Embryogénèse somatique, variations somaclonales et tolérance à la salinité chez le blé dur (Triticum durumDesf.).

Abstract

The main objective of this work is to overcome the effect of salt stress on wheat through different techniques and biotechnology approaches, which are used to improve the behavior of different varieties of durum wheat and to select the best performing. Somatic embryogenesis is currently integrated into many selection schemes since it can significantly reduce the length of improvement cycles. Development of somatic embryos was obtained after cultivation of six varieties of durum wheat (Waha, GuemGoum Rkhem, Beliouni Adnan- 2, Beni and Adnan mestina-1) on a nutrient medium supplemented with 3.5mg / l 2.4-D. The selection of tolerant varieties to the salt stress was achieved by the addition of a selective agent: NaCl. This study is based on the addition of different concentrations of NaCl (0, 4, 8, 12, 16 g/l) to the medium to study the salt stress effect on the development of somatic embryogenesis. NaCl introduced to the regeneration medium was carried out by a sequential addition of different graded concentrations to determine the callus growth rate, the water content, the content of K +, Na + contents and the K + / Na + ratio in the presence orabsence of stress. Moreover, the application of salt stress through direct addition of different NaCl concentrations during the induction phase of callogenesis was exploited to determine the influence of stress on the rate of callogenesis, the germination rate, the rate of embryogenic calli, the regeneration rate and the average number of regenerated plants per callus. in vitro regeneration has proved susceptibelty to the development of somaclonal variation, because when callogenesis, somatic cells must be adapted to the culture medium and generate new changes in the genome. The detection of these variations is generally performed through revelation techniques by molecular methods. In this study, DNA extracted from the regenerated plants was subjected to polymerase chain reaction (PCR) that allowed, from this template DNA in the presence of arbitrary 9 RAPD primers to obtain a degree of polymorphism indicating the presence of somaclonal variation. Analysis of RAPD profiles revealed that the presence of somaclonal variation may be the result of many crop cycles, application of a severe stress weans and different responses of durum wheat genotypes for cultivation in vitro regeneration.