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Purpose Plant microbial biostimulants, such as arbuscular mycorrhizal fungi (AMF), enhance nutrient concentration in fruits, including tomato. However, field studies on tomato AMF inoculation are scarce. AMF species belonging to Gigasporaceae and Glomeraceae families known to vary in life-history strategies may determine differential effects on plant nutrient benefits and residue decomposition. Despite this, the effect of different life-history strategies on nutrient acquisition of tomato fruits has not been investigated yet. Methods We studied the effect of inoculation of two tomato varieties with four AMF species belonging to Glomeraceae and Gigasporaceae. Fungal colonization, yield, fruit nutrient concentration, litter decomposition, and bacterial and fungal abundances in soil were assessed in the field under organic agriculture. Results Overall Gigasporaceae promoted the concentration of nutrients in tomato fruits compared to Glomeraceae. A variability in AM fungal colonization and fruit nutrient concentration was detected within Glomeraceae. Scutellospora pellucida increased the yield (+ 27%) of var. Rio Grande with respect to Gigaspora gigantea . In var. Rio Grande, inoculation with Funneliformis mosseae did not change litter decomposition as compared to non-inoculated controls, whereas it was lower than in Sclerocystis sinuosa and Gigasporaceae species, which showed the highest decomposition rates. AMF inoculation promoted soil total bacterial and fungal abundance and fungal:bacterial (F:B) ratio compared to controls, and members of Gigasporaceae had the highest F:B ratio. Conclusion These findings pointed at the inclusion of AM fungal life-history strategy within the selection criteria for the development of biofertilizers able to enhance the nutritional value of vegetables under organic farming systems.

Determining the effects of nitrogen (N) and phosphorus (P) application on arbuscular mycorrhizal fungi (AMF) communities is important for predicting AMF responses to nutrient deposition. The AMF parameters and soil properties were monitored in karst grassland after 2 years of N and P addition. Then, AMF abundance, diversity, and community composition significantly differed between seasons. AMF abundance was higher in July (summer) than in December (winter), whereas richness and Chao1 estimator values showed the opposite results. The numbers of the genera Funneliformis and Sclerocystis were significantly more abundant in December, but the proportions of Scutellospora, Redeckera, and Diversispora were significantly higher in July. N and NP treatments significantly increased AMF abundance; richness and Chao1 values in the P treatment were significantly higher than those of the control in July. AMF community composition changed substantially between December and July but did not respond to fertilization. AMF abundance was significantly correlated with total N (TN), while AMF richness was also significantly correlated with available P (AP) and pH. pH and nitrate N (NO3−-N) strongly affected AMF community composition. These results suggested that P became more limiting with N fertilization, AMF investment increased access to more P, and richness was lower when certain AMF taxa (Diversisporales) increased in abundance during the growing season and under more P-limiting conditions. These results also suggested that N and P addition have specifically different effects on AMF abundance and diversity, and consequently potential effect on long-term vegetation composition and productivity.

Contrasting life-history characteristics of arbuscular mycorrhizal (AM) fungal families may have important implications for mycorrhizal functioning. Nevertheless, the effect of inoculation with AM fungi having different life-history strategies on the quality parameters of tomato fruits was not investigated. In this study, fruit and sauce quality of two tomato varieties were evaluated in field conditions after inoculation with four AM fungal species belonging to Glomeraceae and Gigasporaceae. The functional relationship between AM fungal traits (i.e., root colonization structures, community diversity) and fruit quality parameters was analyzed. AM fungal inoculation increased total phenols (TPC) and lycopene concentration in fruits of both varieties (47% and 247%, respectively) and antioxidant activity in var. Rio Grande (85%). Gigasporaceae were more effective in increasing TPC and antioxidant activity compared to Glomeraceae in var. Rio Grande. Gigaspora gigantea outperformed Scutellospora pellucida in var. Pisanello for TPC, antioxidant activity, and lycopene. Inoculated strains of G. gigantea, S. pellucida, Funneliformis mosseae, and Sclerocystis sinuosa were molecularly retrieved within tomato roots. In both varieties, a functional relationship between occurrence of arbuscules in roots and fruit quality was found. In var. Rio Grande, the abundance of some native AM fungal taxa shaped the pattern of fruit quality parameters. Gigasporaceae might be of great relevance for the synthesis of health-promoting compounds in tomato and should be included in biostimulant programmes targeting the production of high-quality vegetables.

1. General theories of plant defence often fail to account for complex interactions between the resources required for defence expression. For example, the carbon that is used for carbon‐based defence is acquired using nutrient‐rich photosynthetic pigments, while nutrient gain itself requires substantial carbon allocation belowground. We should therefore expect the expression of plant defence to reflect the tight linkage between carbon and nutrient gain, yet mechanistic studies linking resource gain with plant defence theory have been slow to emerge. 2. The overwhelming majority of plants participate in nutrition mutualisms with fungal or bacterial symbionts. We propose the resource exchange model of plant defence (REMPD) in which the costs and benefits associated with nutrition mutualisms affect plant resource status and allocation to growth and defence. The model predicts quadratic relationships between mutualist abundance and expression of defence. Within plant genotypes, both plant biomass and defence expression are maximized at optimal nutrient exchange among mutualistic partners, and as a consequence, the two are positively associated. 3. We tested the model by growing Asclepias syriaca, the common milkweed, with two mycorrhizal fungal species in nine fungal abundance treatments. Plant growth and defence traits and mycorrhizal colonization were quantified after 14 weeks of plant growth. Linear, quadratic, saturating and exponential decay models were fit to curves relating the proportion of root colonized by mycorrhizal fungi to plant traits, and compared using AICc. 4. As predicted by our model, increasing colonization by Scutellospora pellucida produced quadratic responses in plant growth, latex exudation and cardenolide production. In contrast, Glomus etunicatum appeared to act as a parasite of A. syriaca, causing exponential decline in both plant growth and latex exudation. As predicted by our model, plant growth was positively correlated with all defences quantified. 5. Synthesis. The REMPD combines cost-benefit analysis of mutualisms with plant resource acquisition strategies to predict the expression of plant defence. The effects of S. pellucida and G. etunicatum on defence expression differ; however, both provide support for the model and suggest that resource mutualisms affect the expression of defence in a predictable nonlinear fashion.

The study aimed to assess the symbiosis between maize ( Zea mays L.) and sorghum ( Sorghum bicolor L. Moench) with four AMF (Arbuscular Mycorrhizal Fungi) genera: Glomus, Acaulospora, Gigaspora , and Scutellospora . Based on their morphological characteristics, these genera were identified after being isolated from 40 rhizosphere soil samples collected in a vegetable-growing region of Ho Chi Minh City, Vietnam. The trial results demonstrated that growth parameters, including root number, root length, root biomass, and plant height of maize and sorghum plants, all increased significantly in the presence of AMF strains compared to plants without AMF supplementation. After 45 days of inoculation, the genus Glomus exhibited a 62.7% symbiosis rate with the host plant, with an average total spore count of 153.2 spores per 100 g of soil. Acaulospora had an average symbiosis rate of 50.7%, with 138 spores per 100 g of soil. Gigaspora and Scutellospora had lower symbiosis rates (45.8% and 46.7%, respectively), with average spore counts of 123.2 and 106.2 spores per 100 g of soil. Maize had an average spore density of 116.0 spores per 100 g of soil after 45 days of AMF inoculation, making it a more suitable host plant than sorghum for promoting an increase in AM fungal spore production.

The impact of lead (Pb) pollution on native communities of arbuscular mycorrhizal fungi (AMF) was assessed in soil samples from the surroundings of an abandoned Pb smelting factory. To consider the influence of host identity, bulk soil surrounding plant roots soil samples of predominant plant species (Sorghum halepense, Bidens pilosa, and Tagetes minuta) growing in Pb-polluted soils and in an uncontaminated site were selected. Molecular diversity was assessed by sequencing the 18S rDNA region with primers specific to AMF (AMV4.5NF/AMDGR) using Illumina MiSeq. A total of 115 virtual taxa (VT) of AMF were identified in this survey. Plant species did not affect AMF diversity patterns. However, soil Pb content was negatively correlated with VT richness per sample. Paraglomeraceae and Glomeraceae were the predominant families while Acaulosporaceae, Ambisporaceae, Archaeosporaceae, Claroideoglomeraceae, Diversisporaceae, and Gigasporaceae were less abundant. Acaulosporaceae and Glomeraceae were negatively affected by soil Pb, but Paraglomeraceae relative abundance increased under increasing soil Pb content. Overall, 26 indicator taxa were identified; four of them were previously reported in Pb-polluted soils (VT060; VT222; VT004; VT380); and five corresponded to cultured spores of Scutellospora castaneae (VT041), Diversispora spp. and Tricispora nevadensis (VT060), Diversispora epigaea (VT061), Glomus proliferum (VT099), and Gl. indicum (VT222). Even though AMF were present in Pb-polluted soils, community structure was strongly altered via the differential responses of taxonomic groups of AMF to Pb pollution. These taxon-specific differences in tolerance to soil Pb content should be considered for future phytoremediation strategies based on the selection and utilization of native Glomeromycota.

Sengon is a plant the Government of Indonesia uses to develop National Forestry programs such as HTI, reforestation, and community forests. Reality shows that sengon plants can adapt to critical environmental conditions and improve soil fertility without difficult silvicultural treatment. This can happen because sengon plants associate with arbuscular mycorrhizal fungi and nitrogen-fixing root nodule bacteria ( rhizobium ). This study aimed to determine the types of mycorrhizae related to sengon plants’ roots in Maluku’s natural habitat conditions. This research occurred at the Forestry Biotechnology Laboratory, IPB Bogor Biotechnology Research Center. Plant samples were taken from Maluku regions: Ambon Island, Banda, Mangole, and Sulabesi. This study used soil and root samples, staining solution, glucose, Melzer, and aquades. Parameters observed were the number of spores and % root infection. The experimental design used was a completely randomized design. The results of the identification of CMA spores showed that four genera were found: Glomus, Acaulospora, Gigaspora , and Scutellospora . The genus Acaulospora had the highest number and density of spores, followed by Glomus , Gigaspora , and Scutellospora . This study also showed that trapping results increased the percent infection of the roots of sengon plants. The structure of external hyphae, internal vesiculas, and spores indicates this.

Some plant species took an alternative evolutionary pathway in which they lost their photosynthetic capacity to depend exclusively on carbon supplied by arbuscular mycorrhizal fungi (AMF) in an association called mycoheterotrophy. Among them is Voyriella parviflora, a species of the family Gentianaceae, which is found in tropical regions such as the Amazon basin. Here, we assessed the identity of AMF symbionts associated with this species. DNA was isolated from eight Gentianaceae specimens and from litter and surrounding roots of photosynthetic plants. The atp1 gene was amplified by Sanger sequencing to determine the taxonomic affiliation of the mycoheterotrophic plants. A 280 bp region of the 18S rRNA gene of AMF was amplified with primers NS31/AML2 by high-throughput sequencing. The mycoheterotrophic specimens were assigned to V. parviflora with a bootstrap support of 72%. Glomus was the most abundant AMF genus, both in the mycoheterotrophic plants and in the litter and roots of photosynthetic plants. In addition, a few Glomus genotypes were abundantly enriched in the mycoheterotrophic plants, with only a few specimens colonized by Gigaspora, Acaulospora, and Scutellospora in a low proportion. These genotypes formed a cluster within a larger clade, suggesting that V. parviflora shows a preferential association with a narrow Glomus lineage which is not phylogenetically close to a previously identified V. parviflora’s associated lineage. Furthermore, detecting fungi from other families suggests that V. parviflora is colonized by other genera, although with low frequency. These findings provide new insights into the association between AMF and mycoheterotrophic species and highlight the importance of considering trap culture-independent approaches in understanding this symbiosis.

This study aimed to evaluate the occurrence of mycorrhizal fungi and glomalin content in soil under different cover crops with and without the application of nitrogen in the cover. The following cover plants were used: Crotalaria juncea ( Crotalaria juncea L.), wild beans from Ceará ( Canavalia brasiliensis Mart. ex Benth.), Guandú ‘BRS mandarin’ [ Cajanus cajan (L.) Millsp.], millet ‘BR05’ [ Pennisetum glaucum (L.) R.Br.] and sorghum ‘BR 304’ [ Sorghum bicolor (L.) Moench]. The absolute control of the experiment was the treatment without the use of cover crops, that is, the vegetation of spontaneous occurrence in the area. The experimental design was randomized blocks in subplots with three replications. Spore density, mycorrhizal colonization rate, easily extractable glomalin, and species present in the rhizosphere of the cover crops were determined. No differences were found in the diversity of mycorrhizal fungi associated with the different cover crops studied or in the values of spore density, root colonization, or glomalin content. Nitrogen application did not influence the mycorrhizal activity in the investigated cover crops. The most frequent species associated with cover crops were Scutellospora pellucida and Scutellospora persica in C. juncea ; Gigaspora sp. on Sorghum; Glomus macrocarpum in Guandu; G. macrocarpum and Glomus clavisporum in millet; and Glomus microaggregatum and Glomus tortuosum in Spontaneous Vegetation.

This study explored whether wildfire alters the soil properties and arbuscular mycorrhizal fungi (AMF) community composition when compared with burnt rangeland, non-burnt rangeland and adjacent tilled in mesothermal ecosystems. The study was carried out in August 2020, 1 year later after wildfire. The results of this study showed that the wildfire played a key role in altering soil characteristics and AMF community composition in Bartin Province located in the Western Black Sea Region. Soil samples were made according to standard methods. AMF spores were isolated according to the wet sieving method, and the spores of AMF were identified according to their morphological characteristics. Analysis of variance was performed to determine the differences between the parameters, and correlation analysis was performed to determine the relationships between the parameters. The highest values of soil organic carbon (2.20%), total nitrogen (0.18%), K 2 O (74.68 kg/da), root colonization (87.5%) and the frequency of occurrence of Funneliformis geosporum (20%) , Claroideoglomus claroideum (16%) and Claroideoglomus etunicatum (11%) were found in burnt rangeland. Sporulation of Acaulospora dilatata, Acaulospora morrowiae, Acaulospora tuberculata, Scutellospora castanea, Scutellospora coralloidea, Scutellospora scutata, Glomus coremioides and Glomus multicaule was either decreased or completely inhibited in the burnt rangeland. While species diversity of AMF (12) decreased, the number of AMF spores (325.6 (number/50 gr soil)) increased in burnt areas. In conclusion, the number of spores and root colonization of AMF increased but species diversity of AMF reduced after the wildfire. In ecosystems with high fire risk where AMF transfer is planned, it is suggested that it would be more appropriate to select species with an increase in spore number after fire.