Regulation of endogenous abscisic acid levels and transpiration in oilseed rape by plant growth retardants

(+)-Abscisic Acid 8′-Hydroxylase Is a Cytochrome P450 Monooxygenase

“…Tetcyclacis is not a specific inhibitor of Cyt P450-type enzymes; rather, any enzyme having an exposed Fe group that could interact with the unpaired electrons of the N on the heterocyclic ring of tetcyclacis may be a target (Rademacher et al, 1987). Therefore, inhibition by tetcyclacis does not confirm that (ϩ)-ABA 8Ј-hydroxylase is a Cyt P450, but is consistent with that classification (Rademacher et al, 1987;Hauser et al, 1990). The sensitivity that we have established for this inhibitor in these assays is several orders of magnitude greater than that reported in some in vivo studies involving ABA hydroxylase (Daeter and Hartung, 1990;Wasternack et al, 1995).…”

Relationship between gibberellins, height, and stress tolerance in barley (Hordeum vulgare L.) seedlings

“…The increase in the levels of ABA is a result of the inhibition of its conversion to the physiologically inactive phaseic acid (Rademacher, 1997). This C s true in most plant systems tested (Hauser et al, 1990; and Mackay et al, l9:9O), however a reduction in ABA is observed in the fungi Cercospora rosicola with paclobutrazol inhibiting the synthesis of ABA at a step after farnesyl diphosphate (Norman et al, 1986).…”

“…PGRs have been used to increase yield by reducing lodging and increasing shoot to root ratios, improving quality, increasing value and decreasing costs of production in agriculture and horticulture (Lever, 1982;and Davis and Curry, 1991). PGRs have also played a crucial role in physiological research involving hormones and hormone action (Grossmann, 1990). There are three main classes of GA inhibitors based on their site of action (reviewed by Rademacher, 2000).…”

A Plant Growth Retardant, Uniconazole, Is a Potent Inhibitor of ABA Catabolism inArabidopsis

“…14,[24][25][26][27][28] In addition, triazoletype growth retardants are effective in protecting plants from various environmental stresses. 11) These results are fully consistent with our observations, suggesting that the CYP707A family ubiquitously regulates endogenous ABA levels in higher plants.…”

“…Radiotracer experiments demonstrate that the conversion of ABA to PA is impaired in tetcyclacistreated plants. [12][13][14] Moreover, tetcyclacis has been shown to inhibit the ABA 8 0 -hydroxylase activity of the microsomal fraction from maize suspension cells 15) or from yeast heterologously expressing Arabidopsis CYP707A1. 5) Recent cloning of CYP707A has enabled us to examine the biochemical nature of these P450 inhibitors blocking ABA 8 0 -hydroxylase activity.…”