Effet PGPR de deux isolats de Streptomyces sp. sur les plants de tomate et leur tolérance à la salinité

Abstract

In the present study we isolated six bacterial morphotypes from Marrubium vulgare rhizospheric soil of, two of them (S1 and S4) belong to Streptomyces genus. Their biochemical characterization has shown that they are Gram positive, unable to degrade Simmons citrate, possess the catalase enzyme and tolerate up to 75mM of NaCl. They are also capable of producing auxin (Indole-3-acetic acid) and solubilizing inorganic phosphate. These two isolates have no effect on tomato seed germination and no inhibitory activity against the tested microorganisms. In vivo inoculation effect of tomato plants by the two isolates under salinity constraint (25 and 50mM NaCl) showed, that their growth, relative water content, chlorophyll pigment and mineral (K and Na) contents are significantly better, their plant tissues are less damaged and their mortality rate is lower compared to uninoculated plants.