potential of microbial functional communities across the analyzed sites. Also, the soil parameters that significantly varied in the 3 soil variants were bacterial number, pH, humus, exchangeable aluminum, coarse sand, dust, and fine sand. The Pearson correlation was computed to study the links between bacterial numbers and chemical parameters. The results showed strong correlations between most of the studied soil properties. The Ecoplates approach to soil functional microbiome highlighted various differences between the microbial communities of the three tested sites. Mycorrhizal colonization shows different potentials for symbiosis formation. The peak of mycorrhizal colonization was in declined forest, with 43.36% colonization frequency and 24.56% intensity. Arbuscules reached 11.36% in declined forest, while in control and decayed sites, the indicator was under 4%. Vesicles are more associated with control and decayed forests, with values of presence over 1.30%. As an indicator of microbial general activity, the sum of recorded activities was higher in declined and decayed forests. At these sites, the activity of the functional microbiome was amplified. The decline process activates a higher diversity of functional groups and is associated with a larger area of substrate decomposition capacity, which indicates a more extensive range of microbial functions related to breaking down organic matter.

The effect of herbicides on arbuscular mycorrhizal fungi associated with annual invasive Asteroideae weeds

Invasive plants Galinsoga parviflora and Erigeron canadensis are common in crops and adjacent territories. One of the factors contributing to their spread is the community of arbuscular mycorrhizal fungi associated with these species. The nature of the symbiotic relationship between the host plant and AMF is determined by their phylogenetic position and place of growth. The aim of this work was to determine the level of mycorrhizal colonization of E. canadensis и G. parviflora growing in arable fields and along them. For plants at the flowering stage, high rates of frequency and intensity of mycorrhization were revealed. It has been shown that the level of mycorrhizal colonization of E. canadensis and G. parviflora is significantly influenced by the range of herbicides applied. The application of 2.4 D slightly reduced the intensity of colonization, but significantly stimulated the formation of arbuscules in plant roots. In turn, metribuzin prevented the formation of mycorrhiza. AMF associated with these plants formed a separate clade. This group, in our opinion, is responsible for more effective symbiosis with invasive plants of the Asteroideae subfamily and requires further closer study.

Mycorrhizas and Trichoderma fungi increase the accumulation of secondary metabolites in grain legume leaves and suppress foliar diseases in field-grown conditions of the humid forest of Cameroon

BackgroundArbuscular mycorrhizal and Trichoderma fungi alter the synthesis of secondary metabolites of plants and confer tolerance from pathogens attacks. However, there is less supportive evidence from on-field studies confirming the above-mentioned hypothesis, particularly for the humid forest zone of Cameroon where pathogens are important sources of yield losses for legumes such as soybean and common bean.Materials and methodsWe evaluated the impacts of mycorrhiza isolates of Rhizophagus intraradices (Ri) and Trichoderma asperellum (Ta) fungi and their co-inoculations (Ta x Ri) in the synthetizing of leaves secondary metabolites, foliar disease symptoms, growth, N and P uptake, and yields of three genotypes of soybean (TGx 1485-1D, TGx 1990-93 F, and TGx 1990-97 F) and common beans (NUA-99, DOR-701, and PNN) under field conditions of Cameroon.ResultsWe found that common bean plants showed a lower foliar infection rate but a higher increase in root colonization intensity, shoot dry weight, and N and P uptakes than soybeans when inoculated with Ri and Ta treatment. However, the grain yield of soybean soybean was higher (2000 kg ha 1) than the common bean plants for the Ri × Ta treatment. The soybean genotype TGx 1990-93F had increased root colonization intensity and the lowest foliar infection rate, making it stronger and tolerant to pathogen attacks when co-inoculated with Ri × Ta fungi (F). Bean plants inoculated with Ri and the co-inoculated with Ri × Ta demonstrated lower symptoms of foliar attack, and increased root colonization, particularly the PNN variety. The total amino acid and proline accumulations were higher for soybean than common bean plants due to fungi inoculations, and soybean genotypes accumulated more excellent contents of amino acid and proline in the control (10.1 mg g− 1 fwt) that significantly increased under the Ri × Ta inoculation (13.4 mg g− 1 fwt).ConclusionsCommon bean plants inoculated with Ta and Ri fungi accumulated higher phenolic compounds in their leaves that aided them in overcoming the pathogen attacks than soybean plants.

Higher colonization but lower diversity of root-associated arbuscular mycorrhizal fungi in the topsoil than in deep soil

Arbuscular mycorrhizal fungi (AMF) colonizing plant roots play a pivotal role in maintaining soil nutrient cycling and ecosystem stability, and this role may vary in different habitat environments. However, the influence of soil depth on root AMF colonization, diversity, and the complex interactions among AMF taxa is still not well understood. In this study, we investigated the frequency, intensity, and abundance of root AMF colonization, as well as root AMF diversity, composition, and co-occurrence patterns across three soil depths: 0–20 cm, 20–40 cm, and the soil-rock mixing layer. Soil nutrients (e.g., organic matter, nitrogen, and phosphorus) and root biomass were higher in the 0–20 cm layer than in the soil-rock mixing layer, while soil pH showed an opposite relationship. The higher root biomass in the upper soil layer may enhance root secretions and exudates, thereby promoting root AMF colonization. In contrast, the lower soil nutrient content and higher soil pH observed in the 20–40 cm and soil-rock mixing layers may contribute to greater AMF diversity in the deeper soil layers compared to the topsoil. Although no significant differences were observed in the composition of the root AMF community, specific amplicon sequence variants affiliated with Glomus, Racocetra, and unclassified taxa were more enriched in the 20–40 cm and soil-rock mixing layers compared to the 0–20 cm layer. Network analysis revealed that deep soil, compared to topsoil, enhances interactions among root AMF by intensifying competitive relationships. This suggests that the complex interactions among root AMF taxa within deep soil contribute to the resilience of root AMF in resource-scarce conditions, particularly in the 20–40 cm layer and the soil-rock mixing layer. At the genus level, Glomus, Racocetra, and unclassified taxa emerged as keystone taxa due to their prominent linkage with other root AMF groups. Collectively, the results suggest that higher soil nutrient levels and root biomass can promote root mycorrhizal colonization but suppress AMF diversity and weaken interactions among root AMF taxa in the upper soil layer compared to deeper soil layers. Furthermore, the distinct functions of AMF colonization and diversity at different soil depths should be considered when evaluating vegetation reconstruction in karst ecosystems with varied soil depth distribution.

Impact of roots on the hydrogeological properties of silty soil covers

Mine tailings storage poses significant environmental risks such as the formation of acid mine drainage. Engineered covers offer a solution by controlling water ingress. Their performance is based on specific soil hydrogeological properties (SHPs). They must support vegetation which can impact saturated hydraulic conductivity ( ksat) and water retention curve (WRC). This study assesses the impact of 4-year-old willow root colonization on silty soil covers using flexible wall parameters and water retention tests. The obtained SHPs were compared with root traits. The results suggested that the hydrogeological properties of the studied in situ samples were not significantly affected by roots. The variation of measured and predicted ksat values spanned an order of magnitude, regardless of the root colonization intensity, up to a root length density (RLD) of 2.98 cm/cm3. RLD showed a significant and positive linear relationship with measured ksat values ( R2 = 0.54). However, when root colonization was low (RLD < 1 cm/cm3), RLD was negatively correlated with the nvG ( R2 = 0.44) parameter of the van Genuchten WRC model, while the opposite relationship was observed for samples with RLD > 1 cm/cm3 ( R2 = 0.61). Additionally, RLD and the coarse root (diameter > 1 mm) volume to fine root volume (C/F ratio) influenced WRCs. Over time, coarser roots may have a more pronounced impact on SHPs; further research is needed.

Positioning absorptive root respiration in the root economics space across woody and herbaceous species

Abstract1. Root respiration is essential for nutrient acquisition. The respiration rate of absorptive roots theoretically relates to the economics of carbon‐nutrient exchange, but its empirical role remains largely unexplored in the trait space defining nutrient uptake strategies.2. Here, we measured the respiration rates of the distal, non‐woody, absorptive roots of 252 woody and herbaceous species from subtropical and temperate climate zones, including both arbuscular mycorrhizal and ectomycorrhizal fungal hosts.3. We found a consistent and positive correlation between root respiration rate and specific root length (root length per dry weight), irrespective of growth form, mycorrhizal type and climate zone. Root respiration rate was also positively, but less strongly and less frequently correlated with root nitrogen concentration. Root morphology strongly explained the fast‐slow gradient of root respiration in the root economics space.4. By quantifying the ratio of arbuscular mycorrhizal fungal DNA copy number and root tissue DNA copy number using qPCR, we found that the morphology‐driven gradient did not explain the full variation in fungal collaboration; thick roots were consistently well colonised, but medium and thin roots displayed a wide range of colonisation intensity.5. Synthesis: These results advance our understanding of the fundamental trait relationships that underpin the root economics space. Our study also provides a physiological linkage to the frequently measured root morphological traits and relates the root economics space to root‐derived carbon‐nutrient cycling processes.

Symbiotic compatibility between rice cultivars and arbuscular mycorrhizal fungi genotypes affects rice growth and mycorrhiza-induced resistance.

Arbuscular mycorrhizal fungi (AMF) belong to the Glomeromycota clade and can form root symbioses with 80% of Angiosperms, including crops species such as wheat, maize and rice. By increasing nutrient availability, uptake and soil anchoring of plants, AMF can improve plant's growth and tolerance to abiotic stresses. AMF can also reduce symptoms and pathogen load on infected plants, both locally and systemically, through a phenomenon called mycorrhiza induced resistance (MIR). There is scarce information on rice mycorrhization, despite the high potential of this symbiosis in a context of sustainable water management in rice production systems. We studied the symbiotic compatibility (global mycorrhization & arbuscules intensity) and MIR phenotypes between six rice cultivars from two subspecies (indica: IR64 & Phka Rumduol; japonica: Nipponbare, Kitaake, Azucena & Zhonghua 11) and three AMF genotypes (Funneliformis mosseae FR140 (FM), Rhizophagus irregularis DAOM197198 (RIR) & R. intraradices FR121 (RIN)). The impact of mycorrhization on rice growth and defence response to Xanthomonas oryzae pv oryzae (Xoo) infection was recorded via both phenotypic indexes and rice marker gene expression studies. All three AMF genotypes colonise the roots of all rice varieties, with clear differences in efficiency depending on the combination under study (from 27% to 84% for Phka Rumduol-RIN and Nipponbare-RIR combinations, respectively). Mycorrhization significantly (α=0.05) induced negative to beneficial effects on rice growth (impact on dry weight ranging from -21% to 227% on Azucena-FM and Kitaake-RIN combinations, respectively), and neutral to beneficial effects on the extent of Xoo symptoms on leaves (except for Azucena-RIN combination which showed a 68% increase of chlorosis). R. irregularis DAOM197198 was the most compatible AMF partner of rice, with high root colonisation intensity (84% of Nipponbare's roots hyphal colonisation), beneficial effects on rice growth (dry weight +28% (IR64) to +178% (Kitaake)) and decrease of Xoo-induced symptoms (-6% (Nipponbare) to -27% (IR64)). Transcriptomic analyses by RT-qPCR on leaves of two rice cultivars contrasting in their association with AMF show two different patterns of response on several physiological marker genes. Overall, the symbiotic compatibility between rice cultivars and AMF demonstrates adequate colonization, effectively restricting the nutrient starvation response and mitigating symptoms of phytopathogenic infection.

The opportunistic protist, Giardia intestinalis, occurs in gut-healthy humans in a high-income country

ABSTRACT Giardia intestinalis, a cosmopolitan gastrointestinal protist, is detected mainly in patients with clinical giardiasis in high-income countries. In contrast, there is very little information on the presence of Giardia in asymptomatic individuals. Therefore, the aim of this study was to determine the presence and prevalence of Giardia in gut-healthy volunteers in the Czech Republic and to perform a comparative evaluation of different diagnostic methods, since Giardia diagnostics is complicated. Our results confirmed that the qPCR method is the most sensitive method for detecting Giardia and revealed a prevalence of 7% (22/296) in asymptomatic individuals. In most cases, the colonization intensity ranged from 10−1–101. A conventional PCR protocol targeting the TPI gene was used to identify the assemblages. However, this protocol had limited sensitivity for Giardia amplification, effectively detecting colonization above an intensity of 104. In addition, Giardia was detected in 19% of the animals, which were closely associated with the study participants. However, due to methodological limitations, zoonotic transmission could not be clearly confirmed. Notably, contact with animals proved to be the only factor that had a significant impact on the incidence of Giardia in gut-healthy humans.

Quantifying root colonization by a symbiotic fungus using automated image segmentation and machine learning approaches

Arbuscular mycorrhizas (AM) are one of the most widespread symbiosis on earth. This plant-fungus interaction involves around 72% of plant species, including most crops. AM symbiosis improves plant nutrition and tolerance to biotic and abiotic stresses. The fungus, in turn, receives carbon compounds derived from the plant photosynthetic process, such as sugars and lipids. Most studies investigating AM and their applications in agriculture requires a precise quantification of the intensity of plant colonization. At present, the majority of researchers in the field base AM quantification analyses on manual visual methods, prone to operator errors and limited reproducibility. Here we propose a novel semi-automated approach to quantify AM fungal root colonization based on digital image analysis comparing three methods: (i) manual quantification (ii) image thresholding, (iii) machine learning. We recognize machine learning as a very promising tool for accelerating, simplifying and standardizing critical steps in analysing AM quantification, answering to an urgent need by the scientific community studying this symbiosis.

Effects of Phosphorus-dissolving Dark Septate Endophytes on the Growth of Blueberry.

Dark septate endophytes (DSEs) are widely distributed and improve plant growth. DSEs secrete large amounts of enzymes to mineralize insoluble phosphorus in soil and convert it into soluble phosphorus, promoting plant uptake of phosphorus. However, the effects of DSEs with phosphate-solubilizing ability on host plants need further study. In this study, phosphorus-dissolving DSEs were screened for growth-promoting effects. We isolated, identified and characterized three DSE species (Thozetella neonivea, Pezicula ericae and Hyaloscyphaceae sp.) showing phosphate-solubilizing ability. The impact of single, dual or triple inoculation of DSEs on blueberry plant characteristics was studied. Their effects on colonization intensity, seedling biomass, nutrients in plants and soil, and activities of plant resistance enzymes and soil enzymes were markedly upregulated relative to the control (P < 0.05). The available phosphorus and acid phosphatase levels in different combinations were significantly increased. These findings indicate that the application of the three DSEs may be valuable in facilitating the cultivation of blueberry with a higher biomass and improved plant quality.

Predicting the seasonal flight activity of Myzus persicae, the main aphid vector of Virus Yellows in sugar beet.

Virus Yellows (VY), a disease caused by several aphid-borne viruses, is a major threat to the global sugar beet production. Following the ban of neonicotinoid-based seed treatments against aphids in Europe, increased efforts are needed to monitor and forecast aphid population spread during the sugar beet growing season. In particular, predicting aphid flight seasonal activity could allow anticipation of the timing and intensity of crop colonisation and contribute to the proper implementation of management methods. Forecasts should be made early enough to assess risk, but can be updated as the season progresses to refine management. Based on a long-term suction-trap dataset gathered between 1978 and 2014, we built and evaluated a set of models to predict the flight activity features of the main VY vector, Myzus persicae, at any location in the French sugar beet production area (c. 4 × 105 ha). Flight onset dates, length of flight period and cumulative abundance of flying aphids were predicted using climatic and land-use predictors as well as geographical position. Our predictions outperformed current models published in the literature. The importance of the predictor variables varied according to the predicted flight feature but winter and early spring temperature always played a major role. Forecasts based on temperature were made more accurate by adding predictors related to aphid winter reservoirs. In addition, updating the model parameters to take advantage of new weather data acquired during the season improved the flight forecast. Our models can be used as a tool for the mitigation in sugar beet crops. © 2023 Society of Chemical Industry.

Edaphic factors and elevation gradient influence arbuscular mycorrhizal colonization and spore density in the rhizosphere of Shorea robusta Gaertn

Arbuscular mycorrhizal fungi (AMF) are important ecosystem engineers that improve nutrient uptake and help plants adapt to a variety of abiotic stresses. Few studies have examined the relationship between AMF and a specific host tree along an elevation gradient. Shorea robusta is the dominant tree species in Nepal's tropical forests, with very high timber value. The goal of this study was to ascertain how edaphic factors and elevation gradient influence AMF colonization and spore density within the rhizosphere of Shorea robusta. The present study was conducted in four S. robusta dominated forests ranging from 82 m to 950 m asl. Among the four forests, Tarai Sal forest (TSF); Bhabar Sal forest (BSF) belonged to lower elevation Sal forest and Plateau Sal forest (PSF); Hill Sal forest (HSF) belonged to high elevation Sal forest. The percentage of AMF colonization and soil spore density were assessed by magnified intersect method and wet sieving and decanting method respectively. The edaphic factors viz. organic matter, nitrogen, phosphorous, potassium, pH, soil temperature, bulk density, moisture content, and water holding capacity of soil were determined by standard methods. Total AMF colonization ranged from 33% to 57%. Spore density, on the other hand, ranged from 25 to 366 per 100 g of soil. The maximum AMF root colonization and spore density for lower elevation Sal forest was 52% and 39/100 g of soil respectively while that for higher elevation Sal forest was 57% and 366/100 g of soil respectively. Pearson's correlation test revealed that total AMF colonization as well as spore density in the rhizosphere of S. robusta were affected by phosphorus content, pH, moisture content, water-holding capacity, soil temperature, and elevation. Moreover, the spore density was also affected by nitrogen content. Total AMF colonization and spore density were found to be highly correlated. Overall, the intensity of AMF colonization and spore density were higher in higher elevation Sal forest compared to the lower elevation Sal forest. This study can be used to gain insights into the active involvement of AMF in the sustainable management of the forest ecosystem.

Changes in arbuscular mycorrhizal fungal communities, mycorrhizal soil infectivity, and phosphorus availability under Chromolaena odorata (Asteraceae) invasions in a West-African forest-savanna ecotone.

Substantial areas of agricultural lands in Sub-Saharan Africa have been invaded by Chromolaena odorata (Asteraceae), but the consequences for arbuscular mycorrhiza fungi (AMF) remains poorly understood. This study explores changes in diverse AMF community attributes and soil available phosphorus following C. odorata invasion in forest and savanna fragments in Côte d'Ivoire (West Africa). Invaded-forest (COF) and savanna (COS) sites were compared to adjacent natural forest (FOR) and savanna (SAV) fragments, respectively. Physico-chemical variables and AMF spore density parameters were determined for soil samples from 0-20cm depth. An 18S ribosomal RNA metabarcoding analysis of AMF communities was conducted. In addition, cowpea (Vigna unguiculata)was grown on soils collected from these sites under greenhouse conditions for determination of soil mycorrhizal infectivity. Noticeable changes in the composition of AMF communities in C. odorata relative to nearby forest and savanna non-invaded sites were observed. AMF-specific richness in COS (47 species) was lower than that in SAV (57 species) while it was higher in COF (68 species) than in FOR (63 species). COF and COS differed in AMF specific composition (Dissimilarity index = 50.6%). Chromolaena odorata invasions resulted in increased relative abundances of the genera Claroideoglomus and Glomus in COF, a decreased relative abundance of Paraglomus in COS and decreased relative abundances of Ambispora in both COF and COS. Total and healthy spore densities, cowpea root colonization intensity and soil available P were all higher in invaded sites than in natural ecosystems. Remarkably, although these values were different in FOR and SAV, they turned out to be similar in COF and COS (4.6 and 4.2 total spores g-1 soil, 2.3 and 2.0 healthy spores g-1 soil, and 52.6 and 51.6% root colonization, respectively) suggesting a C. odorata-specific effect. These findings indicate that soil mycorrhizal potential and phosphorus availability have improved following C. odorata invasion.

Old-growth Acer macrophyllum trees host a unique suite of arbuscular mycorrhizal fungi and other root-associated fungal taxa in their canopy soil environment

ABSTRACT Canopy soils occur on tree branches throughout the temperate rainforests of the Pacific Northwest Coast and are recognized as a defining characteristic of these ecosystems. Certain tree species extend adventitious roots into these canopy soil environments. Yet, research on adventitious root-associated fungi remains limited. Our study used microscopy to compare fungal colonization intensity between canopy and forest floor roots of old-growth bigleaf maple (Acer macrophyllum) trees. Subsequently, two high-throughput sequencing platforms were used to explore the spatial and seasonal variation of root-associated fungi between the two soil environments over one year. We found that canopy and forest floor roots had similar colonization intensity and were associating with a diversity of arbuscular mycorrhizal fungi and other potential symbionts, many of which were resolved to species level. Soil environment and seasonality affected root-associated fungal community composition, and several fungal species were indicative of the canopy soil environment. In Washington State’s (USA) temperate old-growth rainforests, these canopy soil environments host a unique suite of root-associated fungi. The presence of arbuscular mycorrhizae provides further evidence that adventitious roots form fungal associations to exploit canopy soils for resources, and there may be novel relationships forming with other fungi. These soils may be providing a redundancy compartment (i.e., “nutrient reserve”), imparting a resiliency to disturbances for certain old-growth trees.

Arbuscular Mycorrhizal Fungi as an Important Factor Enabling the Adaptation of Anthyllis vulneraria L. to Zn-Pb-Polluted Tailings.

The old Zn-Pb-contaminated (calamine) tailings in southern Poland are spontaneously colonized by metal-tolerant Anthyllis vulneraria L. (Fabaceae), which can form simultaneously symbiotic association with nitrogen-fixing rhizobia and phosphorus-acquiring arbuscular mycorrhizal fungi (AMF). So far, fungal colonization and the AMF diversity of calamine-inhabiting legumes have been poorly studied. Thus, we determined AMF spore density in the substratum and the mycorrhizal status of nodulated A. vulneraria plants occurring on calamine tailings (M) and on a reference non-metallicolous (NM) site. The results indicate the presence of the Arum-type of arbuscular mycorrhiza in the roots of both Anthyllis ecotypes. Despite the presence of AM fungi in M plant roots, the dark septate endophyte (DSE) fungi (hyphae and microsclerotia) were occasionally also detected. Metal ions were accumulated mainly in the nodules and intraradical fungal structures rather than thick plant cell walls. Mycorrhization parameters (frequency of mycorrhization and intensity of root cortex colonization) for M plants were markedly higher and differed in a statistically significant manner from the parameters for NM plants. Heavy metal excess had no negative effect on the number of AMF spores, the amounts of glomalin-related soil proteins and AMF species composition. Molecular identification of AMF using PCR-DGGE analysis based on the 18S rDNA ribosomal gene by nested-PCR with primers AM1/NS31 and NS31-GC/Glo1 revealed similar genera/species of AMF in the roots of both Anthyllis ecotypes: Rhizophagus sp., R. fasciculatus, and R. iranicus. The results of this work indicate the presence of unique fungal symbionts, which may enhance A. vulneraria tolerance to heavy metal stress and plant adaptation to extreme conditions on calamine tailings.

QUALITATIVE AND QUANTITATIVE COMPOSITION OF MYCOFLORA OF GRAY FOREST SOIL UNDER DIFFERENT DIRECTIONS OF AGRICULTURAL LAND USE

This article presents the results of research on the quantitative and species composition of soil fungi, including pathogenic, gray forest soils in the conditions of the Right Bank Forest Steppe. The mycoflora of the soil was considered for different directions of agricultural land use including soils under intensive apple orchards, intensive crop cultivation and fallow. The condition of soil micromycetes was studied based on the indicators of the abundance of the main ecological and trophic groups. In soils, fungi are determined to be critical players in the ecosystem and play a huge role in agriculture and soil microbiome. The results of research showed certain changes in the content and composition of mycobiota in soils, as a result of their fourteen-year use under fallow, garden and field crop rotations. The difference in the intensity of micromycete colonization of soils of different agricultural lands was revealed: fallow 125.7 thousand CFU/g, intensive gardening 130.5 thousand CFU/g, field crop rotation 191.2 thousand CFU/g. The negative influence of intensive horticulture on quantitative and qualitative indicators of soil mycoflora was established. It was investigated that the lowest percentage of saprotrophic fungi, the highest percentage of pathogenic fungi and toxin-producing species of fungi from the total number of isolated species were observed in the soils of the apple orchard under intensive horticulture, compared to the soils of fallow and field crop rotation. A common feature of all soils of various uses is the presence of representatives of genera Penicillium, Gliocladium and Trichoderma in the soil. Fallow soils were not represented by species from the genera Rhizopus, Arthrinium and Cladosporium, compared to the other soils. However, only they contained representatives of genera Mucor and Absidia. Common to all the three presented soils was the presence of representatives of the species Trichoderma viride Pers. and Gliocladium roseum Bainier.