**1. Introduction**

ROS are usually thought as hazardous molecules, attacking to biomolecules, leading to membrane and DNA injuries, and deleterious effects in seed germination processes [1–5]. Seed aging is a process that the roles of ROS are well documented [6–9]. ROS also have damages in desiccation of seeds by dehydration [10, 11]. Although ROS have been considered as detrimental to seeds up to now [12–16], recent advances in plant physiology signaling pathways have led to reconsider their role [17–29]. ROS accumulation can therefore be also beneficial for seed germination and seedling growth by regulating cellular growth, providing a protection against pathogens, and controlling the cellular redox status [30–33]. ROS are

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

also proved to act as a positive signal in seed dormancy release [30–33]. The dual function of ROS in plants depends on the levels of antioxidant compounds, and enzyme activities release [34–38]. By this way, plants can eliminate potentially harmful ROS that is produced under stress conditions, or control ROS concentrations in order to regulate various signaling pathways [34–38]. This dual function of ROS is a very interesting subject in seed physiology. Even though there is a huge progress in this field, and the dual functions of ROS are quite well documented in the literature, it should also be regarded from a different point of view. The involvement of ROS in seed filling processes is not well documented, and the mobility of ROS in seeds has not yet been documented, thus, more data is needed on roles of ROS in seed germination and development physiology. Under light of the increasing progress made in the understanding of mechanisms driven by ROS, the role of ROS in seed biology may need to be revisited. To date, many distinct roles for ROS, apart from their toxic effects, have been identified.
