Selective MS medium

2.5 mM phosphoric acid (H₃PO₄)

5 mM potassium nitrate (KNO₃)

2 mM MgSO₄

1 mM Ca(NO₃)₂

1 mM 2-[N-morpholino]ethanesulfonic acid (MES)

1% (w/v) sucrose

0.7% (w/v) agar type A (adjust pH to 5.7 with KOH)

Add potassium arsenate from a sterile stock solution to the desired final concentration, e.g., 250 μM-2 mM.