ROS production and antioxidative system activity in embryonic axes of Quercus robur seeds under different desiccation rate conditions

Abstract

The seeds of pedunculate oak (Quercus robur L.) were subjected to slow (S) and rapid (R) desiccation at desiccation rates of 0.16 and 0.39% H 2 O per hour, respectively. Till ca. 40% water content (WC) the germination capacity of seeds in the S and R variants was high (ca. 100%). Between 40 and 28% WC, germination capacity declined to 20 and 50% in S and R variants, respectively. The decrease in seed viability was accompanied by a significant increase of electrolyte leakage from embryonic axes (28% for S and 15% for R variants). In the embryonic axes of seeds subjected to slow desiccation, malondialdehyde (MDA) and free fatty acid (FFA) contents were significantly higher than those in R variants, indicating greater membrane damage due to lipid peroxidation. The production of ROS (H 2 O 2 and O 2 Á-) was significantly higher in S than in R variants. The low molecular weight antioxidants a-tocopherol, ascorbic acid (ASA), and phenolic compounds indicated different reactions in response to desiccation stress. ASA levels decreased during desiccation to a similar degree in both the S and R variants. A significant decrease of total phenols was observed in R variant, which coincided with a significant increase of guaiacol peroxidase (POX) activity. a-Tocopherol content was significantly higher in the embryonic axes of seeds subjected to rapid drying. The activities of the enzymatic scavengers APX and GR had similar runs and were slightly higher in R variant. The activities of POX and SOD were significantly higher in the embryonic axes of seeds subjected to rapid drying. These results show that rapid dehydration of Q. robur seeds leads to the greater mobilization of antioxidant system in embryonic axes, particularly increased levels of a-tocopherol and POX and SOD activities, in the first stages of water loss. This mobilization has a greater impact on maintenance of higher viability of seeds after drying to lower level of WC.

Roles of enzymes in anti-oxidative response system on three species of chenopodiaceous halophytes under NaCl-stress condition

“…The reduction of APX and GR activities at 50-400 mM NaCl correlated with water content in leaves. This is similar to the behavior of APX and GR activities in seed of Quercus robur L. in drought-stress environments (Pukacka et al 2011). It appears that APX and GR activity in S. salsa was affected by water content.…”

Do recalcitrant seeds really exist?

“…Regardless the definitions of desiccation tolerance and the factors that are needed to develop or to guarantee it (Vertucci & Farrant 1995, Han et al 1997, Barbedo & Marcos Filho 1998, Alpert & Oliver 2002, Berjak 2006, Pukacka et al 2011), desiccation sensitivity is not an all-or-nothing situation. Instead, there are different levels amongst seeds of different species, and also among seeds within the same species, depending on the environmental conditions in which the seeds are developed (Berjak & Pammenter 1994, Walters 2000, Bovi et al 2004, Daws et al 2004, Lamarca et al 2011, Delgado & Barbedo 2012, Pereira et al 2012, Lamarca et al 2013.…”

Factors influencing the storability of Fagus sylvatica L. seeds after release from dormancy

“…One of the consequences of increased ROS attack on the membranes is lipid peroxidation and phospholipid de-esterification (McKersie et al 1988;Van Bilsen et al 1994). The results of this study showed that the levels of FFA, the products of phospholipid de-esterification and neutral lipids hydrolysis due to free radical attack (McKersie et al 1988;Dussert et al 2006;Pukacka et al 2011), were coincident with changes in seed viability. The FFA content increased more rapidly in embryonic axes of ND seeds stored at 20°C and 45 and 75 % RH as well as at 4°C and 75 % RH.…”

“…1b), which was most likely a result of prechilling and preparation for germination, as well as desiccation stress. During the above processes, enchanced production of ROS was observed (Oracz et al 2009;Pukacka and Ratajczak 2006;Pukacka et al 2011). High levels of GSSG can decrease the efficiency of ROS removal from cells of ND seeds (Bailly et al 2008).…”