Influence of elevated CO2 atmosphere, nitric oxida and fungai elicitors on production of phytoalexins in soyobean seedlings / Influencia de atmosfera enriquecida em CO2, do radical oxido nitrico e de eliciadores fungicos na produção de fitoalexinas em plantulas de soja

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Soybean seedlings (Glycine max L. Merr) grown in open top chambers under high CO2 concentrations have shown photosynthetic increment and increase in productivity, which in turn may modify the productio n of secondary metabolites with farmacological importance. The aim of this work was to analyze the synthesis of flavones, isoflavones and pterocarpans in soybean seedlings (IAC-18, a cultivar resistant to the causal agent of the stem canker disease Diaphorthe phaseolorum f. sp. Meridionalis), kept under 380 and 760 mmol mol-1 CO2 atmospheres stimulated by biotic and abiotic elicitors. The b-glucan from mycelial walls of Phythophytora megasperma, autoclaved espores of D. phaseolorum (Dpm) and the NO donors, GSNO and SNP, were used as elicitors. The assays were performed by applying the elicitors on detached cotyledons from 9 days old soybean seedlings (VC stage). The exposition to 760 mmol mol-1 of CO2 stimulated photosynthesis, increased the area and fresh mass of leaves and cotyledons, and raised the production of coumestrol, daidzein, genistein, luteolin and apigenin, mainly induced by SNP. For glyceollins and daidzin the CO2 stimulatory effect was observed only by the induction with the b-glucan. Biochemical parameters related to soluble and structural carbohydrates from soybean seedlings also showed significant differences between the two CO2 treatments. These results strengthen the suggestion that the increment in the carbon availability may modify the inducible defenses in soybean against pathogens. However, these alterations occur in specific metabolites and depend on the elicitor.

ASSUNTO(S)

oxido nitrico carbon dioxide soybean isoflavonas isoflavones nitric oxide dioxido de carbono soja fitoalexinas phytoalexins

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