Molecular requirements for abscisic acid activity in two bioassay systems

McWha, James A.; Philipson, J. J.; Hillman, J. R.; Wilkins, Malcolm B.

doi:10.1007/bf00387101

Cited by 23 publications

(9 citation statements)

References 14 publications

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“…2). These results are consistent with previous reports of acetylenic analogs having high activity with regard to freezing tolerance (5) and other physiological processes (2,4,10,13,20). However, acetylenic analog activity is dependent on the presence of other 'active' functional groups, particularly at C-1 (10,20).…”

Section: Optical Isomerismsupporting

confidence: 92%

“…2), an actual or potential ring double bond at C-2', C-3' is not absolutely required for activity as reported in other assays (10,13,25). In addition, the activity of cyclohexenone-and cyclohexanone-based analogs depends in part on the level of oxidation at C-1 (Fig.…”

Section: Ring Bond Order At C-2' C-3'mentioning

confidence: 87%

“…Therefore, specificity at C-1 for the induction of freezing tolerance differs from that reported for previous assays (25). Specificity is more stringent than for several other ABA bioassays, which may only require a single C-1 oxygen (10,13,20,25), but less stringent than recognition by three ABA antibodies (artificial receptors) raised against C-4' conjugates of (S)-ABA, which require a free carboxyl group (24).…”

Section: Structure-activity Relationshipsmentioning

confidence: 99%

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Structure-Activity Relationships of Abscisic Acid Analogs Based on the Induction of Freezing Tolerance in Bromegrass (Bromus inermis Leyss) Cell Cultures

Churchill¹,

Ewan²,

Reaney³

et al. 1992

Plant Physiol.

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The induction of freezing tolerance in bromegrass (Bromus inermis Leyss) cell culture was used to investigate the activity of abscisic acid (ABA) analogs. Analogs were either part of an array of 32 derived from systematic alterations to four regions of the ABA molecule or related, pure optical isomers. Alterations were made to the functional group at C-1 (acid replaced with methyl ester, aldehyde, or alcohol), the configuration at C-2, C-3 (cis double bond replaced with trans double bond), the bond order at C-4, C-5 (trans double bond replaced with a triple bond), and ring saturation (C-2', C-3' double bond replaced with a single bond so that the C-2' methyl and side chain were cis). All deviations in structure from ABA reduced activity. A cis C-2, C-3 double bond was the only substituent absolutely required for activity. Overall, acids and esters were more active than aldehydes and alcohols, cyclohexenones were more active than cyclohexanones, and dienoic and acetylenic analogs were equally active. The activity associated with any one substituent was, however, markedly influenced by the presence of other substituents. cis, trans analogs were more active than their corresponding acetylenic analogs unless the C-1 was an ester. Cyclohexenones were more active than cyclohexanones regardless of oxidation level at C-1. An acetylenic side chain decreased the activity of cyclohexenones but increased the activity of cyclohexanones relative to their cis, trans counterparts. Trends suggested that for activity the configuration at C-i' has to be the same as in (S)-ABA, in dihydro analogs the C-2'-methyl and the side chain must be cis, small positional changes of the 7'-methyl are tolerable, and the C-1 has to be at the acid oxidation level.The phytohormone ABA is implicated in numerous physiological responses, such as control of stomata aperture, dormancy, abscission, germination, and growth inhibition (27). Many of these processes are used as bioassays in conjunction with ABA analogs to assess the molecular requirements for ABA action (7,11,25 further the molecular requirements for ABA action (1, 6-8, 23, 24) and the practical consequences of finding analogs that could ameliorate abiotic stress (2,4,5,7,17,20). Assessing the molecular requirements of ABA action from analog-bioassay studies is complicated by several assumptions, e.g. that compounds act at the same site of action as ABA, that the rates of migration to the active site are similar, and that metabolism neither activates nor deactivates compounds (11,25). The effect of any given assumption, however, is dependent on the specific bioassay. For example, rapid assays (e.g. stomatal closure) minimize metabolic complications.In this study a bromegrass (Bromus inermis Leyss) cell suspension culture that cold hardens in response to exogenous ABA at nonhardening temperatures (250C) (3, 14-16) was used as a bioassay for structure-activity investigations. This cell culture is also used as a model system to investigate changes in gene expression during acclimatio...

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Section: Optical Isomerismsupporting

confidence: 92%

Section: Ring Bond Order At C-2' C-3'mentioning

confidence: 87%

Section: Structure-activity Relationshipsmentioning

confidence: 99%

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Structure-Activity Relationships of Abscisic Acid Analogs Based on the Induction of Freezing Tolerance in Bromegrass (Bromus inermis Leyss) Cell Cultures

Churchill¹,

Ewan²,

Reaney³

et al. 1992

Plant Physiol.

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show abstract

“…Chromatography of the residual oil on silica gel with hexane-EtOAc (5:1-13:7) afforded 27.4g (86% yield) of 13 as a mixture of diastereomers. A portion of the mixture was chromatographed on silica gel with hexane-EtOAc (15). (14).…”

Section: (± )-2-hydroxymethyl-26-dimethyl-l-cyclohexanone Ethylene Kmentioning

confidence: 99%

“…NaHC0 3 and H 2 0, dried over Na 2 S0 4 , and evaporated. The residual oil was chromatographed on silica gel with hexane-EtOAc (± )-3-(2'-Methoxymethyl-2' ,6'-dimethyl-/'-cyclohexene-/'-y/)-l-methyl-2-propynyl acetate (15). To a stirred solution of 14 (29.3 g) in pyridine (200ml), a mixture of POCI 3 (144g) and pyridine (l80ml) was added dropwise at 5°C during I h, and the mixture was then heated at 105°C for 6 h. The mixture was cooled, poured into ice-cooled H 2 0, and extracted with ether.…”

Section: (± )-2-hydroxymethyl-26-dimethyl-l-cyclohexanone Ethylene Kmentioning

confidence: 99%