Callose Staining Solution (Aniline Blue, Bright-Field Method)

Guide (The following is our recommended protocol. This protocol is only a guide and should be modified according to your specific needs).

1. Stock Solution Preparation
1.1 Solvent: For most dyes, organic solvents such as anhydrous DMSO are typically used for dissolution.
1.2 Concentration recommendation: Prepare a high-concentration stock solution of 1-10 mM.

2. Working Solution Preparation
2.1 Diluent: Options include 150 mM K2HPO4 (pH 9.5) and Sørensen phosphate buffer (0.1 M, pH = 8.0).
2.2 Working concentration: 0.01-1% (w/v).
2.3 Precautions: Adjust the working solution concentration as needed and prepare fresh immediately before use.

3. Staining Procedure
3.1 Sample Type Description
3.1.1 Arabidopsis thaliana leaf tissue (infiltrated with pathogen or PAMP elicitor)^[1]:
3.1.2 Streptophyte green algal filaments or single cells^[2]:
3.1.2.1 Suspension cells: Pellet the biomass by centrifugation at approximately 1000 x g and remove the liquid.
3.1.3 Tobacco suspension cells, Noni fruit suspension cell clusters, or tobacco protoplasts at the regeneration/elongation stage^[3]:
3.2 Incubation Conditions
3.2.1 Arabidopsis thaliana leaf tissue: Incubate with Aniline Blue working solution for 1 h with gentle agitation.
3.2.2 Streptophyte green algal filaments or single cells:
3.2.2.1 Pretreatment: Incubate the samples with 8 N NaOH at 60 °C for 20 min.
3.2.2.2 Staining: Incubate the samples with Aniline Blue solution in the dark with gentle agitation for 1 h, maintaining low light intensity (~5 μmol photons m^-2 s^-1) throughout the procedure.
3.2.3 Suspension cells or protoplasts: Mix 25 μL of the cell/protoplast suspension with 5 μL of decolorized Aniline Blue solution.
3.3 Washing Steps
3.3.1 Arabidopsis thaliana leaf tissue:
3.3.1.1 Remove the lactophenol solution, add 5 mL of 50% ethanol, gently agitate for 5 min, and then remove the ethanol.
3.3.1.2 Add 5 mL of distilled water, gently agitate for 10 min, and then remove the water.
3.3.2 Streptophyte green algal filaments or single cells:
3.3.2.1 After NaOH incubation, wash the samples with double-distilled water 3 times, each for at least 5 min.
3.3.2.2 After staining, wash the samples with Sørensen phosphate buffer 2 times, each for 5 min.
3.3.3 Suspension cells or protoplasts: No washing is required.

4. Control Setup
4.1 Set up a negative control infiltrated with buffer (10 mM MgCl₂), a positive control infiltrated with flg22 or Pto DC3000 hrcC-, and a blank control to exclude reagent fluorescence interference.
4.2 Validate the staining effect using reference materials, including pollen tubes, onion epidermal cell strips, root tips, stylar tissue, chicory epidermal cell strips, tobacco macro/microsporogenesis tissue, and the glandular cells of Drosera.
4.3 Induce wound callose by vigorously pipetting cells/protoplasts or cutting tissue strips along the glass edge to distinguish endogenous callose.

5. Detection and Analysis
5.1 Instrument type: Epifluorescence microscope, fluorescence microscope, or laser scanning confocal microscope (CLSM).
5.2 Excitation/Emission Wavelengths
5.2.1 Options include: excitation wavelength 370 nm, emission 420-530 nm; excitation bandpass (BP) 365/12 nm, emission longpass (LP) 397 nm; or a BG3 250-450 excitation filter with an S405 barrier filter.
5.3 Result Analysis
5.3.1 Fluorescence intensity: Callose deposits associated with defense responses show bright fluorescence, while background signals from unexcited cell walls and vascular tissue are of lower intensity; strong radiating granular fluorescence appears at the cell plates and transverse walls of tobacco suspension cells; transverse fibrous callose deposits gradually appear on lateral walls during the logarithmic growth phase and disappear by the early stationary phase; strong radiating spots appear at wound sites.
5.3.2 Fluorescence localization: Callose deposits in the intercellular spaces of Arabidopsis leaf cells appear as discrete fluorescent spots; callose in plant cell walls exhibits blue fluorescence; callose is distributed on the cell plates, transverse walls, and lateral walls of suspension cells, while regenerating/elongating protoplasts show linear, patchy, or granular callose deposits.
5.3.3 Color change: Fluorescence emission falls within the blue range; upon binding to callose, it produces a green-yellow fluorescence.
5.3.4 Quantitative analysis: Use Image J software to count the number of callose deposits and calculate the number per mm².
5.3.5 Expected patterns: Transversely arranged fibrous callose is present on the lateral walls of tobacco suspension cells in the logarithmic growth phase; fine granular spotted callose is present in Noni fruit cell clusters; linear/patchy callose is present in regenerating protoplasts; and transversely oriented fine linear callose, interspersed with granular spots, is present in elongating protoplasts.

MedChemExpress (MCE) has not independently confirmed the accuracy of these methods. They are for reference only.