|Authors: ||L. Kowitcharoen, V. Srilaong, S. Kondo|
|Keywords: ||abscinazole, ascorbic acid, chlorophyll, O2- radical scavenging activity, stomatal aperture|
The effects of the inhibition of abscisic acid (ABA) 8'-hydroxylase in sugar apple (Annona squamosa L. 'Fai') seedlings were examined.
Changes in endogenous ABA and stomatal aperture in sugar apple seedlings under dehydration and rehydration conditions were investigated.
The plants were divided into three groups which were well-watered, dehydrated, and a combination of dehydration + 50 ppm Abz-F1 (ABA 8' hydroxylase inhibitor) application by spraying (DAbz-F1). Leaves of the seedlings were sampled at 1, 3, 7, 12, 18, 26 and 28 days after treatment (DAT). The stomatal aperture was significantly lower in Abz-F1-treated seedlings than that in the other treatments.
The stomatal conductance in both dehydrated and DAbz-F1-treated seedlings was lower than that in well-watered one.
In addition, ABA concentrations in the leaves of DAbz-F1-treated seedlings significantly increased at 7 DAT. The EC50 values in DAbz-F1-treated seedlings were higher than those in dehydrated seedlings.
Total ascorbic acid concentrations in DAbz-F1-treated seedlings reached the peak at 26 DAT, and the concentrations were lower than those in dehydrated seedlings.
Total chlorophyll concentration in DAbz-F1-treated seedlings were higher than those in dehydrated seedlings.
The results suggest that the Abz-F1 application induces the increase of endogenous ABA concentration, resulting in the drought tolerance in sugar apple seedlings.
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