Arbuscular Mycorrhizal Fungi Inoculation Research Articles

Impact of arbuscular mycorrhizal fungi on maize rhizosphere microbiome stability under moderate drought conditions.

With an alarming increase in global greenhouse gas emissions, unstable weather conditions are significantly impacting agricultural production. Drought stress is one of the frequent consequences of climate change that affects crop growth and yield. Addressing this issue is critical to ensure stable crop productivity under drought conditions. Arbuscular mycorrhizal fungi (AMF) establish symbiotic relationships with plants and enhance their resistance to adverse conditions. Effects of arbuscular mycorrhizal associations on the rhizosphere microbiome and root transcriptome under drought conditions have not been explored. Here, we investigated the effects of AMF and drought stress on rhizosphere microorganisms and root transcriptome of maize plants grown in chernozem soil. We used high-throughput sequencing data of bacterial 16S rRNA and fungal internal transcribed spacer regions (ITS) to identify rhizosphere microorganisms. Transcriptomic data were used to assess gene expression in maize plants under different treatments. Our results show that AMF maintains the composition of maize rhizosphere microorganisms under drought stress. In particular, the bacterial and fungal phyla maintained were Actinomycetes and Ascomycota, respectively. Transcriptomic data indicated that AMF influenced gene expression in maize plants under drought stress. Under drought stress, the expression of SWEET13, CHIT3, and RPL23A was significantly higher in the presence of AMF than it was without AMF inoculation, indicating better sugar transport, reduced malondialdehyde accumulation, and improved water use efficiency in AMF-inoculated maize plants. These findings suggest that AMF can enhance the resistance of maize to moderate drought stress by stabilising plant physical traits, which may help maintain the structure of the rhizosphere microbial community. This study provides valuable theoretical insights that should aid the utilization of AMF in sustainable agricultural practices.

Synergism or Antagonism: Do Arbuscular Mycorrhizal Fungi and Plant Growth-Promoting Rhizobacteria Work Together to Benefit Plants?

In agriculture, abiotic and biotic stress reduce yield by 51–82% and 10–16%, respectively. Applications of biological agents such as plant growth-promoting rhizobacteria (PGPR) and arbuscular mycorrhizal fungi (AMF) can improve plant growth. Applications of lone PGPR and AMF also help plants resist abiotic and biotic stressors. The reports for dual inoculation of AMF and PGPR to benefit plants and tackle stressors are largely unknown. It is speculated that PGPR colonization in plants enhances AMF infection during dual AMF and PGPR application, although increased AMF colonization does not always correlate with the increased benefits for the plant hosts. Further research is needed regarding molecular mechanisms of communication during dual inoculations, and dual-inoculation enhancement of induced systemic resistance under pathogen stress, to understand how dual inoculations can result in enhanced plant benefits. The influence of application timing of AMF and PGPR dual inoculations on mitigating abiotic and biotic stress is also not well understood. This review documents the factors that govern and modulate the dual application of AMF and PGPR for plant benefits against stress responses, specifically abiotic (drought) stress and stress from pathogen infection.

Arbuscular mycorrhizal fungi affected soft wheat quality properties and nutritional index by regulating the composition and secondary structure of protein

Arbuscular mycorrhizal fungi (AMF) inoculation has important regulatory influence on plant growth and nitrogen uptake, which are intimately associated with soft wheat yield and quality. The study aimed to investigate the impact of AMF inoculation on soft wheat grain yield, protein compositions, protein quality, secondary structure of gluten, dough properties and biscuits baking quality. In this study, AMF inoculation significantly increased grain yield. AMF inoculation decreased grain protein content by 5.1%, glutenin content by 8.5%, GMP by 14.3%, and HMW-GS by 8.8% compared with CK. Conversely, AMF inoculation increased the ratio of gliadin/glutenin. Further analysis showed AMF treatment had a looser gluten network than CK, significantly reduced β-sheet and β-turn content, while α-helix content increased. The nutritional index of grain protein was slightly reduced under AMF inoculation, yet the biological value was improved. Reduced wet gluten content, gluten performance index and dough development time under AMF treatment through regulation of soft wheat protein composition and gluten protein structure. Therefore, biscuits in AMF treatment showed reduced thickness, hardness, significantly greater spread ratio and sensory score compared with CK. These indicate that AMF application would be a beneficial agronomic practice to synergistically optimize yield and grain quality in soft wheat.

Response of wheat to arbuscular mycorrhizal fungi inoculation and biochar application: Implications for soil carbon sequestration

The sequestration of atmospheric CO₂ in soil is suggested as an effective climate change mitigation strategy. Biochar application shows promise in this regard, while the role of fungi in soil carbon cycling and sequestration is also under investigation. Using a novel high-throughput plant phenomics approach, we explore the impact of arbuscular mycorrhizal fungi (AMF) inoculation and biochar application on wheat growth and soil carbon, guided by one of the leading global carbon credit schemes. Wheat was successfully colonised by AMF, achieving an average root length colonisation of 35.9%. We uncover an indirect fungal-mediated pathway to soil carbon sequestration, with mycorrhizal plants generating more biomass across all soil treatments without yield penalties, suggesting colonised plants deliver more plant derived carbon to the soil, potentially leading to long-term soil carbon gains. Conversely, fungal-driven carbon loss occurred, significantly reducing soil carbon accumulation in unamended soil, but not in biochar-amended soil, suggesting that biochar moderates fungal activity and positively impacts the soil carbon balance. While both biochar and AMF enhance plant growth, their direct effects on soil carbon are complex. Although biochar did not significantly increase soil carbon stocks beyond its own contribution, its ability to regulate fungal activity could play an important role in influencing soil carbon sequestration.

Effect of mutations in the <i>Sym7</i>, <i>Sym19</i> and <i>Sym34</i> genes on the interaction of pea (<i>Pisum sativum</i> L.) with the arbuscular mycorrhizal fungus <i>Rhizophagus irregularis</i>

BACKGROUND: Within the pea (Pisum sativum L.) species, genotypes with high and low responsiveness to inoculation with arbuscular mycorrhizal fungi can be distinguished. AIM: The aim of this study was to test the hypothesis that pea responsiveness to arbuscular mycorrhizal fungi inoculation may be inversely correlated with root colonization levels. MATERIALS AND METHODS: The wild-type line Finale with low responsiveness to arbuscular mycorrhizal fungi inoculation and symbiotic mutants obtained on its basis were used. Plants were grown under controlled climatic conditions with a deficiency of available phosphorus; the fungus Rhizophagus irregularis was used for inoculation. Parameters of plant growth and development of reproductive organs were determined 52 and 71 days after inoculation, which corresponded to the flowering and pod filling stages, respectively. RESULTS: All mutant lines under conditions without inoculation had generally reduced parameters compared to the original line Finale. Inoculation led to a decrease in many parameters in the line Finale. Mutations in the Sym7 and Sym34 genes, which led to a decrease or delay in the start of mycorrhization, respectively, contributed to the manifestation of a positive plant response to inoculation. The mutant in the Sym19 gene almost completely lacked intrartadical colonization, while inoculation had no effect on the growth and development of above-ground organs. CONCLUSIONS: The study results support the idea that reducing mycorrhization levels can have a positive effect on pea plants.

Experimental evidence that poor soil phosphorus (P) solubility typical of drylands due to calcium co-precipitation favors autonomous plant P acquisition over collaboration with mycorrhizal fungi

Calcareous dryland soils are rich in precipitated phosphate and represent >30% of Earth's land, yet the relative importance of phosphorus-acquisition strategies (PAS) among plant species in these systems is not well known. No experiment has investigated potential interactions between varying amounts of added calcium carbonate (CaCO3) and arbuscular mycorrhizal fungi (AMF) on plant performance and PAS which could test for potential mechanisms without the limitations of in-situ comparisons along natural gradients. To fill this knowledge gap, we conducted an experiment with CaCO3 addition, AMF inoculation, and three invasive and five native grassland plants. We expected an increase in soil [CaCO3] of an alkaline subsoil to 1) reduce soil-available phosphorus (P), 2) reduce plant biomass and P uptake, and 3) shift PAS toward increased root mining as Ca-bound P increases. The largest CaCO3 addition reduced available P by as much as 57%. On average, the largest addition of CaCO3 reduced total biomass of plants by 19% and plant uptake of P by 15%. The PAS seemed to have changed, and CaCO3 additions tended to increase an indicator of root exudation (shoot [Mn]) to mobilize Ca-bound P, suggesting plasticity for some inducible root mining, especially Artemisia frigida and Poa secunda. However, CaCO3 and plant species interacted to affect shoot [Mn]. The invasive grass Bromus tectorum was superior at acquiring P (> P uptake, > shoot [Mn]) and thus tolerating low soluble P conditions. Rarely did AMF and CaCO3 interact to affect plant biomass. When they did, mycorrhizal responsiveness did not increase where P was less available, suggesting AMF become less beneficial upon P and Ca coprecipitation. In dryland soils with less soluble P, plants are thus likely to rely more on root mining PAS than mycorrhizal scavenging, except for the invasive forb Euphorbia esula that always benefitted from AMF inoculation.

Enhanced fig tree production through endomycorrhizal fungi inoculation: A nursery study on tree cuttings derived from the Ifrane Region, Morocco

The mycorrhizal association represents a crucial symbiotic bond necessary for the vitality of the majority of plants. This report aims to investigate the impact of endomycorrhizal fungi on the production of fig trees from cuttings. The research took place in a nursery environment by inoculating fig cuttings sourced from three sites in Morocco with a composite inoculum of arbuscular mycorrhizal fungi (AMF). The mean root and vegetative masses of the inoculated plants after 140 days were 33.1 g and 35 g compared with 1.8 g and 6.4 g in the control. The mean shoot length and number of leaves developed from treated cutting were 98.5 cm and 17, respectively 29 cm and 4 leaves in control. Thus, the newly formed roots showed a well-established mycorrhizal colonization and contained different structures characteristic of arbuscular endomycorrhizae: arbuscules, vesicles, endophytes, hyphae and spores. The frequency and intensity of root mycorrhization were approximately 80% and 15.5%, respectively. The contents of arbuscules and vesicles were 2.5% and 5.5%. The study of formed spores showed a combination of 52 spores per 100 g of soil, belonging to 11 species and 3 genera: Glomus, Acaulospora and Rhizophagus with dominance of the genus Glomus (85%). Glomus macrocarpum and Glomus deserticola were the most abundant species, appearing at 30.77% and 19.23%, respectively. The results demonstrate a pronounced stimulating effect on both root formation and vegetative shoot development in the inoculated cuttings. Specifically, the early inoculation of fig cutting with the AMF inoculum significantly enhanced rhizogenesis end root system development. Consequently, the gradual establishment of mycorrhizal symbiosis at the root level of inoculated plants led to good development of the root mass and the vegetative mass. The inoculated plants showed good root and vegetative mass development due to the installation and the progressive development of mycorrhizal symbiosis at their roots.

Inoculation with Arbuscular Mycorrhizal Fungi Supports the Uptake of Macronutrients and Promotes the Growth of Festuca ovina L. and Trifolium medium L., a Candidate Species for Green Urban Infrastructure.

Green roofs and walls play an important role in promoting biodiversity, reducing the urban heat island effect and providing ecosystem services in urban areas. However, the conditions on green walls/roofs (low nutrient and organic matter content, drought, high temperatures) are often unfavorable for plant growth. Arbuscular mycorrhizal fungi (AMF) can improve the growth and development of plants under stress conditions as they can increase nutrient and water uptake. In a 6-month pot experiment, we investigated the effect of AMF inoculation on the growth and NPK uptake of Festuca ovina L. and Trifolium medium L., which are used for green roofs and walls. Two variants of mycorrhizal inoculation were used in the experiment: a commercial mycorrhizal inoculant AM Symbivit (Symbiom Ltd., Lanskroun, Czech Republic) and a mycorrhizal inoculant collected from calcareous grassland in the Silesia region (Poland). Funneliformis mosseae was the most abundant species in the roots of F. ovina and T. medium with IM inoculum. In the CM variant, a dominance of F. mosseae was observed in the roots of F. ovina. In contrast, Archaeosporaceae sp. node 317 dominated in the roots of T. medium. Both inoculations had a positive effect on the increase in dry weight of the shoots of T. medium, but only the commercial inoculum had a positive effect on the growth of F. ovina. Both inoculations improved the P uptake by the roots and the P and K uptake into the shoots of T. medium. In addition, both inoculations improved the K uptake by the roots of F. ovina and the N, P and K uptake into the shoots. In conclusion, both AMF communities included in the inoculations had a positive effect on plant growth and nutrient uptake, but the effect depends on the plant and the mycorrhizal fungus species.

Assembly and functional profile of rhizosphere microbial community during the Salix viminalis-AMF remediation of polycyclic aromatic hydrocarbon polluted soils

Arbuscular mycorrhizal fungi (AMF) are positive to the phytoremediation by improving plant biomass and soil properties. However, the role of AM plants to the remediation of polycyclic aromatic hydrocarbons (PAHs) is yet to be widely recognized, and the impact of AM plants to indigenous microbial communities during remediation remains unclear. In this work, a 90-day study was conducted to assess the effect of AMF-Salix viminalis on the removal of PAHs, and explore the impact to the microbial community composition, abundance, and function. Results showed that AMF-Salix viminalis effectively enhanced the removal of benzo[a]pyrene, and enriched more PAH-degrading bacteria, consisting of Actinobacteria, Chloroflexi, Sphingomonas, and Stenotrophobacter, as well as fungi including Basidiomycota, Pseudogymnoascus, and Tomentella. For gene function, AM willow enhanced the enrichment of genes involved in amino acid synthesis, aminoacyl-tRNA biosynthesis, and cysteine and methionine metabolism pathways. F. mosseae inoculation had a greater effect on alpha- and beta-diversity of microbial genes at 90 d. Additionally, AMF inoculation significantly increased the soil microbial biomass carbon and organic matter concentration. All together, the microbial community assembly and function shaped by AM willow promoted the dissipation of PAHs. Our results support the effectiveness of AM remediation and contribute to reveal the enhancing-remediation mechanism to PAHs using multi-omics data.

Arbuscular mycorrhizal fungi enhance nitrogen assimilation and drought adaptability in tea plants by promoting amino acid accumulation.

The development and quality of tea plants (Camellia sinensis (L.) O. Ktze.) are greatly hampered by drought stress (DS), which affects them in a number of ways, including by interfering with their metabolism of nitrogen (N). Arbuscular mycorrhizal fungi (AMF) are known to enhance water and nutrient absorption in plants, but their specific effects on tea plant N metabolism under DS and the associated regulatory mechanisms remain unclear. This study aimed to evaluate the impact of Claroideoglomus etunicatum inoculation on N assimilation in tea plants (C. sinensis cv. Fuding Dabaicha) under well-watered (WW) and DS conditions, and to explore potential molecular mechanisms. After 8 weeks of DS treatment, root mycorrhizal colonization was significantly inhibited, and the biomass of tea shoots and roots, as well as the contents of various amino acids (AAs) were reduced. However, AMF inoculation significantly increased the contents of tea polyphenols and catechins in leaves by 13.74%-36.90% under both WW and DS conditions. Additionally, mycorrhizal colonization notably increased N content by 12.65%-35.70%, various AAs by 11.88%-325.42%, and enzymatic activities associated with N metabolism by 3.80%-147.62% in both leaves and roots. Gene expression analysis revealed a universal upregulation of N assimilation-related genes (CsAMT1;2, CsAMT3;1, CsGS1, CsNADH-GOGAT, CsTS2, CsGGT1, and CsADC) in AMF-colonized tea roots, regardless of water status. Under DS condition, AMF inoculation significantly upregulated the expressions of CsNRT1;2, CsNRT1;5, CsNRT2;5, CsNR, CsGS1, CsGDH1, CsGDH2, CsTS2, CsGGT1, CsGGT3, and CsSAMDC in tea leaves. These findings suggest that AMF improved tea plant adaptability to DS by enhancing N absorption and assimilation, accompanied by the synthesis and accumulation of various AAs, such as Glu, Gln, Asp, Lys, Arg, GABA and Pro. This is achieved through the upregulation of N metabolism-related genes and the activation of related enzymes in tea plants under DS condition. These findings provide valuable insights into the role of AMF in regulating tea plant N metabolism and enhancing stress tolerance.

Zinc finger protein LjRSDL regulates arbuscule degeneration of arbuscular mycorrhizal fungi in Lotus japonicus.

In arbuscular mycorrhizal (AM) symbiosis, appropriate regulation of the formation, maintenance, and degeneration of the arbuscule are essential for plants and fungi. In this study, we identified a Cysteine-2/Histidine-2 zinc finger protein (C2H2-ZFP)-encoding gene in Lotus japonicus named Regulator of Symbiosome Differentiation-Like (LjRSDL) that is required for arbuscule degeneration. Evolutionary analysis showed that homologs of LjRSDL exist in mycorrhizal flowering plants. We obtained ProLjRSDL::GUS transgenic hairy roots and showed that LjRSDL was strongly upregulated upon AM colonization, particularly at 18 days post AM fungi inoculation and specifically expressed in arbuscular-containing cells. The mycorrhization rate increased in the ljrsdl mutant but decreased in LjRSDL overexpressed L. japonicus. Interestingly, we observed higher proportions of large arbuscule in the ljrsdl mutant but lower proportions of larger arbuscule in LjRSDL overexpressing plants. Transcriptome analyses indicated that genes involved in arbuscule degeneration were significantly changed upon the dysregulation of LjRSDL and that LjRSDL-dependent regulation in AM symbiosis is mainly via the hormone signal transduction pathway. LjRSDL, therefore, represents a C2H2-ZFP that negatively regulates AM symbiosis. Our study provides insight into understanding plant-AM fungal communication and AM symbiosis development.

Genome-wide transcriptome and gene family analysis reveal candidate genes associated with potassium uptake of maize colonized by arbuscular mycorrhizal fungi

BackgroundPotassium (K) is an essential nutrient for plant growth and development. Maize (Zea mays) is a widely planted crops in the world and requires a huge amount of K fertilizer. Arbuscular mycorrhizal fungi (AMF) are closely related to the K uptake of maize. Genetic improvement of maize K utilization efficiency will require elucidating the molecular mechanisms of maize K uptake through the mycorrhizal pathway. Here, we employed transcriptome and gene family analysis to elucidate the mechanism influencing the K uptake and utilization efficiency of mycorrhizal maize.Methods and resultsThe transcriptomes of maize were studied with and without AMF inoculation and under different K conditions. AM symbiosis increased the K concentration and dry weight of maize plants. RNA sequencing revealed that genes associated with the activity of the apoplast and nutrient reservoir were significantly enriched in mycorrhizal roots under low-K conditions but not under high-K conditions. Weighted gene correlation network analysis revealed that three modules were strongly correlated with K content. Twenty-one hub genes enriched in pathways associated with glycerophospholipid metabolism, glycerolipid metabolism, starch and sucrose metabolism, and anthocyanin biosynthesis were further identified. In general, these hub genes were upregulated in AMF-colonized roots under low-K conditions. Additionally, the members of 14 gene families associated with K obtain were identified (ARF: 38, ILK: 4, RBOH: 12, RUPO: 20, MAPKK: 89, CBL: 14, CIPK: 44, CPK: 40, PIN: 10, MYB: 174, NPF: 79, KT: 19, HAK/HKT/KUP: 38, and CPA: 8) from maize. The transcript levels of these genes showed that 92 genes (ARF:6, CBL:5, CIPK:13, CPK:2, HAK/HKT/KUP:7, PIN:2, MYB:26, NPF:16, RBOH:1, MAPKK:12 and RUPO:2) were upregulated with AM symbiosis under low-K conditions.ConclusionsThis study indicated that AMF increase the resistance of maize to low-K stress by regulating K uptake at the gene transcription level. Our findings provide a genome-level resource for the functional assignment of genes regulated by K treatment and AM symbiosis in K uptake-related gene families in maize. This may contribute to elucidate the molecular mechanisms of maize response to low K stress with AMF inoculation, and provided a theoretical basis for AMF application in the crop field.

Role of Arbuscular Mycorrhizal Fungi in Alleviating Salinity Stress and Improving Physiological Parameters of Wheat (Triticum aestivum L.): A Review

Salinity stress poses a significant threat to global wheat production, impacting crop yield and food security. In recent years, Arbuscular Mycorrhizal Fungi (AMF) have gained attention as potential bioinoculants capable of mitigating salinity-induced stress and improving plant physiological parameters. This review provides a comprehensive examination of the role of AMF in alleviating salinity stress and enhancing physiological parameters in wheat (Triticum aestivum L.). Through a systematic analysis of relevant literature, we explore the mechanisms underlying the beneficial interactions between AMF and wheat under saline conditions. Key findings from various studies demonstrate that AMF colonization enhances wheat growth, nutrient uptake, and antioxidant enzyme activities, while reducing the adverse effects of salinity stress. However, challenges such as variability in AMF effectiveness and compatibility with modern agricultural practices persist. Future research directions should focus on refining AMF inoculation techniques and developing strains with enhanced salt tolerance to maximize their potential in sustainable agriculture. Overall, this review underscores the promising role of AMF in revolutionizing wheat cultivation in saline environments, offering insights for enhancing crop productivity and resilience to salinity stress.

Arbuscular mycorrhizal fungi improve the disease resistance of Lycium barbarum to root rot by activating phenylpropane metabolism.

Root rot is one of the common diseases of Lycium barbarum. Pathogens can cause devastating disasters to plants after infecting host plants. This study investigated the effect of arbuscular mycorrhizal fungi (AMF) Rhizophagus intraradices inoculation on phenylpropane metabolism in L. barbarum and evaluated its resistance to root rot. The experiment was set up with AMF inoculation treatments (inoculated or not) and root rot pathogen-Fusarium solani inoculation treatments (inoculated or not). The results showed that AMF was able to form a symbiosis with the root system of L. barbarum, thereby promoting plant growth significantly and increasing plants' resistance to disease stress. The plant height of AMF-colonized L. barbarum increased by 24.83% compared to non-inoculated diseased plants. After inoculation with AMF, the plant defense response induced by pathogen infection was stronger. When the enzyme activity of the leaves reached the maximum after the onset of mycorrhizal L. barbarum, phenylalanine ammonia-lyase, cinnamic acid-4-hydroxylase, and 4-coumaric acid-CoA ligase increased by 3.67%, 31.47%, and 13.61%, respectively, compared with the non-inoculated diseased plants. The products related to the lignin pathway and flavonoid pathway downstream of phenylpropane metabolism such as lignin and flavonoids were also significantly increased by 141.65% and 44.61% compared to nonmycorrhizal diseased plants. The activities of chitinase and β-1,3-glucanase increased by 36.00% and 57.96%, respectively. The contents of salicylic acid and jasmonic acid were also 17.7% and 31.63% higher than those of nonmycorrhizal plants in the early stage of plant growth, respectively. The results indicated that AMF significantly promoted plant growth and enhanced disease resistance by increasing enzyme activities and the production of lignin and flavonoids.

Leveraging the complex interplay between arbuscular mycorrhizal fungi, seasonal dynamics, and genotypic diversity to optimize maize productivity in semi-arid agroecosystems

Maize production under low-input agricultural systems in semi-arid areas of Sub-Saharan Africa faces significant challenges, primarily stemming from the synergistic impacts of climate variability and suboptimal agronomic practices. Harnessing soil microbiota, particularly arbuscular mycorrhizal fungi (AMF), represents a pivotal strategy for bolstering low-input systems. However, their functional utility is contingent upon their compatibility with the prevailing environmental conditions and biotic interactions. This study examines the influence of two distinct AMF inoculants on the growth and yield attributes of diverse maize genotypes across varying seasons within semi-arid regions of Kenya. We hypothesized that AMF inoculants exhibit differential adaptability to varying environmental sites and seasons, and their interaction will enhance the provision of key ecosystem services important for maize production. Field experiments were conducted in three semi-arid Counties (Tharaka-Nithi, Embu, and Kitui) during the 2019/2020 cropping seasons. A randomized complete block design with three replications and three treatments was adopted. Treatments consisted of Rhizatech (a commercial AMF inoculant), a consortium of AMF isolates (Rhizophagus irregularis and Funneliformis mosseae), and a non-inoculated control. In season one, notable interaction effects were observed for both site × maize genotype (p = 0.0007) and site × AMF inoculation (p < 0.0001), whereby Duma 43 genotype had the highest yield in Embu (11.93 t ha−1) and Kitui (11.76 t ha−1) counties, and Rhizatech and consortium inoculation consistently led to elevated grain yields across all three genotypes in Kitui, surpassing non-inoculated controls. AMF inoculation notably augmented phosphorus (P) uptake, with Rhizatech demonstrating a 79.7 % increase and consortium showing a 38.7 % increase in shoot P content compared to control plants in season 1. These findings highlight the complex interplay between AMF effectiveness, seasonal variations, and maize diversity. Further research is needed to elucidate the underlying mechanisms driving these seasonal shifts, allowing for optimized AMF inoculation strategies for improved maize performance under diverse conditions.

Combined inoculation of arbuscular mycorrhiza fungi with Meso‐rhizobium improves nutrient uptake, growth performance, and moisture stress tolerance of chickpea (Cicer arietinum L.)

AbstractBiofertilizers can be better alternatives to chemical fertilizers to enhance plant nutrition and productivity as they improve the soil fertility and crop productivity in an eco‐friendly and cost‐effective manner. A pot experiment was conducted between December 2018 and March 2019 in southern Ethiopia to evaluate the combined inoculation of arbuscular mycorrhizal fungi (AMF) and Meso‐rhizobium (MR) on biomass yield, nutrient uptake, and moisture stress tolerance of chickpea (Cicer arietinum L.) (variety: Habru). The experiment was executed as a factorial arrangement using a completely randomized design with three replications. The treatments were control (non‐fertilized), sole AM fungi inoculation, AM fungi inoculation with phosphorus fertilizer (20 kg P ha−1) and MR, and sole inorganic fertilizers (20 kg P;10 kg N ha−1) at four different moisture levels (optimum throughout the growing season, stressed at vegetative, flowering, and seed filling stages). The results demonstrated that biomass yields were limited by moisture stress, especially at vegetative and flowering stages of chickpea. Sole and co‐application of AMF with MR and inorganic P increased biomass yields on average by 19%, 39%, and 33% under water stress conditions, respectively, compared to the non‐inoculated control. The application of AMF with MR and inorganic P also significantly increased nodulation, AMF colonization, and nutrient uptake, but these effects were dependent on soil moisture status. In conclusion, there are potential advantages to be gained from sole and combined AMF application with rhizobium to improve growth and productivity of chickpea through enhanced nutrient and water uptake, though the results of this pot experiment should be validated through field trials.

Effect of arbuscular mycorrhizal symbiosis on grapevine response to Neofusicoccum parvum, a major trunk disease fungus

Grapevine is an economically-important culture worldwide but is currently the target of decline, especially caused by grapevine trunk diseases (GTD). One of the major grapevine trunk disease is Botryosphaeria dieback, which is associated with Botryosphaeriaceae fungi. Among the different methods that could contribute to increase grapevine fitness under stresses, viticulture could take advantage of symbiosis with arbuscular mycorrhizal fungi. Within this context, we investigated the effect of V. vinifera cv. Gewurztraminer colonization with the arbuscular mycorrhizal fungus Rhizophagus irregularis on plant tolerance to wood inoculation with Neofusicoccum parvum Bt67, one of the most aggressive fungus associated with Botryosphaeria dieback. We showed that grapevine mycorrhization resulted in a small but significant reduction of wood necrosis size and less intense necrosis symptoms on the leaves. We further characterized the response of grapevine leaves and roots to both arbuscular mycorrhizal fungus (AMF) symbiosis and GTD fungus inoculation, especially the interaction between these two conditions, with a non-targeted metabolomic approach. In the roots, both mycorrhization and N. parvum infection triggered metabolite reprogramming, especially sugars and stilbenes, which were downregulated by both AMF symbiosis and pathogen infection. Furthermore, N. parvum infection triggered a significant decrease in fatty acids and oxylipins in leaves of non-mycorrhized plants, whereas contents were maintained or increased in Rhizophagus irregularis-colonized plants. In conclusion, AMF symbiosis may be an interesting tool to improve health of young grapevines and help sustaining infection by trunk disease fungi, by harnessing lipid metabolism.

Mycorrhizal inoculation and fertilizer microdosing interactions in pearl millet (Pennisetum glaucum) under greenhouse conditions.

Soil fertility is a major constraint to agricultural development in the Sahel region of Africa. One alternative to reducing the use of mineral fertilizers is to partially replace them with microbes that promote nutrition and growth, such as arbuscular mycorrhizal fungi (AMF). Mineral fertilizer microdosing is a technique developed to enhance fertilizer efficiency and encourage smallholder farmers to adopt higher mineral fertilizer applications. A pot experiment was set up to study the effects of AMF inoculation on the mineral nutrition of pearl millet under mineral fertilizer microdosing conditions. The experimental setup followed a randomized complete block design with five replicates. The treatments tested on millet were an absolute control and eight microdoses derived from the combination of three doses of 15- 10-10 [nitrogen, phosphorus, and potassium (NPK)] mineral fertilizer (2 g, 3 g, and 5 g per pot), three doses of urea (1 g, 2 g, and 3 g per pot), and three doses of organic manure (OM) (200 g, 400 g, and 600 g), combined with and without AMF (Rhizophagus irregularis and Rhizophagus aggregatum). The parameters studied were growth, root colonization by AMF, and mineral nutrition. Plant height, stem diameter, root dry biomass, and percentage of root mycorrhization were measured. The results revealed a significant effect of the fertilizers on the growth of pearl millet compared to the control. AMF and OM treatments resulted in the highest biomass production. AMF combined with microdoses of NPK improved N and calcium (Ca) concentrations, while their combination with organic matter mainly improved the K concentration. Combining AMF with microdosed NPK and compost enhanced zinc (Zn) and nickel (Ni) concentrations. Root colonization varied from 0.55 to 56.4%. This investigation highlights the positive effects of AMF inoculation on nutrient uptake efficiency when combined with microdosing fertilization.

Growth, profitability, nutritional, and anti-nutritional properties of seven Manihot esculenta Crantz (cassava) varieties as affected by arbuscular mycorrhizal fungi

Despite a range of methods used to promote modern agriculture with several outcomes, food quality and availability problems remain. This work aims to evaluate the effect of AM fungi inoculation on the growth, yield, nutritional, and antinutritional properties of 7 varieties of cassava. Growth characteristics, yields, rentability, nutritional, and antinutritional of tubers of each treatment were determined at harvest. All the cassava varieties used form a symbiosis with AM fungi at various frequencies, with the I090590 variety being the best (61.66 %). The best amount of chlorophyll, carotenoid, and height of plants were recorded at 9 months old. The 96/1414, TME/693 and MD varieties respectively show the best amount of chlorophyll, size, and carotenoids at 9 months old. Following AM fungi inoculation, an increase in the content of chlorophyll, size, and carotenoids was recorded for all the varieties with the best rate attributed respectively to 92/0326, MD, and 92/0326. Tuber yields vary significantly depending on the cassava varieties, with the best (56.16 t/ha) recorded for the I090590 variety. Following inoculation with AM fungi, a significant increase in yields was recorded, with the best ratio (2.7) obtained with the AE variety. The I090590 variety shows the best yield and by then the most profitable. Inoculation with AM fungi leads to a significant increase in the sugar, protein, fibre, and phosphorus content of all cassava varieties, with the best ratios obtained in 96/1414, 01/1797, and I090590 varieties respectively. Similarly, the inoculation of cassava varieties with AM fungi leads to a significant reduction in the content of cyanides, oxalates, and phytates. The best ratio of reduction for cyanide was 1.91 for the MD variety. AM fungi inoculation is an important way to ensure safe, exponential production and high economic profitability of foodstuffs.

Application of AMF Alleviates Growth and Physiological Characteristics of Impatiens walleriana under Sub-Low Temperature

Impatiens walleriana is of great ornamental value, but it may suffer growth inhibition when it is exposed to sub-low temperatures for a long time. Although there are many studies on the positive effect of arbuscular mycorrhizal fungi (AMF) on cold tolerance, whether AMF could alleviate the sub-low temperature injury of Impatiens walleriana is unknown. In this experiment, two kinds of Impatiens walleriana were inoculated with AMF and treated with sub-low temperature to evaluate the physiological and biochemical characteristics of Impatiens walleriana seedlings. The results showed that the plant height of ‘Super Elf (Rose red)’ under stress and inoculated with 50 g and 100 g AMF compared to sub-low temperature treatment increased by 4.94% and 19.01%, and the plant height of ‘Super Elf (red)’ under stress and inoculated with 50 g and 100 g AMF increased by 3.11% and 17.03%, respectively. Compared to sub-low temperature treatment, the stem diameter of ‘Super Elf (Rose red)’ under stress and inoculated with 50 g and 100g AMF increased by 47.17% and 50.94%, respectively. The same mitigation effect was observed in ‘Super Elf (red)’. Compared with sub-low temperature treatment, Fv’/Fm’, Y(II) and qP of ‘Super Elf (Rose red)’ inoculated with 50 g AMF significantly increased by 75.76%, 52.17%, and 43.48%, while NPQ significantly decreased by 2.96 times, whereas the corresponding values for ‘Super Elf (Rose red)’ inoculated with 100 g AMF increased by 87.88%, 82.61%, and 65.22%, while NPQ significantly increased by 1.47 times. Compared with sub-low temperature treatment, Fv’/Fm’, Y(II) and qP of ‘Super Elf (red)’ inoculated with 50 g AMF significantly increased by 53.49%, 28.95%, and 29.31%, while NPQ significantly decreased by 0.84 times, whereas the corresponding values for ‘Super Elf (red)’ inoculated with 100 g AMF increased by 53.49%, 23.68%, and 22.41%, while NPQ significantly increased by 3.48 times. Meanwhile, ‘Super Elf (Rose red)’ and ‘Super Elf (red)’ vaccination with AMF reduced the levels of O2− and H2O2 accumulation in leaves at sub-low temperatures and mitigated the extent of damage to cell membrane lipid peroxidation. Therefore, AMF inoculation can improve the tolerance of plants to sub-low temperatures.