L’accumulation de la proline sous déficit hydrique, synthèse et devenir après retour de l’arrosage chez les végétaux

Abstract

The objective of this work consists in evaluating the effect of a hydrous deficit created using a restriction of irrigation for a period of twenty (20) days on two durum wheat genotypes (Triticum durum Desf.): Gamgoum Rekham ( GGR) and Haurani; two genotypes of common wheat (Triticum aestivum L.): Florence Aurore 8193 (FA) and Mexipak and two genotypes of barley (Hordeum vulgare L.): Manel and Saida 183 and to follow the impact of this controlled stress after 24 hours (APR1) and one week (APR2), following the return of watering. A first experiment is carried out in order to compare the relation between Proline and chlorophyll, the application of prolonged hydric stress causes an accumulation of the content of proline in the leaves of the two kinds tested compared to that of their witnesses. However, this accumulation is in favor of the Triticum kind beside the Hordeum kind with a remarkable diversity within the different varieties. As for the total chlorophyll composition of the organs studied, it evolves in a sawtooth pattern that does not lead to any indicative trend during the various treatments. After rehydration, there is a progressive decrease in proline content (APR1 and APR2), particularly at the two barley genotypes, and any change concerning the chlorophyll content. One second experimentation is carried out on the same genotypes with the same hydric treatments but this time to determine the influence of the oxydative stress produced by the dryness on the antioxydant metabolism. We were particularly interested in the activity of the superoxyde dismutase (SOD), malonedialdéhydes (MDA) content, catalase (CAT), peroxidases content (POD), as well as the ascorbate peroxidases (APX), and the content of proteins, aiming to characterize varieties according to their defense mechanisms against the effects of free radicals induced by water stress more precisely during the most critical stage and more affected by this Lack (heading stage) and to evaluate the impact of the oxydative defensive system (Indicators of oxidation and antioxidant enzymes activities) on the synthesis and the degradation of the proline in order to identify the elements of the signaling pathways involved, and to evaluate the effect of this stress on the synthesis of this compound since the precursor molecules and its fate after the return of watering.