摘要:

The effects of a synthetic growth promoter, 4‐ethoxy‐l‐(p‐tolyl)‐S‐triazine‐2,6 (1H, 3H)‐dione [TA], on growth and gravireaction ofZea maysL. (cv. LG 11) roots were investigated. In horizontal, intact roots, pretreatment with TA at 4 × 10−4Minhibited the gravireaction. If the pretreated roots were rinsed with a buffer solution before incubation, the TA effect was reduced, indicating that a continuous presence of TA was necessary for its maximal activity. On the other hand, the TA pretreatment (1×10−5, 1×10−4and 4 × 10−4M) promoted the elongation of these roots. The TA effect was stronger for illuminated roots than for those kept in darkness. TA also decreased the lateral curvature of half‐decapitated roots maintained vertically in light. This indicates that the action of TA could be associated with some growth inhibiting substances prod

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00721.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Although use of embryonic or seedling tissues for mass clonal micropropagation in vitro in conifer reforestation programmes is questionable, there is a potential application in the regeneration of plants from scarce and costly seed derived from controlled pollination. In addition, in vitro culture shortens considerably the lag phase in numbers during the initial stages of vegetative propagation via rooted cuttings. Successive steps of the present technique are described whereby cotyledonary needles (secondary explants) were subcultured on a hormone‐free medium after administration of cytokinin or auxin to 14‐day‐old seedling (primary) explants ofPicea abies. For bud induction, N6‐benzyladenine (BA) was applied either as a short‐duration (3 h), high‐concentration (125 μM) pulse or by vacuum infiltration and incubation in a BA‐containmg (5 μM) infusion medium. Induced adventitious shoots were elongated with the aid of far‐red light and rooted in vivo after a long‐duration (12 h), high‐concentration (625 μM) application of indolebutyric acid. Pulse and infusion treatments resulted in the induction of greater numbers of adventitious buds (average of 12 per needle) over a three to four week shorter culture period than was the case with the conventional inclusion of growth regulators in the agarified medium. No exogenous auxin was required in the bud‐induction programme; its inclusion even at nanomolar levels promoted histo‐ rather than morphogenesis. In cotyledonary needles, to the primary explants of which BA was applied as a pulse or by infusion, the cell divisions which gave rise to the meristemoids from which adventitious buds were produced, appeared to commence mainly in undifferentiated hypodermal layer cells but also in the mesophyll immediately below. By contrast, where BA was incorporated in the agarified medium the first divisions occurred mainly in cells of the epidermal layer.A number of factors affected plantlet regeneration, for instance seed variability, age of seedlings, and mode of application of growth substances. It should also be accepted that the xeromorphic nature of the conifer leaf might impose physiological and morphological constraints on its culture in vitro that could militate against easy morphogenic manipulation. It is deemed essential that the current mean ratio of regenerated plants to cotyledonary needles of 1:1 be increased 10 to 20 fold in order to appro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00722.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Provitamin D2(ergosterol), vitamins D2and D3reduced the calcium‐mediated peroxidase secretion in three types of sugarbeet cells in suspension cultures. Vitamin D2was the most effective in habituated non‐organogenic cells which were the less sensitive to calcium; provitamin D2was the most effective in habituated organogenic cells, while normal non‐organogenic cells were equally sensitive to the three types of vitamin D. The calcium ionophore A23187 slightly restricted peroxidase release in all cases, except in the habituated organogenic cells in the presence of calcium where it exerted a promotive effect. The inhibiting effect of vitamin D2was not counteracted by the ionophore except in this habituated organogenic cell

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00723.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Mesophyll cells isolated fromPhaseolus vulgarisandLycopersicon esculentumshow decreasing photosynthetic rates when suspended in media containing increasing concentrations of osmoticum. The photosynthetic activity was sensitive to small changes in osmotic potential over a range of sorbitol concentrations from 0.44M(−1.08 MPa) to 0.77M(−1.88 MPa). Photorespiration assayed by14CO2release in CO2‐free air and by14CO2release from the oxidation of [1–14C] glycolate also decreased as the osmotic potential of the incubation medium was reduced. The CO2compensation points of the cells increased with increasing concentration of osmoticum from approximately 60 μ I−11 at −1.08 MPa to 130 μl 1−1for cells stressed at −1.88 MPa. Changes in photosynthetic and photorespiratory activities occurred at moderate osmotic potentials in these cells suggesting that in whole leaves during a reduction in water potential, non‐ stomatal inhibition of CO2assimilation and glycolate pathway metabolism occurs simultaneously wi

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00724.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Dark‐grown wheat leaves (TriticumL. cv. Starke II Weibull) were illuminated repeatedly with light flashes giving partial phototransformation of protochlorophyllide to chlorophyllide. After short flashes (e.g. 15 ms red light, 250 W m−2), transforming only a minor part of the protochlorophyllide present, the first more stable chlorophyll(ide) measured ca 15 s after the phototransformation had its absorption maximum in the red around 672 nm. It stayed there during the following 30 min in darkness. After longer flashes (e.g. 125 ms), transforming a larger portion of the protochlorophyllide, the chlorophyll(ide) formed had its maximum absorption more towards 684 nm and shifted to 672 nm during a subsequent period in darkness. Thus, in this case a Shibata shift took place.The conditions which produce the “stable” 672 nm form, without a Shibata shift, are discussed. The presence of large amounts of non‐transformed protochlorophyllide remaining after the phototransformation seems to be important. Under such conditions it is possible that the Shibata shift is completed within a very short time.Also the possible existence of two kinds of phototransformable protochlorophyllide is discussed. According to this idea one of the two protochlorophyllide forms produces a chlorophyllide absorbing at 672 nm shortly after phototransformation without having passed a Shibata shift. The other protochlorophyllide form photo‐transforms to a chlorophyllide which proceeds through the Sh

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00725.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Nicotiana tabacum(cv. Xanthi),N. plumbaginifoliaViviani,N. sylvestrisSpeg. and Comes andPetunia axillaris× (P. axillaris × P. hybrida) (cv. Mitchell) mesophyll protoplast‐derived cells were able to grow at low densities in chemically‐defined media. Protoplasts of different origins (mesophyll, epidermis, pith, suspension culture) also gave rise to protoplast‐derived cells that were able to grow at low densities. When auxin requirements at low densities were compared for different sources of auxins, IAA was found to be efficient in the same range of concentrations as NAA. This was unexpected since tobacco mesophyll protoplasts cannot be induced to divide when plated at high density in the presence of IAA. Optimal 2,4‐D concentrations for low density growth were higher and clearly pH‐dependent. On the contrary, picloram induced low density growth over a wide range of concentrations suggesting a distinct mechanism of action. These results confirm and extend previous observation on the tobacco mesophyll protoplast and show that the low‐density growth technique has a potential use for the study of the action of

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00726.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In order for far‐red radiation at 760 nm to delay dark closing ofAlbizzia julibrissinpinnules, red light must be given simultaneously with or just prior to it. Studies have been made to determine whether a phytohormone can replace this red light requirement. Abscisic acid, gibberellin, kinetin, and indole‐3‐acetic acid have been found to replace the red light. Indole‐3‐carboxylic acid and a cytokinin antagonist are ineffective. In this hormone and far‐red interaction, all hormones are effective at μMor lower concentrations. The hormones show no interaction with red light at 660 nm. Simultaneous irradiation at 550 nm negates the effect of hormone and far‐red interaction in delaying leaflet closing. These results are additional evidence that an unidentified far‐red absorbing pigment could be involved with phytochrome in some far‐red

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00727.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Borstlap (Naturwissenschaften 68: 41–43, 1981; Plant Cell Environ. 4: 189–195, 1981) has alleged that the concept of multiphasic uptake of solutes in plants is invalid. This claim is considered in detail and shown not to be justified. Contrary to Borstlap, the concentration‐dependence of uptake cannot be adequately represented by the sum of two Michaelis‐Menten terms and a linear term, or by similar continuous functions, if sufficiently detailed and precise data are used. Published evidence for the multiphasic concept, including the existence of discontinuities and separate uptake and transition sites, remain

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00728.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In the cucumber (Cucumis sativusL. cv. Straight Eight) cotyledon expansion assay, cytokinin‐stimulated ethylene production was separated from cytokinin‐stimulated growth through the use of potassium and calcium salts. Low concentrations of KC1, which dramatically promoted growth induced by cytokinin, inhibited ethylene evolution, while CaCl2at a concentration that had no effect on growth, strongly promoted the cytokinin‐induced ethylene evolution. In contrast to the growth response, stimulation of ethylene production was not directly related to the presence of potassium or calcium but to their relative concentrations. Concentrations of KCl and CaCl2which promoted ethylene evolution singly, strongly inhibited it when mixed together. Low rates of exogenous ethylene had no effect on the growth response. Both the growth and ethylene responses were found to be general cytokinin phenomena. Cotyledon respiration was promoted by KC1, CaCl2and cytokinin, but its stimulation was not correlated with either growth or ethylene production. In the presence of KClm cytokinin‐induced respiration sharply lowered the content of certain sugars during the large growth response and followed KCl uptake. Analysis of KCl uptake showed that its growth promoting synergism with cytokinin was not due to osmotic

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00729.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The electrical resting potential across the plasmalemma ofLemna gibbaL. (G 1) cells is −230 to −250 mV and the diffusion potential in the presence of 1 mol m−3KCN + 1 mol m−3salicylhydroxamic acid is about −100 mV. A concentration of 0.01 mol m−3HgCl2depolarises the transmembrane electrical potential in a largely reversible way. When the cells after 16 min of HgCl2‐application are returned to Hg‐free solution, the transmembrane electrical potential is only depolarised by 24 × 13 mV (SD, n = 13) compared with the potential prior to HgCl2treatment. In contrast, a 16 min pretreatment with HgCl2followed by a wash with mercury‐free solution reduces the transient depolarisations of transmembrane potential observed after addition of 5 mol m−3D‐glncose or 1 mol m−3L‐alaoine to about 60% of controls. These transient depolarisations are due to the onset of solute uptake. Accordingly, HgCl2‐pretreatment inhibits uptake of14C‐3‐O‐methyl‐d‐glucose by more than 50% and uptake of14C‐l‐alanine by more than 70%. Washing with 1 mol m−31,4‐dithiothreitol does not reverse this inhibition. It is, therefore, concluded that Hg2+irreversibly binds to essential SH‐groups of the H+‐hexose and the H+‐amino‐acid cotransport carriers ofLemna gibbaand inhibits these carriers without apprec

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb00730.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY