Biological Sciences
Glomeromycota
Glomeromycota is a phylum of fungi that form symbiotic relationships with the roots of plants, known as arbuscular mycorrhizae. These fungi play a crucial role in nutrient uptake for the plants, particularly phosphorus, and are widespread in terrestrial ecosystems. Glomeromycota are important contributors to soil fertility and plant health, making them significant in ecological and agricultural contexts.
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11 Key excerpts on "Glomeromycota"
- Gero Benckiser, Sylvia Schnell, Gero Benckiser, Sylvia Schnell(Authors)
- 2006(Publication Date)
- CRC Press(Publisher)
In contrast, ectomycorrhizas are established between a great variety of mostly Basid-iomycota and the roots of many woody plants. This symbiosis is very common in forest ecosystems in the temperate zone and can be applied to plant production systems in tree nurseries (3). The most widespread type, however, is represented by the arbuscular endomycorrhiza, and this chapter concentrates on this type of symbioses, because the plant hosts include the most important crops used in agri- and horticulture. Arbuscular mycorrhizal (AM) fungi are ancient microorganisms. Fossil data and molecular phylogenetic analyses indicate that they appeared between 460 and 400 Myr ago during the Ordovician-Devonian (4–6). During this period the plants started to colonize the land and it is tempting to speculate that the AM fungi might have been essential for this process (7,8). Nowadays they are integral components of most terrestrial ecosystems (9), and some 80% of terrestrial, vascular plant families act as hosts for the fungal endosymbionts (10). Despite the considerable radiation of the plant hosts (approx. 225,000 species), only about 130 species of AM fungi are described. It was recently suggested that these symbiotic microorganisms should be removed from the Zygo-mycota as they represent their own new phylum, the Glomeromycota with four different orders (11). Two of these orders, the Glomerales and Diversisporales, contain the genera Glomus , Gigaspora , Scutellospora, and Acaulospora , to which most isolates have been assigned. The small number of different fungal species might suggest that their biodiversity is limited. However, we would like to show in the following that this is not the case. The variation at the morphological, physiological, and genetic levels is rather high and this results in a functional diversity that has an important impact for ecology and applications in plant production systems.
eBook - PDFMycorrhizas
A Molecular Analysis
- K R Krishna(Author)
- 2005(Publication Date)
- CRC Press(Publisher)
The present-day AM fungal genera Glomus, Acaulospora, Entrophospora, Scutellospora, Gigaspora, Paraglomus and Archaeospora are considered to be primi-tive because of their simple asexual spores and lack of sexual reproduction. Molecu-lar diversity noticed within ribosomal gene is in consonance with the absence of a sexual cycle among these fungi (Pringle et al. 2000). Glomeromycota are considered to be one of the oldest true fungi. Based on the phylogenic assessment of DNA sequence data, Simon et al. (1993) opined that the age of Glomeromycota and land plants is similar. Other types of mycorrhizal fungi are evolutionary younger to Glomales (Tehler, 2000). Fungi resembling the genera of Glomales were recorded on the roots of Triassic plants, thus confirming the existence of mycorrhizal association during 2 Mycorrhizas: A Molecular Analysis that period. The molecular analysis of a small subunit (SSU) rDNA (18S) sequence data for Geosiphon indicates that it is a primitive glomeromycetous fungus. The Geosiphon associations involve swollen hyphae similar to arbuscules in AM symbio-sis. Therefore, it is believed that characteristics such as arbuscules required for effective endomycorrhizal symbiosis might have evolved with Cyanobacteria during the early Devonian period. Brundrett (2002) suggests that Glomales descended from endophytes of algal precursors, mainly because their fossils do not show any close resemblance to parasitic fungi (e.g. Oomycetes and Chytrids) found on early plants. Glomales are a unique monophyletic mycorrhizal fungal lineage that has co-evolved with land plants, whereas, other types of mycorrhizal fungi are polyphyletic. These species represent either parallel or convergent evolution. Actually, two main branches of AM symbiotic fungi have been hypothesized that must have evolved from a com-mon arbuscular ancestor.
- Katti, Gururaj(Authors)
- 2018(Publication Date)
- Daya Publishing House(Publisher)
There are atleast 300,000 respective hosts in the world flora and around 230 species of AM fungi (Bagyaraj, 2011). AM fungi belong to the phylum Glomeromycota, which has a single class Glomeromycetes with four orders Glomerales, Diversisporales, Paraglomerales and Archaeosporales. There are 11 families, 17 genera and This ebook is exclusively for this university only. Cannot be resold/distributed. 228 species. The commonly occurring genera of AM fungi are Glomus, Gigaspora, Acaulospora, Entrophospora and Scutellospora. The AM endophytes are not host specific, although evidence is growing that certain endophytes may form preferential association with certain host plants. These fungi are obligate biotrophs. Increased plant growth because of AM colonization is attributed to enhanced uptake of diffusion limited nutrients, hormone production, biological nitrogen fixation, drought resistance and suppression of root pathogens. Biological control can be defined as the directed, accurate management of common components of ecosystems to protect plants against pathogens. Biological control of plant pathogens is currently accepted as a key practice in sustainable agriculture because it is based on the management of a natural resource, i.e., certain rhizosphere organisms. Thus, biological control preserves environmental quality by reduction in chemical inputs and is characteristic of sustainable management practices (Barea and Jeffries, 1995). Several workers have reported that AM fungi can act as biocontrol agents for alleviating the severity of disease caused by root pathogenic fungi, bacteria and nematodes. It is evident that an increased capacity for nutrient acquisition resulting from mycorrhizal association could help the resulting stronger plants to resist stress.
eBook - PDFBeneficial Plant-microbial Interactions
Ecology and Applications
- M. Belén Rodelas González, Jesús Gonzalez-López, M. Belén Rodelas González, Jesús Gonzalez-Lopez, M. Belén Rodelas González, Jesús Gonzalez-Lopez(Authors)
- 2016(Publication Date)
- CRC Press(Publisher)
Diverse chemical, physical and biological factors are involved in the framework of plant-soil interactions responsible for a sustainable ecosystem functioning (Barea et al. 2005a). The biological components are based on diverse genetic and functional groups of soil microbial populations able to carry out critical ecosystem functions such as the biogeochemical cycling of mineral nutrients, organic matter decomposition and the formation and maintenance of soil structure, key issues in a sustainable production scenario (Barea et al. 2005b, Chaudhary et al. 2009, Richardson et al. 2009). Among the beneficial microbes, mycorrhizal fungi are recognized as one of the most influential group of soil biota in the context of ecosystem sustainability once they establish mutualistic plant-fungus symbioses, so-called mycorrhizas (Jeffries and Barea 2012). Mycorrhizal associations are formed by most vascular plant species on Earth and can be found in almost all terrestrial ecosystems worldwide (Smith and Read 2008, Brundrett 2009), being universally accepted that they are fundamental to improve plant performance and soil quality (Jeffries et al. 2003). Mycorrhizal functioning is based on the exchange of nutrients and energy between both the plant and fungal partners (Brundrett 2002). A variety of mycorrhizal types are formed, depending on the plant and fungal taxa involved. However, arbuscular mycorrhizal (AM) symbiosis is the most common and over 70 percent of plant species are capable of forming these associations (Smith and Read 2008, Brundrett 2009). This chapter will focus on AM symbiosis but the importance and ecological meaning of other mycorrhizal types are reviewed in this book (Chapter 17). AM fungi, included in the phylum Glomeromycota (Schüßler et al. 2001), are ubiquitous soil-borne fungi, whose origin and divergence have been dated back over 450 million years (Redecker et al. 2000, Honrubia 2009, Schübler and Walker 2011).
eBook - ePub- Frans J. de Bruijn(Author)
- 2019(Publication Date)
- Wiley-Blackwell(Publisher)
CHAPTER 12.12.1Organelle protein changes in arbuscular mycorrhizal Medicago truncatula roots as deciphered by subcellular proteomicsGhislaine Recorbet, Christelle Lemaître-Guillier and Daniel WipfAgroécologie, AgroSupDijon, CNRS, INRA, Université de Bourgogne Franche-Comté, Dijon, France12.12.1.1 Introduction
Beneficial biotrophic microorganisms colonize plant tissues and have access to nutrients outside the plant, thus raising the possibility for bi-directional nutrient movement and the development of a mutualistic rather than a parasitic interaction (Smith and Smith 1990). Among them, arbuscular mycorrhizal (AM ) soil-borne fungi belonging to the phylum Glomeromycota engage in a mutualistic relationship with the roots of more than 80% of vascular land plants. AM fungi notably assist the plant with the acquisition of mineral nutrients, mainly inorganic phosphate (Pi) and nitrogen (N) that are absorbed from the soil solution by the extra-radical mycelium. In turn, AM fungi are supplied with the organic carbon forms essential for them to achieve their full life cycle (Gutjahr and Parniske 2013; see Chapter 7.1.1). As a result, AM fungi are obligate plant biotrophic microorganisms that have a global impact on plant mineral nutrition and on the carbon cycle (Parniske 2008).In AM symbiosis, the fungus enters the root through the epidermal cells and grows into the cortex where it differentiates a highly branched hyphal structure called the arbuscule. These tree-like hyphae are the site of Pi and N delivery to the plant (Bonfante and Genre 2008; Gutjahr and Parniske 2013). At all stages of development, fungal hyphae are always surrounded by a host membrane, which is referred to as the perifungal membrane around intracellular hyphae or the periarbuscular membrane (PAM ) around the arbuscules (Harrison 2012; see Chapter 7.1.1). One of the first plant membrane extension and remodeling cytological events during AM symbiosis occurs during infection of the root epidermis that involves the formation of an intracellular prepenetration apparatus (PPA ) (Genre et al. 2005, 2008). The PPA serves to guide the hypha through the cell and biogenesis of the perifungal membrane is achieved through secretory organelles within the PPA (Genre et al. 2012). Arbuscule development also involves an architectural reorganization of the colonized cortex cell with the enlargement of the plant plasma membrane (PM ) and the de novo synthesis of the PAM, an extension of the PM which displays two distinct domains. While the domain around the arbuscule trunk shares proteins with the PM of the host, the domain around the arbuscule branches contains a unique set of phosphate transporters (PT s) such as MtPT4 in Medicago truncatula and displays close contacts with other organelles (Pumplin and Harrison 2009; Ivanov and Harrison 2014; see Chapter 7.1.1). Besides the PM, the amount of organelles such as Golgi, endoplasmic reticulum (ER ), plastids, and mitochondria is amplified in mycorrhizal roots (Bapaume and Reinhardt 2012). Noteworthy, the occurrence of unusual elongated plastids together with a general increase in plastid number has been described for AM plant roots, including M. truncatula
eBook - PDF- Charles W. Bacon, James White(Authors)
- 2000(Publication Date)
- CRC Press(Publisher)
Mycorrhizal roots take up more soil nutrients, at least phosphate, from lower concentration pools than do nonmycorrhizal roots (Cress et al., 1979). My-corrhizal plants take up more water during periods of drought than nonmycorrhi-zal plants (Allen et al., 1981; Allen and Boosalis, 1983) and have been shown to delay flowering (Allen and Allen, 1986) and to retain leaves longer, thus fixing a greater amount of carbon (Kormanik, 1985). Different Glomalean species have distinct external hypha! characteristics that may permit differences in resource acquisition (Abbott and Robson, 1985). Since more than one Glomalean fungus can occupy a root system and, according to Read et al. (1985), root systems may be connected by a mycelial matrix, mycorrhizal plants may benefit from the differential resource acquisition of several Glomalean fungi simultan-eously. There is in addition some evidence of seasonal variation in activity among Glomalean fungi (Allen et al.,1984a; Jakobson and Neilson, 1983), which can thus spread the benefits of the mycorrhizal association over the entire growing season. In these various ways, mycorrhizal fungi contribute to the survival and fitness of plants in an ecosystem, particularly under conditions of stress (i.e., drought, resource depletion, and seedling establishment). Although many studies have looked at the effects of Glomalean fungi on plant growth, after perusing the ecological literature it is hard not to conclude that the real benefit to plants from the mycorrhizal association is the enhanced ability to survive and repro-duce, to withstand the ecological crunches postulated by Allen and Allen (1986). Mycorrhizal Endosymblosls 177 8.3. Dispersal and Establishment In New Habitats Glomalean fungi can persist as propagules for varying lengths of time in the absence of adequate nutrition or suitable host plant (Allen et al., 1984b; Carpenter et al., 1987).
eBook - PDFHandbook of Soil Sciences
Properties and Processes, Second Edition
- Pan Ming Huang, Yuncong Li, Malcolm E. Sumner, Pan Ming Huang, Yuncong Li, Malcolm E. Sumner(Authors)
- 2011(Publication Date)
- CRC Press(Publisher)
These data suggest that mixotro-phic plants that live in forests derive photosynthates by sharing symbiotic fungi (Selosse and Roy, 2009). 24.4.3 Diversity in Mycorrhizal Features: Mycorrhizal Fungi Develop Structures Outside and Inside the Roots According to their ability to colonize the root cells, mycorrhizal fungi are divided into two main categories: endo- and ectomy-corrhizae. Since a detailed structural description of mycorrhizae is not the main aim of this chapter, we here only briefly review the main structural features that characterize mycorrhizal mor-phologies. More detailed information can be found in Peterson et al. (2004). Endomycorrhizal hyphae adopt a variety of colo-nization patterns during their penetration of host root cells. AM fungi depend on their hosts on a great extent and cannot survive for long without them. Once the fungus has overcome the epidermal layer, it develops an appressoria and grows inter- and intracellularly all along the root in order to spread fungal structures. During the symbiotic phase, some Glomeromycota (i.e., Glomus species) develop structures, called vesicles, that fill the cellular spaces, and probably act as storage pools. Only when the fungus has reached the cortical layers, does a peculiar branching process start, which leads to highly branched arbus-cules (Bonfante et al., 2009; Bonfante and Genre, 2010). These are the key structures that are produced during the symbioses, and are considered the site of nutrient exchange (Figure 24.8a). During endosymbiosis, regardless of the involved partners, a new apoplastic space, based on membrane proliferation, is built around all the intracellular hyphae (Bonfante, 2001). In AM, this new compartment is known as the interfacial compartment, and it consists of the invaginated membrane, the cell wall-like material, and the fungal wall, and plasma membrane (Balestrini and Bonfante, 2005).
- Chandra, Ram(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
Vesicles, which contain lipids and are carbon storage structures, are This ebook is exclusively for this university only. Cannot be resold/distributed. formed commonly in most genera of Glomeromycota, although this will depend on environmental conditions (Smith and Read, 1997). Gianinazzi-Pearson (1996) pointed out that these obligatory biotrophs, the AM fungi, have a very broad host range, which makes them definitely different from the biotrophic fungal plant pathogens as well as other root symbionts. Fossil records suggest that the AM symbiosis dates back to the Ordovician age, 460 million years ago (Redecker et al ., 2000). These fossils indicate that Glomeromycota-like fungi may have played a critical role in facilitating the colonisation of land by plants. As AM fungi are obligate symbionts, they are not yet successfully cultured in the absence of plant root. The symbiosis is normally mutualistic and based on bidirectional nutrient transfer between the symbionts. However, the mycorrhizal association may vary along a symbiotic continuum from strong mutualism to antagonism (Carling and Brown, 1980; Modjo and Hendrix, 1986; Howeler et al ., 1987; Johnson et al ., 1997). More than 150 species are described within the phylum Glomeromycota on the basis of their spore development and morphology, although recent molecular analyses indicate that the definite number of AM taxa may be much higher (Daniell et al ., 2001; Vandenkoornhuyse, et al ., 2002). However, the biological knowledge is lacking for some of the described species and others are synonyms (Walker and Trappe, 1993; Walker and Vestberg, 1998). All members of the AM fungi are asexual and the vegetative mycelium and intraradical structures are aseptate and multinucleate. Most spores are between 50 and 500 µm in diameter depending on the species. Another type of mycorrhizal association is the ectomycorrhiza, in which the fungal hyphae form a mantle consisting of densely interwoven hyphae around the root.
eBook - PDF- Ramasamy K. And K.Kumar(Author)
- 2020(Publication Date)
- NEW INDIA PUBLISHING AGENCY (NIPA)(Publisher)
Roots of over 80% of all terrestrial plant species (including agricultural and horticultural 347 348 Plant-Microbe Interactions crops) associate symbiotically with fungi. This interaction was instrumental in successful colonization of land by plants [1]. The name of this correlation comes from Greek words: myces = fungus and rhiza = root. The term “mycorrhiza” was coined in 1885 by Bernhardt Frank. Arbuscular mycorrhizas (AM) were named according to the structures they form within plant cells, called arbuscules (from the Latin arbusculum , little tree). The mycorrhizae are divided in to three major types: ectomycorrhizal fungi (belonging to the basidiomycota, ascomycota and zygomycota), ericoid mycorrhizal fungi (mostly from ascomycota order Helotiales) and endomycorrhizal fungi also called arbuscular mycorrhizal fungi (AMF) (formed only by Glomeromycota phylum) [2, 3]. Arbuscular mycorrhizal (AM) symbiosis is the commonest among all mycorrhizal interactions. Arbuscular mycorrhizal fungi comprise intra-and extraradical structures. In Glomeromycota, intraradical hyphae can penetrate the outer cell wall of root and grow between or inside of the root cell wall and plasma membrane where they develop the intraradical structures, arbuscules and vesicles. The extraradical structures are hyphae and spores that develop outside of the roots in the soil (Fig I). Fig. 1 : AMF structures during symbiosis with plant root (Sêdzielewska KA, 2012) Relevance in agriculture :AM fungi are mutualistic symbiotic soil fungi colonizing the roots of most crop plants. These fungi are mainly responsible for phosphorus (P) uptake and have proven potential to enhance growth, water relations and disease resistance [5]. There are voluminous reports dealing with the nutritional benefits that plants derive from mycorrhizal associations [6-9]. AM symbiosis has significant implications in sustainable agricultural systems [10] contributing to reduced input of chemical fertilizers and pesticides.
- Gautam, P L(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
It is, therefore, necessary to look for an alternate strategy, which could fit in the present agriculture scenario considering the measures mentioned and the practical problems of feeding growing population. Use of arbuscular mycorrhizal fungi, an essential component of terrestrial plants, could necessarily be the integral part of agriculture/forestry/horticulture system. Arbuscular Mycorrhizal Fungi and Carbon Sequestration Arbuscular mycorrhizal (AM) fungi form symbiotic relationships within roots of approximately 80 per cent of all plant taxa. The AM fungi colonize fine roots behind the area of active cell elongation. Hyphae radiate out from This ebook is exclusively for this university only. Cannot be resold/distributed. the roots, effectively performing the functions of uptake of nutrients, particularly phosphorus (P), and of water in exchange for photosynthetically derived carbon (C) from their host. They form a significant pathway for the transfer of photosynthetic C to soils. For example, AM fungi are estimated to utilize 5–25 per cent of photosynthetically fixed C in temperate herbaceous plant species and up to 45 per cent in temperate trees. Studies in tropical forests have indicated that 20–80 per cent of fine root length is colonized by AM fungi, and that spore production can be substantial. Many tree species are highly dependent on AM fungi, being unable to grow beyond the seed reserves if they are not inoculated with AM fungi. The C allocated to arbuscular mycorrhizas and thus their contribution to soil C could be particularly high in the tropics because of the low nutrient levels in highly weathered tropical soils. One of the compounds produced by AM fungi is a recalcitrant glycoprotein, glomalin. Concentrations of glomalin range from 2 to 15 mg g –1 of soil in temperate climates, and over 60 mg cm –3 were found in a chronosequence of Hawaiian soils.
eBook - PDFBiodiversity
The Dynamic Balance of the Planet
- Oscar Grillo(Author)
- 2014(Publication Date)
- IntechOpen(Publisher)
Arbuscular mycorrhiza: the mother of plant root endosymbioses. Nature Reviews Microbiology 2008;6:763–75. [2] Wang B, Qiu Y-L. Phylogenetic distribution and evolution of mycorrhizas in land plants. Mycorrhiza 2006;16:299–363. [3] Bonfante P, Genre A. Mechanisms underlying beneficial plant–fungus interactions in mycorrhizal symbiosis. Nature Communications 2010;1:48. [4] Schüβ ler A, Schwarzott D, Walker C. A new fungal phylum, the Glomeromycota: phylogeny and evolution. Mycological Research 2001;105:1413–21. [5] Simon L, Bousquet J, Levesque RC, Lalonde M. Origin and diversification of endo‐ mycorrhizal fungi and coincidence with vascular land plants. Nature 1993;363:67–9. [6] Tulasne LR, Tulasne C. Fungi nonnulli hipogaei, novi v. minus cogniti auct. Giornale Botanico Italiano 1844;2:55 – 63. [7] Schüßler A, Walker C. 7 Evolution of the “Plant-Symbiotic” Fungal Phylum, Glomer‐ omycota. In: Pöggeler S, Wöstemeyer J, editors. Evolution of Fungi and Fungal-Like Organisms, Springer Berlin Heidelberg; 2011, p. 163–85. [8] Oehl F, Sieverding E, Palenzuela J, Ineichen K, da Silva GA. Advances in Glomero‐ mycota taxonomy and classification. IMA FUNGUS 2011;2:191–9. [9] Krüger M, Krüger C, Walker C, Stockinger H, Schüßler A. Phylogenetic reference da‐ ta for systematics and phylotaxonomy of arbuscular mycorrhizal fungi from phylum to species level. New Phytologist 2012;193:970–84. [10] Redecker D, Schüßler A, Stockinger H, Stürmer SL, Morton JB, Walker C. An evi‐ dence-based consensus for the classification of arbuscular mycorrhizal fungi (Glom‐ eromycota). Mycorrhiza 2013:1–17. Biodiversity - The Dynamic Balance of the Planet 178 [11] Öpik M, Moora M, Liira J, Zobel M. Composition of root-colonizing arbuscular my‐ corrhizal fungal communities in different ecosystems around the globe. Journal of Ecology 2006;94:778–90. [12] Smith SE, Smith FA. Roles of Arbuscular Mycorrhizas in Plant Nutrition and Growth: New Paradigms from Cellular to Ecosystem Scales.
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