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Registro Completo
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Biblioteca(s): |
Embrapa Agrobiologia. |
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Data corrente: |
23/10/2003 |
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Data da última atualização: |
31/05/2007 |
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Autoria: |
PINHEIRO, R. de O.; BODDEY, L. H.; JAMES, A. K.; SPRENT, J. I.; BODDEY, R. M. |
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Título: |
Adsorption and anchoring of Azospirillum strains to roots of wheat seedlings. |
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Ano de publicação: |
2002 |
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Fonte/Imprenta: |
Pant and Soil, Netherlands, v. 246, p. 151-166, 2002. |
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Idioma: |
Inglês |
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Conteúdo: |
Recent microscopic evidence acquired using strain-specific monoclonal antibodies and specific gene probes confirms earlier claims that some strains of Azospirillum lipoferum and A. brasilense, but not others, are capable of infecting the interior of wheat roots. The present study was performed to determine whether this strain specificity in the infection of the interior of wheat roots was apparent in the first 24 h of adsorption ('anchoring') of Azospiri1lum cells to the root surface. Strains of A. brasilense, originally isolated from surface-sterilized wheat roots (Sp 245, Sp 107) or with a proven ability to infect the interior of wheat roots (Sp 245), showed no greater ability to anchor to the roots than other Azospirillum strains isolated from the wheat rhizosphere (Sp 246) or from the rhizosphere or rhizosphere soil of other gramineae (Sp 7, Cd, S 82). The SEM images showed that at the root tip the Azospirillum cells were principally located in cracks between epidermal cells. In the root hair zone the bacteria were more numerous but again principally located in the depressions between epidermal cells. In all zones of the roots mucilage was present, and near the tip this appeared to have been partially digested, forming 'halos' aroun4 the bacteria and revealing fibril-like strands attached to the bacteria. Subsequent studies were conducted using à technique originally developed for investigating competition of rhizobia for adsorption sites on legume roots. In the adaptation of this technique it was found that the presence of any significant concentration of Ca++ in the incubation medium reduced bacterial adsorption, as did concentrations of (PO4)3- above 50 m M. The influence of the pH of the incubation medium on the adsorption of ten different strains of Azospirillum showed, that with one exception, strains isolated from the roots or rhizosphere of wheat showed optimum adsorption at pH 6.0, and all other strains pH 7.0. Apart from this effect of pH no differences in adsorption were detected between strains with a proven capacity to infect wheat roots and those unable to do so. However, strains varied in their capability to compete for adsorption sites, there being a tendency for strains with a proven capacity to invade the internal tissues of wheat roots to be more competitive for adsorption sites. MenosRecent microscopic evidence acquired using strain-specific monoclonal antibodies and specific gene probes confirms earlier claims that some strains of Azospirillum lipoferum and A. brasilense, but not others, are capable of infecting the interior of wheat roots. The present study was performed to determine whether this strain specificity in the infection of the interior of wheat roots was apparent in the first 24 h of adsorption ('anchoring') of Azospiri1lum cells to the root surface. Strains of A. brasilense, originally isolated from surface-sterilized wheat roots (Sp 245, Sp 107) or with a proven ability to infect the interior of wheat roots (Sp 245), showed no greater ability to anchor to the roots than other Azospirillum strains isolated from the wheat rhizosphere (Sp 246) or from the rhizosphere or rhizosphere soil of other gramineae (Sp 7, Cd, S 82). The SEM images showed that at the root tip the Azospirillum cells were principally located in cracks between epidermal cells. In the root hair zone the bacteria were more numerous but again principally located in the depressions between epidermal cells. In all zones of the roots mucilage was present, and near the tip this appeared to have been partially digested, forming 'halos' aroun4 the bacteria and revealing fibril-like strands attached to the bacteria. Subsequent studies were conducted using à technique originally developed for investigating competition of rhizobia for adsorption sites on legume roots. In the adaptati... Mostrar Tudo |
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Palavras-Chave: |
Wheats. |
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Thesagro: |
Trigo. |
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Thesaurus NAL: |
Azospirillum. |
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Categoria do assunto: |
-- |
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Marc: |
LEADER 02896naa a2200205 a 4500
001 1624717
005 2007-05-31
008 2002 bl --- 0-- u #d
100 1 $aPINHEIRO, R. de O.
245 $aAdsorption and anchoring of Azospirillum strains to roots of wheat seedlings.
260 $c2002
520 $aRecent microscopic evidence acquired using strain-specific monoclonal antibodies and specific gene probes confirms earlier claims that some strains of Azospirillum lipoferum and A. brasilense, but not others, are capable of infecting the interior of wheat roots. The present study was performed to determine whether this strain specificity in the infection of the interior of wheat roots was apparent in the first 24 h of adsorption ('anchoring') of Azospiri1lum cells to the root surface. Strains of A. brasilense, originally isolated from surface-sterilized wheat roots (Sp 245, Sp 107) or with a proven ability to infect the interior of wheat roots (Sp 245), showed no greater ability to anchor to the roots than other Azospirillum strains isolated from the wheat rhizosphere (Sp 246) or from the rhizosphere or rhizosphere soil of other gramineae (Sp 7, Cd, S 82). The SEM images showed that at the root tip the Azospirillum cells were principally located in cracks between epidermal cells. In the root hair zone the bacteria were more numerous but again principally located in the depressions between epidermal cells. In all zones of the roots mucilage was present, and near the tip this appeared to have been partially digested, forming 'halos' aroun4 the bacteria and revealing fibril-like strands attached to the bacteria. Subsequent studies were conducted using à technique originally developed for investigating competition of rhizobia for adsorption sites on legume roots. In the adaptation of this technique it was found that the presence of any significant concentration of Ca++ in the incubation medium reduced bacterial adsorption, as did concentrations of (PO4)3- above 50 m M. The influence of the pH of the incubation medium on the adsorption of ten different strains of Azospirillum showed, that with one exception, strains isolated from the roots or rhizosphere of wheat showed optimum adsorption at pH 6.0, and all other strains pH 7.0. Apart from this effect of pH no differences in adsorption were detected between strains with a proven capacity to infect wheat roots and those unable to do so. However, strains varied in their capability to compete for adsorption sites, there being a tendency for strains with a proven capacity to invade the internal tissues of wheat roots to be more competitive for adsorption sites.
650 $aAzospirillum
650 $aTrigo
653 $aWheats
700 1 $aBODDEY, L. H.
700 1 $aJAMES, A. K.
700 1 $aSPRENT, J. I.
700 1 $aBODDEY, R. M.
773 $tPant and Soil, Netherlands$gv. 246, p. 151-166, 2002.
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