Joe B. Zaerr

Analysis of picogram quantities of indole-3-acetic acid by high performance liquid chromatography-fluorescence procedures

The use of spectrofluorimeter coupled to a reverse phase high performance liquid chromatography column permits selective detection of indole-3-acetic acid at the low picogram level. The value of the technique is demonstrated by the analysis of endogenous IAA in elongating shoots, xylem sap and callus of Douglas-fir. The data are also used to illustrate a procedure whereby the accuracy of chromatographic analyses can be verified within definable probability limits.

Spring shoot growth in douglas-fir may be initiated by gibberellins exported from the roots.

Trials conducted under controlled environments demonstrated that the delay of bud activity of Douglas-fir (Pseudotsuga menziesii) seedlings occasioned by low temperature of the soil could be eliminated by application of gibberellic acid. Analyses of field-grown plants showed a parallel increase in bud activity, level of gibberellin-like compounds in xylem sap, and soil temperature during February and March.

A liquid cytokinin pulse induces adventitious shoot formation from Douglas-fir cotyledons

SummaryThe effects of high-concentration, 2-h liquid pulses of N6-benzylaminopurine (BA) and thidiazuron (TD) on adventitious bud and shoot formation were tested in cotyledons of Douglas-fir (Pseudotsuga menziesii). Seedling age proved important; on average, cotyledons from the youngest seedlings formed 10-fold more buds than cotyledons from the oldest seedlings. Optimal cytokinin concentrations for the youngest cotyledons were 400 and 800 μM BA, and 100 and 200 μM TD. Shoots developed best from buds induced with 300, 400, and 800 μM BA. Four gelling agents were tested; BRL agarose yielded more than three times the number of buds, and Gelrite nearly twice the number of buds, as either Sigma agar or Difco Bacto-Agar. One of the best treatments (400 μM BA, agarose) yielded more cotyledons with buds, and more buds per cotyledon, than when cytokinins were incorporated into the growth medium.

Trace enrichment of cytokinins from Douglas-fir xylem extrudate

SummaryQuantitative trace-enrichment of cytokinins from a plant source (xylem sap from the Douglasfir, Pseudotsuga menziesii (Mirb.) Franco) has been achieved by adsorption onto octadecyl-silica columns followed by elution with ethanol. Adsorption is rapid and efficient and allows complete recovery of cytokinins at the nanomolar level. Douglas-fir sap contains at least four compounds having cytokinin activity, one of which co-elutes with zeatin and another with ribosylzeatin.

Transient gene expression of microprojectile-introduced DNA in Douglas-fir cotyledons

SummaryPlasmid DNA containing the reporter gene uidA encoding β-glucuronidase (GUS), driven by the cauliflower mosaic virus 35S promoter, was introduced on high-velocity microprojectiles into cultured cotyledons of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco]. Transient gene expression was measured by counting the number of distinct loci of GUS activity per cotyledon. Contrary to published results on angiosperms, repeated bombardments did not increase expression in Douglas-fir. Expression varied significantly among cotyledons from different seedlings. The amount of time between DNA delivery and treatment of cotyledons with auxins and cytokinins strongly affected GUS expression. The optimal cytokinin pretreatment produced an average of 20 loci per cotyledon. In several experiments, more than 95% of the treated cotyledons exhibited at least some transient expression. Expression remained constant up to three days following DNA delivery into cotyledons.

Reversed- and normal-phase high-performance liquid chromatography of gibberellin methoxycoumaryl esters

Abstract The methoxycoumaryl esters of thirteen gibberellins were synthesized by crown ether catalysis. These derivatives are highly fluorescent (λ ex max 320 nm, λ em max 400 nm) and can be detected at the low picogram level with a spectrophotofluorimeter after reversed-phase high-performance liquid chromatography. The various gibberellin esters were readily resolved by high-performance liquid chromatography on both ODS-Hypersil and CPS-Hypersil supports. There were marked differences in the behaviour of mono, bis and tris esters. Chemical ionization negative-ion mass spectra of the gibberellin methoxycoumaryl esters were obtained by direct-probe mass spectrometry.

High-performance steric exclusion chromatography of plant hormones☆

Abstract Details are presented of high-performance steric exclusion chromatography of plant hormones on a μSpherogel support with a molecular exclusion limit of

4-Bromophenacyl Esters of Gibberellins, Useful Derivatives for High Performance Liquid Chromatography

Abstract The 4-bromophenacyl esters of six gibberellins were prepared by crown-ether catalyzed reaction between the potassium salts of the gibberellins and 4-bromophenacyl bromide under mild non-aqueous conditions. The derivatives were stable, possessed high UV absorbance and were well separated by HPLC on μC18 or cyanopropyl silica. The esters (and the corresponding TMS ethers) gave well-defined mass spectra with easily identifiable molecular ions. The combination of chromatographic and mass spectroscopic properties suggests that the derivatives may be very useful for analysis of naturally-occurring gibberellins.

The effect of flurprimidol on bud flush, shoot growth, and on endogenous gibberellins and abscisic acid of Douglas-fir seedlings

For 4-month-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] seedlings under 17-h photoperiods in controlled environment conditions, flurprimidol (α-(1-methlyethyl-α-[4-(trifluoromethoxy)phenyl]-5-pyrimidine-methanol) decreased incidence of second flushing from 81 to 54% and significantly reduced height growth in the second year following low-temperature treatment, in comparison to untreated controls. For seedlings under 15-h photoperiods, flurprimidol had only limited early effects, but after a period of bud dormancy, shoot growth was reduced to one-third that of the untreated controls. Under both photoperiods flurprimidol significantly depressed abscisic acid levels and gibberellin-like bioactivity. These results suggest that growth reduction in this conifer by flurprimidol may well involve inhibition of gibberellin biosynthesis.

Douglas-Fir [Pseudotsuga menziesii (Mirb.) Franco]

The genus Pseudotsuga (Pinaceae) consists of eight species (El-Kassaby et al. 1983). Six species occur naturally in eastern Asia in non-overlapping ranges. Pseudotsuga japonica (Shiras.) Beissn. occurs in Japan and P. wilsoniana Hayata in Taiwan. Pseudotsuga forrestii Craib., P. sinensis Dode, P. gaussenii Flous and P. brevifolia Chang et L. K. Fu. are located in China. There are two North American species: P. macrocarpa (Torr.) Mayr, with a limited range in Southern California, and P. menziesii (Mirb.) Franco (Douglas-fir), which occurs throughout western North America (Fowells 1965). The latter has two varieties: the coastal P. menziesii var. menziesii and the interior P. menziesii var. glauca.