Vol. 84 No: 3

Title:
Abscisic acid levels and anti-oxidant activity are affected by an inhibitor of cytochrome P450 in apple seedlings

Authors:
SUTTHIWAL SETHA and SATORU KONDO

pp: 340-344

Abstract:
The effects of an inhibitor of cytochrome P450 (uniconazole) on the levels of abscisic acid (ABA) and on anti-oxidant activity were investigated in apple seedlings. In uniconazole-treated seedlings, ABA reached its highest concentrations 24 h after the beginning of a dehydration treatment, and remained at high concentrations compared to levels in well watered, uniconazole-untreated seedlings. Uniconazole decreased stomatal aperture up to 9 h after its application, and stomatal aperture remained constant for 72 h. Although the EC₅₀ values of the 1,1-diphenyl-2-picrylhydrazyl hydrate (DPPH) and superoxide (OM₂ ^∙−) radical-scavenging activities were decreased by dehydration treatment, those in uniconazole-treated seedlings were higher than those in untreated seedlings. Superoxide dismutase (SOD) activity in uniconazole-untreated seedlings increased at the start of the dehydration treatment, but SOD activity in uniconazole treated and well-watered seedlings did not increase. These facts suggest that application of the cytochrome P450 inhibitor induced stomatal closure earlier by increasing ABA concentrations, increased anti-oxidant activities, and may induce tolerance against water-stress damage.

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