This video demonstrates a double staining method using ruthenium red and lactophenol cotton blue to visualize pectins and chitins during plant-fungus interactions in a coffee rust plant. The procedure helps understand plant defense mechanisms during fungal infections.
Protocol
1. Double staining process
Begin with ultrathin, resin-embedded leaf sections of Coffee arabica cv. Catuaí infected with coffee rust. Cover the sections with 2 mL of 5% cotton blue in lactophenol (40% glycerol, 20% phenol, and 20% lactic acid in water) and heat them on a hot plate at 45 °C for 5 min (Figure 1A).
Remove the excess dye by washing the slide three times in a beaker filled with distilled water (Figure 1B-D).
Stain with 2 mL of 0.01% ruthenium red in water for 1 min (Figure 1E).
Remove the excess dye by washing the slide three times in a beaker filled with distilled water (Figure 1F,G).
Put a drop of distilled water over the sections and cover the sections with a 24 mm x 60 mm coverslip for performing light microscopy analysis.
Representative Results
Figure 1: Details of the individual steps of the double-staining protocol. (A) Cover the sections with drops of cotton blue lactophenol and heat the slides on a hot plate at 45 °C. (B-C) Remove the excess dye by washing in distilled water. (D) Sections on the glass slides after washing (denoted by arrows). (E) Cover the sections with drops of ruthenium red. (F-G) Remove the excess dye by washing in distilled water.
Double-Staining Method: A Technique to Visualize Plant-Fungus Interactions Using Ruthenium Red and Lactophenol Cotton Blue. J. Vis. Exp. (Pending Publication), e21054, doi: (2023).