Arbuscular Mycorrhizal Fungi Inoculation Research Articles

Arbuscular mycorrhizal fungi enhanced the drinking water treatment residue-based vertical flow constructed wetlands on the purification of arsenic-containing wastewater

Arsenic (As) is a toxic metalloid that poses a potential risk to the environment and human health. In this study, drinking water treatment residue (DWTR) and ceramsite-based vertical flow constructed wetlands (VFCWs) were built to purify As-containing wastewater. As a method of bioaugmentation, arbuscular mycorrhizal fungi (AMF) was inoculated to Pteris vittata roots to enhance the As removal of the VFCWs. The results showed that the As removal rates reached 87.82–94.29% (DWTR) and 33.28–58.66% (ceramsite). DWTR and P. vittata contributed 64.33–72.07% and 7.57–29% to the removal of As, while AMF inoculation intensified the As accumulation effect of P. vittata. Proteobacteria, the main As3+ oxidizing bacteria in the aquatic systems, dominated the microbial community, occupying 72.41 ± 7.76%. AMF inoculation increased As-related functional genes abundance in DWTR-based wetlands and provided a reliable means of arsenic resistance in wetlands. These findings indicated that the DWTR-based VFCWs with AMF inoculated P. vittata had a great purification effect on As-containing wastewater, providing a theoretical basis for the application of DWTR and AMF for As removal in constructed wetlands.

Genotypic variation of tomato to AMF inoculation in improving growth, nutrient uptake, yield, and photosynthetic activity

Arbuscular mycorrhizal fungi (AMF) promote water and mineral nutrients uptake by plant roots, which can reduce the chemical fertilizer inputs in crop production. To gain better insight into the comparative effect of different strains of AMF in improving tomato performance at morphological and physiological levels, seedlings of two tomato cultivars (i.e., Better Boy and Roma) were inoculated with four strains of Glomus mosseae (i.e., HS 1–2, BEG 12, BEG 55, and BEG 54) under greenhouse conditions. Results showed that tomato growth and yield varied largely depending on the mycorrhizal strain and tomato cultivar, with wide variations in root colonization ranging from 5.30 to 78.63%. Overall, mycorrhization with BEG 54 showed significantly better tomato performance when compared to the BEG 55, HS 1–2 and BEG 12 strains. In the case of cultivars, Better Boy performed better than Roma cultivar in terms of growth, physiological traits, yield, and fruit quality. The highest plant height, dry matter, nitrogen, phosphorus, potassium, chlorophyll a, chlorophyll b, AMF colonization, yield, fruit juice, ascorbic acid, and titratable acidity contents were recorded in Better Boy cultivar while the highest stem diameter was found in Roma cultivar. Taken together, AMF colonization suggested a promising approach for large-scale tomato production by efficient absorption and utilization of nutrients, and encouraging plants’ symbiotic relationships with soil microorganisms.

Positive Changes in Fruit Quality, Leaf Antioxidant Defense System, and Soil Fertility of Beni-Madonna Tangor Citrus (Citrus nanko × C. amakusa) after Field AMF Inoculation

Citrus plants rely heavily on arbuscular mycorrhizal fungi (AMF) due to their lack of root hairs. Most experiments have been conducted with AMF inoculation under potted conditions, while field inoculation of AMF on citrus, especially a high economic hybrid tangor variety Beni-Madonna (Citrus nanko × C. amakusa), has been rarely recorded. This study aimed to analyze the effects of two AMF inoculations (a single Funneliformis mosseae and a mixture of F. mosseae, Diversispora versiformis, and Rhizophagus intraradices) on the internal and external fruit quality, leaf antioxidant defense system, and soil fertility and structure of top-worked Beni-Madonna tangor citrus trees. Three and a half years after AMF inoculations, soil hyphal length and root mycorrhizal colonization rate increased by 61.2–101.8% and 15.85–29.6% in inoculated plants, respectively. Inoculated trees had higher external fruit coloration value, fruit horizontal diameter, and fruit weight, and lower fruit rigidity than uninoculated trees. AMF-inoculated trees had higher glucose levels of fruit peels, fructose and sucrose levels of fruit fleshes, and the ratio of fruit soluble solids/titratable acids, as well as lower titratable acids concentrations than non-AMF-inoculated trees. AMF inoculation significantly increased leaf nitrogen balance index, chlorophyll index, peroxidase, catalase, superoxide dismutase, and glutathione reductase activities, as well as reduced glutathione and oxidized glutathione concentrations, resulting in lower hydrogen peroxide and malondialdehyde levels when compared to the uninoculated treatment. In addition, inoculated trees presented higher soil nutrient levels, including organic carbon, available K, and Olsen-P as, well as soil aggregate stability (based on mean weight diameter) than uninoculated trees. This study concluded that field AMF inoculation improved fruit quality, enhanced leaf antioxidant defense system, and improved soil fertility of Beni-Madonna trees, with mixed AMF being prominent in improving fruit quality and F. mosseae being prominent in enhancing leaf antioxidant defense system and improving soil fertility.

Arbuscular mycorrhizal fungi increased peanut (Arachis hypogaea L.) yield by changing the rhizosphere microbial community structure in saline-alkali soil.

Arbuscular mycorrhizal fungi (AMF) have demonstrated the potential to enhance the saline-alkali tolerance in plants. Nevertheless, the extent to which AMF can ameliorate the tolerance of salt-sensitive plants to alkaline conditions necessitates further investigation. The current study is primarily centered on elucidating the impact of AMF on the growth of the Huayu22 (H22) when cultivated in saline-alkaline soil. We leveraged DNA of rhizosphere microorganisms extracted from saline-alkali soil subjected to AMF treatment and conducted high-throughput sequencing encompassing 16S rRNA gene and ITS sequencing. Our findings from high-throughput sequencing unveiled Proteobacteria and Bacillus as the prevailing phylum and genus within the bacterial population, respectively. Likewise, the predominant fungal phylum and genus were identified as Ascomycota and Haematonectria. It is noteworthy that the relative abundance of Proteobacteria, Actinobacteria, Chloroflexi, Bacteroidetes, and Ascomycota exhibited significant increments subsequent to AMF inoculation. Our investigation into soil enzyme activity revealed a remarkable surge post-AMF inoculation. Notably, the amounts of pathogen growth inhibitory enzymes and organic carbon degrading enzymes rise, as predicted by the putative roles of microbial communities. In saline-alkali soil, inoculation of AMF did boost the yield of H22. Notable improvements were observed in the weight of both 100 fruits and 100 grains, which increased by 20.02% and 22.30%, respectively. Conclusively, this study not only provides a theoretical framework but also furnishes empirical evidence supporting the utilization of AMF as a viable strategy for augmenting the yield of salt-sensitive plants grown in alkaline conditions.

The effect of indigenous Arbuscular mycorrhizal fungi (AMF) on phyto-accumulation in Carica papaya hybrids

Papaya (Carica papaya L.) is a climacteric fruit with a resilient and distinctive aroma. The consumption of the fruit is global due to its high nutritive and medicinal values. However, there has been low production of quality papaya fruits due to unavailability of crucial mineral elements in the soils. The current study therefore, focuses on the effect of indigenous arbuscular mycorrhizal fungi (AMF) as a biofertilizer on the quality of papaya fruits. In order to verify AMF effectiveness on papaya fruits, four treatments were used: AMF inoculum only, composted farm yard manure (FYM) only, combination of AMF inoculum and compost FYM and control where only soil and sand media were used at a ratio of 1:1. Jomo Kenyatta University of Agriculture and Technology (JKUAT) and Malkia papaya hybrids were used. The papaya seeds from JKUAT and Malkia papaya hybrids were sown in trays and transplanted at 3 leaves stage into 5 litre pots within a green house. The AMF spores were bulked using sorghum plants to obtain the AMF inoculum. The treatments were added into the soil media of the papaya plantlets at a ratio of 1:3, every 4 weeks after first transplanting until they were 20 weeks old. They were then transplanted to 100 litre containers, where completely randomized design was used and replication of six papaya plants for each treatment and hybrid. Watering, weeding and cooling the green house with water fumes was carried out when necessary; as the papaya plants grew until the fruits attained physiological maturity. The fruits were separately harvested and ripened to a predetermined stage. They were then analysed for moisture content, crude fibre, minerals (nitrogen, phosphorous, potassium, magnesium, calcium, iron and zinc), ascorbic acid, total carotenoids and total polyphenols. Data obtained was subjected to two-way ANOVA at p ≤ 0.05 significance level; means were separated using Tukey's HSD test in Genstat's 15th edition. JKUAT hybrid with AMF inoculum treatment had 3.07%crude fibre and 8.42mg/100g phosphorous content while JKUAT hybrid with both AMF inoculum and manure treatments had 4.9 % crude fibre and 9.88 mg/100g phosphorous content. Malkia and JKUAT hybrids with compost FYM treatment had potassium content of 98.31mg/100g and 109.4 mg/100g respectively while the controls had 31.58 mg/100g and 35.32mg/100g respectively. Incorporating soil media with manure and AMF inoculum improved the nutritive quality of papaya fruits and this was contingent on papaya hybrids. Key words: biofertilizer, inoculum, mineral elements, nutritive quality, physiological maturity

The physiological responses of celery (Apium graveolens L.) and its ability to accumulate selenium when inoculated with Funneliformis mosseae

Celery (Apium graveolens L.) has a strong capacity to enrich selenium (Se) and is a good system for research on Se enrichment in vegetables. Arbuscular mycorrhizal fungi (AMF) are commonly used plant symbionts that affect plant growth and their effectiveness is plant species specific. However, there is little research on the effects of AMF inoculation on the accumulation and translocation of Se in celery. The treatments in this study included inoculation with AMF (+AMF) and the application of different types and concentrations of exogenous Se. We evaluated the growth, root mycorrhizal colonization, photosynthetic pigment content, ascorbate-glutathione cycle (ASA-GSH cycle), the accumulation and translocation of Se and the combination of AMF + Se compared with an untreated control. The application of low concentrations of Se (≤10 mg kg−1) stimulated celery growth, while high concentrations (>20 mg kg−1) had the opposite effect. The inhibition of celery growth was more severe with Se6+ than Se4+ when applied at the same concentration. The accumulation of Se improved in all the organs of celery as the supply increased. AMF had a significant positive effect on the accumulation and translocation of Se. In addition, +AMF significantly increased the shoot height and root fresh weight of celery and reduced the inhibitory effect of Se on growth. However, +AMF had slight effects on the levels of photosynthetic pigments and the ASA-GSH cycle. +AMF combined with 10 mg kg−1 sodium selenite (Se4+) is an effective way to produce Se-rich celery.

Effects of Bio-Amendment of Coconut Dust with Empty Fruit Bunch Compost on the Efficacy of Mycorrhizae Under Deficit Fertigation

It has been known that the application of beneficial fungi and compost, has a favourable effect on easing water deficiency stress in plants, hence helping to boost agricultural activities in times of climate uncertainty. In this study, the influence of arbuscular mycorrhizal fungi (AMF) in combination with oil palm empty fruit bunch compost (EFB) on the growth, yield, and physiology of chilli under deficit fertigation was investigated. Throughout the study, five-week-old chilli seedlings were fertigated daily with 100% and 60% of daily evapotranspiration (ET) readings. Three days after transplanting, 10g of sandy soil containing roughly 120-150 mycorrhizal spores was applied to the root zone. Physiological data such as real-time photosynthesis and stomatal conductance were measured at vegetative, early flowering, fruit setting, and maturity or harvesting stages. Meanwhile, yield and morphological measurements were recorded at the end of the study. It was discovered that the addition of EFB to the coconut coir dust media enhanced the beneficial effects of AMF on all parameters including total biomass, chlorophyll fluorescence Fv/Fm, total chlorophylls, photosynthesis rate and stomatal conductance regardless of fertigation levels. The study also revealed that AMF inoculation alone was less effective than non-inoculation + EFB. In conclusion, it is suggested that incorporation of AMF and EFB compost positively affect the yield, growth and physiology of chilli under deficit fertigation.

Nano-iron and AM fungi inoculation in dryland wheat field: A sustainable alternative to plastic film mulching

ContextPlastic film mulching is a primary cultivation measure in the dryland agricultural areas of northwest China, but comes with the drawback of plastic pollution. To overcome this issue, the biological inoculants such as arbuscular mycorrhizal (AM) with nanotechnology might be a critical pathway, but their positive effects on plants are context-dependent and vary with species, application method, concentration, size, surface charge, and other physio-chemical properties. There is so far limited information available on the combined effects of AM fungi with nanoparticles in agriculture. ObjectivesThis study aimed to investigate the potential of iron nanoparticles (FeNPs) in combination with AMF regarding wheat productivity maintenance and its driving mechanism. MethodsHerein, we used a completely randomized block design for the field experiments in the years 2018 and 2019. We conducted two field experiments using nanopriming of seeds with iron nanoparticles (FeNPs) and AMF in two growing seasons in 2018 and 2019 on wheat (Triticum aestivum L., cv. Longchun29) in the field. Each plot had a 5 m × 5 m total area having 6 rows of 0.2 m spacing and 0.5 m buffer strip among the neighboring plots. There were 8 treatments in the field experiment, and each treatment was repeated 3 times, including four nano iron concentration seed soaking treatments (0 mg L-1, 5 mg L-1, 10 mg L-1, 15 mg L-1) and two inoculation treatments of arbuscular mycorrhizal fungi (inoculated with Gi and non-inoculated). ResultsCombined treatments with arbuscular mycorrhizal fungi and iron nanoparticles led to significant increases in wheat biomass and yield across 2018 and 2019. When compared with control treatment there was an increase of 111% in biomass for the year 2018 and a 102% increase was observed for the year 2019; while the increase in the yield percent when compared to control was 91% in 2018 and 85% in 2019 respectively. Water use efficiency for yield (WUE) increased by 92% in 2018 and 57% in 2019. The colonization rate of AMF + FeNPs 10 mg L-1 treatment increased by 223%, 88%, and 211%, respectively compared with control at the jointing, anthesis, and maturity stage in 2018; and increased by 48%, 37%, and 56% respectively in the year 2019. FeNPs at 10 mg L-1 led to small increases in total organic carbon (TOC), total nitrogen (TN), microbial biomass carbon and nitrogen (MBC), and (MBN), in both growing seasons, and AMF inoculation further significantly increased these carbon fractions by 2.6%, 20%, 21% and 26% in 2018; while 1.3%, 14.8%, 12.5%, and 35% in 2019 respectively. ConclusionThe combined treatments of FeNPs and AMF at an optimal concentration (10 mg L-1) significantly increased net economic income by 229% in 2018 and 138% in 2019 when compared to the control. In this study, wheat aboveground biomass and yield and other related parameters have been improved under field trials, which verified that AMF inoculation alongside FeNPs, can play a beneficial role in promoting dryland spring wheat. ImplicationsTaken together, the co-inoculation with FeNPs and AMF displayed a promising perspective in green production with the potential replacement of plastic film mulching in semiarid dryland regions.

Systematic analysis of the Rboh gene family in seven gramineous plants and its roles in response to arbuscular mycorrhizal fungi in maize

BackgroundPlant respiratory burst oxidase homolog (Rboh) gene family produces reactive oxygen species (ROS), and it plays key roles in plant–microbe interaction. Most Rboh gene family-related studies mainly focused on dicotyledonous plants; however, little is known about the roles of Rboh genes in gramineae.ResultsA total of 106 Rboh genes were identified in seven gramineae species, including Zea mays, Sorghum bicolor, Brachypodium distachyon, Oryza sativa, Setaria italica, Hordeum vulgare, and Triticum aestivum. The Rboh protein sequences showed high similarities, suggesting that they may have conserved functions across different species. Duplication mode analysis detected whole-genome/segmental duplication (WGD)/(SD) and dispersed in the seven species. Interestingly, two local duplication (LD, including tandem and proximal duplication) modes were found in Z. mays, S. italica and H. vulgare, while four LD were detected in T. aestivum, indicating that these genes may have similar functions. Collinearity analysis indicated that Rboh genes are at a stable evolution state in all the seven species. Besides, Rboh genes from Z. mays were closely related to those from S. bicolor, consistent with the current understanding of plant evolutionary history. Phylogenetic analysis showed that the genes in the subgroups I and II may participate in plant-AM fungus symbiosis. Cis-element analysis showed that different numbers of elements are related to fungal induction in the promoter region. Expression profiles of Rboh genes in Z. mays suggested that Rboh genes had distinct spatial expression patterns. By inoculation with AM fungi, our transcriptome analysis showed that the expression of Rboh genes varies upon AM fungal inoculation. In particularly, ZmRbohF was significantly upregulated after inoculation with AM fungi. pZmRbohF::GUS expression analyses indicated that ZmRbohF was induced by arbuscular mycorrhizal fungi in maize. By comparing WT and ZmRbohF mutant, we found ZmRbohF had limited impact on the establishment of maize-AM fungi symbiosis, but play critical roles in regulating the proper development of arbuscules.ConclusionsThis study provides a comprehensive analysis of the evolution relationship of Rboh genes in seven gramineae species. Results showed that several Rboh genes regulate maize-AM fungal symbiosis process. This study provides valuable information for further studies of Rboh genes in gramineae.

AmPHO2 gene expression and interaction protein screening of snapdragon inoculated with AM fungi under low phosphorus stress

Phosphorus (P) is involved in flowering and fruiting in plants. P deficiency inhibits the formation of plant reproductive organs and affects the process of flower bud differentiation, leads to delayed flowering and affects the number and quality of flowers. Our previous experiment showed that arbuscular mycorrhizal (AM) fungal inoculation could promote snapdragon (Antirrhinum majus L.) uptaking P, prolong the flowering period, and increase the number of flower buds and flowers at the full bloom stage under low P stress. The aim of this study is to preliminarily explore the molecular mechanism of AM fungus enhancing P absorption by snapdragon under low P stress. Four treatments were set up in this experiment, namely, low P level (0.1 mmol /L P), low P level (0.1 mmol /L P) +AM fungi, normal P level (0.7 mmol /L P), and normal P level (0.7 mmol/L P) + AM fungi, to evaluate regulation of AM fungi on the phosphate signaling factor PHOSPHATE 2 (PHO2) and the snapdragon flowering. Results showed that the P content in the roots, shoot apical meristem, buds and flowers of snapdragon inoculated with AM fungi increased and the expression of AmPHO2 decreased, suggesting that mycorrhizal symbiosis may inhibit the expression of AmPHO2. Total 28 AmPHO2 interacting proteins were screened by Yeast two-hybrid technique, among which the thioredoxin AmTrx was involved in the flowering process of the plant, and point-to-point validation and dual luciferase assay of AmTrx was further verified. This study showed that inoculation with AM fungi could negatively regulate AmPHO2, promote P uptake, flowering, and improve flower quality of snapdragon under low P stress.

Beneficial Interactive Effects Provided by an Arbuscular Mycorrhizal Fungi and Yeast on the Growth of Oenothera picensis Established on Cu Mine Tailings

Phytoremediation, an environmentally friendly and sustainable approach for addressing Cu-contaminated environments, remains underutilized in mine tailings. Arbuscular mycorrhizal fungi (AMF) play a vital role in reducing Cu levels in plants through various mechanisms, including glomalin stabilization, immobilization within fungal structures, and enhancing plant tolerance to oxidative stress. Yeasts also contribute to plant growth and metal tolerance by producing phytohormones, solubilizing phosphates, generating exopolysaccharides, and facilitating AMF colonization. This study aimed to assess the impact of AMF and yeast inoculation on the growth and antioxidant response of Oenothera picensis plants growing in Cu mine tailings amended with compost. Plants were either non-inoculated (NY) or inoculated with Meyerozyma guilliermondii (MG), Rhodotorula mucilaginosa (RM), or a combination of both (MIX). Plants were also inoculated with Claroideoglomus claroideum (CC), while others remained non-AMF inoculated (NM). The results indicated significantly higher shoot biomass in the MG-NM treatment, showing a 3.4-fold increase compared to the NY-NM treatment. The MG-CC treatment exhibited the most substantial increase in root biomass, reaching 5-fold that in the NY-NM treatment. Co-inoculation of AMF and yeast influenced antioxidant activity, particularly catalase and ascorbate peroxidase. Furthermore, AMF and yeast inoculation individually led to a 2-fold decrease in total phenols in the roots. Yeast inoculation notably reduced non-enzymatic antioxidant activity in the ABTS and CUPRAC assays. Both AMF and yeast inoculation promoted the production of photosynthetic pigments, further emphasizing their importance in phytoremediation programs for mine tailings.

Soil microbiome indicators can predict crop growth response to large-scale inoculation with arbuscular mycorrhizal fungi

Alternative solutions to mineral fertilizers and pesticides that reduce the environmental impact of agriculture are urgently needed. Arbuscular mycorrhizal fungi (AMF) can enhance plant nutrient uptake and reduce plant stress; yet, large-scale field inoculation trials with AMF are missing, and so far, results remain unpredictable. We conducted on-farm experiments in 54 fields in Switzerland and quantified the effects on maize growth. Growth response to AMF inoculation was highly variable, ranging from −12% to +40%. With few soil parameters and mainly soil microbiome indicators, we could successfully predict 86% of the variation in plant growth response to inoculation. The abundance of pathogenic fungi, rather than nutrient availability, best predicted (33%) AMF inoculation success. Our results indicate that soil microbiome indicators offer a sustainable biotechnological perspective to predict inoculation success at the beginning of the growing season. This predictability increases the profitability of microbiome engineering as a tool for sustainable agricultural management.

Soil microbial properties are improved by the adoption of soil management and conservation practices in no-tillage system

ABSTRACT No-tillage system (NTS) plays a prominent role in conservation agriculture, however, its benefits can be further improved by adopting complementary soil management and conservation practices, such as using autumnal cover crops, contour seeding, and terraces. This study aimed to evaluate how soil biological activity responds to soil management and conservation systems. The treatments consisted of three macroplots with an area of 11.000 m 2 each, as follows: a) Non-Terraced catchment (NTC), cultivated in NTS similar to most farmers of the region, in which the agricultural operations are carried out in the direction of the slope and without terraces used; b) Best Management Practices (BMPs) were adopted in NTS with additional autumnal cultivation of cover crops, and also the direction of machine traffic was transverse to the slope direction; and c) Terraced catchment (TC), cultivated in NTS was associated to mechanical practices to erosion control, using wide base terrace on level. Soil microbial properties sampled in the 0.00-0.10 m layer were evaluated during 2019, 2020, and 2021, all shortly after the summer crop harvest. Natural inoculum potential of arbuscular mycorrhizal fungi (AMF), respirometry, metabolic coefficient, acid phosphatase activity, and organic carbon and nitrogen in the microbial biomass were assessed. Averages of each microbiological properties were compared through the confidence intervals (p<0.05). The results showed a greater potential for AMF inoculum in BMPs and TC systems. The NTC showed the highest values of respirometry and metabolic quotient, releasing 31.7 and 27.3 % more CO 2 compared to BMPs and TC, respectively. The BMPs and TC were able to retain 13.8 and 16.5 % more carbon in the microbial biomass and 8.0 and 8.8 % more nitrogen in the biomass than NTC, respectively. Adopting soil management and conservation practices such as autumn cover crops, level seeding, and wide base terrace on level improved the soil microbial properties, with an increase in AMF inoculum potential, higher levels of acid phosphatase activity, and increment of carbon and nitrogen in microbial biomass.

AMF-mediated mitigation of Cd-induced toxicity in Cicer arietinum and their influence on growth, photosynthesis efficiency, cell viability, antioxidants and yield attributes

An experiment was conducted to investigate the impact of cadmium (Cd) on growth, photosynthetic pigments (total chlorophyll and carotenoids), stress biomarkers (malondialdehyde, MDA; superoxide radicles; cell viability), mineral nutrients (sodium and phosphorus), leave protein content, defence (proline, superoxide dismutase, peroxidase, catalase), stomatal behaviour, and the key enzymes in nitrate absorption (nitrate reductase, NR) and Calvin Cycle (carbonic anhydrase; CA) of chickpea, including and excluding arbuscular mycorrhizal fungus (AMF). The development and physio-biochemical characteristics under study underwent considerable modifications as a result of cadmium stress (50 mg Cd kg−1 soil). By increasing the levels of chlorophyll, carotenoid, CA, and NR activity, arbuscular mycorrhizal fungi (AMF) inoculation was found to be the most effective method for increasing Cd-stress resistance. The negative effects of Cd on the parameters under investigation were lessened by AMF. Malonaldehyde synthesis was enhanced by cadmium stress but decreased by AMF via reducing oxidative stress. The plant's defensive mechanism was strengthened by the increased antioxidant enzyme activity caused by Cd treatment and AMF inoculation. Plants treated with Cd and inoculated with AMF both had higher proline contents, which effectively warded off Cd stress. Fascinatingly, AMF-infected plants showed enhanced growth and yield characteristics, minimal superoxide radicles, regulated cell viability, and functional stomata in leaves. The current result lends support to the biological strategy of using AMF to counteract chickpea alterations brought on by Cd stress.

Enhancing the Yield, Quality and Antioxidant Content of Lettuce through Innovative and Eco-Friendly Biofertilizer Practices in Hydroponics

Hydroponics is a contemporary agricultural system providing precise control over growing conditions, potentially enhancing productivity. Biofertilizers are environmentally friendly, next-generation fertilizers that augment product yield and quality in hydroponic cultivation. In this study, we investigated the effect of three bio-fertilizers in a hydroponic floating system, microalgae, plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF), combined with a 50% reduction in mineral fertilizer, on lettuce yield and quality parameters including antioxidants: vitamin C, total phenols and flavonoids. The treatments tested were: 100% mineral fertilizer (control 1), 50% mineral fertilizer (control 2), 50% mineral fertilizer with microalgae, 50% mineral fertilizer with PGPR and 50% mineral fertilizer with AMF. The research was conducted during the winter months within a controlled environment of a glasshouse in a Mediterranean climate. The PGPR comprised three distinct bacterial strains, while the AMF comprised nine different mycorrhizal species. The microalgae consisted of only a single species, Chlorella vulgaris. AMF inoculation occurred once during seed sowing, while the introduction of PGPR and microalgae occurred at 10-day intervals into the root medium. Our findings revealed that the treatment with PGPR resulted in the highest growth parameters, including the lettuce circumference, stem diameter and fresh leaf weight. The 100% mineral fertilizer and PGPR treatments also yielded the highest lettuce production. Meanwhile, the treatment with AMF showed the highest total phenol and flavonoid content, which was statistically similar to that of the PGPR treatment. Furthermore, the PGPR recorded the maximum range of essential nutrients, including nitrogen (N), potassium (K), iron (Fe), zinc (Zn) and copper (Cu). Thus, the inclusion of PGPR holds promise for optimizing the lettuce growth and nutrient content in hydroponic systems. In conclusion, PGPR has the potential to enhance nutrient availability in a floating hydroponic system, reducing the dependence on chemical fertilizers. This mitigates environmental pollution and fosters sustainable agriculture.

Arbuscular Mycorrhizal Fungi Colonization of Jatropha curcas Roots and Its Impact on Growth and Survival under Greenhouse-Induced Hydric Stress

Arbuscular mycorrhizal fungi (AMF) provide benefits to host plants by enhancing nutrition and overall fitness. In this study, AMF species were isolated from the soil rhizosphere of Jatropha curcas and were identified and evaluated for their potential in fostering the development of Jatropha seedlings within a controlled greenhouse environment. The first experiment assessed the interplay between hydric stress and AMF inoculation on mycorrhizal colonization. The next experiment examined the impact of quercetin on mycorrhizal colonization. Out of 204 glomerospores corresponding to 28 species spanning 10 genera, Acaulospora (14) and Scutellospora (5) were the most abundant taxa. Six new records of AMF for Costa Rica are reported. Mycorrhizal colonization was observed in 43.2% of Jatropha plants (34.7% by AMF typical hyphae; arbuscules 8.9%; coils 5.6%; and vesicles 5.4%). Significant survival effects due to AMF inoculation under hydric stress were observed. On day 85, non-mycorrhizal plants subjected to hydric stress showed a mere 30% survival rate, whereas their mycorrhizal counterparts under hydric stress exhibited survival rates of 80% and 100% with and without irrigation, respectively. Furthermore, plants with irrigation and mycorrhizas showed greater hydric stress tolerance and superior growth. The inoculated plants, irrespective of irrigation, demonstrated mycorrhizal colonization rates of 63% and 72%, respectively. Quercetin did not affect Jatropha’s growth, but there were differences in AMF root colonization. In summary, these findings accentuate the viability of a native consortium in augmenting Jatropha survival, warranting consideration as a potent biofertilizer within greenhouse settings. The AMF described can be used for Jatropha propagation programs.

Arbuscular mycorrhizal fungi with contrasting life-history strategies differently affect health-promoting compounds in field-grown tomato by changing arbuscule occurrence and mycorrhizal assemblages in roots

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.

Combined use of seaweed extract and arbuscular mycorrhizal fungi for alleviating salt stress in bell pepper (Capsicum annuum L.)

Salinity is the most catastrophic abiotic stress that aggravating its detrimental effects on productivity of horticultural crop especially bell pepper that might be alleviated through judicious application of seaweed extract (SWE) and arbuscular mycorrhizal fungi (AMF). Therefore, the present study was focused on the interactive effects of SWE and AMF to improve growth, physiological responses and yield performance of bell pepper grown under salt stress. Factorial experiment consisted of three factors namely SWE dose (non-treated control, 2.5 g L–1, 5.0 g L–1 and 7.5 g L–1 designated as SWE0, SWE2.5, SWE5.0 and SWE7.5, respectively); water salinity levels (control- 0.54, 4, 8 and 12 dS m–1) and two levels of AMF inoculation (with AMF [+AMF] and without AMF [–AMF]). Factorial experiment was laid out where treatment combinations were assigned completely randomized design (CRD) with three replications. SWE treated plants upgraded leaf relative water content, leaf greenness and membrane stability index 16 %, 19 % and 13 %, respectively with lower electrolyte leakage (15 %) at 12 dS m–1 water salinity compared to non-treated plants. In addition, higher proline content (79 %) was observed at SWE5.0 in AMF inoculated plants over control (non-inoculated plants. Marketable fruit yields were higher (31 %) with the combined application of SWE and AMF at extreme salt stress conditions (12 dS m–1). Apart from that, SWE7.5 treated plants exhibited more accumulation of potassium (26 %) and phosphorous (32 %) while less accumulation of sodium (16 %) was displayed at higher salinity level (12 dS m–1) compared to control plants. Moreover, SWE and AMF treated plants showed better postharvest quality (pH, Brix) performance during storage condition compared with control. Taken together, it might be inferred that integrated application of SWE and AMF had boosted up morpho-physiological traits, yield and ion homeostasis to ameliorate the baleful effects of salt stress on bell pepper.

Effects of exogenous brassinolide and AM fungi on growth, photosynthetic characteristics and antioxidant enzyme system of Leymus chinensis under salt and alkali stress

Salinity and alkali stresses are a major abiotic stress negatively affecting crop productivity around the globe. Therefore, it is mandatory to develop the effective measures to mitigate the adverse impacts of these stresses for ensuring sustainable crop productivity and food security. Therefore, a pot experiment determined the effects of brassinolide application, inoculation with AM fungi (Funneliformis mosseae) and their combined use on the growth, photosynthesis and antioxidant system of Leymus chinensis under saline-alkali stress (0, 150 mmol/L). The mechanism of the two to alleviate the saline-alkali stress of L. chinensis was explored. The physiological and biochemical indexes of Leymus chinensis were significantly affected under saline-alkali stress (150 mmol/L). Inoculation of AM fungi and application of brassinolide effectively increased the biomass accumulation in the upper part (∼ 25-40%) and root (15-35%) system of L. chinensis under saline-alkali stress. Further AMF also improved photosynthetic pigments (chlorophyll a, chlorophyll b), photosynthetic rate (Pn), Intercellular CO2 concentration (Ci), stomata conductance (Gs), transpiration rate (Tr), chlorophyll fluorescence antioxidant enzymes (SOD: superoxide dismutase. CAT: catalase APX: ascorbate peroxidase, GR: Glutathione reductase) activity, and decreased malondialdehyde (MDA: ∼ 40-50%) and hydrogen peroxide (H2O2: ∼ 30-40%) accumulation. Therefore, under saline-alkali stress conditions, the combination of brassinolide and AM fungi proved better to mitigate their toxic effects.

Arbuscular mycorrhizal fungi inhibit necrotrophic, but not biotrophic, aboveground plant pathogens: a meta-analysis and experimental study.

Microbial mutualists can profoundly modify host species ecology and evolution, by extension altering interactions with other microbial species, including pathogens. Arbuscular mycorrhizal fungi (AMF) may moderate infections by pathogens, but the direction and strength of these effects can be idiosyncratic. To assess how the introduction of AMF impacts the incidence and severity of aboveground plant diseases (i.e. 'disease impact'), we conducted a meta-analysis of 130 comparisons derived from 69 published studies. To elucidate the potential mechanisms underlying the influence of AMF on pathogens, we conducted three glasshouse experiments involving six non-woody plant species, yielded crucial data on leaf nutrient composition, plant defense compounds, and transcriptomes. Our meta-analysis revealed that the inoculation of AMF lead to a reduction in disease impact. More precisely, AMF inoculation was associated with a decrease in necrotrophic diseases, while no significant impact on biotrophic diseases. Chemical and transcriptome analyses suggested that these effects may be driven by AMF regulation of jasmonic acid and salicylic acid signaling pathways in glasshouse experiments. However, changes in plant nutritional status and secondary chemicals may also regulate disease impact. These results emphasize the importance of incorporating pathogen life history when predicting how microbial mutualisms affect disease impact.