Briefly, callus tissue was ground in
liquid nitrogen with extraction buffer (100 HIM sodium acetate,
pH 4.8, 50 mM EDTA, pH 8.0, 500 HIM NaCI, 2% PVP-
40, mixture adjusted to pH 5.5, then SDS to 1.4%, and Cys
to 10 HIM), incubated at 65°C for 20 min and centrifuged.