Chilling tolerance of maize, cucumber and rice seedling leaves and roots
are differentially affected by salicylic acid
Salicylic acid (SA) is one component of a complex signalling
pathway that is induced by a number of biotic and abiotic
stresses. Exposing seedling radicles to aqueous solutions of
0.5 mM salicylic acid for 24 h before chilling at 2.5æC for
1–4 days reduced the chilling-induced increase in electrolyte
leakage from maize and rice leaves, and cucumber hypocotyls,
but not from their radicles. The SA treatments that induced
chilling tolerance in the aerial portion of the seedlings did not
induce chilling tolerance in the radicles, even though the SA
treatments were applied to the radicles. A comparison of activity
among five antioxidant enzymes showed that SA did not
alter enzyme activities in the radicles, but that chilling tolerance
induced by SA in the aerial portions of maize and cucumber
plants was associated with an increase in the activity
of glutathione reductase and guaiacol peroxidase