Reactive Oxygen Species as Markers of Seed Quality
The principal objective of this project is to enhance the current understanding of the metabolism of Reactive Oxygen Species (ROS) and redox homeostasis in dry and in dormant seeds. As outlined in the project 'Oxidative stress and seed death phenomena,' ROS can be harmful, and are involved in the induction of seed ageing and cell death. However, ROS can also be beneficial to seeds. For example, they can be involved in the alleviation of seed dormancy, which is the inability to germinate under optimal conditions. In particular the formation and metabolism of ROS in the so-called orthodox (desiccation tolerant) seeds that can tolerate extreme dehydration during storage, is poorly understood. A major project aim is to enhance our understanding of the role of ROS in seeds, and to apply the new fundamental knowledge obtained to improve the methods of ex situ conservation of seeds in seed banks. This project is part of the ‘Stress and Survival’ research theme.
Together with our French collaborators we found that ROS play critical roles in the alleviation of seed dormancy and they are key element of cellular signaling pathways during germination in sunflower seeds. The crosstalk between ROS and hormonal signaling pathways also regulates seed dormancy in barley.
Moreover, in germinating pea seeds, imbibition is accompanied by an immediate burst of redox activity, and later on, radicle emergence corresponds to a more gradual increase in extracellular production of superoxide, both of which could be related to pathogen defence. In the pea system, we could provide clear evidence that superoxide production is an important component of seed germination, seedling growth and development. In addition, ROS appear to participate in the signaling required for secondary root formation in pea seedlings.
The outputs of the project are being published in peer-reviewed journals. Two PhD students and several work experience students have been trained in the framework of this project and have contributed to the publication output. The project was also supported by a tri-national collaboration between the UK, France and Germany, which involved staff (7) and student (9) exchange between Kew, the University of Paris 6 and the University of Freiburg.
Project partners and collaborators
University of Paris 6
University of Freiburg
Leverhulme Trust (£100 k, PI Ilse Kranner)
British Council, French Embassy London and the German Academic Exchange Service (DAAD): Alliance grant 07.075 and ARC grant 1298 to Ilse Kranner with Christophe Bailly and Gerhard Leubner-Metzger, respectively.
Key papers published since 2006
Roach, T., Kranner, I. (2011). Extracellular superoxide production associated with secondary root growth following desiccation of Pisum sativum seedlings. Journal of Plant Physiology 168: 1870-1873.
Bahin, E., Bailly, C., Sotta, B., Kranner, I., Corbineau, F., Leymarie, J. (2011). Crosstalk between reactive oxygen species and hormonal signaling pathways regulate grain dormancy in barley. Plant, Cell and Environment 34: 980-993.
Roach, T., Beckett, R.P., Minibayeva, F.V., Colville, L., Whitaker, C., Chen, H.Y., Bailly, C. & Kranner I. (2010). Extracellular superoxide production, viability and redox poise in response to desiccation in recalcitrant Castanea sativa seeds. Plant Cell and Environment 33: 59-75.
Kranner, I., Roach, T., Beckett, R.P., Whitaker, C. & Minibayeva F.V. (2010) Extracellular production of reactive oxygen species during seed germination and early seedling growth in Pisum sativum. Journal of Plant Physiology 167: 805-811.
Oracz, K., El Maarouf-Bouteau, H., Kranner, I., Bogatek, R., Corbineau, F., Bailly, C. (2009). The mechanisms involved in seed dormancy alleviation by hydrogen cyanide unravel the role of reactive oxygen species as key factors of cellular signaling during germination. Plant Physiology 150: 494-505.
Roach, T., Ivanova, M., Beckett, R.P., Minibayeva, F.V., Green, I., Pritchard, H.W. & Kranner I. (2008). An oxidative burst of superoxide in embryonic axes of recalcitrant sweet chestnut seeds as induced by excision and desiccation. Physiologia Plantarum 133: 131-139.
Conferences and workshops
Since 2006 14 oral and poster contributions have been presented at 10 international conferences, 4 of which were keynote or plenary lectures; including the XVI FESPP satellite meeting ‘Peroxidase 2008’ (Tampere, Finland, 2008), the ‘9th International Symposium on Peroxidases’ (Leipzig, Germany, 2010) and the ‘Plant Oxygen Group meeting on reactive oxygen and nitrogen species: Signalling & Metabolism, Oxidative stress, Antioxidants’ (Ghent, Belgium, 2007).