Ink and vinegar, a simple staining technique for arbuscular-mycorrhizal fungi

Abstract

We developed a reliable, inexpensive, and simple method for staining arbuscular-mycorrhizal fungal colonizations in root tissues. Apart from applications in research, this nontoxic, high-quality staining method also could be of great utility in teaching exercises. After adequate clearing with KOH, an ink-vinegar solution successfully stained all fungal structures, rendering them clearly visible.

FIG. 1

G. mosseae-colonized roots stained with an ink-vinegar solution. Roots in panels a to e were stained with black ink (Shaeffer). (a) Colonized (dark) and noncolonized ryegrass roots. The colonized root is easily distinguishable from the noncolonized root. Bar = 25 μm. (b) Individual hyphae in both heavily and partially colonized sections of a bean root are clearly visible. Bar = 20 μm. (c) Arbuscules in ryegrass root tissue. Bar = 20 μm. (d) Vesicles and internal hyphae in ryegrass root tissue. Bar = 20 μm. (e) Arbuscules and internal hyphae in bean root tissue. Bar = 5 μm. (f) Penetration unit of G. mosseae in a ryegrass root stained with blue ink (Pelikan). Bar = 20 μm.