Caracterização de Azospirillum brasilense e Azospirillum lipoferum isoladas de Teosinte e milho e sua interação com raizes de milho

AUTOR(ES)
DATA DE PUBLICAÇÃO

1988

RESUMO

In recent years much attention has been given to the biological nitrogen fixation in grasses and cereal crops. Many studies have been carried out aiming at a better understanding of the plant-bacteria reIationship. The present paper deals with the isolation of Azospirillum brasilense and Azospirillum lipoferum strains from the roots of teonsinte and maize. Twenty-three strains were obtained. These strains were screened for antibiotics resistance and indol-acetic acid (IAA) production. A great variability for both characteristics was observed. Indol-ethanol (IEt), indol-methanol (IM) and indol-lactic acid (I LA) were the main indolic components detected in Azospirillum brasilense supernatants, when cells were grown with a 0,1 mg/ml tryptophan supply, by high-pressure liquid cromatagraphy and mass spectrometry analysis. Maize roots both inoculated and non-inoculated with Azospirillum presented indol-acetic acid (IAA) and oxindol-acetic acid (Ox IAA) as their main indolic components. Maize seedling root extracts with different genetic backgrounds added to Azospirillum growth media affected the bacterial growth rate. The maize hybrid Fi 1227 extracts differed significatively from the extracts o, an American Maize Inbred Line. The results of the seedling root growth rates of maize hybrids with different genetic backgrounds inoculated with distinct strains of é brasilense contrasted significatively. The differences observed are indicative that a main role is performed by the plant material used without correlation to the bacterial IAA production. The addition of tryptophan to the growth media of plants in combination with Azospirillum inoculation caused a severe inhibition of radicular growth. Similar results were observed in the presence of IAA and also tryptophan+phenylalanine+tyrosine+IAA

ASSUNTO(S)

milho - melhoramento genetico azospirillum

ACESSO AO ARTIGO

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