The Biology of Mycorrhiza in the Ericaceae

Bajwa, Rukhsana; Abuarghub, S. M.; Read, David

doi:10.1111/j.1469-8137.1985.tb02853.x

Cited by 94 publications

(34 citation statements)

References 46 publications

(35 reference statements)

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“…Plant, animal and microbial tissue must represent the ultimate source of all proteinaceous material entering the soil, and in view of the ability of the mycorrhizal fungus to utilize released amino residues and peptide moieties up to at least 6 amino units in length it is clearly important to determine its ability to utilize protein. Such determinations are reported in the following paper (Bajwa, Abuarghub & Read, 1985).…”

Section: Discussionmentioning

confidence: 92%

The Biology of Mycorrhiza in the Ricaceae

Bajwa

Read

1985

New Phytologist

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SUMMARYThe ericoid mycorrhizal endophyte Hymenoscyphus ericae (Read) Korf & Keman was grown both in pure culture and in mycorrhizal association with the host plant Vaccinium corymbosum L. on media containing peptides of differing chain length as sole nitrogen sources. The ability to utilize the peptide nitrogen was assessed in terms of growth of the fungus and of growth and nitrogen content of the plants.The tripeptide, glutathione, and alanine units of 1-6 amino acid residues in length were all readily utilized by the endophyte, though assimilation was less rapid in the case of the longer chain lengths. Mycorrhizal seedlings showed significantly higher yields and had higher nitrogen contents than non-mycorrhizal seedlings in almost all cases.The physiological and ecological implications of these results are discussed.

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Section: Discussionmentioning

confidence: 92%

The Biology of Mycorrhiza in the Ricaceae

Bajwa

Read

1985

New Phytologist

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“…Microbes and soil fauna have been considered crucial for converting soil protein into nitrogen compounds of low molecular mass, and microbes compete with plants for soil nitrogen (1). It is not well understood how nonmycorrhizal plant species like Hakea and Arabidopsis compete for nitrogen with mycorrhizal plants, but root-derived proteases may function similarly to proteases of ectoand ericoid mycorrhizal fungi (2,12). Our initial hypothesis was that Hakea uses specialized cluster roots for acquisition of protein similar to what has been described for other soil nutrients (23).…”

Section: Discussionmentioning

confidence: 96%

Plants can use protein as a nitrogen source without assistance from other organisms

Paungfoo‐Lonhienne

Lonhienne²,

Rentsch³

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

306

208

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Nitrogen is quantitatively the most important nutrient that plants acquire from the soil. It is well established that plant roots take up nitrogen compounds of low molecular mass, including ammonium, nitrate, and amino acids. However, in the soil of natural ecosystems, nitrogen occurs predominantly as proteins. This complex organic form of nitrogen is considered to be not directly available to plants. We examined the long-held view that plants depend on specialized symbioses with fungi (mycorrhizas) to access soil protein and studied the woody heathland plant Hakea actites and the herbaceous model plant Arabidopsis thaliana, which do not form mycorrhizas. We show that both species can use protein as a nitrogen source for growth without assistance from other organisms. We identified two mechanisms by which roots access protein.Roots exude proteolytic enzymes that digest protein at the root surface and possibly in the apoplast of the root cortex. Intact protein also was taken up into root cells most likely via endocytosis. These findings change our view of the spectrum of nitrogen sources that plants can access and challenge the current paradigm that plants rely on microbes and soil fauna for the breakdown of organic matter.nitrogen uptake ͉ organic nitrogen ͉ plant nutrition ͉ plant roots ͉ soil protein

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“…For example, the pro-teolytic activity of H. ericae in pure culture, or in association with Vaccinium corymbosum, was maximal at pH 4*0 with very little activity at pH 3'0 (Bajwa et al, 1985). However, the extracellular proteinase produced by cultures of H. ericae grown at pH 3-5 with bovine serum albumin (BSA) as sole N source has a well-defined, extremely acidic pH optimum at pH 2-2, with negligible activity at pH values of 4-0 and above (Leake & Read, 1989).…”

Section: Introductionmentioning

confidence: 99%

Proteinase activity in mycorrhizal fungi

Leake

Read

1990

New Phytologist

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SUMMARYThe effect of pH on the production and specific activity of tbe extracellular proteinase enzymes of two ecologically distinct ericoid mycorrhizal fungi is described. Tbe proteinase of Hymenoscyphus ericae (Read), Korf & Kernan, isolated from roots of Calluna vulgaris (L.) Hull growing in soil of pH 35, was compared with a similar enzyme from an endopbyte of tbe calcicolous alpine sbrub Rhodothamnus chamaecistus (L.) Reicbenb. growing in soil of pH 6-5. Tbe fungi were grown in liquid culture at pH values ranging from 3-0 to 8-0 witb pure protein, bovine serum albumin, as sole source of N.Botb fungi yielded an extracellular acid proteinase witb pH optimum for activity between 20 and 3-0. Tbe production and activity of tbese enzymes was strongly affected by pH of tbe culture medium. Maximum enzyme production during exponential growtb occurred in botb fungi at a culture pH of 40-50, wbereas bigber pH treatments severely inbibited enzyme production.Tbe acid proteinase of H. ericae was tolerant of extreme acidity and retained near-optimal activity in solutions of pH 2-0. In contrast, tbe activity of tbe enzyme from tbe Rhodothamnus endopbyte was almost completely inbibited at tbis pH. However, proteinase from tbe Rhodothamnus endopbyte retained activity at mucb bigber pH values tban did tbe proteinase from H. ericae. Unlike H. ericae, tbe isolated endopbyte of Rhodothamnus was able to grow and use protein as sole source of N at pH 7-0 and 8 0.Tbe effects of pH on enzyme production and upon growtb of tbe fungi are discussed in relation to tbe cbaracteristics of tbe environments of tbeir bost plants.

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The Biology of Mycorrhiza in the Ericaceae

Cited by 94 publications

References 46 publications

The Biology of Mycorrhiza in the Ricaceae

The Biology of Mycorrhiza in the Ricaceae

Plants can use protein as a nitrogen source without assistance from other organisms

Proteinase activity in mycorrhizal fungi

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