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. 2022 Mar 8;11(6):721. doi: 10.3390/plants11060721

Figure 1.

Figure 1

Bacterial strains that have a positive Salkowski assay result do not always result in primary root length inhibition. Representative image of wild-type root development after 7 days of treatment with bacteria or IAA. Out of 21 DAB strains producing a positive Salkowski assay result, only four Microbacterium strains—RU19B, RU19A, RU1A, and RU1D—caused an auxin root phenotype. Azospirillum baldaniorum strains Sp7 and Sp245 are known auxin-producing, plant-growth-promoting strains derived from wheat. Bacillus RU3D produced a negative Salkowski assay result and Microbacterium RU33B, Rhizobium RU20A, Rhizobium RU33A, Herbaspirillum RU5E, and Azospirillum RU37A produced a positive Salkowski assay result yet did not cause an auxin root phenotype.