Oxidative stress in the regulation of seed dormancy and germination in two sunflower inbred lines

PEREZ CHACA V.; MOLINA A.S.; ANDRADE A.; ALEMANO S.; ZIRULNIK F.; VIGLIOCCO, A.

Congreso; XXXIV Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2016

Reactive oxygen species (ROS) play important roles in the regulation of seed dormancy and germination. Our aim was to evaluate the content of hydrogen peroxide (H2O2) and the activity of two antioxidant enzymes: catalase (CAT) and ascorbate peroxidase (APX) in embryonic axis and cotyledons of dry and imbibed seeds of two sunflower inbred lines (B123: with dormancy; B91 without dormancy) at harvest (day 0) and after storage at 25°C during 33days. Higher levels of H2O2 were detected in dry embryonic axis than in cotyledons. At day 0, H2O2 was higher in B91 embryonic axis of dry seed than B123. After 33 days of storage, B123 increased H2O2 concentration, while B91 decreased. During the imbibition, H2O2 did not change in B91 embryonic axis at 6 h on day 0; whereas in B123 embryonic axis a decrease was observed at 33 days under storage at room temperature at 6 h. In cotyledons, H2O2 decreased at 12 h of imbibition in both lines. CAT activity showed a high level in cotyledons respect to the embryonic axis. A decrease in CAT activity was observed in embryonic axis and cotyledons of B91 and B123 dry seeds under storage. APX activity decreased in both lines during the imbibitions. The pattern of H2O2 accumulation in B123 embryo axis during dry storage might be a key signal in the dormancy release allowing the germination of embryo.