Figure 4.

Different secreted metabolites produced by PS01 implicated in RSA of Arabidopsis. Effect of VOCs blend and diffusible compounds on (a) primary root elongation; (b) LRs formation; (c) RHs density and (d) RHs length were assessed. Cell-free culture supernatant of PS01 growing on TSB medium supplemented with (Culture*) or without tryptophan (Culture) was prepared by filtration. Then, 20 µL of filtrate was applied on a paper disk which was then placed in agar medium. TSB and TSB* (TSB supplemented with Trp) were used as control. VOCs treatment was performed by applying 20 µL of bacterial suspension (10⁶ CFU/mL) on a paper disk which was placed in the left side of the split plate. VOCs emitted by bacteria will expose to the seedlings at the left side. Data are depicted as boxplots representing the range of values, the exclusive median. Different letters indicate statistically significant differences (Tukey’s HSD test; p < 0.05).