Abstract :
[en] The industrial revolution in the 1800s and the subsequent industrialization had the
consequence of an anthropogenic release of many organic and inorganic pollutants.
Among these pollutants, cadmium is very problematic due to its high toxicity. It can
induce significant damage to the vegetation and an accumulation in farmland
introduces the pollutant into the food chain. This creates a possible major health risk
for humans. Poplar plants, as a member of the Salicaceae family, seem to possess a
certain tolerance to this toxic metal and accumulate significant amount in their aerial
parts, making poplar a possible candidate for phytoremedation. The metabolic and
physiological impact of cadmium have been studied as well in field trials as in
controlled laboratory conditions, but mostly in clearly targeted studies focusing on a
few key aspects. The recent advent of more global techniques such as transcriptomics
and proteomics, make it possible to obtain new results.
In the thesis presented here, a proteomic study of the short-term and long-term effects
of cadmium on poplar leaf and roots metabolic processes in controlled laboratory
conditions was carried out. With the help of this technique, complemented with
biochemical and physiological approaches and with morphological observations, it
was possible to obtain results on the stress-coping mechanisms underlying an acute
first response, but also on the more general adaptation mechanism which make it
possible for the poplar plants to tolerate significant amounts of cadmium. Results
showed a negative impact on important cell processes like photosynthesis and ATP
synthesis and the antioxidant system, explaining the impaired growth. Similar results
could be obtained in roots, although the stress seemed much more acute, as evidenced
by the stronger accumulation of typical stress proteins (i.e. heat shock proteins). In a final set of experiments a controlled combination of two stresses (cadmium and nonlethal
chilling stress; 4°C) allowed separating specific cadmium responses from a
more general stress response. Cadmium had a much more severe impact on plant
survival when combined with an additional constraints. In this present work, the
procedures, results and conclusions obtained are presented in detail.
