Effects of Na2SO4, K2SO4 and KCl on Growth and Ion Uptake of Callus Cultures of Vaccinium corymbosum L. cv. Blue Crop

Non-selected and Na₂SO-, K₂SO₄- or KCl-selected callus culturesof Vaccinium corymbosum L. cv. Blue Crop were grown on mediasupplemented with 0, 25 and 50 mM Na₂SO₄ (non-selected and Na₂SO(-selectedonly), 0, 25 and 50mMK₂SO₄ (non-selected and K₂SO₄-selectedonly) or 0, 50 and 100 mM KCl (non-selected and KCl-selectedonly). On all media, growth of selected callus (on a fresh-weightor dry-weight basis) was greater than that of non-selected callus,and selected callus grew optimally on the level and type ofsalt on which it was selected. Selected callus was friable andmaintained a higher f. wt:d. wt ratio. Tissue water potentialin selected callus was more negative than in non-selected callus. Flame photometry and chloridometry showed Na⁺, K⁺ and Cl^–accumulated in callus to concentrations equal to or greaterthan the initial concentration in the medium. Turbidometry showedthat tissue SO₄^2- concentration was lower than the concentrationin the medium. In most cases selected callus accumulated moreNa⁺, K^sup, SO₄^2– or Cl^– than non-selected callus.Vacuolar ion concentration was measured by electronprobe X-raymicroanalysis, and on most media selected callus had highervacuolar ion concentrations than non-selected callus. SO₄^2–and Cl^– were accumulated in the vacuoles at concentrationshigher than the external medium, but vacuolar Na⁺ concentrationdid not reach external concentration on Na₂SO₄ and on potassiumsalts was maintained between 12 and 17 mM. Vacuolar K⁺ concentration(approx. 142–191 mM on no salt) decreased on Na₂SO₄ andincreased on K₂SO₄ and KCl. There was no precise correlation between total or specific ionaccumulation (Na⁺, K⁺, SO₄^2– and Cl^– and fresh-weightyield. Results suggest that selection results in adaptationin response to decreased water potential of the medium. Vaccinium corymbosum, blueberry, electronprobe X-ray microanalysis, callus, in vitro selection, salt tolerance, KCl, K₂SO₄, Na₂SO₄     

Effects of Inhibitors of Protein and Nucleic Acid Synthesis on the Development of Ion Uptake Mechanisms in Beetroot Slices (Beta vulgaris)

Mechanisms for the uptake of K⁺, Na⁺ and Cl^- develop sequentially in thin slices of beetroot tissue washed under aerobic conditions. Actinomycin D inhibited or prevented the development of K⁺, Na⁺ and Cl^- uptake mechanisms when added to freshly cut slices, but had no effect on net ion uptake when added after the development of the ion uptake mechanisms. The use of puromycin as a specific inhibitor of protein synthesis was unsatisfactory as it caused leakage of pigments and excessive loss of ions from the disks. Cycloheximide prevented the development of ion uptake mechanisms when added at the start of the experiment, but when added after the development of ion uptake mechanisms its inhibitory effect did not become apparent until after a certain time interval which varied from 3 hours for Cl^- to 25 hours for K⁺ uptake in the same experiment. p-Fluorophenylalanine caused an appreciable shortening of the time required for the development of Na⁺ and K⁺ uptake capabilities, while it completely prevented the development of a Cl^- uptake mechanism. p-Fluorophenylalanine-induced early uptake of Na⁺ and K⁺, however, was followed by periods of net leakage of these ions. It is suggested that the development of ion uptake mechanisms depends on the production of m-RNA, which appears to be relatively stable after its synthesis. The synthesis and decay characteristics of specific proteins required for the ion uptake mechanisms appear to differ for each ion species.     

The Effect of Abscisic Acid on the Uptake and Distribution of Ions in Intact Seedlings of Phaseolus vulgaris cv. Redland Pioneer

Abscisic acid (ABA) was found to increase the accumulation of ³⁶Cl, total Cl, ²²Na and total Na⁺ in roots of intact bean seedlings. After an initial promotion. ABA inhibited longdistance transport of these ions from the root to the shoot. However, it consistently inhibited both uptake and transport of ⁴²K and total K⁺ in intact bean seedlings. A promotion of net ³⁶Cl influx (ψ_oc) and its accumulation in the root (Q*_v) concomitant decrease in transport index (long-distance transport as percentage of total influx) showed that ABA stimulates -³⁶Cl transport at the tonoplast. It inhibited H⁴ extrusion and net ⁸⁶Rb influx which agrees with a cation exchange theory K⁺/Rb⁺ transport.     

Factors Affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): III. ENDOGENOUS GROWTH SUBSTANCES IN VIRUS-INFECTED AND HEALTHY PLANTS AND THEIR EFFECT ON ABSCISSION

Extracts of small and mature-size lupin pods yielded four substancesaffecting the growth of wheat-coleoptile sections: one acidpromotor (A), two acid inhibitors(B and X), and one neutralinhibitor(Y). Inhibitor B was extremely active, however, coleoptile sectionsshowed no signs of toxic effects; they resumed growth at a rapidrate after rinsing them and adding ß-indolylaceticand (IAA) to the medium. 1 µg of IAA was required to counteractthe effect of ‘B’ extracted from 230 mg. Of tissue.On an equal fresh weight basis the inhibiting action of ‘B’in lupin pods was 500–1,500 times more potent than thatof ‘inhibitor ß’ in etiolated pea seedlings. Small pods of plants infected with pea-mosaic virus yielded3 times the amount of ‘A’ of healthy plants (equivalentto 1 µg. IAA 0.3 µg. IAA per 25 g. of tissue respectively),and approximately the amount of ‘B’. Mature podsof virus-infected plants again yielded more‘A’,but also 2? times more ‘B’ than pods of healthyplants. Healthy pods yielded more ‘A’ than virus-infectedpods, and there was no difference in ‘X’. A lupin abscission test was developed and the effects of proximaland distal application of -naphthyl acetic acid (NAA) are presented,and discussed with respect to results of other abscission tests. ‘A’ accelerated abscission when applied proximally,and delayed or prevented it when applied distally. ‘B’strongly accelerated abscission when applied in either way.A possible mechanism explaining the abscission-inducing effectof developing pods on later flowers is discussed in terms ofthe substances ‘A’ and ‘B’. The partlyprevented abscission observed on virus-infected plants was foundto agree well with the proposed mechanism.     

Factors affecting the Abscission of Reproductive Organs in Yellow Lupms (Lupinus luteus L.): II. THE EFFECTS OF GROWTH SUBSTANCES, DEFOLIATION, AND REMOVAL OF LATERAL GROWTH

Abscission of flowers in Lupinus luteus L. (var. Weiko II) withoutgrowth of ovaries is followed by abscission of small pods (15–20mm. long). Normally flower abscission is much more pronouncedthan pod abscission. Abscission was delayed on plants from which laterals or theirterminal and axifliary buds were removed. Flower abscissionwas not affected, but pod abscission increased as a result ofdefoliation. When flowers at the base of the main inflorescence were replacedby auxins and anti-auxins flower abscission was induced in eitheran auxin pattern in which most of the flowers near the siteof application dropped, and pods developed on the apical whorls,or an anti-auxin pattern in which pods developed on basal whorlsnear the site of application but not higher up. The anti-auxinpattern was similar to the pattern of abscission normally inducedby developing pods on basal whorls. -Naphthylacetic acid (NAA) was much more effective in inducingabscission than ß-indolylacetic acid (IAA). 2:3:5-triiodobenzoicacid (TIBA), NAA, and IAA applied in mixtures at various concentrationsacted mainly antagonistically, i.e. the abscission-inducingeffect of NAA and LAA was depressed in basal whorls, and inapical whorls the effect of TIBA was less prevalent. Consequentlythe effect of the mixtures on the total number of pods was aboutequal to that of the most active component by itself. All growth substances seemed to move much more efficiently inacropetal direction than in basipetal direction in the flowerstalk. Transport in lateral direction was very limited. The effect of growth substances applied on laterals was enhancedby defoliating the main 8tem. The influence of assimilates on flower and pod abscission andtransport of growth substances is discussed.     

Inhibition of the Development of a Cation Accuniulatory System and of Tris-induced Uptake in Storage Tissues by N6-benzyladenine and Kinetin

The effect of N⁶-benzyladenine (BA) and kinetin on cation uptake in disks of beetroot (Beta vulgaris L.) and swede (Brassica napobrassica Mill.) tissue was measured in aerated solutions, containing 1 mM NaCl or 1 mM KCl, and in the presence or absence of trishydroxymethyl ammo methane (tris) buffer at pH 8. This investigation followed a suggestion that the immediate activation of cation uptake in freshly sliced beetroot disks by tris (the tris-effect) may depend on stimulation of hexokinase activity. BA, a competitive inhibitor of hexokinase, caused a complete inhibition of tris stimulated cation uptake in beetroot disks, but the effect was delayed and preceded by a 3–4 hour period of promoted cation uptake. Generally, the effects of BA and kinetin were identical. Use of ¹⁴C-kinetin indicated a rapid incorporation of kinetin into the tissue. BA and kinetin also prevented the development of a cation uptake capability during the aging of the beetroot disks. Swede disks which do not show a tris-effcct and no lag phase in development of cation uptake capability were not affected by BA and kinetin treatments. Mechanisms of tris induced cation uptake are discussed with emphasis on its role as a proton acceptor.     

Ultrastructural Localization of Ions: IV. LOCALIZATION OF CHLORIDE AND BROMIDE IN NITELLA TRANSLUCENS AND X-RAY ENERGY SPECTROSCOPY OF SILVER PRECIPITATION PRODUCTS

The cytoplasmic distribution of Cl^– in Nitella translucenswas assessed by means of two contrasting approaches. The firstinvolved the histochemical precipitation of Cl^– with Ag⁺followed by X-ray analytical verification of the silver precipitationproducts, and the second, quench-freezing of whole Nitella cellsfollowed by freeze-substitution in the presence of silver underanhydrous conditions. Both methods produced identical evidencefor Cl^– distribution, showing that a large proportionof the Cl^– is present in the stationary cortical gel layerwhich includes the chloroplasts. However, the chloroplasts appearedto be low in Cl^– content while the bulk of the Cl^–appeared to be situated between the chloroplasts and plasmalemma. Experiments were carried out in other to detect the pathwayof the ‘fast component’ of halide ion transfer tothe vacuole. Br^– was supplied for various time intervalsto low Cl^– Nitella cells, followed by attempts to differentiatebetween AgCl and AgBr deposits. Solutions of various strengthof NH₄OH or ammonium carbonate were used to remove AgCl (butnot AgBr) deposits by formation of a Ag(NH₃)₂⁺ complex. AlthoughX-ray analytical verification showed that the method had somepotential usefulness it could not be carried out successfullybecause of loss of structural detail caused by NH⁺₄. The distribution and density of deposits near the plasmalemmasuggested the occurrence of a process in which cytoplasmic loadingis achieved by a sequential rupture and repair of the plasmalemmamembrane. Vesicles and reticulate structures in the streamingcytoplasmic phase generally showed very little deposit, butthese structures, together with the tonoplast, became greatlyenriched with deposits when cells had been given a brief exposers(3 min) to a Cl^– or Br^– solution. These rapid changesmay possibly be related to the ‘fast component’of halide ion transfer to the vacuole.     

Factors affecting the Abscission of Reproductive Organs in Yellow Lupins (Lupinus luteus L.): I. THE EFFECT OF DIFFERENT PATTERNS OF FLOWER REMOVAL

1. The effect of various patterns of flower removal on pod settingwas investigated in Lupinus luteus L. Four-fifths, three-fifths,or two-fifths of the flowers of the main inflorescence wereremoved according to ten different patterns. 2. All flowers could produce pods but later ones were less efficientin doing so. Developing pods had an abscission-inducing effecton later flowers, which became increasingly effective towardsthe apical part of the inflorescence. More pods were retained when flowers on each consecutive whorlwere arranged in a spiral than when the same number was arrangedvertically. Pod setting was incomplete when the number of flowers per inflorescencewas reduced well below the total number of pods normally present. 3. The number of ovules in consecutive flowers gradually decreasedfrom an average of 5.7 at the base to 4.3 at the top of theinflorescence. The ratio of seeds to ovules fluctuated irregularlybetween 65 and 94 per cent, and did not indicate a general trendin embryo abortion. 4. The growth-rate of pods at the top of the inflorescence wasmuch slower than at the bottom. Vascular differentiation wasalmost absent at the top of the inflorescence when the flowerswere fertilized, and further vascular tissue was produced onlywhen flowers produced pods.     

The Occurrence of Funnel Leaflets and Ring Fasciations in Yellow Lupins

Funnel leaflets in yellow lupins (Lupinus luteus L.) were observedon a mutant, on pea-mosaic infected plants, and on plants treatedwith 2,4-D. In addition typical ring fasciations were producedon plants treated with 2,4-D. The above phenomena have beendiscussed in the light of similar morphogenetic effects, reportedto be induced in other plants by various growth substances.A possible explanation for the ring-shaped structures has beengiven by assuming a change in the influence of the apical meristemon developing leaf primordia and by considering the ‘physiologicalfield’ concept for organ formation respectively.