Mycorrhizal Fungus Funneliformis Mosseae Research Articles

Coordinated influence of Funneliformis mosseae and different plant growth-promoting bacteria on growth, root functional traits, and nutrient acquisition by maize.

Rhizospheric interactions among plant roots, arbuscular mycorrhizal fungi, and plant growth-promoting bacteria (PGPB) can enhance plant health by promoting nutrient acquisition and stimulating the plant immune system. This pot experiment, conducted in autoclaved soil, explored the synergistic impacts of the arbuscular mycorrhizal fungus Funneliformis mosseae with four individual bacterial strains, viz.: Cronobacter sp. Rz-7, Serratia sp. 5-D, Pseudomonas sp. ER-20 and Stenotrophomonas sp. RI-4A on maize growth, root functional traits, root exudates, root colonization, and nutrient uptake. The comprehensive biochemical characterization of these bacterial strains includes assessments of mineral nutrient solubilization, plant hormone production, and drought tolerance. The results showed that all single and interactive treatments of the mycorrhizal fungus and bacterial strains improved maize growth, as compared with the control (no fungus or PGPB). Among single treatments, the application of the mycorrhizal fungus was more effective than the bacterial strains in stimulating maize growth. Within the bacterial treatments, Serratia sp. 5-D and Pseudomonas sp. ER-20 were more effective in enhancing maize growth than Cronobacter sp. Rz-7 and Stenotrophomonas sp. RI-4A. All bacterial strains were compatible with Funneliformis mosseae to improve root colonization and maize growth. However, the interaction of mycorrhiza and Serratia sp. 5-D (M + 5-D) was the most prominent for maize growth improvement comparatively to all other treatments. We observed that bacterial strains directly enhanced maize growth while indirectly promoting biomass accumulation by facilitating increased mycorrhizal colonization, indicating that these bacteria acted as mycorrhizal helper bacteria.

Arbuscular Mycorrhizal Fungus Funneliformis mosseae Improves Soybean Growth Even in Soils with Good Nutrition

Arbuscular mycorrhizal fungi (AMF) improve plant growth and may be useful in maintaining and even restoring soil. However, data on the latter function are sparse and only indirect, which is especially true for conventional management conditions with adequate nutrient availability. Our study focused on utilizing the prevalent AMF species, Funneliformis mosseae, to enhance Glycine max production, while also exploring its partly explored impact on soil aggregation. Working in greenhouse conditions, we examined whether, in a nutrient-sufficient environment, AMF would improve crop biomass accumulation and nutrition, as well as the stability of soil aggregates (SAS). We also looked for a synergistic effect of dual inoculation using AMF and symbiotic rhizobium. Plants were or were not inoculated with AMF or Bradyrhizobium japonicum in a two-factorial design. AMF inoculation increased soybean biomass, but AMF inoculation had no impact on P and N input to the shoots. Mycorrhiza did not affect either glomalin abundance or SAS. All the impacts were, however, independent from rhizobial inoculation, which was ineffective in this nutrient-available environment. Our assay suggests that arbuscular mycorrhiza may have a positive effect on soybean growth even under conventional management with adequate nutrition. The positive effects of AMF on soybean growth, together with the fact that AMF generally do not thrive in good nutrient availability, should be taken into account when planning mineral fertilization levels.

Influence of Funneliformis mosseae in the growth and accumulation of dry biomass in Dalia plants

Objetive: in the production of Dahlia spp., only chemical fertilization has been used, and an option that has not yet been explored is the implementation of a microbial inoculant. Therefore, the objective of this study was to evaluate the effect of the mycorrhizal fungus Funneliformis mosseae on the growth and development of the dahlia (Dahlia variabilis var. Variegated dwarf). Design/methodology/approach: the seeds were sown in polyethylene bags containing a mixture of black soil, peat moss, and agrolite. A completely randomized design was used, and the treatment structure was 2x3 factorial. The study factors were F. mosseae, chemical fertilization, and substrate sterilization. Results: an analysis of variance was performed, and the mean values of the treatments were compared with Tukey’s test (α = 0.05). Conclusions: with the inoculation of F. mosseae, a significant increase was obtained in the study variables: plant height, stem diameter, number of buds and flowers per plant; leaf + stem, flower, root, and total biomass, compared to non-inoculated plants. A colonization of 89 % in the roots was recorded. A limitation of the study is that the effect of the inoculum on plant growth can vary according to the mycorrhiza species used. In conclusion, inoculation with Funneliformis mosseae increased growth and biomass accumulation in Dahlia plants.

Arbuscular Mycorrhizal Fungi Increase Nutritional Quality of Soilless Grown Lettuce while Overcoming Low Phosphorus Supply.

Lettuce is widely used for its healthy properties, and it is of interest to increase them with minimal environmental impact. The purpose of this work was to evaluate the effect of the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae in lettuce plants (Lactuca sativa L. cv. Salinas) cultivated in a soilless system with sub-optimal phosphorus (P) compared with non-inoculated controls at two different P concentrations. Results show that lettuce inoculation with the selected AMF can improve the growth and the nutritional quality of lettuce even at sub-optimal P. Leaf content of chlorophylls, carotenoids, and phenols, known as important bioactive compounds for human health, was higher in mycorrhizal lettuce plants compared with non-mycorrhizal plants. The antioxidant capacity in AMF plants showed higher values compared with control plants grown at optimal P nutrition level. Moreover, leaf gas exchanges were higher in inoculated plants than in non-inoculated ones. Nitrogen, P, and magnesium leaf content was significantly higher in mycorrhizal plants compared with non-mycorrhizal plants grown with the same P level. These findings suggest that F. mosseae can stimulate plants growth, improving the nutritional quality of lettuce leaves even when grown with sub-optimal P concentration.

Mycorrhizae enhance drought tolerance of trifoliate orange by regulating circadian clock response patterns

Either arbuscular mycorrhizal fungus or circadian clock plays an important role in enhancing the tolerance of plants to soil drought, whereas it is not known whether the change of circadian rhythm is involved in mycorrhiza-enhanced drought tolerance in host plants. The purpose of this study was to investigate effects of an arbuscular mycorrhizal fungus Funneliformis mosseae on biomass production, root morphology, and expressions of circadian clock genes and drought-responsive genes in roots of trifoliate orange plants under drought stress conditions. After 8 weeks of soil drought, root mycorrhizal colonization rate and the length of soil mycelium significantly decreased, together with improved leaf, stem, and root biomass production and root morphology by mycorrhizal fungus. Expressions of six circadian clock genes (PtPRR7, PtCCA1, PtLHY, PtGI, PtPIF3, and PtSRR1) and three drought-responsive genes (PtMn-SOD, PtPOD, and PtCAT1) showed obvious circadian rhythm during the day. Under soil drought, F. mosseae induced the expression of PtPRR7, PtGI, and PtSRR1 at 17:00, PtPIF3 and PtSRR1 at 21:00, and PtPRR7, PtPIF3, and PtSRR1 at 1:00, whereas decreased the expression of PtLHY at all the tested time points. F. mosseae also up-regulated expressions of drought-responsive gene (PtFe-SOD, PtMn-SOD, PtCu/Zn-SOD, PtPOD, and PtLEA) at 17:00, 21:00 and 1:00 under drought conditions. Correlation analysis indicated the significant correlation between circadian clock gene expressions and drought-responsive gene expressions. These results conclude that mycorrhizal fungi regulate the circadian rhythm of trifoliate orange to respond to drought.

Combined effects of root-associated entomopathogenic and mycorrhizal fungi on the foliar pathogen Botrytis cinerea in tomato

Many fungi live intimately associated with plants and may benefit or harm the host plant. Improved knowledge of such interactions is needed for increasing plant health and crop productivity by implementation of fungal inoculants. Co-inoculations of different beneficial fungi offer the possibility to understand complex plant–microbe interactions that may be functionally complementary for improved plant production and protection. Here, we studied the individual and combined effects of the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae with three isolates of entomopathogenic fungi (EPF), representing Metarhizium brunneum, M. robertsii and Beauveria bassiana, on protection against the foliar phytopathogen Botrytis cinerea and on plant growth. Seedlings of tomato (Solanum lycopersicum L. var. Moneymaker) were inoculated in the substrate with AMF or EPF alone and in dual combinations under greenhouse conditions. Inoculation with the different EPF isolates reduced lesion sizes of B. cinerea on inoculated tomato leaves, but only in the experimental repetition that showed highest level of disease severity. The AMF F. mosseae had no additional effect on B. cinerea lesion size in combinations with EPF. In the experimental repetition with least disease severity, the AMF treatment led to limited increase of B. cinerea lesion sizes. In general, F. mosseae caused an increase in plant biomass, and the co-inoculations of AMF and EPF did in some combinations increase plant growth. Below-ground interactions between AMF and EPF were observed, as the presence of AMF in the roots was associated with a decrease of EPF root colonization densities. However, AMF colonization rates were unaffected by EPF presence. The study indicated a functional complementarity between EPF and AMF by suppressing phytopathogens and increasing plant growth, respectively. However, it further revealed the challenge of obtaining consistent results of plant–microbe-phytopathogen interactions, which must be overcome for future implementation of beneficial fungi as inoculants in plant production.

Impact of the Arbuscular Mycorrhizal Fungus Funneliformis mosseae on the Physiological and Defence Responses of Canna indica to Copper Oxide Nanoparticles Stress.

Copper oxide nanoparticles (nano-CuO) are recognized as an emerging pollutant. Arbuscular mycorrhizal fungi (AMF) can mitigate the adverse impacts of various pollutants on host plants. However, AMF’s mechanism for alleviating nano-CuO phytotoxicity remains unclear. The goal of this study was to evaluate how AMF inoculations affect the physiological features of Canna indica seedlings exposed to nano-CuO stress. Compared with the non-AMF inoculated treatment, AMF inoculations noticeably improved plant biomass, mycorrhizal colonization, leaf chlorophyll contents, and the photosynthetic parameters of C. indica under nano-CuO treatments. Moreover, AMF inoculation was able to significantly mitigate nano-CuO stress by enhancing antioxidant enzyme activities and decreasing ROS levels in the leaves and roots of C. indica, thus increasing the expression of genes involved in the antioxidant response. In addition, AMF inoculation reduced the level of Cu in seedlings and was associated with an increased expression of Cu transport genes and metallothionein genes. Furthermore, AMF inoculations increased the expression levels of organic acid metabolism-associated genes while facilitating organic acid secretion, thus reducing the accumulation of Cu. The data demonstrate that AMF–plant symbiosis is a feasible biocontrol approach to remediate nano-CuO pollution.

Single and coinoculation of Serendipita herbamans with arbuscular mycorrhizal fungi reduces Fusarium wilt in tomato and slows disease progression in the long-term

Soil-borne plant pathogens are difficult to control, and the application of individual biocontrol agents is often limited. This limitation calls for an integrated approach, and the combination of microorganisms might result in more effective control than individual inoculations. In our study, we investigated the effects of single inoculation and coinoculation of the endophytic fungus Serendipita herbamans and the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae in protecting tomato plants from the soil-borne pathogen Fusarium oxysporum f. sp. lycopersici (Fol). We conducted two independent greenhouse experiments in which plants were grown for either eight or sixteen weeks. Plants cultivated for eight weeks received Fol chlamydospores on the day of transplanting (simultaneous Fol inoculation), whereas plants grown for sixteen weeks obtained Fol either simultaneously or two weeks later (delayed Fol inoculation). S. herbamans was inoculated via root dipping for 24 h, while AMF was applied on the day of transplanting. The disease incidence was reduced by 67% when S. herbamans was inoculated individually or by 53% when it was coinoculated with AMF in the eight-week cultivation period. Even until sixteen weeks, a reduction in disease incidence by 25% and 42%, respectively, was evident. Delayed inoculation with Fol did not affect the disease incidence, but the disease severity was increased in plants treated solely with AMF. With regard to the other parameters, the AMF partner colonized the roots readily, enhanced the phosphorus status and compensated for the growth of tomato plants challenged with Fol. In combination with the bioprotective effect mediated by the endophyte, AMF strengthened the morphological and nutritional features, providing tomato plants a long-term protective advantage when challenged with Fol.

Effect of an arbuscular mycorrhizal fungus on maize growth and cadmium migration in a sand column

The ecological role of arbuscular mycorrhizal fungi (AMF) on altering cadmium (Cd) migration in polluted soil is still unresolved. The present experiment aimed to clarify whether AMF can reduce Cd loss due to leaching at different Cd concentrations (0, 5, 10, and 15 mg L−1) with maize as a host plant cultured in a sand column. The effects of the arbuscular mycorrhizal fungus Funneliformis mosseae on the root morphology, exudate content, and Cd uptake by maize and Cd loss due to leaching were investigated. The AMF altered the root morphology and exudate content of the maize, resulting in increases in the root length, volume, surface area, tips and branch number and in the contents of soluble sugars, proteins, and amino acids in the root exudates, and the AMF increased maize biomass and Cd uptake by 22.0–31.0%. Moreover, the AMF significantly increased the contents of total and easily extractable glomalin-related soil protein (GRSP), increased Cd adsorption by sand particles and decreased the Cd concentration in the solution at a depth of 20 cm, resulting in a 67.5–97.2% decrease in the Cd loss due to leaching from the sand column. Furthermore, the root exudate content was very significantly positively correlated with Cd adsorption by the sand particles. Root length was significantly positively correlated with Cd uptake by the maize roots, but the average root diameter was very significantly negatively correlated with Cd uptake by maize. Thus, the AMF altered Cd migration by increasing the contents of GRSP and exudates and root morphology, which contributed to reducing the Cd concentration in the solution and Cd loss due to leaching from the sand column. Taken together, these results indicated that AMF serve an ecological function in reducing Cd loss due to leaching from polluted soil.

Pteris vittata Arsenic Accumulation Only Partially Explains Soil Arsenic Depletion during Field-Scale Phytoextraction

Soil arsenic heterogeneity complicates our understanding of phytoextraction rates during arsenic phytoextraction with Pteris vittata, including in response to rate stimulation with nutrient treatments. In a 58-week arsenic phytoextraction field study, we determined the effects of soil arsenic concentrations, fertilizer application, and mycorrhizal fungi inoculation on P. vittata arsenic uptake rates, soil arsenic depletion, and arsenic soil–plant mass balances. Initial soil arsenic concentrations were positively correlated with arsenic uptake rates. Soil inoculation with mycorrhizal fungus Funneliformis mosseae led to 1.5–2 times higher fern aboveground biomass. Across all treatments, ferns accumulated a mean of 3.6% of the initial soil arsenic, and mean soil arsenic concentrations decreased by up to 44%. At depths of 0–10 cm, arsenic accumulation in P. vittata matched soil arsenic depletion. However, at depths of 0–20 cm, fern arsenic accumulation could not account for 61.5% of the soil arsenic depletion, suggesting that the missing arsenic could have been lost to leaching. A higher fraction of arsenic (III) (12.8–71.5%) in the rhizosphere compared to bulk soils suggests that the rhizosphere is a distinct geochemical environment featuring processes that could solubilize arsenic. To our knowledge, this is the first mass balance relating arsenic accumulation in P. vittata to significant decreases in soil arsenic concentrations under field conditions.

Influence of Microbial Consortium in the Production of China Aster and Gaillardia Seedlings

Abstract China aster and gaillardia are flowering plants with high economic importance in floriculture. In the present investigation, response of China aster and gaillardia seedlings to inoculation with the arbuscular mycorrhizal fungus Funneliformis mosseae + the plant growth-promoting rhizobacterium Bacillus sonorensis was studied by growing in multipots (pro trays). The germination percentage and plant growth parameters: length of shoots, roots and whole seedlings, stem diameter, biovolume index, plant strength, vigor index, dry weight and nutrient uptake, were analyzed 60 days after sowing. The microbial parameters, mycorrhizal root colonization and spore count, and the population of B. sonorensis in the substrate were also determined. The results brought out that growth of inoculated seedlings was significantly improved as compared to uninoculated seedlings. Based on the plant growth and microbial parameters studied, it was concluded that inoculating the substrate in pro trays with the microbial consortium results in producing vigorously growing seedlings.

Effects of beneficial endophytic fungal inoculants on plant growth and nutrient absorption of trifoliate orange seedlings

Citrus plants heavily depend on soil arbuscular mycorrhizal fungi (AMF), while the application of AMF in citrus is limited because of no propagation in vitro. The present work tried to apply a culturable (in vitro) endophytic fungus Piriformospora indica into trifoliate orange (Poncirus trifoliata) and to compare the role of P. indica in plant growth and nutrient acquisition especially phosphorus (P), relative to an arbuscular mycorrhizal fungus Funneliformis mosseae. After 20 weeks, roots of trifoliate orange could be colonized by P. indica, and both P. indica and F. mosseae existed in roots together. Root fungal colonization and soil easily extractable, difficultly extractable, and total glomalin-related protein concentrations were higher under single F. mosseae inoculation than under single P. indica and dual inoculation of F. mosseae and P. indica. Single or dual microbial inoculant collectively improved plant growth including plant height, leaf number, and leaf, stem, and root biomass, compared with non-inoculation. In addition, single fungal treatment raised the content of root N, P, and Mg, and dual inoculation increased only Mg and B contents. The improvement of P by single microbial inoculant was associated with the fungi-accelerated soil phosphatase activity and the fungi-induced root phosphate transporter genes (PT3, PT5, and PT6) expression levels. The positive effects on growth and nutrients were more significant under single F. mosseae than under single P. indica and dual inoculations. It concluded that P. indica has the stimulated roles in plant growth and P acquisition of trifoliate orange, and thus has more applied potentiality in citriculture than AMF as a biofertilizer.

The Fungal Endophyte Serendipita williamsii Does Not Affect Phosphorus Status but Carbon and Nitrogen Dynamics in Arbuscular Mycorrhizal Tomato Plants.

Some members of the root endophytic Serendipitaceae were observed to frequently coexist with arbuscular mycorrhizal fungi (AMF), but their interactions and potential synergistic effects in plants have not yet been well elucidated. Here, we inoculated three-week-old tomato seedlings with Serendipita indica or Serendipita williamsii alone or in combination with the arbuscular mycorrhizal fungus Funneliformis mosseae and cultivated the plants in a greenhouse until the late vegetative stage. Our data show that the simultaneous presence of Serendipita spp. did not affect root colonization by AMF, proving the feasibility of their combination for future agronomic uses. The photosynthetic performance was enhanced in AM tomato plants, although growth remained unresponsive following single or dual inoculation with Serendipita spp. and AMF. With regard to nutrient status under dual inoculation, AMF-induced phosphorus increases remained unaffected, but nitrogen and carbon dynamics were highly altered. Specifically, the application of S. williamsii to mycorrhizal tomato plants significantly enhanced nitrogen concentration in the shoots, but this effect was also compensated with a carbon cost. Our findings indicate that S. williamsii performs differently from S. indica when co-inoculated with AMF, and this suggests an unknown mechanism that needs more detailed investigation.

The arbuscular mycorrhizal fungus Funneliformis mosseae induces changes and increases the concentration of volatile organic compounds in Vitis vinifera cv. Sangiovese leaf tissue

Arbuscular mycorrhizal fungi (AMF) are beneficial obligate symbionts of plant roots. Volatile organic compounds (VOCs) participate in plant communication and defence. The aim of this study was to analyse the effects of the arbuscular mycorrhizal fungus Funneliformis mosseae IMA1 on VOCs in Vitis vinifera cv. Sangiovese leaf tissue. Grapevine plants inoculated with F. mosseae IMA1 were incubated for 23 weeks. VOCs were extracted from leaves and identified using headspace solid-phase microextraction (HS–SPME) coupled to GC-MS. VOCs in leaf tissue were strongly enhanced (85%) by F. mosseae IMA1. The mycorrhizal fungus IMA1 modified the levels of specific VOCs synthesised in different anabolic pathways. An increase in volatiles that have been related to plant defences under pathogen/herbivore attack or linked to water stress, such as (E)–2–hexenal, 3–hexenal, geraniol, benzaldehyde and methyl salicylate, was observed in mycorrhizal plants. In contrast, some C13–norisoprenoids decreased strongly in mycorrhizal plants. The study of the effects of AMF on VOCs in grapevine plants may provide useful information to establish sustainable viticultural practices.

Microbial Consortium Promotes Growth of Zinnia and Balsam Seedlings Raised in pro trays

Zinnia and Balsam are flowering plants with high economic importance in floriculture. Inoculation of the planting medium with a beneficial microbial consortium is an innovative approach to produce quality and healthy seedlings in floriculture. In the present study the influence of a microbial consortium of the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae and a plant growth promoting rhizobacterium (PGPR) Bacillus sonorensis on flowering plants Zinnia and Balsam in pro-trays under poly house conditions was investigated. Estimation of various plant growth parameters such as plant height, stem diameter, bio-volume index, vigour index, plant strength, fresh weight, dry weight and nutrient uptake was carried out to analyse the ability of the consortium to improve seedling growth. Microbial parameters such as mycorrhizal root colonization and spore count, and population of PGPR in substrate was also studied. The results suggested that inoculating the substrate in pro trays before sowing the seeds with the consortium increased plant growth significantly compared to the uninoculated plants.

MLO Differentially Regulates Barley Root Colonization by Beneficial Endophytic and Mycorrhizal Fungi.

Loss-of-function alleles of MLO (Mildew Resistance Locus O) confer broad-spectrum resistance to foliar infections by powdery mildew pathogens. Like pathogens, microbes that establish mutually beneficial relationships with their plant hosts, trigger the induction of some defense responses. Initially, barley colonization by the root endophyte Serendipita indica (syn. Piriformospora indica) is associated with enhanced defense gene expression and the formation of papillae at sites of hyphal penetration attempts. This phenotype is reminiscent of mlo-conditioned immunity in barley leaf tissue and raises the question whether MLO plays a regulatory role in the establishment of beneficial interactions. Here we show that S. indica colonization was significantly reduced in plants carrying mlo mutations compared to wild type controls. The reduction in fungal biomass was associated with the enhanced formation of papillae. Moreover, epidermal cells of S. indica-treated mlo plants displayed an early accumulation of iron in the epidermal layer suggesting increased basal defense activation in the barley mutant background. Correspondingly, the induction of host cell death during later colonization stages was impaired in mlo colonized plants, highlighting the importance of the early biotrophic growth phase for S. indica root colonization. In contrast, the arbuscular mycorrhizal fungus Funneliformis mosseae displayed a similar colonization morphology on mutant and wild type plants. However, the frequency of mycorrhization and number of arbuscules was higher in mlo-5 mutants. These findings suggest that MLO differentially regulates root colonization by endophytic and AM fungi.

Beneficial Plant Microorganisms Affect the Endophytic Bacterial Communities of Durum Wheat Roots as Detected by Different Molecular Approaches.

This study aimed at characterising the endophytic bacterial communities living in durum wheat roots, as affected by wheat cultivar and inoculation of the Arbuscular mycorrhizal fungus Funneliformis mosseae IMA1 and the wheat root endophytic bacterium Lactobacillus plantarum B.MD.R.A2. These microorganisms were inoculated, alone or in combination, in durum wheat (cultivars Odisseo and Saragolla). Non-inoculated plants of each cultivar represented the controls. Forty-three days after sowing, roots were deprived of the epiphytic microbiota and subjected to DNA extraction. The DNA was used as template in PCR-DGGE analysis of the 16S rRNA gene (variable region V3–V5) and 16S (region V1–V3) metagenetics. Odisseo and Saragolla root endophytic bacterial biotas differed for number of OTUs and composition. In detail, Pseudomonas was higher in Odisseo than in Saragolla. The inoculation of F. mosseae and L. plantarum increased the abundance of Pseudomonas, some Actinobacteria (e.g., Streptomyces, Microbacterium, two genera including several plant growth promoting (PGP) strains) and Bacteroidetes in both cultivars. However, the endophytic bacterial biota of Saragolla roots inoculated just with lactobacilli did not differ from that of the control. The inoculation of Saragolla with F. mosseae, alone or in combination with lactobacilli, led to higher abundance of Rhodococcus, belonging to Actinobacteria and encompassing PGP strains. First, this work showed that F. mosseae and L. plantarum shape the endophytic bacterial biota of durum wheat roots. Abundance of some OTUs was affected by the microbial inoculation, depending on the cultivar. This result represents a starting point for exploitation of beneficial endophytes of wheat roots.

Effects of cadmium-resistant plant growth-promoting rhizobacteria and Funneliformis mosseae on the cadmium tolerance of tomato (Lycopersicon esculentum L.)

Microorganisms are used to alleviate heavy metal stress in plants cultivated in contaminated fields. However, the relevant mechanisms have been rarely explored. The goal of this study was to investigate effects of arbuscular mycorrhizal fungus Funneliformis mosseae and two Cd-resistant bacterial strains (Enterobacter sp. EG16 and Enterobacter ludwigii DJ3) on growth and Cd tolerance of tomato when applied with different inoculation strategies (single or dual) and Cd concentrations (50 and 100 mg kg−1). Better plant growth was observed in mycorrhizal alone or combined treatments. In F. mosseae and EG16 co-inoculation treatment, shoot and root dry weight were 119–154% and 91–173% higher than those of the control, respectively. Higher bacterial and mycorrhizal colonization rate and root Cd concentration were also found in this treatment. However, the decrease of shoot Cd concentration and translocation factor values indicated this treatment was effective in improving Cd tolerance of the host plants. In addition, the increase in soil pH and decline in bioavailable Cd in the rhizosphere might be partly involved in reduction of Cd accumulation in plants. Our results suggest that co-inoculation with suitable microorganisms is important in plant growth and tolerance to Cd in Cd-contaminated soil.

ITRAQ Proteomic Analysis of Continuously Cropped Soybean Root Inoculated With Funneliformis mosseae.

Soybean (Glycine max) is susceptible to root rot when subjected to continuous cropping, and this disease can seriously diminish the crop yield. Proteomics analyses can show the difference of protein expression in different treatment samples. Herein, isobaric tag for relative and absolute quantitation (iTRAQ) labeling and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were employed for proteomic analysis of continuously cropped soybean inoculated with the arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae. The AMF can reduce the incidence of root rot and increase plant height, biomass index in 1, 2, and 4 year of continuous cropping. Differential expression of proteins in soybean roots was determined following 1 year of continuous cropping. A total of 131 differentially expressed proteins (DEPs) were identified in F. mosseae-treated samples, of which 49 and 82 were up- and down-regulated, respectively. The DEPs were annotated with 117 gene ontology (GO) terms, with 48 involved in biological processes, 31 linked to molecular functions, and 39 associated with cell components. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis mapped the DEPs to 113 mainly metabolic pathways including oxidative phosphorylation, glycolysis, and amino acid metabolism. Expression of glucan 1,3-beta-glucosidase, chalcone isomerase, calcium-dependent phospholipid binding and other defense-related proteins was up-regulated by F. mosseae, suggesting inoculation promotes the growth and development of soybean and increases disease resistance. The findings provide an experimental basis for further research on the molecular mechanisms of AMF in resolving problems associated with continuous soybean cropping.

Effects of mycorrhizal fungi on root-hair growth and hormone levels of taproot and lateral roots in trifoliate orange under drought stress

ABSTRACTA pot experiment was used to evaluate the effects of an arbuscular mycorrhizal fungus (AMF) Funneliformis mosseae on plant growth performance, root-hair growth, and root hormone levels in trifoliate orange (Poncirus trifoliata) seedlings under well-watered (WW) and drought stress (DS). A 9-week mild DS treatment significantly reduced mycorrhizal colonization of 2nd- and 3rd-order lateral roots. Root mycorrhizal colonization was relatively higher in the 2nd- and 3rd-order lateral roots than in the taproot and the 1st-order lateral root under WW and DS. AMF seedlings exhibited significantly higher root-hair density, length (except for the taproot) and diameter in taproot and 1st-, 2nd-, and 3rd-order lateral roots under WW, and considerably higher root-hair density (except for 1st-order lateral root), length (except for 2nd-order lateral root) and diameter under DS. Mycorrhizal inoculation remarkably increased root abscisic acid (ABA), indole-3-acetic acid (IAA), methyl jasmonate, and brassinosteroids (BRs) concentrations under DS, in company with the decrease in root zeatin riboside and gibberellins levels and root IAA effluxes. Root-hair traits were significantly positively correlated with root colonization and root ABA and BRs levels. It is concluded that mycorrhizal plants possessed better root-hair growth to adapt mild DS, which is associated with mycorrhizal colonization and endogenous hormone changes.