Differential response of antioxidative enzymes in embryonic axes and cotyledons of germinating lupine seeds

Abstract

Germination of lupine (Lupinus luteus L.) seeds was accompanied by an increase in concentration of free radicals with g 1 and g 2 values of 2.0056 ± 0.0003 and 2.0033 ± 0.0005, respectively. The highest intensity of free radical signal was observed in embryo axes immediately after radicle protruded through the seed coat. Hydrogen peroxide accumulated in embryonic axes and cotyledons during imbibition before the onset of germination in the seed population. The activities of superoxide dismutase (SOD, EC 1.15.1.1) and catalase (CAT, EC 1.11.1.6) rose progressively in embryo axes. In cotyledons SOD activity did not change significantly, while that of CAT increased during germination. The enhancement of Cu, Zn-SODs and Mn-SOD isoforms in embryonic axes was observed. A new isoform of catalase was synthesized, suggesting that it plays a relevant role during germination. SOD and CAT activities were detected in dry seeds. Free radical generation and response of antioxidative enzymes differed between embryo axes and cotyledons during the germination timecourse.

Ability of lupine seeds to germinate and to tolerate desiccation as related to changes in free radical level and antioxidants in freshly harvested seeds

“…However, dry lupine seeds seem to be endowed with a full antioxidant machinery to avoid oxidative stress that occurs during germination [13,14]. Additionally, at low moisture content water is tightly bound on to macromolecule structure thus decreasing molecular mobility and accessibility of enzymes to their substrates, so accumulation of low molecular weight antioxidants might play an important role in protecting cells against oxidative stress during desiccation.…”

Plant responses to water stress: Role of reactive oxygen species

“…41 Indeed ROS have now been recognized to serve positive roles in growth and development apart from their destructive role induced by stresses. Thus ROS including H 2 O 2 have been demonstrated to play role in radicle emergence during seed germination, 42,43 root growth and root hair elongation 44,45 as well as defense against pathogens during seed germination. 46 Relative stability of H 2 O 2 compared with other ROS and its ability to cross the membrane makes it suitable for signaling.…”

Effect of ascorbic acid on seed germination of three halophytic grass species under saline conditions

“…Initiation of seed germination is coupled with mitochondrial activity, which leads to the production of reactive oxygen species (ROS; Schopfer et al ., ; Garnczarska and Wojtyla, ; Kranner et al ., ). This ROS production may protect germinating seeds from pathogens (Schopfer et al ., ), softening the cell wall (Müller et al ., ) to promote radicle emergence and oxidize inhibitors (Ogawa and Iwabuchi, ).…”