Ian D. Railton

Effects of Benzyladenine on the Growth of Waterlogged Tomato Plants

SummaryTreatment of waterlogged tomato plants with benzyladenine relieved most of the symptoms of flooding injury. The effects of benzyladenine included maintenance of chlorophyll levels, reduced epinastic curvature of petioles, absence of adventitious roots, and stem growth greater than that of waterlogged control plants.

Interconversion of gibberellin A20 to gibberellin A29 by etiolated seedlings and germinating seeds of dwarf Pisum sativum

Abstract Tritium labelled gibberellin A 20 ([ 3 H]-GA 20 ) applied to etiolated shoots and germinating seeds of dwarf pea ( Pisum sativum L. cv. Meteor) was converted to gibberellin A 29 . Identifications were made by GLRC and GC-MS.

Red-light-enhanced conversion of tritiated gibberellin A9 into other gibberellin-like substances in homogenates of etiolated barley leaves

SummaryIrradiation of homogenates of etiolated barley leaves with red light resulted in an increase in the levels of gibberellin (GA)-like substances as compared to dark controls. When homogenates were fed with [3H]-GA9 there was as incorporation of the radioactivity into a number of other GAs: this process occurred to a greater extent in red light than in darkness, and could be inhibited by boiling the extract prior to addition of the [3H]-GA9.

Interconversion of gibberellin A5 to gibberellin 3 in seedlings of dwarf Pisum sativum

Abstract [3H]-Gibberellin A5 ([3H]-GA5) applied to seedlings of dark-grown dwarf pea (Pisum sativum L. cv. Meteor), was converted to two acidic compounds, GA3 and a chromatographically similar unknown. Identification of GA3 was made by gas-liquid radiochromatography using three stationary phases.

Studies on gibberellins in shoots of light grown peas I. A re-evaluation of the data

Abstract Light-grown shoots of ‘Alaska’ pea seedlings were found to contain at least 6 gibberellin-like substances. Chloroplasts isolated from young, fully expanded leaves exhibited a similar spectrum of gibberellin-like activity to the shoots but the absence of a very polar gibberellin, normally present in total leaf extracts, was apparent. Centrifugation studies indicated the association of a gibberellin A 5 20 like (GA 5 20 ) substance with chloroplasts and its absence in the cytoplasm. Tritium-labelled GA5 ([3H]GA5) and GA1 ([3H]GA1) applied to light-grown pea shoots were both found to diffuse into agar gel. Preliminary evidence suggests that pea chloroplasts exert a compartmentalization effect on gibberellins in the pea shoot.

Conversion of gibberellin A14 to other gibberellins in seedlings of dwarf Pisum sativum

Abstract Gibberellin A 14 -[17- 3 H] applied to seedlings of dark grown dwarf pea ( Pisum sativum L. cy. Meteor) was converted to GA 1 , GA 8 , GA 18 , GA 23 , GA 28 , and GA 38 . The sequence of interconversion of GA 14 → GA 18 → GA 38 → GA 23 → GA 1 → GA 8 is indicated. Identifications were made by gas-liquid radiochromatography using three liquid stationary phases.

The influence of benzyladenine on the growth and gibberellin content of shoots of waterlogged tomato plants

Abstract Flooding the roots of tomato plants is known to cause decreased stem growth and lowered gibberellin (GA) levels in the shoots. Benzyladenine (BA) applied as a foliar spray partially overcame the dwarfing effect of flooding and completely restored overall GA levels in the shoots as compared to that found in non-flooded plants. It is suggested that an exogenous supply of cytokinins possibly exerts some control over GA metabolism in the shoots and thus indirectly influences stem growth.

Studies on gibberellins in shoots of light grown peas III. Interconversion of [3H]Ga9 and [3H]GA20 to other gibberellins by an in vitro system derived from chloroplasts of Pisum sativum

Abstract Isolated pea chloroplasts interconverted [3H]GA9 into two zones of radio-activity, both of which exhibited gibberellin (GA)-like activity in the Tanginbozu dwarf rice assay. [3H]GA20 was converted by isolated pea chloroplasts into a single acidic metabolite, chromatographically identical to GA29. It is suggested that pea chloroplasts are a major site of gibberellin interconversion in the pea shoot.

Gibberellins and geotropism in Zea mays coleoptiles.

SummaryDiffusible gibberellins were obtainable in agar from excised 4 mm tips of etiolated coleoptiles of Zea mays. Placing the tips in a horizontal position increased the total yield of gibberellins by approximately five times. With horizontal tips, the ratio of gibberellin activity recovered from lower and upper halves, expressed as a percentage of total yield, was 80.76:19.24 (lower:upper).

Activity of the aldehyde and alcohol of gibberellins A12 and A14, two derivatives of gibberellin A15 and four decomposition products of gibberellin A3 in 13 plant bioassays

SummaryThe biological activities of the aldehyde and alcohol of gibberellins (GAs) A12 and A14, 3α-OH-GA15, 3β-OH-GA15 wrong lactone (i.e. GA37 wrong lactone) and the four major decomposition products of GA3 (isogibberellic, allogibberic, epiallogibberic and Δ9(11)-dehydroallogibberic acids) were tested over a wide range of concentrations on 13 plant bioassays in order to ascertain certain of the structural requirements for biological activity. Generally modification of the basic GA-molecule decreased its activity in all assays except for derivatives of GA12 and GA14 (suggesting conversion of these derivatives to more polar, active GAs). Modification of the 3-OH from the usual 3β to 3α configuration markedly reduced activity. Neither the presence of an inverted lactone ring (i.e. 3β-OH-GA15 wrong lactone) nor changes to the lactone ring of GA3 (4→10) to form iso-GA3 (4→2) appreciably reduce activity. Further decomposition of GA3 to allogibberic and Δ9(11)-dehydroallogibberic acid reduced activity only slightly, but epimerization of allogibberic acid at C-9 essentially eliminated biological activity.