Calcium is involved in the abscisic acid-induced ascorbate peroxidase, superoxide dismutase and chilling resistance in Stylosanthes guianensis

Abstract

The objective of this work was to test whether Ca2+, a second messenger in stress response, is involved in ABA-induced antioxidant enzyme activities in Stylosanthes guianensis. Plants were sprayed with abscisic acid (ABA), calcium channel blocker, LaCl3, calcium chelator, ethylene glycol-bis(β-amino ethyl ether)-N,N,N′, N′-tetraacetid acid (EGTA), and ABA in combination with LaCl3 or EGTA. Their effects on superoxide dismutase (SOD) and ascorbate peroxidase (APX) activities and chilling resistance were compared. The results showed that ABA decreased electrolyte leakage and lipid peroxidation but increased maximum photochemical efficiency measured as variable to maximum fluorescence ratio (Fv/Fm) under chilling stress. Treatment with LaCl3 or EGTA alone and in combination with ABA increased electrolyte leakage and lipid peroxidation, decreased Fv/Fm, suggesting that the block in Ca2+ signalling decreased chilling resistance of S. guianensis and the ABA-enhanced chilling resistance. ABA-induced SOD and APX activities were suppressed by LaCl3 or EGTA. The results suggested that Ca2+ is involved in the ABA-enhanced chilling resistance and the ABA-induced SOD and APX activities in S. guianensis.