ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06220.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06221.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Two cultivars of wheat(Triticum aestivumL. cvs Kadett and WW 20299) were grown for 9 days with 20% relative increase in nutrient supply per day at pH 4.1. Aluminium at 50 μMretarded the growth of roots more than that of shoots in both cultivars, thus decreasing the root/shoot ratio. The inhibition was largest in WW 20299. With long term Al treatment (9 days), Kmfor K+(86Rb) influx increased five times in both cultivars and Vmaxdecreased in WW 20299. Efflux of K+(86Rb) was little affected. When the roots were treated with aluminium for two days, only relative growth rate of roots was retarded, while growth of shoots was unaffected and influx of K+(86Rb) adjusted to the actual K+demand of the plants. It is concluded that the effects of aluminium on K+uptake in these wheat cultivars are not primary factors contributing to aluminium sensitivity. However, in soil with Al the demand for a comparatively high concentration of K+to maintain an adequate K+uptake rate, in combination with a slow growth rate of the roots, may secondarily lead to K+deficiency in the plants

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06188.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The survival at sub‐zero temperatures of leaf blade cells of rye (Secale cerealeL. cv. Voima), which had not been cold acclimated, was determined by measuring the efflux of ninhydrin‐positive substances: 50% of the cells were dead at −4°C (LT50) and none survived at −12°C or below. Examination of ultrastructural changes during cold hardening and freezing injury requires frozen tissues prepared for transmission electron microscopy without thawing. Specimens were prepared from leaf blade segments at room temperature, −4°C or −12°C by plunge freezing at 3 m s−1into a cooling medium at −170°C followed by freeze‐substitution in acetone with OsO4fixation. Comparisons of room temperature specimens were made with those prepared by chemical fixation using glutaraldehyde/paraformaldehyde/tannic acid. On freezing to −12°C, the cells were severely dehydrated and distorted, the vacuoles severely shrunken and the cytoplasm and mitochondria disorganized whereas the chloroplasts were little affected. On freezing to −4°C, some cells were as disorganized as those at −12°C, others were relatively intact, and some showed evidence of intr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06189.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In heterotrophic tobacco cells (Nicotiana tabacumL. cv. Samsun) inhibition of sulfate transport by reduced glutathione (GSH) is a reversible process. When GSH was removed from the culture medium subsequent to a 10‐h treatment with 1 mMGSH, sulfate transport began to recover after a lag period of ca 4 h and reached the transport rates of controls without GSH within another 3–4 h. Recovery was prevented when inhibitors of protein synthesis, i.e. cycloheximide or puromycin, were added to the medium upon removal of GSH, even if low concentrations (cycloheximide 1 μM; puromycin 250 μM) were applied. At these low concentrations the rate of synthesis of sulfate transport entities was maintained at the rate of degradation in the absence of GSH. The post‐transcriptional polyadenylation inhibitor cordycepin and the transcription inhibitor α‐amanitin only slightly reduced recovery of sulfate transport from inhibition by GSH. Apparently, protein synthesis is required for this recovery, suggesting that inhibition of synthesis of sulfate carrier entities is the mechanism of action of GSH on sulfate transport in heterotrophic tobacco cells. An initial rate of net increase in sulfate transport during recovery from inhibition of GSH of 3.6±0.2 U h−1was calculated [1 U=1 nmol sulfate (g DW)−1min−1]. This rate of increase is small compared with the rate of decrease in sulfate transport at maximum inhibition by cycloheximide (110±3 U h−1). However, with increasing time of exposure without GSH, the net increase in sulfate transport was enhanced to a maximum rate of 96±3 U h−1, measured 5–7 h after GSH had been removed from the media. Apparently, the rate of synthesis of sulfate transport entities in heterotrophic tobacco cells is about twic

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06190.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

In order to establish the relationship of nitrogen nutrition to root formation in vitro, efficiency of various forms of nitrogen supply was investigated in micropropagated shoots ofPinus pinaster.Nitrate (3.3 mMas N) containing medium supplemented with glutamine (2 mMas N) resulted in optimal rooting (control medium) whereas the rooting response was inhibited by the presence of glutamate (2 mMas N) in the medium. Study of15NO−3behaviour in shoots cultured on the control medium showed a marked increase of15N incorporation during the second half of a period of auxin treatment (total duration 16 days). The majority of the nitrogen incorporated from the medium was accumulated into protein in the rooting zone. Autoradiography of [3H]‐thymidine in this reacting zone showed strong DNA synthesis at this time. Addition of glutamate both prevented the root formation process and resulted in a marked slowdown of nitrate uptake and decrease of protein synthe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06191.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Tobacco callus (Nicotina tabacumcv. Badischer Geudertheimer) took up sorbitol rapidly and without a lag period from media with up to 0.7Mof the polyol. Accumulation of proline was greatly enhanced under these conditions and was proportional to the absorbed sorbitol, while the viability of the callus cultures was quite low after a few hours of incubation. Under moderate conditions (0.1Msorbitol) as well as under severe osmotic shock (0.7Msorbitol), the cells adapted by adjusting the sorbitol/proline ratio to ca 3. NaCl (0.1M) had the same effect as sorbitol (0.7M) on the survival rate, but only slightly affected proline synthesis in the first hours of incubation. Addition of 107or 105Mabscisic acid (ABA) did not increase the proline content, but 107MABA delayed the deleterious effect of NaCl and improved the state of the cells. No influence of abscisic acid during the incubation with sorbitol could be detected. Two different strategies for the adjustment of tobacco callus to salinity and sorbitol are suggested: Non‐ionic stress is controlled by the accumulation of proline, whereas ABA could be involved in the adaptation to ionic stres

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06192.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

A study has been made to identify the contribution of senescent changes occurring in embryonic and non‐embryonic (endosperm and aleurone layer) tissues on germination of wheat (Triticum durumL. cv. Appulo) seed lots of 97, 93 and 70% viability. Measurements of germination and rates of macromolecular synthesis of embryos excised from dry seeds showed that as seed viability declined from 97 to ca 93%, there was a decrease in the capacity of embryos to grow and synthesise protein, RNA and DNA. However, no significant differences were observed between embryos from 93 and 70% viability seed stocks. Changes in nutrients, fresh and dry weights of embryonic and non‐embryonic tissues and electrophoretic patterns of endosperm proteins by sodium dodecyl‐sulfate polyacrylamide gel electrophoresis showed a reduced mobilisation of reserve material in 70%‐viable seeds. α‐Amylase (EC 3.2.1.1) production was also decreased. It is suggested that alterations occurring in non‐embryonic structures play a significant role in seed viability loss. This role might be mediated by failing nutrient supply, but the involvement of some inhibitor or toxic substance is a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06193.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The activity of L‐arginine decarboxylase (EC 4.1.1.19) and L‐ornithine decarboxylase (EC 4.1.1.17), polyamine content, and incorporation of arginine and ornithine into polyamines, were determined in mung bean [Vigna radiata(L.) Wilczek] plants subjected to salt (hypertonic) stress (NaCl at 0.51–2.27 MPa). Changes in enzyme activity in response to hypotonic stress were determined as well in several halophytes [Pulicaria undulata(L.), Kostei,Salsola rosmarinus(Ehr.) Solms‐Laub,Mesembryanthemum forskahleiHochst, andAtriplex halimusL.].NaCl stress, possibly combined with other types of stress that accompanied the experimental conditions, resulted in organ‐specific changes in polyamine biosynthesis and content in mung bean plants. The activity of both enzymes was inhibited in salt‐stressed leaves. In roots, however, NaCl induced a 2 to 8‐fold increase in ornithine decarboxylase activity. Promotion of ornithine decarboxylase in roots could be detected already 2 h after exposure of excised roots to NaCl, and iso‐osmotic concentrations of NaCl and KCl resulted in similar changes in the activity of both enzymes. Putrescine level in shoots of salt‐stressed mung bean plants increased considerably, but its level in roots decreased. The effect of NaCl stress on spermidine content was similar, but generally more moderate, resulting in an increased putrescine/spermidine ratio in salt‐stressed plants. Exposure of plants to NaCl resulted also in organ‐specific changes in the incorporation of both arginine and ornithine into putrescine: incorporation was inhibited in leaf discs but promoted in excised roots of salt‐stressed mung bean plants.In contrast to mung bean (and several other glycophytes), ornithine and arginine decarboxylase activity in roots of halophytes increased when plants were exposed to tap water or grown in a pre‐washed soil—i.e. a hypotonic stress with respect to their natural habitat. NaCl, when present in the enzymatic assay mixture, inhibited arginine and ornithine decarboxylase in curde extracts of mung bean roots, but did not affect the activity of enzymes extracted from roots of the halophytePulicaria.Although no distinct separation between NaCl stress and osmotic stress could be made in the present study, the data suggest that changes in polyamines in response to NaCl stress in mung bean plants are coordinated at the organ level: activation of biosynthetic enzymes concomitant with increased putrescine biosynthesis from its precursors in the root system, and accumulation of putrescine in leaves of salt‐stressed plants. In addition, hypertonic stress applied to glycophytes and hypotonic stress applied to halophytes both resulted in an increase in the activity of polyamine

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06194.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

The loss of flesh firmness during muskmelon (Cucumis melovar.reticulatusL. Naud. cv. Galia) fruit ripening was related temporally to modifications of pectic and hemicellulosic polysaccharides, and a net loss of non‐cellulosic neutral sugars. An increase in solubility and a decrease in molecular size of polyuronides occurred during ripening; however, the decrease in molecular size was apparently not the result of polygalacturonase (EC 3.2.1.15) activity. Molecular size of hemicelluloses shifted from larger to smaller polymers during ripening, and this decrease was accompanied by changes in neutral sugar composition. Galactose, glucose, and xylose were the predominant neutral sugars in the hemicellulosic polymers. On a mol% basis there were decreases in galactose and glucose in large hemicellulosic polymers with ripening. Relative xylose content approximately doubled in the large polymers during ripening; xylose was the predominant neutral sugar in the small polymers and remained fairly constan

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1989.tb06195.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY