Membrane potential hyperpolarisation in vesicular arbuscular mycorrhizae ofAllium porrum L.: a non-nutritional long-distance effect of the fungus

Fieschi, M.; Alloatti, Giuseppe; Sacco, Silvano; Berta, Graziella

doi:10.1007/bf01666259

Cited by 19 publications

(4 citation statements)

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“…H+-ATPase activity is not observed on the peripheral plasma membrane of cortical root cells, whether or not these are colonized by an AM fungus, or around hyphae crossing epidermal or hypodermal cells. The modified ATPase distribution in mycorrhizal roots of leek is mirrored by an overall and stable hyperpolarization of plant membranes, as compared with nonmycorrhizal roots (Fieschi et al, 1992). In nonmycorrhizal roots, immunologically detectable plasma membrane H+-ATPase is located in the root cap, epidermis, and stele, but it is not present in cells of the cortical parenchyma (Parets-Soler et al, 1990;Stenz et ai., 1993;Bouché-Pillon et al, 1994).…”

Section: The Symbiotic Interface: From Structure To Functionmentioning

confidence: 96%

Plant Cell Responses to Arbuscular Mycorrhizal Fungi: Getting to the Roots of the Symbiosis.

1996

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INTRODUCTIONSince their colonization of terrestrial ecosystems, plants have developed numerous strategies to cope with the diverse biotic and abiotic challenges that are a consequence of their sedentary life cycle. One of the most successful strategies is the ability of root systems to establish mutualistic and reciprocally beneficial symbiotic relationships with microorganisms. Mycorrhizas, the intricate associations roots form with specific fungal groups, are by far the most frequent of these and represent the underground absorbing organs of most plants in nature (Gianinazzi-Pearson, 1984). Through their function in the efficient exploitation of soil mineral resources and their bioprotective role against a number of common soilborne pathogens, mycorrhizas are instrumental in the survival and fitness of many plant taxa in diverse ecosystems, including many crop species (reviewed in Allen, 1991; Bethlenfalvay and Linderman, 1992).Severa1 kinds of mycorrhizal associations can be distinguished according to their morphology and the plant and fungal taxa concerned. They fall almost exclusively into two broad groups: (1) the ectomycorrhizas of woody Angiosperms and Gymnosperms, in which Basidiomycetes, Ascomycetes, or Zygomycetes develop intercellular hyphae from a mycelial sheath covering the surface of short lateral roots; and (2) the endomycorrhizas, characterized by intraradical mycelium growth and intracellular fungal proliferation, which are formed by Basidiomycetes in the Orchidaceae (orchidoid mycorrhiza), Ascomycetes in the Ericales (ericoid mycorrhiza), and Zygomycetes in most other terrestrial plant taxa (arbuscular mycorrhiza; reviewed in Harley and Smith, 1983).Plant compatibility with mycorrhizal fungi is a generalized and ancient phenomenon. Species in >80% of extant plant families are capable of establishing arbuscular mycorrhiza (AM), and fossil evidence suggests that symbioses of this kind existed >400 million years ago in the tissues of the first land plants (Pirozynski and Dalpé, 1989;Remy et al., 1994). As such, the ability of plants to form AM must be under the control of mechanisms that have been conserved in new plant taxa as they appeared during evolution. This compatibility also implies that selective recognition processes in plants discriminate between beneficial and harmful microorganisms and that the essential genetic determinants for AM establishment are common to an extensive part of the plant kingdom.In contrast to their extremely wide host range and despite their ancient origins, only six genera of fungi belonging to the order Glomales of the Zygomycetes have evolved the ability to form AM (Morton and Benny, 1990). lnteractions between an AM fungus and a plant begin when a hypha from a germinating soilborne spore comes into contact with a host root. This step is followed by induction of an appressorium, from which an infection hypha penetrates deep into the parenchyma cortex (Figure lA), where inter-and intracellular proliferation of mycelium is intense. Here, fungal development culm...

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Section: The Symbiotic Interface: From Structure To Functionmentioning

confidence: 96%

Plant Cell Responses to Arbuscular Mycorrhizal Fungi: Getting to the Roots of the Symbiosis.

1996

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“…isolates (Esch et al 1994). Other morphogenetic factors that have been observed in AM roots include hyperpolarization of the root cortical cells (Fieschi et al 1992).…”

Section: Arbuscular Mycorrhizal (Am) Associationsmentioning

confidence: 99%

Plant root growth, architecture and function

Hodge¹,

Berta²,

Doussan³

et al. 2009

Plant Soil

612

400

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Without roots there would be no rhizosphere and no rhizodeposition to fuel microbial activity. Although micro-organisms may view roots merely as a source of carbon supply this belies the fascinating complexity and diversity of root systems that occurs despite their common function. Here, we examine the physiological and genetic determinants of root growth and the complex, yet varied and flexible, root architecture that results. The main functions of root systems are also explored including how roots cope with nutrient acquisition from the heterogeneous soil environment and their ability to form mutualistic associations with key soil microorganisms (such as nitrogen fixing bacteria and mycorrhizal fungi) to aid them in their quest for nutrients. Finally, some key biotic and abiotic constraints on root development and function in the soil environment are examined and some of the adaptations roots have evolved to counter such stresses discussed.Keywords Root systems . Auxin . Root architecture . Soil heterogeneity . Abiotic and biotic stresses . Soil micro-organisms (including nitrogen-fixing bacteria and mycorrhizal fungi)Physiological and genetic determinants of root growth and achitecture A major difference between plant and animal development is that positional information rather than cell lineage determines cell fate in plants (Singh and Bhalla 2006). Post-embryonically, plant development is essentially driven by stem cells localized in apical regions of shoots and roots, and referred to as apical meristems. This particular characteristic allows plants, Plant Soil (

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“…Longdistance signalling in AM roots has already been reported. Fieschi et al (1992) observed that the transmembrane potential in non-infected cells of mycorrhizal roots is hyperpolarized, compared with that in non-infected cells of non-infected roots. The functional significance of the systemic suppression is unknown.…”

Section: mentioning

confidence: 96%

Spatial distribution of chitinases and β‐1,3‐glucanase transcripts in bean arbuscular mycorrhizal roots under low and high soil phosphate conditions

Lambais

Mehdy

1998

New Phytologist

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Arbuscular mycorrhizal (AM) fungi extensively colonize the root cortex under low-soil-phosphate (P) conditions, whereas infection is limited under high-P conditions. Fungal growth under both P conditions might be influenced by plant defence-related gene expression. In this study, we used in situ hybridization methods to compare the cellular localization of three defence-related mRNAs in non-infected bean roots and in relation to fungal infection units. In non-infected and infected roots, mRNAs encoding acidic and basic endochitinases were generally most abundant in the vascular cylinder. High-P-grown mycorrhizal roots showed localized accumulation of the acidic endochitinase mRNA in cortical cells containing arbuscules and in their immediate vicinity (one to five cell layers). The pattern of accumulation of the basic endochitinase mRNA was not affected by P or AM fungal infection. At the low P concentration, the β-1,3-glucanase mRNA accumulated predominantly in the vascular cylinder of noninfected roots. Suppression of β-1,3-glucanase mRNA accumulation in these tissues was observed in non-infected roots at the high-P and in mycorrhizal roots at both P concentrations. The observed suppression extends at least several mm from fungal infection units, characterizing a systemic effect. Beta-1,3-glucanase mRNA accumulated also around a number of cortical cells containing arbuscules only at the low P concentration. The localized accumulations of the endochitinase and β-1,3-glucanase mRNAs suggest that the encoded proteins might be involved in the control of intraradical fungal growth.

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Membrane potential hyperpolarisation in vesicular arbuscular mycorrhizae ofAllium porrum L.: a non-nutritional long-distance effect of the fungus

Cited by 19 publications

References 19 publications

Plant Cell Responses to Arbuscular Mycorrhizal Fungi: Getting to the Roots of the Symbiosis.

Plant Cell Responses to Arbuscular Mycorrhizal Fungi: Getting to the Roots of the Symbiosis.

Plant root growth, architecture and function

Spatial distribution of chitinases and β‐1,3‐glucanase transcripts in bean arbuscular mycorrhizal roots under low and high soil phosphate conditions

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