Glomus Coronatum Research Articles

Production of Arbuscular Mycorrhizal Spores by Providing Nasa Liquid Organic Fertilizer (LOF)

Arbuscular mycorrhizal fungi (AMF) are root symbionts that are in symbiosis with the majority of plants and are generally found in terrestrial ecosystems. The propagation of AMF is influenced by many factors, including fertilization. This study aims to determine the increase in arbuscular mycorrhizal spore production by administering Nasa LOF. The research was conducted at the Plastic House of the Indonesian Mycorrhizal Association, Southeast Sulawesi Branch and the Laboratory of the Forestry Department, Faculty of Forestry and Environmental Sciences, UHO in January - April 2023 using a factorial Completely Randomized Design (CRD) with two factors, namely the first factor, the type of AMF including Glomus coronatum and Glomus claroideum and the second factor is Nasa LOF control, 2.5 ml/1000 ml water, 5 ml/1000 ml water. The results showed that the combination treatment of Glomus claroideum and administration of 5 ml Nasa LOF increased the number of spores in the 3rd month and spores after drying. Nasa LOF 5 ml is relatively applied for the production of Glomus claroideum.

Suppression of Sclerotium rolfsii and Fusarium oxysporum through Glomalin a Glycoprotein Produced by Arbuscular Mycorrhizal Fungi under in vitro Condition

For sustainable agriculture to succeed, especially in the production of organic food, the use of biofertilizers and biopesticides is essential. Arbuscular mycorrhizal symbiosis is important for improving plant development through increased nutrient intake, soil stabilization, and carbon sequestration through the creation of glomalin, a distinct and specialized protein. It was not determined whether glomalin affects soil-borne fungi infections. Therefore, using glomalin isolated from the soil used to raise maize plants inoculated with various arbuscular mycorrhizal fungi (AMF), the inhibition of soil-borne plant diseases Sclerotium rolfsii and Fusarium oxysporum was examined. The outcomes demonstrated that there was variation in the quantity of glomalin generated by various AMF species. Glomalin isolated from soil inoculated with Glomus coronatum suppressed Sclerotium rolfsii and Fusarium oxysporum more effectively in in-vitro tests than soil inoculated with Glomus intraradices and Glomus mosseae.

Macro and Microelements in Leaves of ‘Meredith’ Peach Cultivar Supplied with Biochar, Organic and Beneficial Biofertilizer Combinations

The content of macro and microelements in the leaves of peach trees treated with biochar, organic fertilization and microorganisms in the field experiment was tested. The experiment was carried out in accordance with the integrated fruit production methods at the NIHR Experimental Orchard in Dąbrowice, from 2015 to 2017. The trees were grafted on P. persica Mandżurska rootstock and planted in the spring of 2013. In 2014, the following products were applied around the trees and mixed into the topsoil: biochar at a dose of 1.6 kg/tree (2000 kg/ha); biochar at a dose of 1.6 kg/tree used together with microorganisms—bacteria Pseudomonas fluorescens, Pantoea and arbuscular mycorrhizal fungi—Glomus caledonium, Glomus intraradices and Glomus coronatum; biochar at a dose of 1.6 kg/tree applied together with Florovit NPK organic fertilizer at a dose of 0.2 kg/tree; Florovit NPK; microorganisms—bacteria Pseudomonas fluorescens, Pantoea and arbuscular mycorrhizal fungi—Glomus caledonium, Glomus intraradices and Glomus coronatum; Florovit NPK organic fertilizer with the same microorganisms; and an untreated control. The average results showed that, compared to the control, the biochar increased the nitrogen content in the leaves by 6%. All experimental combinations increased the content of P and K in the leaves. The most effective at increasing the content of phosphorus in leaves—by 48%—was Florovit. The greatest increase in potassium was after the use of biochar with Florovit—by 38%. The magnesium content ranged from 0.49 to 0.59 g/100 g DW. The highest content of Mg was found in the leaves after the application of biochar with Florovit, and the lowest after the use of biochar alone. The leaves of the trees fertilized with the Florovit organic fertilizer had the lowest calcium content, while the highest calcium content was found in combination with trees treated with biochar only. The use of biochar alone did not increase the content of boron in the leaves compared to the control. In all other combinations, a higher amount of boron was found. The highest—18% more than the control of this microelement had leaves where biochar and Florovit were used. Trees treated with biochar and microorganisms accumulated the least copper in the leaves, while the highest content of this element was found in the combination where biochar fertilization was applied together with Florovit. Lower iron concentrations in peach leaves were found as a result of applying microorganisms, microorganisms with the organic fertilizer and biochar, relative to organic fertilization and the control combination. Trees where only microorganisms were applied to the soil had the least manganese and zinc in the leaves. The accumulation of manganese in the leaves was most favored by fertilization with biochar together with microorganisms, and the zinc content was the highest after the use of biochar alone. In general, studies have shown that a small dose of biochar alone or biochar together with organic fertilizer is a very effective method of feeding peach trees. More research is needed on the use of microorganisms and methods of their application with various products used in orchard fertilization.

Effect of Arbuscular Mycorrhizal Fungi Inoculation on content and nutrient uptake of four-month-old Angsana (Pterocarpus indicus Willd.) plants in post-gold mining land in Bombana, Southeast Sulawesi

Mining activities are the main cause of nutrient-poor land and damage to soil physical properties. This condition also occurs in the post-Bombana gold mining area. thus negatively impacting plant growth response. Therefore, post-mining land remediation is carried out using environmentally friendly approaches such as Arbuscular Mycorrhizal Fungi and the use of adaptive local plant species such as Angsana (Pterocarpus indicus Willd.). This study aims to determine the levels and uptake of nutrients in the mycorrhizal P. indicus plant in post-gold mining field scale. Sampling was carried out in the laboratory of the Faculty of Forestry and Environmental Sciences, Halu Oleo University and observations of nutrient levels were carried out in the soil and plant laboratory of SEAMEO BIOTROP Bogor, this research was carried out for 3 months (May 2021). This research method used a Randomized Block Design (RAK) with 4 treatments, namely control, Glomus coronatum, G. claroideum and mixed AMF. The results showed that mixed AMF was effective in increasing N, Mn and Fe nutrient levels and G. claroideum increased P and K levels. Mixed AMF increased N, Mn and Fe nutrient levels and nutrient uptake in P. indicus plants four months old on the Bombana Gold Post Mining Land, Southeast Sulawesi.

The Effectiviness of Hormone Growth Promoting Fertilizers on Increasing The Production of Arbuscular Mycorrhizal Fungi Spores

Arbuscular Mycorrhizal Fungi (AMF) is one of the fungi that forms a mutualism symbiosis with plants where there is a mutually beneficial relationship between the two parties and acts as a biological fertilizer that needs to be reproduced.AMF propagation is strongly influenced by the availability of nutrients, growing media and host plants. The purpose of this study was to determine the application of hormone growth booster fertilizer to increase the production of arbuscular mycorrhizal fungi spores.This research was conducted at the Plastic House of the Indonesian Mycorrhizal Association (AMI) Southeast Sulawesi Branch and the Laboratory of the Department of Forestry, Faculty of Forestry and Environmental Sciences, Halu Oleo University, Kendari during September – November 2022.This study was arranged based on a Completely Randomized Factorial Design. which consists of 2 factors. The first factor: AMF type which consists of two levels, namely Glomus coronatum and Glomus claroideum. The second factor: Fertilizer application consisting of three levels, namely without fertilizer application (B0), 2, and 5 ml/pot fertilizer (B2) with 3 repetitions. So there are 18 treatment combinations. Each treatment unit contained 9 plants so that the total number of plants was 162 plants. The results of this study indicate that the interaction treatment of G. coronatum and G. claroideum without fertilizer application can give the best results in increasing the number of spores for 3 months and in the treatment of G. coronatum with a fertilizer dose of 2, 5 ml gave the best results for increasing the number of spores after drying. Treatment of G. claroideum with a dose of 5 ml of fertilizer gave the best results in increasing the number of spores after drying.

GROWTH OF ANGSANA (Pterocarpus indicus Willd) MYCORRHIZAE 23 MONTHS AGE IN POST GOLD MINING

Arbuscular Mycorrhizal Fungi (AMF) technology can increase the success of revegetation on post-mining land. In addition to the input of AMF technology, the selection of plant species is very important for the success of post-mining land reclamation. This study aimed to determine the effectiveness of AMF on the viability and growth of the 23-month-old mycorrhizal Angsana (Pterocarpus indicus Willd.) in the post-Bombana gold mining area, Southeast Sulawesi. This research was conducted in the post-gold mining area of ​​PT. Panca Logam Makmur, North Rarowatu District, Bombana Regency and the Laboratory Unit of the Forestry Department, Faculty of Forestry and Environmental Sciences Halu Oleo University, Kendari for 8 months. The research design used a Randomized Block Design which was divided into nine treatments; control (A0), Claroideoglomus etunicatum (A1), Septoglomus constrictum A2), Acaulospora delicata (A3), Glomus claroideum (A4), Glomus coronatum (A5), Ambiospora appendicula (A6), Mixed AMF I (A7); (A1+A2+A6) and Mixed AMF II (A8); (A1+A3+A4+A5). The total number of plants used was 27 plants. The results showed that the application of arbuscular mycorrhizal fungi was effective in increasing the growth of P. indicus plants in post-gold mining areas. The treatment of G. coronatum, G. claroideum, A. appendiculate, and C. etunicatum significantly increased the growth of 23 months old P. indicus plant on post-gold mining land compared to control and other treatments. G. coronatum and G. Claroideum have the potential to be developed as mycorrhizal biofertilizers.

Production of Arbuscular Mycorrhizal Fungi Spores (AMF) Glomus Coronatum and Glomus Claroideum With Ab Mix Nutrition

Arbuscular Mycorrhizal Fungi (AMF) is an obligate fungus that has a symbiosis with plant roots and can stimulate plant growth and productivity so that AMF has the potential to be developed as a biological fertilizer. AMF propagation is influenced by many factors including fertilization. This study aims to determine the effect of giving AB mix nutritional doses on the production of AMF types of Glomus coronatum and Glomus claroideum. The research was conducted at the Plastic House of the Indonesian Mycorrhizal Association Southeast Sulawesi Branch and the Laboratory of the Department of Forestry, Faculty of Forestry and Environmental Sciences, UHO in September - December 2022 using a factorial Completely Randomized Design (CRD) with two factors, namely the first factor was AMF type including Glomus coronatum and Glomus claroideum and the second factor is AB mix nutrition including control, 2.5 ml/1000 ml water, 5 ml/1000 ml water. The results showed that the interaction treatment of AMF Glomus claroideum and the provision of 2.5 ml AB ​​mix nutrition increased the number of AMF spores by 35 spores/5 g zeolite and root colonization by 69.16%.

Arbuscular mycorrhizal fungi to enhance the growth of tropical endangered species Pterocarpus indicus and Pericopsis mooniana in post gold mine field in Southeast Sulawesi, Indonesia

Abstract. Husna, Tuheteru FD, Arif A. 2021. Arbuscular mycorrhizal fungi to enhance the growth of tropical endangered species Pterocarpus indicus and Pericopsis mooniana in post gold mine field in Southeast Sulawesi, Indonesia. Biodiversitas 22: 3844-3853. Gold mining activities contribute to the national economy, but have a serious impact on forest and environmental degradation and pose a threat to tree species in the tropics. Reforestation of post-gold mining with tropical legume tree species is threatened with extinction. Arbuscular mycorrhizal fungi are effective in conservation of endangered plants and restoration of degraded land. The objective of the study was to evaluate the effect of native AM Fungi inoculation on the growth of Pterocarpus indicus and Pericopsis mooniana in nurseries and post-gold mining fields. P. indicus and P. mooniana seedlings were inoculated with Glomus claroideum Schenk & Smith, Glomus coronatum Giovann., and mixed AMF (G. claroideum, G. coronatum). Uninoculated seedlings were used as control treatment, and they were maintained for 4 months under greenhouse conditions. After 4 months in greenhouse, seedlings were transferred to post-gold mine and planted for 4 months. The percentage of AMF colonization, plant growth, nutrient content and uptake of N, P, K, Fe, Mn were measured after 4 months both in the greenhouse and the field. The percentage of AMF colonization under greenhouse conditions in P. indicus and P. mooniana ranged 5.67-75.3% and 2.2-41.2%. All AMF colonization tended to have higher shoot height, leaf numbers and nodules, plant dry weight and N, P, K content under greenhouse conditions. Shoot height, stem diameter, leaf dry weight, N, P, K, Mn and Fe under field conditions had higher inoculated seedlings than control four months after planting. AMF could be used to conserve endangered tree species in post-gold mining reforestation in the tropics.

The conservation of endemic and endangered tree species Kalapia celebica Kosterm with Mycorrhizal bio-fertilizer technology in post-gold mining areas

This research aimed to determine the effectiveness of mycorrhizal fungi of arbuscular (AMF) on the growth of Kalappia celebica Kosterm at 4 months aged after planting in gold mining land of PT. Panca LogamMakmur, Bombana, Southeast Sulawesi. This study was designed using block randomized design (BRD) consisted of 5 treatments, i.e. control, Constrictum etunicatum, Septoglomus constrictum, Glomus claroideum Schenk & Smith, Glomus coronatum Giovann, and mixed AMF (G. claroideum, G. coronatum). Each treatment had three replications. The results showed that AMF colonization significantly increased the growth of K. celebica plants. G. coronatum and C. etunicatum significantly increased the height, diameter, and leaf area and leaves dry weight of K. celebica. AMF can be used for the conservation of extinct tree species in gold mining lands.

Changes in Arbuscular Mycorrhizal Fungal Community Structure in Soybean Rhizosphere Soil Assessed at Different Growth Stages of Soybean

Arbuscular mycorrhizal fungi (AMF) is the most common type of AMF association colonizing the rhizosphere of soybean [Glycine max (L.) Merrill] plants. However, the extent of AMF formation, AMF species composition and diversity at different stages of soybean penology have not yet studied. The current study was aimed to determine AMF species community composition, species distribution and its affinity in the rhizosphere soil of soybean at the different growth stages of soybean. Root and rhizosphere soil samples were collected at different growth stage pre-sowing, nodulation, maturation and harvesting stage from soybean (cultivar JS-335) and were analysed for AMF root colonization, spore diversity, species richness, and relative occurrence of AMF species. The AMF species principally contributing to the crop growth stage was also examined through principal component analysis (PCA). The extent of root length colonized by native AMF (mainly formed arbuscules) in soybean roots was higher at maturation (79.76%) and lowest (25.33%) at nodulation stages, whereas the spore density showed opposite trend. Irrespective of growth stages, a total of 40 AMF morphotypes were observed from which species, viz. Glomus aggregatum, Rhizophagus fasciculatum, Glomus coronatum, Glomus etunicatum, Glomus sp (76.92%), were found to be the most frequent and abundant species followed by species of Acaulospora (12.82%) and Gigaspora (10.25%). The Shannon–Weaver index was the range of 3.22, whereas Simpson’s index was 0.95, which indicates the higher diversity of AMF at pre-sowing. The PCA explains the maximum contribution of all AMF species observed at pre-sowing followed by harvesting concludes that AMF diversity and colonization pattern are greatly affected with the soybean phenological growth stages where rhizosphere was found to be mainly dominated by Glomus morphotypes than the Acaulospora and Gigaspora; hence these can be selected for further exploitation in soybean.

Composition and diversity of arbuscular mycorrhizal fungi spore associated with different land-use types in tropical gold mine

Understanding the composition and diversity of arbuscular mycorrhizal fungi (AMF) is imperative for potentially enhancing their ecological role in different terrestrial ecosystems. Land use can have substantial effects on AMF species composition and diversity, but such effects have been explored less in tropical landscapes. In this study, we assessed the effects of disturbances on AMF species richness, observed the potential development of AMF types to produce mycorrhizal biofertilizer bioinoculants. This study was conducted identifying and selecting AMFs was for the purpose of managing post-mining land in Bombana District, Southeast Sulawesi, Indonesia. AMF spores collected from the field and trap culture were directly isolated and morphologically identified. A total of 15 AMF species were identified, including 11 species from field samples and 9 species from trap cultures. We noted that five AMF species were unique to field conditions and 5 AMF species were uniquely isolated from trap culture. It appears that Glomeraceae family contributed the highest number of species in all land-use types. Glomus sp. 1 was the most frequent species found in all land-use types. The Simpson’s index, Shannon index and evenness ranged from 1.60 ± 0.51 to 2.40 ± 0.40; 0.41 ± 0.17 to 0.62 ± 0.17; 0.25 ± 0.10 to 0.39 ± 0.11, respectively. In this study, we found three new records of AMF species including Entrophospora colombiana , Sclerocystis microcarpa and Glomus coronatum for Indonesia, i.e. from this study, it is clear that different land-use types affected AMF spore composition and species diversity. All AMF species found in this study were then applied to the land to improve land quality.

The potential of arbuscular mycorrhizal fungi to conserve Kalappia celebica, an endangered endemic legume on gold mine tailings in Sulawesi, Indonesia

Kalapi (Kalappia celebica) is an endemic legume of Sulawesi and has been included in the endangered category since the early 1980s. Conservation of the species is possible through ex situ culture techniques. Arbuscular mycorrhizal fungi (AMF) can accelerate plant growth which in turn supports the conservation of endangered species. This study aimed to assess the efficacy of local AMF to accelerate the growth of kalapi and increase nutrient uptake in kalapi grown in gold mine tailing media. There were three AMF treatments, Glomus claroideum, Glomus coronatum, and a mixture of both, plus the control. Each treatment was replicated three times, each consisting of five plants. The results show that the highest AMF colony was obtained by kalapi seedlings inoculated with Glomus coronatum and the mixture of AMF. The range of mycorrhizae inoculation effect values was 59.7–71.3%. AMF inoculation increased growth and dry weight of 4-month-old seedlings compared to controls. Dry and total weights of kalapi inoculated with G. coronatum were significantly different from those inoculated with the AMF mixture. However, they are not significantly different from kalapi inoculated with G. claroideum. The results also show that AMF increased nitrogen and phosphorous uptake by the roots, as well as nitrogen, phosphorous, potassium, manganese and iron by the shoots. All AMF treatments decreased potassium uptake in the roots, except in kalapi inoculated with G. coronatum. The AMF mixture decreased iron contents the roots by 15%. AMF can be developed into biofertilizer to support the conservation of kalapi in tropical Indonesia.

Effect of arbuscular mycorrhizal (AM) fungi inoculation on enzymatic activity and zinc uptake under direct seeded rice system

The application of treatment T3 (Glomus mosseae + 100 % RDF NK) produced significantly more root volume by 72.60 %, 17.80 %, 12.25 %, 14.13 % over the application of treatment T1 (Control), treatment T5 (Glomus coronatum+ 100 % RDF NK), T6 (Gigasporadecipein + 100 % RDF NK) and T7 (BAU AM-1(Glomus sp + 100 % RDF NK), respectively. Similar trend shows at harvesting stage, here the maximum root volume (23c.c) was recorded by the application of T3 (Glomus mosseae + 100 % RDF NK). Maximum AM colonization and spore count was observed at panicle initiation stage with the application of treatment T3 (Glomus mosseae + 100 % RDF NK). This treatment also gave maximum dehydrogenase activity (55.86 µg TPF g-1 24 hr-1), acid phosphatase activity (0.299 mg PNP g-1 hr-1) and alkaline phosphatase activity (0.54 mg PNP g-1 hr-1) at panicle initiation stage. Application of treatment T3 (Glomus mosseae + 100 % RDF NK) significantly increased DTPA extractable Zn in soil and Zn content in plant when compared with all the treatments except treatment T6 (Gigasporadecipien+ 100 % RDF NK). The maximum zinc uptake (0.056 mg pot-1) by grain was recorded under treatment T3 (Glomus mosseae + 100 % RDF NK) followed by application of treatment T6 (Gigasporadecipien + 100 % N and K). Highest grain yield (14.08 g pot-1) was found with the treatment T3 (Glomus mosseae + 100 % RDF NK). As evident from the results, the AM fungal inoculation can effectively modify the soil microbe population and community structure by increasing the soil enzymatic activities and significantly increased the zinc uptake by grain in direct seeded rice (DSR).

Arbuscular mycorrhizal fungi of a Mediterranean island (Pianosa), within a UNESCO Biosphere Reserve

In this work we have determined the community composition of spore-forming arbuscular mycorrhizal fungi (AMF) in a maquis site on Pianosa island, a protected area within the Tuscan Islands UNESCO Biosphere Reserve, Italy. We have analysed rhizosphere soil of the dominant plant species Pistacia lentiscus, Smilax aspera, Rosmarinus officinalis and of the endemic plant Helichrysum litoreum. The AMF species recovered were: Scutellospora dipurpurescens, Glomus coronatum, Glomus mosseae, Glomus etunicatum, Glomus geosporum, Glomus viscosum, Entrophospora sp., Pacispora sp. and Glomus rubiforme. The identification of native S. dipurpurescens and G. coronatum was carried out on spores isolated from rhizosphere soil of H. litoreum, by combining morphological traits and 18S (SSU) and ITS rDNA sequences. Therefore, AMF species of Pianosa rhizosphere soils represent an important repository for the conservation and maintenance in their natural habitat of such beneficial symbionts, key microorganisms of soil fertility.

Impact of antifungals producing rhizobacteria on the performance of Vigna radiata in the presence of arbuscular mycorrhizal fungi

Plant growth-promoting rhizobacteria (PGPR) that produce antifungal metabolites are potential threats for the arbuscular mycorrhizal (AM) fungi known for their beneficial symbiosis with plants that is crucially important for low-input sustainable agriculture. To address this issue, we used a compartmented container system where test plants, Vigna radiata, could only reach a separate nutrient-rich compartment indirectly via the hyphae of AM fungi associated with their roots. In this system, where plants depended on nutrient uptake via AM symbiosis, we explored the impact of various PGPR. Plants were inoculated with or without a consortium of four species of AM fungi (Glomus coronatum, Glomus etunicatum, Glomus constrictum, and Glomus intraradices), and one or more of the following PGPR strains: phenazine producing (P(+)) and phenazine-less mutant (P(-)), diacetylphloroglucinol (DAPG) producing (G(+)) and DAPG-less mutant (G(-)) strains of Pseudomonas fluorescens, and an unknown antifungal metabolite-producing Alcaligenes faecalis strain, SLHRE425 (D). PGPR exerted only a small if any effect on the performance of AM symbiosis. G(+) enhanced AM root colonization and had positive effects on shoot growth and nitrogen content when added alone, but not in combination with P(+). D negatively influenced AM root colonization, but did not affect nutrient acquisition. Principal component analysis of all treatments indicated correlation between root weight, shoot weight, and nutrient uptake by AM fungus. The results indicate that antifungal metabolites producing PGPR do not necessarily interfere with AM symbiosis and may even promote it thus carefully chosen combinations of such bioinoculants could lead to better plant growth.

Stimulation of Plant Growth and Drought Tolerance by Native Microorganisms (AM Fungi and Bacteria) from Dry Environments: Mechanisms Related to Bacterial Effectiveness

In this study we tested whether rhizosphere microorganisms can increase drought tolerance to plants growing under water-limitation conditions. Three indigenous bacterial strains isolated from droughted soil and identified as Pseudomonas putida, Pseudomonas sp., and Bacillus megaterium were able to stimulate plant growth under dry conditions. When the bacteria were grown in axenic culture at increasing osmotic stress caused by polyethylene glycol (PEG) levels (from 0 to 60%) they showed osmotic tolerance and only Pseudomonas sp. decreased indol acetic acid (IAA) production concomitantly with an increase of osmotic stress (PEG) in the medium. P. putida and B. megaterium exhibited the highest osmotic tolerance and both strains also showed increased proline content, involved in osmotic cellular adaptation, as much as increased osmotic stress caused by NaCl supply. These bacteria seem to have developed mechanisms to cope with drought stress. The increase in IAA production by P. putida and B. megaterium at a PEG concentration of 60% is an indication of bacterial resistance to drought. Their inoculation increased shoot and root biomass and water content under drought conditions. Bacterial IAA production under stressed conditions may explain their effectiveness in promoting plant growth and shoot water content increasing plant drought tolerance. B. megaterium was the most efficient bacteria under drought (in successive harvests) either applied alone or associated with the autochthonous arbuscular mycorrhizal fungi Glomus coronatum, Glomus constrictum or Glomus claroideum.B. megaterium colonized the rhizosphere and endorhizosphere zone. We can say, therefore, that microbial activities of adapted strains represent a positive effect on plant development under drought conditions.

Is cortical root colonization required for carbon transfer to arbuscular mycorrhizal fungi? Evidence from colonization phenotypes and spore production in the reduced mycorrhizal colonization (rmc) mutant of tomato

For the first time, the phenotypes formed in the reduced mycorrhizal colonization (rmc) Solanum lycopersicum L. (tomato) mutant with different arbuscular mycorrhizal (AM) fungi were used to explore the potential of different fungal structures to support development of external fungal mycelium and spores. The life cycle of AM fungi with rmc was followed for up to 24 weeks. Results showed that production of external mycelium was slight and transitory for those fungi that did not penetrate the roots of rmc (Pen–) ( Glomus intraradices DAOM181602 and Glomus etunicatum ). For fungi that penetrated the root epidermis and hypodermis (Coi–, Glomus coronatum and Scutellospora calospora ) the mycelium produced varied in size, but was always smaller than with the wild-type 76R. Spores were formed by these fungi with 76R but not with rmc. The only fungus forming a Myc+ phenotype with rmc, G. intraradices WFVAM23, produced as much mycelium with rmc as with 76R. We observed lipid accumulation in hyphae and vesicles in both plant genotypes with this fungus. Mature spores were formed with 76R. However, with rmc, spores remained small and (presumably) immature for up to 24 weeks. We conclude that significant carbon transfer from plant to fungus can occur in Coi– interactions with rmc in which no cortical colonization occurs. We speculate that both carbon transfer and root signals are required for mature spores to be produced.

Temporal temperature gradient gel electrophoresis (TTGE) as a tool for the characterization of arbuscular mycorrhizal fungi

The aim of this study was to assess the feasibility of using temporal temperature gradient electrophoresis (TTGE) of PCR-amplified 18S rDNA fragments of different Glomus species for their detection and characterization. Screening of Glomus clarum, Glomus constrictum, Glomus coronatum, Glomus intraradices, Glomus mosseae and Glomus viscosum by PCR-TGGE revealed that the NS31-AM1 region of the 18S rRNA gene contained insufficient variation to discriminate between them. In contrast, TTGE analysis of the NS31-Glo1 region, which was obtained by nested PCR of the NS31-AM1 amplicon, showed that each species was characterized by a specific TTGE fingerprint. However, isolates of the same species could not be distinguished. The nested PCR-TTGE approach developed allowed identification of the Glomus species colonising the roots of different plant species.

Interactions between arbuscular mycorrhizal fungi and a mycorrhiza‐defective mutant tomato: does a noninfective fungus alter the ability of an infective fungus to colonise the roots – and vice versa?

Summary • We have investigated whether inoculation of a mycorrhiza-defective mutant (rmc) of tomato (Lycopersicon esculentum) with an individual arbuscular mycorrhizal (AM) fungal species affects subsequent colonisation by another AM fungal species that has different infectivity when presented alone. Inoculum was provided by leek (Allium porrum) growing in ‘nurse pots’ into which rmc seedlings were planted, and between which they were subsequently transferred. • Inoculation with Glomus coronatum, an AM fungal species that has low infectivity towards rmc, did not prevent colonisation by Glomus sp. WFVAM 23 (identified as G. versiforme in our previous studies). Also, colonisation by G. sp. WFVAM 23 did not facilitate colonisation by G. coronatum. • The results show that the mechanism by which rmc prevents cortical colonisation by most AM fungi is not dependent on, or modified by, prior plant interactions with individual AM fungal species. The two fungi used here clearly perceive the outcome of the mutation differently. • Growth responses of rmc after sequential inoculation with the two AM fungi are briefly analysed in terms of competition for limiting soil nutrient resources with the nurse plants.

Inoculum type does not affect overall resistance of an arbuscular mycorrhiza-defective tomato mutant to colonisation but inoculation does change competitive interactions with wild-type tomato.

• The influence of inoculum type on colonisation of a mycorrhiza-defective tomato mutant, rmc, by the AM fungus Glomus coronatum was studied by comparing inoculum composed predominantly of spores with hyphae growing from mycorrhizal 'nurse plants', including the wild-type tomato progenitor (WT), other Lycopersicon species, and leek. • Colonisation of rmc was not primarily influenced by inoculum source; minor differences could be attributed to differences in inoculum potential. The mutation is therefore different from other mycorrhiza-defective tomato mutants. • Growth of rmc was reduced in the presence of nurse plants, because of competition with them, so a second experiment examined the effects of AM colonisation on competition between rmc and the WT tomato. This experiment was a replacement series in which rmc and WT were grown in competition and as single plants, inoculated with G.coronatum or uninoculated. • The WT did not respond to G.coronatum when grown alone, but responded positively when in competition with rmc. We conclude from the second experiment that mycorrhizal responsiveness is influenced by competition with (in this case) a surrogate nonhost plant rmc in a situation that mimics interspecific competition. It is therefore a community-based parameter. Results are discussed in the context of responses of mycorrhizal vs nonmycorrhizal species and competition in natural plant ecosytems.