Is stimulation of carotenoid biosynthesis in arbuscular mycorrhizal roots a general phenomenon?

Fester, Thomas; Wray, Victor; Nimtz, Manfred; Strack, Dieter

doi:10.1016/j.phytochem.2005.05.009

Cited by 40 publications

(31 citation statements)

References 23 publications

(33 reference statements)

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“…Similarly, levels of AM-induced plant secondary metabolites, such as cyclohexenone derivatives (Maier et al, 2000) and mycorradicin derivatives (also called yellow pigment; Klingner et al, 1995), which accumulate in mycorrhizal roots and are suggested to play a functional role in AM (Fester et al, 2002;Strack et al, 2003), were not affected by the increased invertase activity (Table I). In nonmycorrhizal plants these metabolites could not be detected (data not shown; see also Fester et al, 2002Fester et al, , 2005Schliemann et al, 2006). Induction of invertase activity starting at the beginning of fungal colonization (3 weeks after inoculation) also had no effect on the mycorrhization (Supplemental Fig.…”

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confidence: 92%

Regulation of Arbuscular Mycorrhization by Carbon. The Symbiotic Interaction Cannot Be Improved by Increased Carbon Availability Accomplished by Root-Specifically Enhanced Invertase Activity

Schaarschmidt

González²,

Roitsch³

et al. 2007

PLANT PHYSIOLOGY

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The mutualistic interaction in arbuscular mycorrhiza (AM) is characterized by an exchange of mineral nutrients and carbon. The major benefit of AM, which is the supply of phosphate to the plant, and the stimulation of mycorrhization by low phosphate fertilization has been well studied. However, less is known about the regulatory function of carbon availability on AM formation. Here the effect of enhanced levels of hexoses in the root, the main form of carbohydrate used by the fungus, on AM formation was analyzed. Modulation of the root carbohydrate status was performed by expressing genes encoding a yeast (Saccharomyces cerevisiae)-derived invertase, which was directed to different subcellular locations. Using tobacco (Nicotiana tabacum) alcTcwINV plants, the yeast invertase was induced in the whole root system or in root parts. Despite increased hexose levels in these roots, we did not detect any effect on the colonization with Glomus intraradices analyzed by assessment of fungal structures and the level of fungus-specific palmitvaccenic acid, indicative for the fungal carbon supply, or the plant phosphate content. Roots of Medicago truncatula, transformed to express genes encoding an apoplast-, cytosol-, or vacuolar-located yeastderived invertase, had increased hexose-to-sucrose ratios compared to b-glucuronidase-transformed roots. However, transformations with the invertase genes did not affect mycorrhization. These data suggest the carbohydrate supply in AM cannot be improved by root-specifically increased hexose levels, implying that under normal conditions sufficient carbon is available in mycorrhizal roots. In contrast, tobacco rolCTppa plants with defective phloem loading and tobacco pyk10TInvInh plants with decreased acid invertase activity in roots exhibited a diminished mycorrhization.Arbuscular mycorrhiza (AM) represents a widespread mutualistic association between soil-born fungi of the phylum Glomeromycota and most land plants. The AM interaction enables the plant to improve its supply of water and mineral nutrients, mainly phosphate. In return, the obligate biotrophic AM fungi are provided with carbon. In the Arum-type interaction, as analyzed here between Glomus sp. and tobacco (Nicotiana tabacum) or Medicago truncatula, the AM fungus colonizes the cortical cells by formation of intra-and intercellular hyphae and very characteristic haustorialike structures, the highly branched intracellular arbuscules. When the carbon supply is sufficient, lipid-rich vesicles are formed intercellularly within the cortex, as fungal storage organs. Intracellular fungal structures are separated from the plant cytoplasm by an extension of the plasma membrane, forming the periarbuscular membrane surrounding the arbuscule. The greatly increased surfaces of host and arbuscule plasma membranes offers optimized conditions for effective nutrient exchange via the established symbiotic interface (for review, see Gianinazzi-Pearson et al., 1996;Harrison, 1999).The exchange of phosphate via the periarbuscular interface and th...

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confidence: 92%

Regulation of Arbuscular Mycorrhization by Carbon. The Symbiotic Interaction Cannot Be Improved by Increased Carbon Availability Accomplished by Root-Specifically Enhanced Invertase Activity

Schaarschmidt

González²,

Roitsch³

et al. 2007

PLANT PHYSIOLOGY

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“…AM symbiosis influences primary and secondary metabolism of host plants (Schliemann et al 2008): it induces important changes both in enzymatic activities (i.e. superoxide dismutase and catalase) (RuizLozano et al 1996;Marin et al 2002) and in physiological mechanisms leading to the accumulation of secondary metabolites, such as carotenoids and polyphenols (Walter et al 2000;Lambais et al 2003;Fester et al 2005;Marulanda et al 2007;Toussaint et al 2007). Some authors reported higher levels of reactive oxygen species (ROS) in colonized roots, and suggested that mycorrhizal plants respond to oxidative stresses by the accumulation of antioxidative enzymes and carotenoids (Fester and Hause 2005).…”

Section: Introductionmentioning

confidence: 99%

Mycorrhizal colonization impacts on phenolic content and antioxidant properties of artichoke leaves and flower heads two years after field transplant

et al. 2010

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Greenhouse and field experiments were carried out in order to investigate the influence of mycorrhizal inoculation on total phenolic content (TPC) and antioxidant activity, expressed as antiradical power (ARP), of artichoke (Cynara cardunculus L. var. scolymus F.) leaves and flower heads extracts. The establishment of mycorrhizal symbiosis was monitored in pot and field grown plants, and the persistence of the inoculated AMF in roots after 2 years' growth in the field was assessed by fungal ITS sequencing. Both in the greenhouse and in the field, marked increases in TPC and ARP were detected in leaves and flower heads of artichoke plants inoculated with the AM fungal species Glomus intraradices, either alone or in mixture with Glomus mosseae. In the field, plants inoculated with Glomus mix showed flower heads ARP content increases of 52.7 and 30.0% in the first and second year, respectively, compared with uninoculated plants. After 2 years' growth in the field ITS rDNA sequences clustering with those of G. mosseae and G. intraradices were retrieved only from inoculated plant roots. Our data show that mycorrhizal inoculation may represent an efficient and sustainable strategy to improve productivity and enhance plant biosynthesis of secondary metabolites with health promoting activities

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“…We expected that selection for higher levels of IG concentrations in P. lanceolata would result in suppression of AMF mutualism and reduced plant growth beneWt through toxicity of IGs in roots, or constraints in carbon allocation between defenses and the symbiont, or genetically correlated plant traits other than IG production with AMF suppressive eVects. Alternatively, it may well be that AMF stimulate and/or tolerate IG levels in roots, as suggested by the observed stimulation of other terpenoids in roots of cereals (Maier et al 1995) and legumes (Fester et al 2005) when colonized with AMF.…”

Section: Introductionmentioning

confidence: 99%

Chemical defense, mycorrhizal colonization and growth responses in Plantago lanceolata L.

et al. 2009

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Allelochemicals defend plants against herbivore and pathogen attack aboveground and belowground. Whether such plant defenses incur ecological costs by reducing benefits from plant mutualistic symbionts is largely unknown. We explored a potential trade-off between inherent plant chemical defense and belowground mutualism with arbuscular mycorrhizal fungi (AMF) in Plantago lanceolata L., using plant genotypes from lines selected for low and high constitutive levels of the iridoid glycosides (IG) aucubin and catalpol. As selection was based on IG concentrations in leaves, we first examined whether IG concentrations covaried in roots. Root and leaf IG concentrations were strongly positively correlated among genotypes, indicating genetic interdependence of leaf and root defense. We then found that root AMF arbuscule colonization was negatively correlated with root aucubin concentration. This negative correlation was observed both in plants grown with monocultures of Glomus intraradices and in plants colonized from whole-field soil inoculum. Overall, AMF did not affect total biomass of plants; an enhancement of initial shoot biomass was offset by a lower root biomass and reduced regrowth after defoliation. Although the precise effects of AMF on plant biomass varied among genotypes, plants with high IG levels and low AMF arbuscule colonization in roots did not produce less biomass than plants with low IG and high AMF arbuscule colonization. Therefore, although an apparent trade-off was observed between high root chemical defense and AMF arbuscule colonization, this did not negatively affect the growth responses of the plants to AMF. Interestingly, AMF induced an increase in root aucubin concentration in the high root IG genotype of P. lanceolata. We conclude that AMF does not necessarily stimulate plant growth, that direct plant defense by secondary metabolites does not necessarily reduce potential benefits from AMF, and that AMF can enhance concentrations of root chemical defenses, but that these responses are plant genotype-dependent.

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Is stimulation of carotenoid biosynthesis in arbuscular mycorrhizal roots a general phenomenon?

Cited by 40 publications

References 23 publications

Regulation of Arbuscular Mycorrhization by Carbon. The Symbiotic Interaction Cannot Be Improved by Increased Carbon Availability Accomplished by Root-Specifically Enhanced Invertase Activity

Regulation of Arbuscular Mycorrhization by Carbon. The Symbiotic Interaction Cannot Be Improved by Increased Carbon Availability Accomplished by Root-Specifically Enhanced Invertase Activity

Mycorrhizal colonization impacts on phenolic content and antioxidant properties of artichoke leaves and flower heads two years after field transplant

Chemical defense, mycorrhizal colonization and growth responses in Plantago lanceolata L.

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