Mechanisms underlying the deterioration of Medicago truncatula primed seeds during storage: molecular characterization of the seed response to the anti-aging compound spermidine

Climate change and the progressive increase of world population require strong efforts in order to ameliorate crop productivity and quality. In this context, research on seed quality, particularly the study of strategies to decrease seed deterioration and loss of vigour in storage conditions, is mandatory. To reach this target, a deeper investigation of the molecular mechanisms that control the pre-germinative metabolism is required. When imbibition starts, water up-take is associated with reactive oxygen species (ROS) accumulation leading to deleterious effects inside cells, such as lipid peroxidation and nucleic acids damages. Seed priming is used to improve germination performance through controlled imbibition followed by desiccation. Depending on the conditions and priming agent applied, it is possible to boost the seed antioxidant response and DNA repair pathways, thus maintaining genome integrity. However, it has been observed that the beneficial effects, acquired by seeds with this method, are lost during storage. An experimental system has been developed, using the model legume Medicago truncatula, able to provide information on the seed ability to withstand the impact of aging and allow to test treatments designed to improve viability of primed seeds. The system was tested using spermidine (Spd), a well-known antioxidant compound, which is able to protect DNA from ROS-mediated oxidative damage. The aim of this study is to assess the potential of Spd-based priming to improve seed storability and to investigate the expression profiles of genes involved in Spd biosynthesis and DNA damage response (DDR).