Effect of Paclobutrazol on Water Stress-Induced Abscisic Acid in Apple Seedling Leaves

Abstract

Abscisic acid (ABA) was quantitated by enzyme-linked immunosorbent assay (ELISA) in water-stressed leaves from control apple seedlings, and also from apple seedlings treated for 28 days with paclobutrazol (12RS, 3RSI-144-chlorophenyll-4,4-dimethyl-2-11,2,4-triazol-1-ylI pentan-3-ol).The ELISA quantitative estimates were also validated by gas chromatography-electron capture detector and lettuce seed germination inhibition bioassay. Paclobutrazol treatment reduced endogenous ABA levels by about one-third, and prevented the marked accumulation of water-stressinduced ABA that occurred in untreated seedlings. The presence of ABA in the apple leaf extracts was confirmed by gas chromatography-mass spectrometry.The accumulation ofABA in the leaves ofwater-stressed plants has been shown by numerous investigators (12,18,22,23). Our previous reports showed that the accumulation of water stressinduced 1 -aminocyclopropane-1 -carboxylic acid, 1 -(malonylamino)cyclopropane-l-carboxylic acid, ethylene production, and polyamines also occurred in water-stressed apple leaves, but these increases were prevented by the treatment with the plant bioregulant ([2RS,

Effect of paclobutrazol on abscisic acid levels in wheat seedlings

“…Recently, however, the levels of cis-abscisic acid (ABA), another plant hormone, were found to be affected by triazole applications to plants. Results have been reported that include increases in ABA levels (Lurssen 1987), a transient rise in ABA levels (Asare-Boamah et al 1986), no change (Izumi et al 1988), and decreases in ABA levels (Grossman et al 1987, Wang et al 1987. The measurements of ABA levels were reported on different species of plants and at different plant growth stages after treatment.…”

Chloroplastic Regulation of Apoplastic α-Amylase Activity in Pea Seedlings

“…San 9785 appears to exert its actions on photosynthesis by affecting the amount and Other than carotenoid synthesis, NF has been found to inhibit ABA synthesis (38). PP333, an inhibitor of both ABA (42) and GA synthesis (7), was found to increase the level of activity of a-amylase in pea seedlings 4.6-fold (Table VII). GA is known to be required for the induction of a-amylases in certain tissues of some plant species (6).…”

Effects of synthetic plant growth retardants and abscisic acid on root functions of Brassica rapa plants exposed to low root‐zone temperature

“…The possible interactions of synthetic PGRs (MEF and PBZ) in the short-term acclimation of B. rapa plants to a cold root-zone temperature was considered because of their known roles as cold protectors and their possible interaction with ABA metabolism (Asare- Boamah et al, 1986 ;Wang et al, 1987 ;Fletcher & Hofstra, 1988 ;Pardossi et al, 1992). This work was performed by pretreating plants with these PGRs (with or without an ABA pretreatment\treatment) before the acclimation to root cooling proper.…”

“…This result is not easy to interprete because the pathways of these antagonistic effects on processes involved during changes (in hydraulic conductivity and\or reflection coefficient) remained unknown. PBZ might interact with the synthesis of endogenous ABA , as shown in the leaves of apple seedlings where PBZ prevented the marked accumulation of water-stress-induced ABA that occurred in untreated control seedlings (Wang et al, 1987). Unfortunately, PBZ (like other triazole compounds) has also been reported to block GA biosynthesis by inhibiting kaurene oxidase (Fletcher & Hofstra, 1988 ;Rademacher, 1991 ;Gilley & Fletcher, 1997).…”