## 3 Results
migulae_ SVB3R4 (SVB3R4), _Pseudomonas_ sp. SVB3R5 (SVB3R5) and _P. brassicacearum_ SVB6R1 (SVB6R1). \begin{table}
\begin{tabular}{c c c} \hline \hline
**Bacterial Strain** & \multicolumn{2}{c}{**Log CFU/g Plant Tissue**} \\ \hline  & **Root** & **Leaves** \\ \hline _Pseudomonas migulae_ SVB3R2 & \(3.48\pm 1.01\) & \(3.76\pm 1.19\) \\ _Pseudomonas migulae_ SVB3R4 & \(3.47\pm 1.15\) & n.d. \\ _Pseudomonas brassicacearum_ SVB6R1 & \(3.18\pm 1.11\) & \(3.43\pm 1.09\) \\ _Pseudomonas migulae_ SVB3R3 & \(3.37\pm 1.00\) & \(3.53\pm 1.02\) \\ _Pseudomonas_ sp. SVB3R5 & \(3.63\pm 1.25\) & \(2.83\pm 1.07\) \\ _Pseudomonas_ sp. SL3R6 & n.d. & n.d. \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Bacterial density inside sorghum plants following plant re-inoculation with the different strains. Considering all the physiological activities as well as the high tolerance to salt (Table 1) expressed by the five bacterial endophytic strains, we decided to assess their ability to increase plant tolerance to salt stress. In a preliminary experiment, performed by treating the plants with 0, 50, 100, 150 and 200 mM NaCl, the 150 mM concentration was found to be the sublethal concentration. All plant parameters, especially shoot weight, were reduced by feeding the plants with a nutrient solution containing 150 mM NaCl. Salinity stress reduced plant biomass by 89.5% (Figure 5A). _P. migulae_ SVB3R4 was the most efficient strain in promoting the growth of the plant exposed to salinity: the plant biomass (+68.3%) as well as the root (+56.6%), shoot (+73.1%) fresh weight and leaf number (+28.5%) were significantly higher in plants inoculated with SVB3R4 than in uninoculated plants fed with 150 mM salt (Figure 5A-D). Moreover, strain _P. migulae_ SVB3R3 also significantly increased the root weight (+52.1%), compared to controls exposed to salt (Figure 5B). Symptom expression in uninoculated plants started on the fourth day of treatment and 42.9% of the plants died after 20 days of growth. In the same way, all plants inoculated with the bacterial endophytes, except those inoculated with _P. brassicacarum_ SVB6R1, began to show minor symptoms on the sixth day. At the time of harvest, 80% of the plants inoculated with strain SVB3R2 were dead. In contrast, none of the plants inoculated with strains SVB3R3 and SVB3R4 died by the 20 th day. However, 83% of the plants inoculated with SVB3R3 and 71.4% of those bacterized with SVB3R4 showed strong symptoms by the end of the experiment. Similarly, only 20% of the plants inoculated with SVB3R5 survived at the end of the experiment besides showing strong symptoms. Only 28.5% of the plants inoculated with _P. brassicacarum_ SVB6R1 died by the last day of the experiment, while 28.5% and 14.3% of the plants showed weak and strong symptoms, respectively, starting from the 18 th day. Moreover, 28.5% of the plants remained symptomless. Weak symptoms were observed in 42.8% of the  
Figure 5: Effects of the selected bacterial strains on growth parameters (plant fresh weight, **(A)**; root fresh weight, **(B)**; shoot fresh weight, **(C)**; and leaf number, **(D)**) of sorghum grown in the presence or in absence of 150 mM NaCl. The values presented in the figures are means \(\pm\) standard errors (\(n=7\)). Bars topped by the same letter do not differ significantly at \(p<0.05\) by one-way ANOVA followed by [PERSON]’s post hoc test. Bars topped by \({}^{\star}\) are significant at \(p<0.05\) by one-way ANOVA followed by [PERSON]’s post hoc test compared to uninoculated control plants exposed to salt. Plant treatments: uninoculated plants **(C)**, Plants inoculated by _P. migulae_ SVB3R2 (SVB3R2), _P. migulae_ SVB3R3 (SVB3R3), _P. migulae_ SVB3R4 (SVB3R4), _Pseudomonas_ sp. SVB3R5 (SVB3R5) and _P. brassicacarum_ SVB6R1 (SVB6R1). plants inoculated with strain SVB6R1, starting from the 12 th day, thus indicating a significant delay in symptom expression compared to the uninoculated control (Figure 6). The clear effects of the strains _P. migulae_ SVB3R3 and _P.