Nitrogen Uptake during Snowmelt by the Snow Buttercup, Ranunculus adoneus

Mullen, Renée B.; Schmidt, Steven K.; Jaeger, C. H.

doi:10.2307/1552126

Cited by 70 publications

(51 citation statements)

References 31 publications

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“…Heteroconium chaetospira, a dark septate endophyte, was able to transfer nitrogen to the roots of cabbage plants (26). It was also found that the roots of Ranunculus adoneus colonized by endophytic fungi had increased nitrogen acquisition early in the growing season that resulted in an increased plant survival rate (27).…”

Section: Discussionmentioning

confidence: 97%

Ubiquity of Insect-Derived Nitrogen Transfer to Plants by Endophytic Insect-Pathogenic Fungi: an Additional Branch of the Soil Nitrogen Cycle

Behie

Bidochka

2014

Appl Environ Microbiol

173

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The study of symbiotic nitrogen transfer in soil has largely focused on nitrogen-fixing bacteria. Vascular plants can lose a substantial amount of their nitrogen through insect herbivory. Previously, we showed that plants were able to reacquire nitrogen from insects through a partnership with the endophytic, insect-pathogenic fungus Metarhizium robertsii. That is, the endophytic capability and insect pathogenicity of M. robertsii are coupled so that the fungus acts as a conduit to provide insect-derived nitrogen to plant hosts. Here, we assess the ubiquity of this nitrogen transfer in five Metarhizium species representing those with broad (M. robertsii, M. brunneum, and M. guizhouense) and narrower insect host ranges (M. acridum and M. flavoviride), as well as the insect-pathogenic fungi Beauveria bassiana and Lecanicillium lecanii. Insects were injected with 15 N-labeled nitrogen, and we tracked the incorporation of 15 N into two dicots, haricot bean (Phaseolus vulgaris) and soybean (Glycine max), and two monocots, switchgrass (Panicum virgatum) and wheat (Triticum aestivum), in the presence of these fungi in soil microcosms. All Metarhizium species and B. bassiana but not L. lecanii showed the capacity to transfer nitrogen to plants, although to various degrees. Endophytic association by these fungi increased overall plant productivity. We also showed that in the field, where microbial competition is potentially high, M. robertsii was able to transfer insect-derived nitrogen to plants. Metarhizium spp. and B. bassiana have a worldwide distribution with high soil abundance and may play an important role in the ecological cycling of insect nitrogen back to plant communities. Despite its atmospheric abundance, nitrogen gas (N 2 ) is not directly available as a source of nitrogen to plants. Free-living or symbiotic soil microbes fix N 2 and produce nitrogen-containing compounds that are directly utilized by plants (1). Traditionally, the paradigm of symbiotic nitrogen transfer to plants has focused on nitrogen-fixing bacteria such as Rhizobium. However, once this nitrogen is fixed and transferred to the plant, it can be lost, primarily through microbial mineralization of decaying vegetation or insect herbivory. With respect to mineralized nitrogen, more than 90% of land plants are able to form symbiotic relationships with soil fungi, and several of these fungi are able to transfer nitrogen to plants (2). Mycorrhizal fungi, specifically from the phylum Glomeromycota, have been shown to provide plants with nitrogen obtained from the soil in exchange for plant-derived carbon (3).Up to 31% of plant nitrogen in an ecosystem can be lost to insects through herbivory (4). Recently, we illustrated a strategy whereby plants can reacquire nitrogen previously lost to herbivorous insects through an association with an endophytic, insectpathogenic fungus (EIPF) (5). In the soil, the EIPF Metarhizium robertsii infected and killed an insect, formed an endophytic relationship with a plant, and subsequently transferred insect-deriv...

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Section: Discussionmentioning

confidence: 97%

Ubiquity of Insect-Derived Nitrogen Transfer to Plants by Endophytic Insect-Pathogenic Fungi: an Additional Branch of the Soil Nitrogen Cycle

Behie

Bidochka

2014

Appl Environ Microbiol

173

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Section: Functions Of Mycorrhizas and Dse In Polar Regionsmentioning

confidence: 99%

“…In a study on the alpine snow buttercup Ranunculus adoneus, Mullen et al (1998) showed that phosphorus uptake by the plant occurs late in the growing season and is associated with the development of arbuscules in roots. Early in the growing season, R. adoneus takes up large amounts of nitrogen from the soil, when the frequency of arbuscules in roots is low, but that by DSE hyphae is an order of magnitude higher, leading to the suggestion that DSE may have a role in nitrogen acquisition by roots (Mullen et al 1998). In a laboratory study, Upson et al (unpublished) similarly showed that, in comparison with uninoculated controls, the growth of D. antarctica inoculated with seven DSE isolated from the roots of the species was typically inhibited in the presence of an inorganic nitrogen source, but was increased by as much as 2.5-fold, typically by members of the Helotiales, when seedlings were supplied with an organic nitrogen source.…”

Section: Functions Of Mycorrhizas and Dse In Polar Regionsmentioning

confidence: 99%

Mycorrhizas and dark septate root endophytes in polar regions

2009

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We review the distributions and functions of mycorrhizas and dark septate root endophytes in polar regions. Arbuscular mycorrhizas (AM) are present in the Arctic and Antarctic to 82 ºN and 63 ºS, respectively, with fine endophyte being the dominant form of AM in roots at higher latitudes. Ecto-(ECM) and ericoid (ERM) mycorrhizas both occur in the Arctic to 79 ºN, owing to the presence of species of Salix, Dryas, Vaccinium and Cassiope to this latitude.ECM and ERM are not present in Antarctic ecosystems, owing to an absence of suitable hosts. Arbutoid and orchid mycorrhizas are infrequent in the Arctic, whilst the latter is present at one location in the sub-Antarctic. Data from studies of AM, ECM and ERM colonisation along a latitudinal transect through the Arctic indicate that the frequency of plant species not colonised by mycorrhizas increases at higher latitudes, largely owing to an increase in nonmycorrhizal and a decrease in obligately mycorrhizal plant families at more northerly locations. A separate group of root-and rhizoid-associated fungi, the dark septate root endophytes (DSE), are widespread to 82 ºN and 77 ºS, and are apparently more frequent than mycorrhizal fungi in polar regions. The functions of DSE are largely unclear, but studies suggest beneficial effects on plant growth under defined conditions. We advocate further research into the effects of DSE on their host plants in polar regions.

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“…La mineralizzazione della sostanza organica nel corso dell'inverno al di sotto di un cospicuo manto nevoso determina la produzione di un pool di azoto e fosforo inorganico prima del disgelo primaverile (Brooks et al, 1996, Freppaz et al, 2001a, potenzialmente lisciviabile se non sincronizzato con i processi di immobilizzazione microbica e di assorbimento radicale (Jaeger et al, 1999), meccanismo alla base della conservazione degli elementi nutritivi negli ecosistemi forestali (Bormann e Likens, 1979;Mullen et al, 1998). La produzione invernale di N nel suolo è generalmente superiore a quello che deriva dalla fusione del manto nevoso, anche di quattro (Williams et al, 1995) -venti volte (Schimel et al, 1994), rispettivamente in suoli poco evoluti di un bacino alpino ed in suoli artici.…”

Section: La Neve E Il Ciclo Degli Elementi Nutritivi Del Suolounclassified

Influence of snow cover distribution on soil temperature and nutrient dynamics in alpine pedoenvironments

Zanini¹,

Freppaz²

2010

Ital J Agronomy

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RiassuntoNegli ambienti agro-forestali alpini la neve permane al suolo dai sei agli otto mesi all'anno in relazione alla quota ed alla esposizione. L'acqua è quindi immobilizzata allo stato solido per la maggior parte del periodo invernale e rilasciata al suolo in un breve periodo di tempo nel corso del disgelo primaverile. In questi ambienti il regime delle precipitazioni nevose esercita un ruolo fondamentale nel condizionare la temperatura e la dinamica degli elementi nutritivi del suolo, ed in particolare dell'azoto, con significative conseguenze sulla nutrizione vegetale. Il riposo vegetativo, le basse temperature e la diffusa copertura nevosa suggeriscono infatti che l'attività biologica del suolo sia concentrata soltanto durante la stagione estiva. In realtà i suoli ricoperti da un consistente manto nevoso sono isolati dalla temperatura dell'aria e possono non gelare nel corso dell'inverno. Un manto nevoso di sufficiente spessore, infatti, accumulatosi presto nella stagione invernale, è in grado di isolare il suolo dall'ambiente circostante mantenendo la temperatura prossima agli 0 °C nel corso della stagione invernale. L'innalzamento del limite delle nevicate e la riduzione della permanenza della neve al suolo in seguito al riscaldamento globale (IPCC, 1996(IPCC, , 2001) può però determinare una riduzione dell'effetto isolante del manto nevoso, esponendo i suoli del piano montano superiore a temperature più basse e ad una maggiore frequenza di cicli gelo/disgelo che possono alterare la dinamica della sostanza organica e la disponibilità di nutrienti nel suolo. Tali stress termici possono determinare la lisi delle cellule microbiche ed il conseguente incremento della mineralizzazione dell'azoto e del carbonio ad opera dei microrganismi sopravvissuti. È inoltre emerso come l'azione dei cicli gelo/disgelo possa determinare l'esposizione di superfici di scambio prima non disponibili, con il rilascio ad esempio di forme di azoto organico di origine non microbica, successivamente mineralizzate. La ridotta o assente attività di immobilizzazione microbica può concorrere a determinare l'accumulo di notevoli quantità di azoto inorganico nel suolo, potenzialmente lisciviabile nel corso del disgelo primaverile, quando le piante non hanno ancora ripreso l'attività vegetativa. La riduzione delle precipitazioni nevose negli ambienti agro-forestali alpini può quindi avere un significativo effetto sul regime termico dei suoli e conseguentemente sul ciclo degli elementi nutritivi. Le ricadute ambientali non possono che essere valutate nel tempo, attraverso studi mirati, in grado di evidenziare gli effetti indiretti del cambiamento climatico in atto sulle caratteristiche dei pedoambienti alpini.

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Nitrogen Uptake during Snowmelt by the Snow Buttercup, Ranunculus adoneus

Cited by 70 publications

References 31 publications

Ubiquity of Insect-Derived Nitrogen Transfer to Plants by Endophytic Insect-Pathogenic Fungi: an Additional Branch of the Soil Nitrogen Cycle

Ubiquity of Insect-Derived Nitrogen Transfer to Plants by Endophytic Insect-Pathogenic Fungi: an Additional Branch of the Soil Nitrogen Cycle

Mycorrhizas and dark septate root endophytes in polar regions

Influence of snow cover distribution on soil temperature and nutrient dynamics in alpine pedoenvironments

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