Oxidative damages and ageing bean seeds Caupi

• Autor(a) principal: Theresa Christine Filgueiras Russo AragÃo
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UFC
• Texto Completo: http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=17178
• topic: Envelhecimento; Estresse oxidativo; Caupi; Aging; Oxidative stress; Caupi; BIOQUIMICA

The present study was carried out to elucidate the relationship between seed ageing and oxidative damage in two cowpea (Vigna unguiculata (L.) Walp.) cultivars, namely PitiÃba and PÃrola.The seeds were articially aged at 45 ÂC and 99% relative humidity until 72 h and daily harvested. Seed germination, electrolyte leakage, lipid and protein oxidation were evaluated. Moreover, changes in superoxide dismutase (SOD), ascorbate peroxidase (APX) and catalase (CAT) activity as their isoform pattern and CAT and APX mRNA expression were also investigated. Only in PÃrola seeds germinability was decreased whereas electrolyte leakage was increased with artificial ageing, indicating membrane damage. Moreover, PÃrola seeds presented higher lipid and protein oxidative damage than the PitiÃba ones. Total SOD activity was not altered by the treatment in both cultivars. Zymogram analysis reveled five different isoforms, designated SOD1 to SOD5 according to the eletrophoretic migration. No significant difference in the SOD isoenzyme pattern up to 72 h were detected. Specific inhibition with peroxide and cyanide showed SOD1 and SOD2 as SOD-Mn and SOD3, SOD4 and SOD5 as SOD-Cu/Zn isoforms. It was verified a cross-talk between CAT and APX activities through artificial ageing. At 72 h of treatment, CAT mRNA expression and activity increased in PitiÃba seeds and decreased in the PÃrola ones. Conversely, APX mRNA expression and activity showed an opposite pattern in the studied cultivars. Imunoblot analysis demostrated that no significant changes in CAT content were verified in PÃrola and PitiÃba seeds during induced aging. Thus, the CAT turnover did not necessarily involve coordinated mRNA synthesis, protein synthesis and protein degradation. In conclusion, lipid and protein oxidative damage were narrowly involved in seed aging in cowpea. PitiÃba seeds were more resistant to age-induced oxidative damage than that of PÃrola. PitiÃba seed resistance against aging were related to induced CAT expression and its activity, suggesting that this enzime play a role in oxidative damage protection.