Materials and Reagents

1. Nylon mesh (300 μm mesh opening) (NBC Meshtec, model: NMG 58 or similar types)
   
2. 9 cm x 9 cm square Petri dishes (Simport, catalog number: D210-16 )
   
3. Plastic frame [exterior dimension, 10 cm (W) x 12 cm (H) x 1.5 cm (D); window size, 7.5 cm (W) x 9 cm (H)]]
   
4. Plastic container [13 cm (W) x 13 cm (H) x 3 cm (D)]-should be transparent and with no color
   
5. Double-sided adhesive tape (NICHIBAN, model: NW-10 or similar types)
   
6. Single-sided adhesive tape (Shamrock Scientific Specialty Systems, model: ST-12-1 or similar types)
   
7. Paper towel (NIPPON PAPER INDUSTRIES CO., catalog number: 37016 or similar types)
   
8. Scintillation vials (Sigma-Aldrich, catalog number: Z190527 or similar types)
   
9. Seeds of Arabidopsis (Arabidopsis thaliana)
   
10. Sterile deionized water
    
11. Agar (Wako Pure Chemical Industries, Siyaku, catalog number: 016-11875 or similar types suitable for plant growth)
    
12. Sterile agar medium for growth of Arabidopsis seedlings [General nutrient medium can be used. Nutrient source and concentrations may be modified depending on research purposes, e.g., sulfate concentrations to be adjusted to 1,500 μM or 15 μM sulfate (Maruyama-Nakashita et al., 2015)]
    
13. Sterile liquid medium for labeling and post-labeling incubation (Nutrient source and concentrations to be adjusted the same as the agar medium mentioned above)
    
14. Na₂³⁵SO₄ aqueous solution, 10 mCi/ml (370 MBq/ml) (American Radiolabeled Chemicals, catalog number: ARS0105 )
    
15. Hydrochloric acid (HCl) (Sigma-Aldrich, catalog number: H1758 )
    
16. Ultima Gold^TM scintillation cocktail (PerkinElmer, catalog number: 6013321 )
    

Equipment

1. Growth chamber (NKsystem, model: LPH-241SP or similar types. Set the growth conditions appropriately depending on research purposes, e.g., 22 °C, 16 h light/8 h dark cycles)
   
2. Autoclave (TOMY SEIKO CO., model: LSX-500 or similar types)
   
3. Mechanical pipettes (Gilson, model: P-200 and P-1000 ) and tips
   
4. Analytical balance (readability, 0.1 mg) (Cole-Parmer Instrument Company, Mettler Toledo, model: MS204TS or similar types)
   
5. Shaker (either reciprocating or rotary shaker) (TAITEC CORPORATION., model: NR-10 or similar types)
   
6. Liquid scintillation counter (Hitachi Aloka Medical, model: AccuFLEX LSC-7400 or similar types)
   
7. Utility knife (KOKUYO, model: HA-S200YR or similar types)
   
8. Stainless steel Forceps (Sigma-Aldrich, catalog number: Z168696 or similar types)
   
9. Surgical scissors (stainless steel dissecting scissors) (Sigma-Aldrich, catalog number: Z265977 or similar types)
   

Procedure