ILEE Lunch Seminar 3/12

Speakers

Imen Ben Amar (URBE, Biology)

How hydropower plants affect the stress and health status in salmon smolts

Atlantic salmon is an anadromous species migrating from upper-reach nursery areas in rivers to the oceanic feeding areas at smolt stage and inversely at adult stage. This species requires unimpeded migration routes between these environments. However, dams associated with hydroelectric power stations disrupt river connectivity and affect fish movement and survival. In the framework of the project Life4fish, salmon populations and their biological condition during their downstream migration in the Lower Meuse River are characterised. Further, innovative solutions are studied and implemented to facilitate the passage through the hydropower facilities. The physiological and health status of salmon smolts and their ability to migrate after the passage through the hydropower plant (HPP) have been evaluated. Several parameters were studied after the passage through the HPP including survival, external damages, stress biomarkers such as cortisol and glucose levels and immune parameters such as ACH50 and immune gene expression. Survival rate was lower and external damages were more important in fish that confronted the HPP compared to the control group. Moreover, the passage through the turbines affected plasma glucose, ACH50 and peroxidase levels and the expression of some immune genes that are linked to native immunity and response to oxidative stress. The passage through the HPP can lead to great energy expenditure and disruption in native immune parameters. This may affect the ability of fish to pursue the migration due to the cumulative effect of encountering several obstacles.

Sophie Moreau (URBV, Biology)

COS-OGA elicitation induces different transcriptional responses between Monocots and Dicots

The induction of plant innate immunity is a promising alternative to the use of chemical pesticides. This strategy is based on compounds called elicitors that trigger non-specific plant defenses against a broad spectrum of pests and diseases. Elicitors used preventively induce a strengthening of the plant natural physical and chemical barriers before the arrival of the threat. Here we focus on an elicitor called FytoSave® whose physicochemical characteristics mimic the natural plant-pathogen interactions. The so-called “COS-OGA” active substance of this product combines plant non self-molecules, i.e. chitooligosaccharides (COS), and plant self-compounds called oligogalacturonides (OGA).
The aim of this study was to compare the mode of action of COS-OGA on Monocots and Dicots. In this view, an RNA-Seq analysis was performed to analyze the large transcriptional changes undergone by tomato (Solanum lycopersicum) and rice (Oryza sativa) plants after three applications of the elicitor.
The data obtained revealed that the pathways induced by COS-OGA differ between rice and tomato plants: the transcript profiles related to the cell wall, the hormone signaling pathways, PR proteins, secondary metabolites, transcription factors and receptor kinases were clearly distinct. Moreover, reactive oxygen species and photosynthesis transcripts presented very divergent profiles following elicitation. These results highlight key differences in the responses of a Monocot and a Dicot to the COS-OGA elicitor and broaden our knowledge on the action of elicitors on the plant transcriptome.