摘要:

Embryonic shoots ofPicea abies(L.) Karst, isolated from 10‐year‐old trees, were excised either with or without the crown. Various short‐term uptake experiments (3, 6 and 24 h) and one long‐term uptake experiment (4 weeks) were performed with these shoots to obtain information about the physiological role of the crown as translocation barrier for different substances. Transport through the embryonic shoots was followed in both acropetal and basipetal directions using radiolabelled substances supplied in an agarified Schenk and Hildebrandt medium. The medium was labelled with [14C]‐IAA and/or [32P]‐phosphate, or with [35S]‐sulphate and86Rb (as a tracer for K+). The experiments were conducted in light at 20°C, with the exception of one of the short‐term experiments, which was carried out at 5°C to evaluate the connection between transport and metabolism. The main observation is that the crown in its collenchymatous stage of development acts as a selective barrier both acropetally and basipetally for transport of substances such as [14C]‐IAA and [32P]‐phosphate or their metabolized forms. This could explain why the embryonic shoot when cultured plus or minus its crown shows different growth and developmen

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06274.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

In apical or subapical root segments of maize (Zea maysL. cv. Dekalb XL640), 10−7–10−5M24‐epibrassinolide (BR), a physiologically active synthetic epimer of the pollen hormone brassinolide, induces a significant stimulation of root growth, associated with an increase of acid secretion. The increase in acid secretion is enhanced by the presence of K+in the medium and is accompanied by an early, significant hyperpolarization of the transmembrane electric potential (PD), which is completely suppressed by the addition of the protonophore uncoupler FCCP. Similar effects of BR have earlier been reported for shoots, and also for IAA in shoots. Contrariwise, 10−8–10−7MIAA inhibits acid secretion and depolarizes the PD in the maize root segments. This suggests different pathways for the action of the two different hormones on th

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06275.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Experiments were done to examine the phototrophic response of sun‐tracking leaves ofLupinus succulentusDougl. to fixed beams of white and broad band light. Upon irradiation with 15 W m−2white light that struck the laminae at an angle of 45°, there was a 45–60 min lag period prior to leaf movement. The greatest rate of movement was 15° h−1, and reorientation ceased when leaves attained a position within 15° of perpendicular to the light beam. Laminar movement was largely pulvinar, and a 60 min inductive light treatment was sufficient to activate a maximum pulvinar response in subsequent darkness. Light striking the lamina at angles between 20 and 70° induced similar maximum pulvinar responses and only light that struck the upper (adaxial) leaf surface was effective. Leaf tracking was fully activated by blue light but not by red or y

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06276.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Brassinosteroid, an analogue of brassinolide, (BR) (2α, 3α, 22β, 23β‐tetrahydroxy‐24β‐methyl‐B‐homo‐7‐oxa‐5α‐cholestan‐6‐one), was tested in conjunction with indole‐3‐acetic acid (IAA), naphthaleneacetic acid (NAA), 2,4‐dichlorophenoxyacetic acid (2,4‐D), indole‐3‐butyric acid (IBA), indole‐3‐propionic acid (IPA), indole‐3‐pyruvic acid (IPyA), indole‐3‐aldehyde (IAld), indole‐3‐carbinol (ICB) or tryptophan (TRP) for its effects on ethylene production by etiolated mung bean (Vigna radiata(L.) Rwilcz cv. Berken) hypocotyl segements. The enhancement of ethylene production due to BR was greatest in conjunction with 1 μMIBA, 2,4‐D, IAA, or NAA (these increases were 2580, 2070, 890, and 300%, respectively). When increasing concentrations of IBA, 2,4‐D, IAA, or NAA were used, there was a decrease in the percentage stimulation by BR. Both IPyA and IPA had different optimal concentrations than the other auxins tested. Their BR‐enhanced maximum percentage stimulations (1430 and 1580%) were greatest with 5 μMIPya and 10 μMIPA, respectively. There was a marked reduction in the percentage stimulation by BR with either 100 μMIPyA or IPA. The inactive indoles (IAld, ICB, or TRP) did not synergize with BR at any of the concentrations tested. Four hours following treatment those segments in contact with 1 μMBR with or without the addition of 10 μMIAA began to show a stimulation in ethylene production above the control and this stimulation became greater over the following 20 h. It was necessary for BR to be in continual contact with the tissue to have a stimulatory effect on auxin‐induced ethylene production. When segments excised from greater distances below the hypocotyl hook, were treated with either IAA alone or in combination with BR, there was a decrease in ethylene production with increasing distance. There was no effect of hypocotyl length on BR stimulation of auxin‐induced ethylene production; however, there wa

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06277.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Previous work has shown that increased irradiance promotes flower initiation in the long‐day plantSinapis albawhen given during the first half of a single, suboptimal long day. It is without flower‐promoting effect, however, when given during a single short day. In the present work it is shown that, in the apex of plants exposed to a single short day at high irradiance, some changes occur that are normally observed during the transition to flowering (full evocation), e.g., elevated soluble sugar and starch levels, increased numbers of mitochondria and changed nucleolus structure. These changes are of similar magnitude and follow the same sequence as the corresponding changes during full evocation. Other changes, normally associated with full evocation, e.g., increased mitotic activity, are not caused by one short day at high irradiance. This treatment thus produces only what we call “partial evoca

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06278.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Differentiation and fine structure were studied in 63 callus lines originating from the haploid megagametophyte ofPicea abies(L.) Karst. Developing cones were collected from 27 trees growing in 13 localities in Finland. Vernalization of cones for 12–42 days at 4°C was optimal for callus initiation from the immature megagametophyte (primary endosperm). Five combinations of media based on the macronutrient elements of Chu et al. (1975; Sci. Sin. 18: 659–668) and the micronutrient elements and vitamins of Murashige and Skoog were tested for callus induction, growth and differentiation. Only about 1.5% of the megagametophytes produced subculturable callus (which may be partly due to the high frequency of lethal genes), although in certain mother trees callus production was as high as 20%. In most of the trees sampled, polyamines could not replace casein hydrolysate and glutamine in induction of megagametophyte callus. About half of the originally haploid, diploid and mixoploid callus lines were able to differentiate. A combination of three polyamines (putrescine 0.25, spermidine 0.1 and spermine 0.025 mM) favoured development of roots. In five callus lines shoots and roots developed in the same piece of callus, but these organs usually had no connection with each other. The fine structure of the callus cells was normal, but their starch stores were rather abundant. Mesophyll cells of needles differentiated from originally haploid callus had chloroplasts with fairly well‐developed grana. Secondary metabolites were observed in the vacuoles of some callus cells and in organ initials. Plasmodesmata were very rare in callus cells but they were characteristic of those of the needles. The electron microscope observations showed that the poor capacity for differentiation ofP. abiescallus cultures was not due to cytological insta

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06279.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Seedlings of wheat (Triticum aestivumL.) were grown in darkness in different concentrations of the herbicide SAN‐9789, an inhibitor of carotenoid synthesis. The ultrastructural appearance of etioplasts, containing different amounts of carotenoids, was compared to the contents of carotenoids and carotenoid precursors (phytoene and phytofluene). A correlation was found between the presence of carotenoids and the presence of partitions between prothylakoids. As the plants were grown in darkness, this correlation is interpreted as the result of a structural role of the carotenoids. The presence of the herbicide SAN‐9789 resulted in an increase in size and a change from osmiophilic to non‐osmiophilic plastoglobuli. This change in plastoglobuli was neither correlated to the increase in phytoene or phytofluene, nor to the decrease in carote

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06280.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

Chlorotetracycline (CTC) shows a strongly enhanced fluorescence upon addition of mitochondria isolated from Jerusalem artichoke (Helianthus tuberosusL.) tubers in a low‐cation medium. This indicates the presence of membrane‐bound divalent cations. The chelation by CTC of the membrane‐bound divalent cations does not affect the oxidation of exogenous NADH significantly. The removal of the bound divalent cations using ethyleneglycol‐bis‐(β‐aminoethylether)‐N,N′‐tetraacetic acid (EGTA) and EDTA causes an 80% decrease in CTC fluorescence. Titration of CTC fluorescence (a direct measure of bound divalent cations) and 9‐aminoacridine fluorescence (a measure of surface potential) with EGTA and EDTA gives similar curves, although CTC fluorescence responds more slowly to the addition of chelators. The same bound divalent cations appear to be monitored by CTC fluorescence or by 9‐amin

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06281.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

A cell free culture filtrate from 6‐day cultures ofFusarium oxysporumf. sp.cubensewas processed to give: (1) a heterogeneous enzyme mixture, (2) purified polygalacturonase (PG), (3) partially‐purified polygalacturonate lyase and (4) β‐1,4‐xylanase. When introduced into explanted castor bean leaves each of these preparations was able to promote the formation of vascular system‐obstructing gels. Exposure of castor bean leaves to ethylene (3 ppm) also triggered gel formation. Explanted leaves produced ethylene in response to the enzyme mixture and PG. Vascular gel formation did not occur when ethylene production in response to enzymes was

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06282.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

The quantitative relationship between C2H2reduction, H2evolution and15N2fixation was investigated in excised root nodules from pea plants (Pisum sativumL. cv. Bodil) grown under controlled conditions. The C2H2/N2conversion factor varied from 3.31 to 5.12 between the 32nd and the 67th day after planting. After correction for H2evolution in air, the factor (C2H2‐H2)/N2decreased to values near the theoretical value 3, or in one case to a value significantly (P<0.05) below 3. The proportion of the total electron flow through nitrogenase, which is not wasted in H2production but used for N2reduction, is often stated as the relative efficiency (1‐H2/C2H2). This factor varied significantly (P<0.05) during the growth period. The actual allocation of electrons to H2and N2, expressed as the H2/N2ratio, was independent of plant age, however. This discrepancy and the observation that the (C2H2‐H2)/N2conversion factor tended to be lower than 3, suggests that the C2H2reduction assay underestimates the total electron flow through nitrog

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1983.tb06283.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY