2.4. ABA extraction and purification
Plant tissues were homogenised in 80% aqueous
MeOH (v:v) in the presence of 0.001% of BHT
(2,6-ditert-butyl-4-methylphenol, Merck) and 1%
Polyclar AT (Sigma), shaken twice (1.5 h each) at
4°C in the dark and centrifuged (215 min, 7000
rpm). The supernatants were then combined and
MeOH dried out. Aqueous phases were adjusted
to pH 7.65–7.85 and partitioned against EtoAc
(1:1 v:v). Aqueous residues were then collected,
the pH adjusted to 2.65–2.85 followed by a threefold
partitioning against EtoAc (1:1 v:v). The
EtoAc fractions were combined and the EtoAc
evaporated to dryness. The extracts were dissolved
in TBS buffer and stored at 30°C until ABA
analysis.