Effects Of Mycorrhizal Symbiosis Research Articles

Effects of mycorrhizal symbiosis and Ulva lactuca seaweed extract on growth, carbon/nitrogen metabolism, and antioxidant response in cadmium-stressed sorghum plant.

In our study on the effect of cadmium (Cd) toxicity (200µM) on the growth of Sorghum bicolor (L.) Moench plants, cultivated with arbuscular mycorrhizal fungi (AMF) (Glomus intraradices) and/or under seaweed treatment (3% Ulva lactuca extract) (U. lactuca), we found that AMF increased the tolerance of sorghum to cadmium stress, either alone or in combination with the seaweed treatment. Morphological parameters were higher in these two culture conditions, with increased chlorophyll content. AMF reduced Cd accumulation in roots and inhibited its translocation to the aerial part, while seaweed treatment alone significantly increased Cd accumulation in leaves and roots without affecting plant growth compared to stressed witnesses. Treatment with AMF and/or U. lactuca attenuated oxidative stress, measured by activation of superoxide dismutase, and resulted in a significant decrease in malondialdehyde and superoxide ions (O2-) in treated plants. Furthermore, it induced significant alterations in carbon and nitrogen metabolic pathways, with a significant increase in the activity of enzymes such as glutamine synthetase, glutamate synthase (GOGAT), glutamate dehydrogenase, phosphoenolpyruvate carboxylase, aspartate aminotransferase and isocitrate dehydrogenase in the leaves of each treated plant. These results confirm that AMF, U. lactuca algae extract and their combination can improve the biochemical parameters of sorghum under Cd stress, through modification of the antioxidant response on one hand, and improved nitrogen absorption and assimilation efficiency on the other.

The Alien Invader, Rhus typhina L., Outperforms Its Native Competitor in the Scenario of Nitrogen Deposition and Arbuscular Mycorrhizal Fungi (AMF) Inoculation

Nitrogen deposition has been proven to facilitate the establishment of alien plants. Previous studies have certified that nitrogen deposition enhances the resource availability of habitats and promotes the growth of alien invaders. Arbuscular mycorrhizal fungi (AMF) symbiose with vascular plants and assist plants in nutrient acquisition. AMF colonization has been proven to be another driving factor of plant invasion. However, few studies have integrated nitrogen deposition and AMF inoculation into the exploration on invasion mechanism. Based on a trait approach, the present study subjected the alien invader, Rhus typhina L., and its co-occurring native species, Acer truncatum Bunge, to nitrogen deposition and AMF inoculation and compared the phenotypic variation in aboveground and belowground traits in an inter-specific competition experiment. Through the effects of different nitrogen deposition and AMF infection on the functional traits of R. typhina and A. truncatum, the effects of mycorrhizal symbiosis between R. typhina and A. truncatum on abiotic factors and interspecific relationships were analyzed. We found that inter-specific competition stimulated the colonization of AMF in R. typhina, however, decreased the colonization rate of AMF in A. truncatum. Correspondingly, inter-specific competition significantly reduced the plant growth of A. truncatum as the aboveground morphological traits including plant height and crown area, and belowground traits including root length, root surface area, root volume, number of root tips, number of root tip branches and number of root cross decreased for A. truncatum. Nitrogen deposition promoted the shoot growth of R. typhina rather than that of A. truncatum. AMF inoculation significantly affected the belowground traits of A. truncatum as the root length and root surface area significantly decreased after AMF inoculation in the mixture planting of the two species. The chlorophyll content of A. truncatum decreased without AMF inoculation, while nitrogen deposition enhanced the net photosynthetic rate of R. typhina. The alien invader R. typhina outperforms its native competitor in the simulated scenario of resource fluctuation and facilitates its establishment. We speculate that AMF colonization promotes the extension of R. typhina rhizosphere and, thus, accelerates the growth and invasion of R. typhina.

Mycorrhizal symbiosis promotes the nutrient content accumulation and affects the root exudates in maize

BackgroundArbuscular mycorrhizal fungi (AMF) are a group of important symbiotic microorganisms found in ecosystems. Maize is the second most produced food crop globally. To investigate the mechanisms by which mycorrhizal symbiosis improves maize yields, the effects of mycorrhizal symbiosis on root vigor, nutrient accumulation in various tissues, and root exudates were investigated. We propose the following hypothesis: The secretion of organic acids in root exudates has antagonistic or synergistic effects, which are related to the rhizosphere environment. AMF symbiosis will enhance this effect.ResultRhizophagus aggreatus, Claroideoglomus etunicatum, and Funneliformis mosseae were used to inoculate maize plants separately; meanwhile, maize was inoculated with the above three fungi together for another processing. The plant tissues were sampled at five growth stages: V12 (twelve-leaf), VT (Tassel), R1 (Silking), R2 (Blister), and R4 (Dough stage). The root vigor, and nutrient content in different maize organs and organic acids in root exudates were determined in these stages. The results show that mycorrhizal symbiosis significantly improved the root vigor of maize, especially for plants inoculated with F. mosseae. AMF symbiosis significantly increased N, P, and K accumulation. Mixed inoculation with arbuscular mycorrhizal fungi significantly promoted the accumulation of N and K in maize. P accumulation was significantly promoted by C. etunicatum inoculation. Mycorrhizal symbiosis reduced the levels of protocatechuic, vanillic, citric, and ferulic acid in maize root exudates and increased the levels of p-hydroxybenzoic and caffeic acid. Except for syringic, chlorogenic and succinic acid, the levels of other organic acids in root exudates were higher in plants inoculated with F. mosseae than in other treatments.ConclusionThis study demonstrates that mycorrhizal symbiosis improves root vigor and promotes nutrient accumulation at various sites; in addition, mycorrhizal symbiosis affects the content of organic acids in root exudates.

Yield and morpho-physiological traits of tobacco (Nicotiana tabacum L.) as affected by azotobacter, mycorrhizal symbiosis and biochar application

The present study was performed to evaluate the effect of mycorrhizal symbiosis and azotobacter with the application of biochar on tobacco growth parameters, yield and nicotine content under rainfed conditions for two growing seasons (2016-2017 and 2017-2018). The factorial experiment was performed based on a randomized complete block design with four replications and three factors including biochar at three levels (0, 4 and 8 ton/ha), mycorrhizal fungi and Azotobacter chroococcum each one at two levels (without and with application). Results showed that biochar application had a significant and positive effect on all evaluated parameters. However, there was no statistically significant difference between 4 and 8 tons per hectare of biochar in yield. Mycorrhizal symbiosis had a significant effect on relative water content. Application of azotobacter had a positive and significant effect on growth parameters, yield and nicotine content under rainfed conditions for two growing seasons (2016-2017 and nicotine content. The greatest effect of azotobacter with a 17% increase was on leaf nicotine content. Whereas tobacco dry yield in rainfed conditions is lower, the combined use of biochar and these biofertilizers can be considered a desirable solution. Then in terms of economic aspects, the use of 4 tons biochar per hectare along with the use of mycorrhiza and azotobacter to achieve acceptable yield while maintaining chemical quality in tobacco farms is recommended.

The effect of mycorrhizal symbiosis and application of organic fertilizers on photosynthetic pigments, yield and nutrient content Nasturtium officinalis

Abstract Background and objectives: Endemic vegetables are a wide range of plants that are known and used in different regions with different names and are native to the region. But a group of them, which are found in most areas, are more common in food, and some of them are used as medical treatment, sedatives, and in health and cosmetics. These plants grow away from chemical fertilizers and in the sun and have a different flavor and are more nutritious and natural than vegetables grown artificially. The increasing use of chemical fertilizers has caused irreparable environmental and health damage. These disadvantages of chemical fertilizers and the high cost of their production have caused the production of biofertilizers to be given serious attention. This study aimed to investigate the effect of organic fertilizers (vermicompost, vermiwash) and mycorrhizal symbiosis on yield and yield components of Nasturtium officinalis. Materials and Methods: This factorial experiment in the form of a randomized complete block design with 8 treatments and 4 replications in Sari with a geographical position of 53 degrees and 63 degrees East, 36 degrees latitude, and 82 minutes north and 43.3 meters above sea level in 2014. The test factors included mycorrhiza Glomus moseae in two levels (0 and 200 spores in a pot), vermicompost in two levels (0 and 200 g in a pot), and foliar application vermiwash in two levels (0 and 1.5 liters in the specified pots). Characteristics such as leaf area index, chlorophyll a, b, and total chlorophyll, the concentration of nitrogen, phosphorus, potassium, fresh weight of leaves and stems, number and diameter of flowers and weight of 1000 seeds were evaluated. Results: The results showed that the use of organic fertilizers (vermicompost, foliar application of vermicompost) and mycorrhizal coexistence increased leaf area index, 1000-seed weight, and percentage of phosphorus, nitrogen, and chlorophyll a, b compared to the control. Mycorrhizal symbiosis treatment with foliar application of vermicompost and application of vermicompost caused 53% increase in 1000-seed weight, 245% nitrogen, 72% phosphorus and 65% chlorophyll b compared to the control. According to the obtained results, combining G. mosseae treatment and foliar application with vermicompost and application of vermicompost had better results than other treatments. Conclusion: generally, Organic and biological fertilizers have a positive impact on the yield and yield components of Nasturtium officinalis The application of vermicompost, compost tea, and mycorrhizal symbiosis through the availability of nutrients has increased the Nasturtium officinalis qualitative and quantitative qualities.

Health-Promoting Compounds in Stevia: The Effect of Mycorrhizal Symbiosis, Phosphorus Supply and Harvest Time.

This work aimed to establish the synergic role of arbuscular mycorrhizal fungi (AMF) symbiosis, phosphorus (P) fertilization and harvest time on the contents of stevia secondary metabolites. Consequently, steviol glycosides (SVglys) concentration and profile, total phenols and flavonoids as well as antioxidant assays, have been assessed in inoculated and no-inoculated plants, grown with or without P supply and collected at different growth stages(69, 89 and 123 days after transplanting).The obtained results suggest that the synthesis of stevia secondary metabolites is induced and/or modulated by all the investigated variability factors. In particular, AMF symbiosis promoted total SVglys content and positively influenced the concentration of some minor compounds (steviolbioside, dulcoside A and rebaudioside B), indicating a clear effect of mycorrhizal inoculation on SVglys biosynthetic pathway. Interestingly, only the mycorrhizal plants were able to synthesize rebaudioside B. In addition, P supply provided the highest levels of total phenols and flavonoids at leaf level, together with the maximum in vitro antioxidant activities (FRAP and ORAC). Finally, the harvest time carried out during the full vegetative phase enhanced the entire composition of the phytocomplex (steviolbioside, dulcoside A, stevioside, rebaudioside A, B, C. total phenols and flavonoids). Moreover, polyphenols and SVglys appeared to be the main contributors to the in vitro antioxidant capacity, while only total phenols mostly contributed to the cellular antioxidant activity (CAA). These findings provide original information about the role played by AMF in association with P supply, in modulating the accumulation of bioactive compounds during stevia growth. At the cultivation level, the control of these preharvest factors, together with the most appropriate harvest time, can be used as tools for improving the nutraceutical value of raw material, with particular attention to its exploitation as functional ingredient for food and dietary supplements and cosmetics.

Effects of mycorrhizal symbiosis and seed priming on yield and water use efficiency of sesame under drought stress condition

In order to study the effect of drought stress, seed priming, and mycorrhizal symbiosis on yield, harvest index, and water use efficiency (WUE) of sesame, an experiment was carried out based on the randomized complete block design as split-factorial arrangement with three replications at Agricultural Research Station of Haji Abad, Hormozgan- Iran, in 2014 and 2015. The results showed that grain yield, biological yield and harvest index were reduced by drought stress. On the other hands, WUE of grain, biological yield and oil product traits increased by drought stress. The highest efficiency of grain yield water usage, biological yield and oil product (0.39, 1.6, and 0.199 kg m−3, respectively) were obtained in the severe drought stress conditions. The results also showed that the highest grain yield, biological yield, and harvest index were related to the normal irrigation. In compared to the appropriate irrigation conditions, moderate to severe water stress reduced grain yield and biological yield rate by 39.4 and 26.7%, respectively. Mycorrhizal symbiosis improved all traits compared to the control group (no mycorrhiza). Inoculation with Funneliformis and Rhizoglomus fungi in optimum irrigation and stress conditions also improved traits compared to the control group.

Plant facilitation through mycorrhizal symbiosis is stronger between distantly related plant species.

The tendency of closely related plant species to share natural enemies has been suggested to limit their co-occurrence and performance, but we lack a deep understanding on how mutualistic interactions such as the mycorrhizal symbiosis affect plant-plant interactions depending on the phylogenetic relatedness of the interacting plants. We hypothesise that the effect of the mycorrhizal symbiosis on plant-plant facilitative interactions depends on the phylogenetic distance between the nurse and facilitated plants. A recently published meta-analysis compiled the strength of plant facilitative interactions in the presence or absence (or reduced abundance) of mycorrhizal fungi. We use phylogenetically informed Bayesian linear models to test whether the effect size is influenced by the phylogenetic distance between the plant species involved in each plant facilitative interaction. Conspecific facilitative interactions are more strongly enhanced by mycorrhizal fungi than interactions between closely related species. In heterospecific interactions, the effect of the mycorrhizal symbiosis on plant facilitation increases with the phylogenetic distance between the nurse and facilitated plant species. Our result showing that the effect of mycorrhizal symbiosis on the facilitation interactions between plants depends on their phylogenetic relatedness provides new mechanisms to understand how facilitation is assembling ecological communities.

Mycorrhizal symbiosis increases the benefits of plant facilitative interactions

The diversity of pathways through which mycorrhizal fungi alter plant coexistence hinders the understanding of their effects on plant‐plant interactions. The outcome of plant facilitative interactions can be indirectly affected by mycorrhizal symbiosis, ultimately shaping biodiversity patterns. We tested whether mycorrhizal symbiosis enhances plant facilitative interactions and whether its effect is consistent across different methodological approaches and biological scenarios. We conducted a meta‐analysis of 215 cases (involving 21 nurse and 29 facilitated species), in which the performance of a facilitated plant species is measured in the presence or absence of mycorrhizal fungi. We show that mycorrhizal fungi significantly enhance plant facilitative interactions mainly through an increment in plant biomass (aboveground) and nutrient content, although their effects differ across biological contexts. In semiarid environments mycorrhizal symbiosis enhances plant facilitation, while its effect is non‐significant in temperate ecosystems. In addition, arbuscular but not ecto‐mycorrhizal (EMF) fungi significantly enhance plant facilitation, particularly increasing the P content of the plants more than EMF. Some knowledge gaps regarding the importance of this phenomenon have been detected in this meta‐analysis. The effect of mycorrhizal symbiosis on plant facilitation has rarely been assessed in other ecosystems different from semiarid and temperate forests, and rarely considering other fungal benefits provided to plants besides nutrients. Finally, we are still far from understanding the effects of the whole fungal community on plant‐plant interactions, and on plant species coexistence.

Mycorrhizal Inoculation Increases Growth and Induces Changes in Specific Polyphenol Levels in Olive Saplings

This study was conducted to investigate the effect of mycorrhizal symbiosis on the levels of polyphenols in olive saplings. Rooted stem cuttings of olive cultivar, ‘Arbequina’, were inoculated with AM fungus Rhizophagus intraradices. The inoculated plants showed more robust growth after six months, and after nine months the increase in the mycorrhizal plant’s height was 146%, and the increase in number of leaves was 117% when compared to uninoculated controls. Polyphenols in the methanol extracts of leaves were separated by HPLC and the peaks identified by using commercially available standard compounds and comparing retention time and the mass obtained with the mass spectrometer. Oleuropein, which is a major component of the olive leaf polyphenols, increased in mycorrhizal plants compared to uninoculated plants by 42%, and its derivatives, oleuroside and ligstroside, increased by 68% and 48%, respectively. The highest increase was found in the levels of luteolin-7’-O-glucoside (107% increase), while its sister compound luteolin-4’-O-glucoside increased by 43%. Only verbascoside levels were lower in mycorrhizal plants versus non-mycorrhizal plants declining to below detectable limits. Thus, inoculation of olive saplings with mycorrhizal fungi produces very positive effects on the levels of olive leaf polyphenols. Higher levels polyphenols mean better quality of leaf material for use as herbal medicine.

Effects of Mycorrhizal Symbiosis on Growth Behavior and Carbohydrate Metabolism of Trifoliate Orange Under Different Substrate P Levels

The carbohydrate regulatory function of arbuscular mycorrhizal fungi (AMF), associated changes in root morphology, and substrate P level are important in the efficiency of AMF. A pot experiment was carried out to study the effects of AMF (Funneliformis mosseae) on growth response, root morphology, and sucrose metabolism of trifoliate orange [Poncirus trifoliata (L.) Raf.] seedlings under varying P substrate levels (0, 3, and 30 mM). Mycorrhizal inoculation stimulated growth performance, biomass production (root and shoot fresh weight), and various root morphological traits, regardless of substrate P level. AMF-induced sucrose accumulation in leaves was more highly positively correlated with leaf sucrose synthase (synthesis direction) activity in AMF than in non-AMF seedlings. Root glucose and fructose concentrations were significantly increased by AMF inoculation, independent of P level. Root colonization was more highly correlated with root glucose than with root fructose. AMF inoculation represented varied effects on activity of acid invertase and neutral invertase in leaves and roots at all the three P levels. These results indicated that AMF-accelerated better growth response and root morphological traits were independent of substrate P level, and AMF-induced sucrose cleavage was dependent on substrate P levels, plant tissue types, and sucrose-cleaving enzyme types.

Effects of Arbuscular Mycorrhizal Fungi on Metals Uptake, Physiological and Biochemical Response of <i>Medicago Sativa</i> L. with Increasing Zn and Cd Concentrations in Soil

The effect of mycorrhizal symbiosis on metal accumulation and plant tolerance are not commonly studied in medicinal plants under metal stress. The objective of this study was to assess the impact of mycorrhiza on alfalfa plants with the increase of Zn and Cd toxicity. The experiment was conducted under controlled laboratory conditions. Zinc (Zn) and cadmium (Cd) uptake, some biochemical and physiological parameters were studied in eight-week-old alfalfa plants in response to inoculation or not with arbuscular mycorrhizal fungi (AMF) and with the increase of Zn (0, 100, 300, 900 mg·kg-1) and Cd concentrations (0, 100, 300, 600 mg·kg-1) in soil. The results showed that mycorrhizal (M) plants exhibited tolerance to Zn and Cd up to 300 mg·kg-1 in comparison to non-mycorrhizal (NM) plants which exhibited a significant growth reduction at the same soil Zn and Cd level. M inoculation reduced the Zn and Cd accumulation in shoot and showed higher Zn and Cd contents in roots which showed a different Zn and Cd distribution in AMF associated or non-associated plants. Mycorrhizal plants increased phosphorus (P) contents at all Zn and Cd concentrations except the highest (600 and 900 mg·kg-1) leading significant alterations in biochemical contents such as proline, antioxidant enzymes in leaves and also in nutrients (N, P, K, Cu, Ni, Fe, Mn). Zn and cadmium toxicity cause to increase the proline content in shoot of NM plants, however, proline contents are lower in M plants. Results confirmed that AMF protected alfalfa plants against Zn and Cd toxicity. Mycorrhizal colonization was able to form an efficient symbiosis with alfalfa plants in moderately contaminated Zn and Cd soils (300 mg·kg-1) and play an important role in food quality and safety.

Effects of mycorrhizal symbiosis and different levels of phosphorus on yield, macro and micro elements of Zea mays L. under water stress condition

Nowadays, Mycorrhizal fungi are widely used due to their symbiosis relation with roots of so many plants. These fungi, by supplying some of plant nutritional and water requirements, have a key role in all ecosystems. In this research the effects of mycorrhizal fungi and different levels of phosphorous chemical fertilizers on yield and nutrient uptake under three levels of irrigation were studied. This experiment was performed in fully randomized blocks and as a split factorial design with four replications in which different irrigation levels (A1, A2, A3) (60.120.180 mm) were placed in the main plots while different phosphor levels including P1=0 kg/ha, P2=60 kg/ha and P3=120 kg/ha of pure phosphorus were placed in the subplots. Half of these subplots inoculated by mycorrhizal fungi and the others regarded as uninoculated ones in inoculated sub plots, at seed sowing, 6 g of Mycorrhizal inoculums were placed 3 cm under the each seed. The results indicated that the effects of Mycorrhizal inoculation were statistically significant and positive on measured characteristics. Among triple interactions irrigation/chemical phosphorus/mycorrhizal inoculation had significant effects (P<0.05, 5045 kg/ha) on grain yield and (P<0.01) on Phosphorus concentration. Highest grain yield and other yield component were in A1P2G2 treatment. Results showed that in moderate water stress, by using proper amount of chemical phosphorus and mycorrhizal inoculation can compensate decrease in grain yield. Other treatments had significant difference with A2P2G2 which means by increasing water stress, increasing or decreasing amount of chemical phosphorus and without mycorrhizal inoculation grain yield of corn will decrease significantly. However, such mycorrhizal ability can help us to decrease amount of phosphorus chemical fertilizes in corn growth. Moreover, under water stress, mycorrhizal inoculation improved most of measured indexes. Therefore this kind of biofertilizer can have an important key role in agriculture of arid and semiarid climates.   Key words: Mycorrhizal symbiosis, phosphorus, water stress, corn.

The effect of mycorrhizal symbiosis on the development of micropropagated artichokes

In this work, microrosettes of Cynara cardunculus L. var. scolymus Fiori of the “catanese” type were subcultured in a medium supplemented with 6-benzylaminopurine (BAP) (0.05 mg l −1). For root induction, indoleacetic acid (IAA), α-naphthalene acetic acid (NAA) and indole-3-butyrric acid (IBA) were used at three concentrations: 2, 5 and 10 mg l −1. The highest percentage of rooted shoots was aided by the presence of 10 mg l −1 IAA. Once transplanted in pots, the plantlets were inoculated with 10 g Glomus viscosum strain A6 (AM fungus). Acclimatisation was clearly facilitated by the addition of the AM fungus. Indeed, the mycorrhizal plantlets registered a survival of between 90 and 95% for the rooting shoots and 60% for the non-rooting shoots. The botanical characterization of the material produced was carried out in field and was based on several morphological and productive parameters. Data collected confirm the characteristics of the original cultivar, the efficiency of the in vitro propagation material and the possibility of using this technique in early types of artichoke.

Mycorrhizal symbiosis has contrasting effects on fitness components in Campanula rotundifolia

Summary • The benefits or costs of mycorrhizal symbiosis for the host plants are most frequently estimated in terms of positive or negative effects on plant growth and biomass. The effect of mycorrhizal symbiosis on evolutionarily important fitness traits, such as reproduction, and effects on the next generation are poorly known. • In a set of glasshouse experiments involving two plant generations we investigated the impact of mycorrhiza on fitness traits in perennial hand-pollinated Campanula rotundifolia. • Mycorrhiza reduced plant growth and flower production, but increased root-shoot ratio, and shoot phosphorus (P) concentration. Mycorrhiza had no effect on seed number per capsule, mean seed weight or germination rate, but increased seed P concentration. Seedlings from mycorrhizal plants had a higher relative growth rate (RGR) than seedlings from nonmycorrhizal plants. Self-pollinations yielded fewer seeds per capsule that had inferior germination than seeds from cross-pollinations. • Mycorrhizal infection was associated with a cost for the reproductive output of the C. rotundifolia host plant, whose progeny, however, were better than those from the nonmycorrhizal plants. Mycorrhiza also showed the potential to affect the plant mating system by increasing self-incompatibility and inbreeding depression expressed during seedling growth.

Plant demographic responses to mycorrhizal symbiosis in tallgrass prairie

The effects of mycorrhizal symbiosis on seedling emergence, flowering and densities of several grasses and forbs were assessed in native tallgrass prairie and in sown garden populations at the Konza Prairie in northeastern Kansas. Mycorrhizal activity was experimentally suppressed with the fungicide benomyl. Flowering and stem densities of the cool-season grass, Dichanthelium oligosanthes, sedges (Carex spp.), and the forb Aster ericoides were higher in non-mycorrhizal (benomyl-treated) than in mycorrhizal plots and the magnitude of these differences was significantly affected by burning. Mycorrhizae significantly enhanced flowering of the warmseason grasses Andropogon gerardii and Sorghastrum nutans in burned prairie, but not in unburned sites. These patterns suggest that mycorrhizal effects on the dynamics of cool-season graminoid and forb populations are likely to be mediated indirectly through effects of the symbiosis on the competitive dominance of their neighbors. Seedling emergence rates of the cool-season C3 grasses Elymus canadensis and Koeleria cristata were significantly reduced in the benomyl-treated plots, whereas benomyl treatment had no significant effect on seedling emergence of the warm-season C4 grasses A. gerardii and Panicum virgatum. The forbs showed variable responses. Seedling emergence of Liatris aspera was greater under mycorrhizal conditions, but that of Dalea purpurea was unaffected by mycorrhizal treatment. These results show that effects of mycorrhizal symbiosis on the population dynamics of co-occurring prairie plants vary significantly both among species and among different life history stages within species. The results also indicate that mycorrhizas and fire interact to influence competitive interactions and demographic patterns of tallgrass prairie plant populations.