The use of wideband filters in distinguish green fluorescent protein in roots of arbuscular mycorrhizal symbiosis.

Arbuscular mycorrhizal (AM) fungi form arbuscules in the inner cortical cells of roots. Accumulation of autofluorescent materials within the roots, especially around senescent arbuscules, has hampered analyses of the localization and dynamics of green fluorescent protein (GFP)-fusion proteins in arbusculated cells. In this report, the author proposes an efficient method to distinguish GFP from autofluorescence. To detect GFP fluorescence, colonized cells were observed with wideband filters rather than GFP-specialized filters because the autofluorescence generally has a broad fluorescent spectrum that can easily be distinguished from GFP by color. Moreover, the autofluorescence of arbusculated cells could possibly contain strong green fluorescence that could not be excluded by GFP-specialized filters. The multicolor imaging and in vivo real-time observations suggested that the expression of autofluorescence in arbusculated cells did not overlap with the expression of OsPT11-GFP, a useful marker for active arbuscules, and that autofluorescent materials appeared after the initiation of senescence in infection units.