© 2006 Heron Publishing—Victoria, Canada
Response of sessile oak seedlings (Quercus petraea) to flooding: an integrated study
Hélène Folzer (1), James F. Dat (1, 2), Nicolas Capelli (1), Dominique Rieffel (1) and Pierre-Marie Badot (1)
1. Laboratoire de Biologie Environnementale, EA 3184 Université de Franche-Comté-INRA, F-25030 Besançon Cedex, France / 2. Corresponding author (james.dat@univ-fcomte.fr) / Received July 8, 2005; accepted October 22, 2005; published online March 1, 2006
Summary
Sessile oak is a species of great ecological and silvicultural importance in Europe; however, increased frequency and severity
of flooding of forested areas pose a threat to its regeneration. We monitored water relations, root anatomical changes and
the expression of two calmodulin genes (QpCaM) in sessile oak seedlings during a 14-day flooding treatment. The response followed two characteristic sequences. The first
phase, in response to between 1 h and 3 days of flooding, was characterized by a dramatic but transient decline in water relations
parameters followed by a recovery towards control values with no noticeable change in root cell morphology. During the second
phase, in response to 3 to 14 days of flooding, water relations parameters gradually and continuously declined and hypertrophied
lenticels developed at the base of the shoot. Concurrently, root cortical cells became larger and less spherical and the root
cortex more porous. These cellular changes were accompanied by a transient rise in root transcript levels of QpCaM-2. We conclude that sessile oak seedlings are capable of withstanding a 3-day period of flooding without significant morphological
alterations. In contrast, exposure to flooding for more than 3 days resulted in anatomical and morphological changes in the
root system. These changes are, however, insufficient to provide sessile oak with long-term tolerance to flooding.
Keywords:
aerenchyma, calmodulin, cell death, flooding, oak, root, water relations.
