1.Facultad de Farmacia y Bioquímica, Departamento de Química Biológica, Cátedra de Química Biológica Vegetal,Universidad de Buenos Aires,Buenos Aires,Argentina;2.IQUIFIB-CONICET,Buenos Aires,Argentina
Abstract:
Polyamines (PAs) produce H2O2 and nitric oxide (NO) during their normal catabolism and modulate plant growth and development. To explore the biochemical basis of PAs-induced growth inhibition in Triticum aestivum L seedlings, we examined the role of O2·-, H2O2 or NO in shoot and root development. Although all PA treatments resulted in a variable reduction of root and shoot elongation, spermine (Spm) caused the greater inhibition in a similar way to that observed with the NO donor, sodium nitroprusside (SNP). In both cases, O2·- production was completely blocked whereas H2O2 formation was high in the root apex under SNP or Spm treatments. Catalase recovered root and shoot growth in SNP but not in Spm-treated plants, revealing the involvement of H2O2 in SNP-root length reduction. The addition of the NO scavenger, cPTIO, restored root length in SNP- or Spm-treated plants, respectively, and partially recovered O2·- levels, compared to the plants exposed to PAs or SNP without cPTIO. A strong correlation was observed between root growth restoration and O2·- accumulation after treating roots with SNP + aminoguanidine, a diamine oxidase inhibitor, and with SNP + 1,8-diaminoctane, a polyamine oxidase inhibitor, confirming the essential role of O2·- formation for root growth and the importance of the origin and level of H2O2. The differential modulation of wheat growth by PAs through reactive oxygen species or NO is discussed.
