Odor detection curves for n-pentanoic acid in dogs and humans*

The ability of dogs and humans to detect vapor concentrationsof n-pentanoic (valeric) acid was measured under directly comparabletesting conditions. The minimum concentrations detected by dogswere 3.3 x 10⁶ molecules/cm³ by two German shepherds, and 8.8x 10⁸ molecules/cm³ by a Fox terrier. The average minimum detectedby humans was 5 x 10¹⁰ molecules/cm³. Detection curves for thetwo best performing human subjects showed double reversals inslope (a "notch") at approximately one-half log₁₀ unit of concentrationabove the minimum detectable level. Two distinct notches, separatedby about 2 log₁₀ units of concentration, occurred in the curvesfor the dogs; the lower notch, present in the curves of thetwo best performers, fell approximately 2 log₁₀ units abovethe lowest minimum concentration detected. Performance differencesproducing these latter notches were statistically significantand, according to one interpretation, could reflect the availabilityof less primary stimulus information at the two concentrationswhere they occur, a possible result of three slightly differentranges of receptor sensitivity.     

Some Experimental and Theoretical Observations Concerning Mass Flow in the Vascular Bundles of Heracleum

The theory and practice of applying the thermodynamics of irreversibleprocesses to mass-flow theories is presented. Onsager coefficientswere measured on cut and uncut phloem and cut xylem strandsof Heracleum muntegazzimum. In 0.3 N sucrose + 1 mN KC1 theyare as follows. In phloem, L_EE = 5 ? 10–⁴ mho cm^–1,L_pE = 9 ? 10^–6 cm³ s^–1 cm^–2 volt^–1 cm,and L_PP = 0.16 cm³ s^–1 cm^–2 (J cm^–3)^–1cm. In uncut phloem strands L_EE is about 1 ? 10^–3 mhocm^–1. In xylem in 2 x 10^–3 N KCI, L_pp = 50 to 225,L_PE = 2 ? 10^–4, and L^EE = 4 ? 10^–3. The measurementsare tentative since the blockage of the sieve plates is an interferingfactor, but if they are valid they lead to the conclusion thatneither a pressure-flow nor an electro-kinetic mechanism envisaginga ‘long distance’ current pathway can be the majormotive ‘force’ for transport in mature phloem. Measurementsof biopotentials along conducting but laterally detached phloembundles of Heracleum suggest, nevertheless, that there may bea small electro-osmotic component of at least 0.1 mV cm^–1endogenous in the phloem.     

Studies on the stimulation of abscission by malformin on cuttings of Phaseolus aureus Roxb

White light irradiance required for complete and slight inhibitionof malformin-induced abscission by cuttings of Phaseolus aureuswas 13.5?10³ and 0.1?10³ ergs/cm^2. sec, respectively. Longerphotoperiods and higher irradiances were required to inhibitabscission by malformin-treated cuttings than by controls. Malforminstimulated dark abscission more rapidly, and at lower concentrations,than Ethrel or abscisic acid. The ability of light to inhibitmalformin-induced abscission diminished rapidly after 36 hrin the dark. Malformin accelerated chlorophyll and fresh anddry weight loss of leaves in the dark. The loss in fresh anddry weight, and perhaps chlorophyll, were inhibited by light.Hydroxyproline had little effect, but sucrose, hadacidin, kinetinand indoleacetic acid delayed malformin-induced abscission.Although puromycin, an inhibitor of protein synthesis, stimulatedabscission on controls, it inhibited malformin-induced abscission. (Received July 18, 1977; )     

Different Intracellular Localization of Two Cytochrome P-450 Systems, Ipomeamarone 15-Hydroxylase and Cinnamic Acid 4-Hydroxylase, in Sweet Potato Root Tissue Infected with Ceratocystis fimbriata

Ipomeamarone 15-hydroxylase activity was mainly recovered inthe pellet fraction between centrifugations at 10,000 and 100,000?gfrom a crude extract of Ceratocystis fimbriata-infected sweetpotato root tissue, whereas cinnamic acid 4-hydroxylase activitywas found between centrifugations at 300 and 10,000?g. Whenparticles in the crude extract were fractionated by sucrosedensity gradient centrifugation, the rough-surfaced microsomeswere distributed over a wide density range from 1.09 to 1.14g cm^–3, judging from the distributions of protein, RNAand NADPH-cytochrome c reductase activity. Phosphorylcholine-glyceridetransferase activity was only in the lighter half of the microsomalfraction (density: 1.09–1.11 g cm^–3). Ipomeamarone15-hydroxylase activity was found in heavier half of the microsomalfraction (density: 1.10–1.14 g cm^–3). We proposethat this tissue has two rough-surfaced endoplasmic reticulumspecies, only one of which carries phosphorylcholine-glyceridetransferase, and that the cytochrome P-450 system is localizedon the species lacking the enzyme. Cinnamic acid 4-hydroxylaseactivity was mainly found in a fraction that had densities of1.17–1.19 g cm^–3 and contained vesicular particlesof various sizes. ¹ Present address: Laboratory of Food Hygienics, Faculty ofAgriculture, Kagawa University, Miki-cho, Kida-gun, Kagawa 761-07,Japan. (Received September 6, 1984; Accepted December 27, 1984)     

Brachiopod Metabolism and Enzymes

Brachiopods consume oxygen at relatively low rates, and sometimesconsume none at all for hours. Specimens of Terebratulina septentrionalissurvived total anoxia for 3.5 days at 3°C. Isolated tissuesconverted ¹⁴Cµglucose into eight carboxylic acids at anaverage rate of 1.5 x 10^–10 mole/SOL;hr per g tissue.Carbon from labelled glucose flowed steadily into citric acidand into an unknown acid for 2 hours under both aerobic andanaerobic conditions. In the first hour, more label was foundin malic acid after aerobic incubation, and more label in succinicacid after anaerobic incubation, while the fraction in lacticacid was the same. Terebratulina carried on a mixed fermentationboth in the presence and in the absence of oxygen. The inarticulate Glottidia pyramidata has a succinate dehydrogenasewith kinetic properties favoring succinate oxidation, whilethe Terebratulina enzyme is more likely to operate in the reversedirection. Lactate metabolism is relatively unimportant in bothspecies. Information on nitrogen-compound metabolism is limited to theinarticulate Lingula reevii, which is ammonotelic. Arginaseand urease activities exceeded those of bivalve mollusks, whileaspartate and alanine aminotransferase rates were both muchlower. Some unique features of DNA, RNA and hemerythrin fromLingula have been discovered in the last few years.     

Morphological and physiological characterization of IAA-less-sensitive and IAA-sensitive phases in rooting of Azukia cuttings

In disbudded epicotyl cuttings taken from light grown 5-dayold Azukia angularis Phaseolus angularis) seedlings, all adventitiousrootlets appeared on the second day of incubation. No root primordiawere observed within the first 24 hr and no increase in thenumber of roots occurred after 48 hr. Puromycin (5.5?10^–5M), p-fluorophenylalanine (1?10^–3M),2-thiouracil (2.3?10^–4M) and 2,6-diaminopurine (2?10^–5M)inhibited rooting when applied to cuttings on the second day,but showed no inhibition when applied on the first day. Unlike these inhibitors, pyrithiamine (7.2?10^–5M) inhibitedrooting when it was applied to cuttings on the first day. A rooting promoting effect was observed with actinomycin D (2.4?10^–6M),2,4-dinitrophenol (3?10^–5M) and p-fluorophenylalanine(1?10^–4M) applied to the cuttings on the first day, whereasindoleacetic acid (1.7?10^–4M) showed its promoting effectmost effectively on the second day. ¹Contribution No. 17 from the Botanical Gardens, Faculty ofScience, University of Tokyo, Tokyo, Japan. (Received June 4, 1969; )     

Water relations and abscisic acid levels of watermelon as affected by rooting volume restriction

Rooting volume restriction (RVR) reduces shoot growth of plantsprovided with sufficient water or nutrients. The effects ofRVR on water status, abscisic acid (ABA) levels in leaves, roots,or xylem sap from detopped plants of watermelon [Citrullus lanatus(Thunb.) Matsum. and Nakai ‘StarBrite’] seedlingswere evaluated with five rooting volumes (18, 26, 36, 46, or80 cm3). Shoot water potential increased with increasing rootingvolume, with no difference between plants from 18 and 26 cm³cells or between plants from 36 and 46 cm³ cells. Stomatal conductancewas not consistently affected by RVR; at 10 and 20 DAE, stomatalconductance in plants grown in 36 cm³ cells was higher thanthat of plants grown in any other cell volume. Severe RVR (18and/or 26 cm³) tended to produce plants with higher ABA levelsin roots (15 DAE only), xylem sap (all dates), and leaves (5and 10 DAE). Plants grown in 18 and 26 cm³ cells had higherroot ABA levels than those from 46 and 80 cm³ cells at 15 DAE.Plants grown in 18 cm³ cells had the highest xylem sap ABA levelat all dates, but ABA levels did not differ among plants grownin the other cell volumes. Plants grown in 18 cm³ cells at 5DAE and 18 and 26 cm³ cells at 10 DAE also had higher leaf ABAlevels than those from other rooting volumes. The results suggestthat ABA may act as a signal for reduced growth of plants underRVR conditions. Key words: Abscisic acid, ABA, root signals, root volume restriction, water relations     

Taurine Transport in N-deprived Chlorella fusca

The development of taurine uptake into the unicellular greenalga Chlorella fusca 211-8b was characterized as a specificresponse to either nitrate or sulphate limitation. Taurine transportunder nitrogen starvation was stimulated by low pH and showeda biphasic kinetics with K_m-values of 1.1 x 10^–3 mol dm^–3and 1.0 x 10^–2 mol dm^–3. Uptake was substantiallyinhibited by all - and ß-amino acids tested, whereassulphonate analogues failed to diminish taurine accumulation.Thus, uptake seemed to be mediated by a ‘general aminoacid permease’, unable to discriminate between carboxyland sulphonyl groups. However, Chlorella fusca could not catabolizethis unusual ß-amino acid and mobilize the amino-boundnitrogen for growth. Only a small group of -amino acids supportedthe growth of Chlorella fusca as an efficient nitrogen source. Key words: Taurine uptake, nitrogen starvation, amino acid uptake, Chlorella fusca.     

Characterization of membrane-bound Mg++-activated ATPase isolated from the lower epidermis of tobacco leaves

Membrane-bound Mg⁺⁺-activated ATPase was separated from thelower epidermis of tobacco leaves (Nicotiand tabacum L. SamsunNN) on stepwise sucrose density gradient centrifugation. Membrane-bound epidermal ATPase was localized in the interfaceof densities in sucrose of 1.12 to 1.16 in the sedimentary fractionbetween 1,500?g to 10,000?g from the homogenate of the lowerepidermis. The epidermal ATPase activity was activated by divalentcations (Mg⁺⁺>Mn⁺⁺Co⁺⁺>Fe⁺⁺>Zn⁺⁺>Ca⁺⁺) and furtherstimulated by KCl by ca. 20%. The pH optimum for Mg⁺⁺-activationof the epidermal ATPase was ca. 6.0. The enzyme hydrolyzed ATPmore rapidly than other nucleoside triphosphates. The optimumtemperature for activation of the epidermal ATPase activitywas ca. 40?C. 50% of the epidermal ATPase activity was lostin 18 min at 55?C and in 2.5 days at 2.5?C. The apparent Kmvalue of the epidermal ATPase was 4.7?10^–4 M and Vmaxwas 65.4 nmoles Pi/mg protein/min. The epidermal ATPase wasstrongly inhibited by N, N'-dicyclohexylcarbodiimide (DCCD)in vitro whereas oligomycin, carbonyl cyanide m-chlorophenylhydrazone(CCGP), indoleacetic acid (IAA) and abscisic acid (ABA) wereinsensitive to the epidermal ATPase activity. (Received May 23, 1978; )     

Purification and some properties of L-tyrosine carboxy-lyase from barley roots

L-Tyrosine carboxy-lyase (E. C. 4. 1. 1. 25) was extracted fromthe roots of barley seedlings and purified approximately 25fold. Optimum pH for the enzyme activity was found to be 7.3.The Km value for L-tyrosine was calulated as 4.5?10^–4M.D-Isomer did not react with the enzyme. L-DOPA, m-tyrosine ando-tyrosine were decarboxylated to some extent. Pyridoxal phosphateactivated the enzyme 4 fold. Caffeic acid and p-coumaric acidare competitive inhibitors. Ki values were 4.5?10^–5M forcaffeic acid and 1.6?10^–4M for p-coumaric acid. L-DOPAand m-tyrosine had an inhibitory effect on the decarboxylationof L-tyrosine. Hydroxylamine, semicarbazide, p-CMB, Fe⁺⁺, Cu⁺⁺,and Hg⁺⁺ inhibited the decarboxylation of tyrosine. Enzyme activitywas also found in extracts from Triticum aestivum, Zea maysand Cytisus scoparius. (Received November 30, 1973; )     

Carrier-Mediated ABA Uptake by Suspension-Cultured Phaseolus coccineus L. Cells: Stereospecificity and Inhibition by Ionones and ABA Esters

Astle, M. and Rubery, P. 1987. Carrier-mediated ABA uptake bysuspension-cultured Phaseolus coccineus L. cells: Stereospecificityand inhibition by ionones and ABA esters.—J. exp. Bot.38: 150–163. The substrate for the abscisic acid (ABA) carrier in Phaseoluscoccineus L. suspension-cultured cells is shown to be the (S)ABAenantiomer, K_m = 1?0 mmol m^–3. The methyl (MeABA) andphenyl (PheABA) esters of ABA inhibit carrier-mediated uptakeof ABA with half-maximal inhibition achieved at about 7?0 mmolm^–3 and 10 mmol m^–3 respectively: with (S)MeABAthis value is decreased to about 2?0 mmol m^–3. There isno demethylation of radioactive MeABA by the cells during 5min incubations. Although MeABA reversibly inhibits the ABAcarrier, it is not a transport substrate: association of radioactiveMeABA with living cells is unaffected by non-radioactive MeABAor ABA and, by comparison with frozen-and-thawed cells, it isshown that the radioactivity remains extracellular. It is proposedthat MeABA binds to the carrier to form an abortive complexthat is not translocated. The terpenoid ABA analogue LAB 144143also inhibits carrier-mediated ABA uptake. At concentrationsup to about 20 mmol m^–3 - and ß-ionone specificallyinhibit the ABA carrier with the half-maximal effect at about0?6 mmol m^–3 ß-ionone. However, at higher iononeconcentrations, the uptake of ABA, indol-3-yl acetic acid andof 5,5-dimethyloxazolidine-2,4-dione (DMO) are all stimulated:this may reflect general permeabilization of the membrane toweak acids by ionone. Key words: Uptake carrier, abscisic acid, methyl and phenyl esters of ABA, ionone, Phaseolus coccineus L. suspension culture     

Separation of marine seston and density determination of marine diatoms by density gradient centrifugation

An attempt has been made to separate constituents of marineseston samples: inorganic material, detritus and the algal species,by density gradient centrifugation, without affecting the physiologicalstate of the algae. A relatively inert gradient material, consistingof Percoll, salt and sucrose, was composed. Since the densitiesof detritus and algae as well as those of different algal speciesoften overlapped, only 10 of the 100 samples processed in thecourse of the year showed a reasonable separation. However,an enrichment with respect to one or more species was oftenachieved. Densities of eleven species of marine diatoms andof one dinoflagellate have been determined at different timesof the year. For eight diatom species and for the dinoflagellatethe following specific density ranges were established: Bidduiphiaaurita: 1.18–1.23 g cm^–3, Biddulphia sinensis: 1.03–1.08g cm^–3, Cerataulina bergonii: 1.03–1.06 g cm^–3,Ditylum brightwellii: 1.07–1.13 g cm^–3, Rhizosoleniadelicatula: 1.04–1.09 g cm^–3, Skeletonema costatum:1.12–1.17 g cm^–3, Streptotheca thamensis: 1.04–1.10g cm^–3 , Thalassiosira rotula: 1.05–1.10 g cm^–3,Peridinium sp.: 1.08–1.12 g cm^–3. No seasonal variationin density was demonstrated. Gradients of different compositiondid not influence density measurements.     

Involvement of cellulose synthesis in actions of gibberellin and kinetin on cell expansion. Gibberellin-coumarin and kinetin-coumarin interactions on stem elongation

In azuki bean (Azukia angularis = Vignia angularis) epicotylsections, 5 ? 10^–4 M coumarin inhibited the incorporationof radioactivity from [U^–14C]glucose into the cellulosefraction by 35% in the absence of indole-3-acetic acid (IAA)and by 40% in the presence of 1 ? 10^–4 M IAA. There wasno inhibitory effect on the incorporation of radioactivity intothe other fractions. Coumarin at 5 ? 10^–4 M reversed thepromoting effect of 1 ? 10^–5 M gibberellin A₃ (GA) andthe inhibitory effect of 1 ? 10^–5 M kinetin on IAA-inducedelongation of sections with no significant effects on IAA-inducedelongation. Neither GA nor kinetin had any appreciable effectson cellulose synthesis. No inhibition of cellulose syntheiswas observed with 1 ? 10^–3 M colchichine, which has beenreported to have effects similar to those of coumarin on GA-or kinetin-affected stem elongation. Coumarin at 5 ? 10^–4M was ineffectual in breaking up wall microtubules, while adisrupting effect on wall microtubules was clearly demonstratedwith 3 ? 10^–4M colchicine. From these results, the possible involvement of cellulose synthesisin cell expansion controlled by GA or kinetin was suggested. (Received August 3, 1973; )     

Analysis of abscission responses to photodecomposition products of 1-naphthaleneacetic acid

This paper presents an analysis of abscission reponses of cottonexplants to (a) 1-naphthaneneacetic acid; (b) photodecompositionproducts of 1-naphthaleneacetic acid: 1-methylnaphthalene, 1-naphthaldehyde,1-naphthoic acid, naphthalene, and phthalic acid; and (c) arelated compound: naphthaleneacetyl aspartate. Abscission wasaccelerated by low amounts and retarded by high amounts of 1-naphthaleneaceticacid and 1-naphthoic acid. No significant effect on abscissionwas observed from 1- methylnaphthalene, 1-naphthaldehyde, orphthalic acid applied in amounts from 10^–8 to 10.0 µgper petiole; or with naphthalene from 10^–3 to 10.0µgper petiole. Naphthaleneacetyl aspartate had no effect at 5?10⁴to 5?10^–3 µg per petiole, but completely inhibitedabscission at 5 ? 10^–1 and 5.0 µg per petiole. Thedata are analyzed on part by a previously described mechanicalmethod for the determination of abscission indexes, and in partby a new method described herein, using a digital computer forthe analysis of the abscission time-course data. The resultshave significance to the understanding of the variability encounteredin fruit thinning by 1-naphthaleneacetic acid and related substances,and are discussed in relation to the known intermediate effectsof 1-naphthaleneacetic acid in fruit thinning. ¹Present address: Department of Biology, Univesity of California,Riverside, California 92502, U.S.A. (Received August 26, 1972; )     

Biosynthesis of alicyclic acids from 14C-labeled glucose and erythrose by isolated cells from Vigna angularis leaves

Mesophyll cells isolated enzymatically from Vigna angularisleaves were fed ¹⁴Cglucose or ¹⁴C-erythrose and the time-courseof ¹⁴C incorporation into shikimic and quinic acids was examined.When ¹⁴C-glucose was fed to the cells, the highest radioactivityin quinic acid was observed after 10 hr of incubation, whilethat in shikimic acid was after 14 hr. In the experiment with¹⁴C-erythrose, the radioactivity in shikimic acid rose strikinglyup to the 3rd hour, but ¹⁴C in quinic acid increased graduallyduring the incubation. The incorporation of ¹⁴C into shikimicacid was enhanced when unlabeled shikimic or quinic acid wassupplied to the cells simultaneously with either ¹⁴C-glucoseor ¹⁴G-erythrose, whereas that into quinic acid was not significantlyincreased by these alicyclic acids. The difference in incorporationrate of ¹⁴C into quinic acid from that into shikimic acid wasmore conspicuous in the isolated mesophyll cells than in theepicotyls of V. angularis seedlings. ¹ Present address: Department of Biology, Faculty of Science,Kumamoto University, Kumamoto 860, Japan. (Received September 22, 1978; )     

The role of amino acids in the chemosensory swarming and feeding of marine copepods

Behavioural observations were made on two copepods, Eurytemoraherdmani and Acartia hudsonica, presented with 18 dissolvedL-amino acids the concentrations of which ranged from 10^–8M to 10^–2 M. The onset and duration of the swarming behaviourwere determined by the structure and concentration of a restrictednumber of molecules, which differed depending on the copepodspecies. Dicarboxylic amino acids were the most stimulatoryagent for E. herdmani, whereas A. hudsonica responded preferentiallyto aliphatic amino acids. Both the feeding and swarming of A.hudsonica could be induced by the same kind of molecules. Thethreshold sensitivity of the copepods appeared to be compatiblewith the natural concentrations of the dissolved free aminoacids measured at sea. These findings are discussed with referenceto the chemically mediated interactions between phytoplanktonand zooplankton.     

Perithecial formation in Gelasinospora reticulispora III. Inhibitory effects of near-UV and blue light during the inductive dark period

Growing hyphae of Gelasinospora reticulispora required a continuousdark period prior to photoinduction of perithecia. The inductivedark period was interrupted by brief exposure of the hyphaeto white light so that the formation of perithecia no longertook place. Photosensitivity of the hyphae in terms of the light-breakeffect gradually changed during the inductive dark period. Sensitivityreached its maximum at the 18th hr of the dark period when anirradiation of 1?10⁵ ergs cm^–2 of near-UV light or 4?10⁴ergs cm^–2 of blue-light was sufficient for the light-break.Red and far-red light had no effect at all. The light-breakeffect was limited to the irradiated portion of the hyphae anddid not affect any unirradiated portions. Inhibitory effecton perithecial formation of continuous white light could betotally replaced for several days with intermittent irradiationof near-UV or blue light if given for 5 min every 4 hr. (Received December 18, 1973; )     

Compositions and Positional Distributions of Fatty Acids in Phospholipids from Leaves of Chilling-Sensitive and Chilling-Resistant Plants

The compositions and positional distributions of fatty acidsin the major leaf phospholipids of phosphatidylglycerol, phosphatidylcholineand phosphatidylethanolamine were analyzed by gas-liquid chromatographyand enzymic hydrolysis, and chilling-sensitive and chilling-resistantplants were comparcd with respect to the relative contents ofpalmitic and trans-³-hexadecenoic acids in the separated phospholipids.A distinct difference between these plants was found in thefatty acid compositions of phosphatidylglycerol, in which thesum of palmitic and trans-³-hexadecenoic acids ranged from 60to 78% of the total fatty acids in 8 species of chilling-sensitiveplants, and from 50 to 57% in 11 species of chilling-resistantplants. The only exception among the chilling sensitive plantsin this respect was the tomato, in which the sum of palmiticand trans-³-hexadecenic acids in phosphatidylglycerol amountedto 54%. The fatty acid compositions and the positional distributionsof fatty acids in phosphatidylglycerol suggest that the occurrenceof high proportions of dipalmitoyl and 1-palmitoyl-2-(trans-³-hexadecenoyl)species in this lipid is correlated with the susceptibilityto chilling of the leaves of higher plants. In the compositionsand positional distributions of fatty acids in phosphatidylcholineand phosphatidylethanolamine, no difference was found betweenthe chilling-sensitive and chilling-resistant plants. ¹ Present address: Department of Biology, Faculty of Science,Universityof Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan. (Received May 21, 1982; Accepted June 25, 1982)     

Identification of Antheridic Acid as an Antheridiogen in Anemia rotundifolia and Anemia flexuosa

Antheridic acid was identified by retention time and full massspectra from GCMS analysis as an antheridiogen in Anemia rotundifoliaand A. flexuosa. In the dark spore germination assay, antheridicacid was active down to 10^–10 and 5 ? 10^–12g.ml^–1in A. rotundifolia and A.flexuosa, respectively. In the antheridiumformation assay, antheridic acid was active down to 10^–10g.ml^–1 in both A. rotundifolia and A.flexuosa (Received April 14, 1987; Accepted July 8, 1987)     

Ethylene and 1 -Aminocyclopropane-1-Carboxylic Acid Production in flacca, a Wilty Mutant of Tomato, Subjected to Water Deficiency and Pre-treatment with Abscisic Acid

Neill, S. J., McGaw, B. A. and Horgan, R. 1986. Ethylene and1-aminocyclopropane-l-carboxylic acid production in flacca,a wilty mutant of tomato, subjected to water deficiency andpretreatment with abscisic acid —J. exp. Bot. 37: 535–541. Plants of Lycoperstcon esculentum Mill. cv. Ailsa Craig wildtype and flacca (flc) were sprayed daily with H²O or 2?10^–2mol m^–3 abscisic acid (ABA). ABA treatment effected apartial phenotypic reversion of flc shoots; leaf areas wereincreased and transpiration rates decreased. Leaf expansionof wild type shoots was inhibited by ABA. Indoleacetic acid (IAA), ABA and l-aminocyclopropane-l-carboxylicacid (ACC) concentrations were determined by combined gas chromatography-massspectrometry using deuterium-labelled internal standards ABAtreatment for 30 d resulted in greatly elevated internal ABAlevels, increasing from 1?0 to 4?3 and from 0?45 to 4?9 nmolg^–1 fr. wt. in wild type and flc leaves respectively.Endogenous IAA and ACC concentrations were much lower than thoseof ABA. IAA content ranged from 0?05 to 0?1 nmol g^–1 andACC content from 0?07 to 0?24 nmol g^–1 Ethylene emanationrates were similar for wild type and flc shoots. Wilting of detached leaves induced a substantial increase inethylene and ACC accumulation in all plants, regardless of treatmentor type. Ethylene and ACC levels were no greater in flc leavescompared to the wild type. ABA pretreatment did not preventthe wilting-induced increase in ACC and ethylene synthesis. Key words: ABA, ACC, ethylene, wilting, wilty mutants