AM Species Research Articles

Native AM fungal colonization in three Hibiscus species under NaCl induced Salinity

The pot experiments were conducted to study influence of sodium chloride salinity on Native Arbuscular Mycorrhizal fungal consortium (NAMC) with respect to three Hibiscus species viz., H. cannabinus, H. sabdariffa and H. tiliaceus (Fam. Malvaceae). All three plant species exhibited appreciable colonization and showed excellent salt tolerance potential at 300 mM NaCl treatment. Results obtained revealed that Arbuscular Mycorrhizal fungal (AM) species spore recovery (SR) was in the range of 50-100% in treated plants. AM species studied in present paper were viz., Claroideoglomus etunicatum, Sclerocystis coremoides (H. cannabinus); Acaulospora myriocarpa, Acaulospora spp. (H. sabdariffa) and Acaulospora foveata, Acaulospora spp., C. etunicatum, Glomus botryoides, G. caledonicum & G. formosanum (H. tiliaceus).

Changes of antioxidative enzymes, lipid peroxidation and chlorophyll content in chickpea types colonized by different Glomus species under drought stress

In order to investigate the effects of Glomus species on some physiological characteristics of two chickpea types (Pirouz cultivar of Desi type and ILC-482 of Kabuli type) under non-stress (NS) and drought stress, an experiment was conducted using a factorial arrangement based on completely randomized design with three replications. Drought stress decreased shoot and total dry weight in plants. However inoculation of plants with mycorrhiza improved these traits. Leaf chlorophyll content was decreased, but leaf proline content and guaiacol peroxidases (EC 1.11.1.7) (POD), catalase (EC 1.11.1.6) (CAT), and ascorbate peroxidase (EC 1.11.1.11) (APX) activities were increased as a result of drought stress. Drought stress had no significant effect on soluble protein content and polyphenol oxidase (EC 1.10.3.1) (PPO) enzymatic activity in chickpea plants. In general, drought stress and especially severe drought stress increased membrane lipid peroxidation (MDA) in chickpea plants, which was more evident in non-inoculated than in inoculated plants. Inoculation of chickpea by AM significantly increased POD and PPO activities compared with non-inoculated chickpea, but had no effect on CAT activity and proline content of leaves. The reaction of chickpea cultivars to inoculation by AM species and irrigation levels were different. ILC-482 showed that antioxidant enzymes activities were more and thus less MDA compared with Pirouz cultivar. In general, the most POD and PPO activities were recorded for inoculated plants with G. etunicatum and G. versiform species, and the most APX activity was observed in plants inoculated with G. intraradices.

Screening and selecting novel AM fungi and Azotobacter strain for inoculating apple under soil solarization and chemical disinfestation with mulch practices for sustainable nursery management

The objective of this study is to investigate the response of screening, and selection of novel indigenous AM fungal species and Azotobacter chroococcum strains for inoculating apple under different soil disinfestations and moisture conservation mulch practices for sustainable nursery management. Two local AM fungal species namely, Glomus fasciculatum (Thaxter sensu Gerdemann) and Glomus mosseae (Nicol. & Gerd.), and two strains of A. chroococcum viz., A. chroococcum strain-I (AZ 1) and A. chroococcum strain-II (AZ 2) were inoculated at nursery stage under soil solarization, chemical disinfestation and natural soil conditions at four different mulch materials namely, black plastic mulch (BPM), and organic mulches, i.e. grass mulch (GM); cover crops (CC); green manuring + clean cultivation (Gm + Cc). The comparative performance of the seedlings on the impact of local AM species and A. chroococcum strains on growth characteristics, microbial population, root colonization and leaf nutrient status was evaluated. The inoculation of seedlings to G. fasciculatum and AZ 1 increased all growth characteristics (plant height, stem diameter, leaf area and total root length), microbial consortium of the rhizosphere soil and leaf N, P, K and Zn content in all those plots where soil solarization and black plastic mulching was used followed by chemical disinfestations and natural soil conditions at all other mulch types used. These findings suggested that the soil inoculation of G. fasciculatum and AZ 1 strain to seeds and/or the saplings under soil solarization with black plastic mulch attained a desirable plant height and become ready for grafting which however saved a period of 1 year for nursery management compared to traditional nursery raising practice, and thus, it may be a viable and feasible approach to maintain soil productivity under nutrient limited soils for sustainable apple nursery production under temperate rain-fed conditions.

Interactive effects of P supply and drought on root growth of the mycorrhizal coriander (Coriandrum sativum L.)

Arbuscular mycorrhizal fungi (AMF) are among the most important plant root symbiosis fungi enhancing plant P uptake. This research was conducted in Iran during 2006. The experimental design was a split factorial on the basis of completely randomized block design with four replicates. The control and AM species, Glomus hoi were assigned to the main plots and the combination of P fertilizer including 0, 35 and 70 kg ha-1 of triple super phosphate and the drought treatment including control (30 mm evaporation) and 60 mm evaporation from the evaporation pan were factorially assigned to the subplots. AM and P fertilizer significantly increased the root yield, root length, primary root dry weight and primary root length of coriander. Although the non-drought stress treatment significantly increased the root of coriander, the longest root length was achieved under the drought stress. It can be stated that AM is able to enhance the growth of coriander under drought stress through enhancing P uptake. This can have very important environmental impact through decreasing the amount of P fertilizer under control and drought stress conditions and also through enhancing the coriander resistance when subjected to the drought stress. Findings may interest farmers and agricultural researches to consider carefully on huge amount of soil phosphorus with interaction to water restriction as a challenge in environmental issues. Key words: AM fungi, drought stress, phosphorus, root growth, coriander.

Mycorrhizal associations and other means of nutrition of vascular plants: understanding the global diversity of host plants by resolving conflicting information and developing reliable means of diagnosis

A comprehensive appraisal of the mycorrhizal literature provides data for 336 plant families representing 99% of flowering plants, with regard to mycorrhizas and other nutritional adaptations. In total, arbuscular (AM), orchid, ectomycorrhizas (EM) and ericoid mycorrhizas and nonmycorrhizal (NM) roots occur in 74%, 9%, 2%, 1% and 6% of Angiosperm species respectively. Many families of NM plants have alternative nutritional strategies such as parasitism, carnivory, or cluster roots. The remaining angiosperms (8%) belong to families reported to have both AM and NM species. These are designated as NM-AM families here and tend to occur in habitats considered non-conducive to mycorrhizal fungi, such as epiphytic, aquatic, extremely cold, dry, disturbed, or saline habitats. Estimated numbers of species in each category of mycorrhizas is presented with lists of NM and EM families. Evolutionary trends are also summarised by providing data on all clades and orders of flowering and non-flowering vascular plants on a global scale. A case study of Western Australian plants revealed that plants with specialised nutritional modes such as carnivory, cluster roots, or EM were much more diverse in this ancient landscape with infertile soils than elsewhere. Detailed information on the mycorrhizal diversity of plants presented here is linked to a website (mycorrhizas.info) to allow data to remain current. Over a century of research effort has resulted in data on mycorrhizal associations of >10,000 plant species that are of great value, but also somewhat of a liability due to conflicting information about some families and genera. It is likely that these conflicts result in part from misdiagnosis of mycorrhizal associations resulting from a lack of standardisation in criteria used to define them. Families that contain both NM and AM species provide a second major source of inconsistency, but even when these are excluded there is a ∼10% apparent error rate in published lists of mycorrhizal plants. Arbuscules are linked to AM misdiagnosis since they are used less often than vesicles to recognise AM associations in roots and apparently occur sporadically in NM plants. Key issues with the diagnosis of mycorrhizal plants are discussed using the Cyperaceae as a case study. Detailed protocols designed to consistently distinguish AM from endophytic Glomeromycotan Fungus Colonisation (GFC) are provided. This review aims to stimulate debate and provide advice to researchers delving into root biology.

Arbuscular mycorrhizal fungi in degraded typical steppe of inner Mongolia

AbstractArbuscular mycorrhizal (AM) fungi may have some potential use in the restoration of degraded grassland through beneficial effects on plant growth and soil quality. A field investigation was conducted in three grassland sites of typical steppe in Inner Mongolia. The three plant communities, one of which was undegraded, one moderately degraded and the third severely degraded, were studied by collecting soil samples and samples of four plant species that occurred in all three sites. The percentage of root length colonized by AM fungi was estimated and the species composition and diversity of AM fungus spores recovered from the soil were determined using spore morphological characteristics. Although differences between the sites may have been due partly to other factors, it is likely that the degree of degradation was an important factor. No decline was found in the AM colonization of the roots of the indicator plant species in the moderately or severely degraded plant communities, and two plant species showed higher colonization status in the two degraded areas. Glomus geosporum and Scutellospora calospora were the dominant AM fungi in the undegraded steppe, while G. geosporum and Glomus aggregatum dominated the two degraded sites which also had low spore densities, species richness and diversity indices. However, different AM species showed different distributions among the three plant communities and the results indicate that both biotic and abiotic factors were important in determining the AMF communities, with biotic factors possibly the more important. Copyright © 2008 John Wiley & Sons, Ltd.

HORDEUM VULGARE : A SUITABLE HOST FOR MASS PRODUCTION OF ARBUSCULAR MYCORRHIZAL FUNGI FROM NATURAL SOIL

Four plant species viz. Hordeum vulgare, Triticum aestivum, Phaseolus vulgaris and Phaseolus mungo were examined for mass production of consortium of AM fungi present in the rhizosphere soil. Rhizosphere soil were collected from teak dominated forest and was used as a source of AM inoculum. Surface sterilized seeds of all the four selected plant species were raised in a mixture of sterilized soil and sand in 3:1 ratio. Mass production of AM fungi was observed in terms of (%) AM colonization, AM spore population, and effectiveness of AM consortia was recorded in terms of height and dry weight of inoculated and uninoculated plants. Out of four test species H. vulgare responded as the most suitable host. After 60 days, H. vulgare showed the highest colonization (92%) and 74 spores per 25 g soil. It was observed that plants having higher AM colonization showed higher AM spore production showing a positive correlation, however, it was not found in T. aestivum. Study indicates that H. vulgare is suitable for early colonization and mass production of AM fungi. After 90 days of pot culture, pot soil from all host were analyzed for AM flora. In all, eleven AM species were identified from the consortium. Maximum numbers of AM species (8 species) were found associated with H. vulgare. Three species of AM fungi i.e. Glomus aggregatum, G. fasciculatum and Sclerocystis pakistanica were found to dominate in the soil of H. vulgare. Keywords. AM fungi, AM colonization, Glomus aggregatum, G. fasciculatum, Sclerocystis pakistanica, mass production

Delta15N values of tropical savanna and monsoon forest species reflect root specialisations and soil nitrogen status.

A large number of herbaceous and woody plants from tropical woodland, savanna, and monsoon forest were analysed to determine the impact of environmental factors (nutrient and water availability, fire) and biological factors (microbial associations, systematics) on plant delta(15)N values. Foliar delta(15)N values of herbaceous and woody species were not related to growth form or phenology, but a strong relationship existed between mycorrhizal status and plant delta(15)N. In woodland and savanna, woody species with ectomycorrhizal (ECM) associations and putative N(2)-fixing species with ECM/arbuscular (AM) associations had lowest foliar delta(15)N values (1.0-0.6 per thousand ), AM species had mostly intermediate delta(15)N values (average +0.6 per thousand ), while non-mycorrhizal Proteaceae had highest delta(15)N values (+2.9 to +4.1 per thousand ). Similar differences in foliar delta(15)N were observed between AM (average 0.1 and 0.2 per thousand ) and non-mycorrhizal (average +0.8 and +0.3 per thousand ) herbaceous species in woodland and savanna. Leguminous savanna species had significantly higher leaf N contents (1.8-2.5% N) than non-fixing species (0.9-1.2% N) indicating substantial N acquisition via N(2) fixation. Monsoon forest species had similar leaf N contents (average 2.4% N) and positive delta(15)N values (+0.9 to +2.4 per thousand ). Soil nitrification and plant NO(3)(-) use was substantially higher in monsoon forest than in woodland or savanna. In the studied communities, higher soil N content and nitrification rates were associated with more positive soil delta(15)N and plant delta(15)N. In support of this notion, Ficus, a high NO(3)(-) using taxa associated with NO(3)(-) rich sites in the savanna, had the highest delta(15)N values of all AM species in the savanna. delta(15)N of xylem sap was examined as a tool for studying plant delta(15)N relations. delta(15)N of xylem sap varied seasonally and between differently aged Acacia and other savanna species. Plants from annually burnt savanna had significantly higher delta(15)N values compared to plants from less frequently burnt savanna, suggesting that foliar (15)N natural abundance could be used as marker for assessing historic fire regimes. Australian woodland and savanna species had low leaf delta(15)N and N content compared to species from equivalent African communities indicating that Australian biota are the more N depauperate. The largest differences in leaf delta(15)N occurred between the dominant ECM Australian and African savanna (miombo) species, which were depleted and enriched in (15)N, respectively. While the depleted delta(15)N of Australian ECM species are similar to those of previous reports on ECM species in natural plant communities, the (15)N-enriched delta(15)N of African ECM species represent an anomaly.

The distribution of arbuscular mycorrhizas in the British flora.

Arbuscular mycorrhizal (AM) associations with higher plants are common in many ecosystems but some plant species are consistently never or rarely infected. These species may differ morphologically or occur in different habitats from species which are usually mycorrhizal. A large data-set on the ecology of British angiasperms was used to test for relationships between the mycorrhizal status of British angiosperms and several morphological and environmental variables (life form, root diameter, seed weight, soil fertility, soil water availability, soil pH and habitat type). No relationship was found between soil fertility or soil water availability and frequency of infection with AM fungi. AM species, however, can grow in habitats with a higher pH than non-mycorrhizal species and perennial AM species occur in a significantly greater number of habitat types than perennial species which are never, or rarely, arbuscular mycorrhizal. Non-mycorrhizal species tend to have thinner roots, smaller seeds and occur mainly in aquatic, wetland and saline habitats.