Function of antioxidant enzymes and metabolites during maturation of pea fruits

Abstract

Panel (S2-P29) presentado en la Reunión de la Sociedad Española de Fisiología Vegetal (SEFV) (18ª. Zaragoza. 8-11 septiembre 2009).Leguminous plants such as pea (Fisum sativum), bean (Fhaseolus vulgaris) or alfalfa (Medicago sativa) are crops of major economical value as protein source for human and animal consumption. They are also essential to sustainable agricultural systems because of their ability to establish nitrogen-fixing symbioses with soil bacteria, thus providing a biological alternative to chemical fertilization. The concentration of antioxidants in fruits is important agronomically, as it is well documented that antioxidants may protect fruit tissues from potentially toxic reactive oxygen species (ROS) and thus contribute to the stress tolerance of crops. Furthermore, following harvest, fruits have a relatively short shelf-life during which they undergo changes in texture, colour and flavour. Because ROS may be involved in the oxidative processes contributing to fruit deterioration, the antioxidant content is important in terms of both the nutritional value and the post-harvest storage of the fruits. Although the antioxidants are believed to play a crucial role in the ripening process of climacteric fruits, their role in the development, maturation and post-harvest storage of legume fruits is poorly defined. We determined the antioxidant capacity (ascorbate-glutathione pathway, superoxide dismutases, catalases, glutathione peroxidases and peroxiredoxins) of mature fruits from nodulated plants and from plants supplied with combined nitrogen, and concluded that pea fruits from plants dependent on nitrogen fixation show similar antioxidant levels to those dependent on chemical fertilization. Furthermore, oir results showed that fruit maturation causes a decline in the antioxidants of pea fruits. However, the concentration of lipid peroxides and oxidized proteins remained unaltered, suggesting that, contrary to the situation described in climacteric fruits, a decrease in the antioxidant capacity does not necessarily lead to oxidative stress in maturing pea fruits. Similarly, oir data showed that despite the decreases in several antioxidants, oxidative processes are probably not involved in legume fruit deterioration during storage at room temperature. Finally, our results underscore the importance of ascorbate, one of the key components of the antioxidant network, in pea fruit growth and development.This work was funded by Ministerio de Ciencia e Innovación (grant AGL2008-01298) and Gobierno de Aragón (PIP137/2005 and group A53).Peer reviewe