[1] Whilst she initially struggled to characterise the fungi she had collected from the Jackson County Iron mine, she eventually worked with Mike Miller at the Argonne National Laboratory.
[2] After graduating, Johnson returned to the University of Minnesota, where she started her doctoral studies with G. David Tilman.
In 1993 Johnson showed that fertilisation of soil created AM fungal communities that are 'inferior mutualists'.
[3] Johnson continued to collaborate with her early advisor Mike Miller throughout her career, investigating the function of mycorrhizae.
[citation needed] Johnson started her independent scientific career at the Northern Arizona University, where she was made Regents' Professor in 2016.