摘要:

When suspension‐cultured rice (Oryza sativaL. cv. Tainan 5) cells were deprived of sucrose, α‐amylase (EC 3.2.1.1) activity in the cells and the culture medium increased markedly. The increase in activity of α‐amylase caused by sucrose starvation in the cells and the medium was strongly reduced in the presence of exogenously added spermine. Putrescine and spermidine also inhibited, though only slightly, the increase in α‐amylase activity caused by sucrose starvation. Preincubation of the enzyme extract or enzyme in the medium with polyamines had no effect on α‐amylase activity. Sucrose starvation resulted in lower polyamine levels in rice suspension cells. D‐Arginine and α‐methylomithine, inhibitors of polyamine biosynthesis, caused reduced levels of polyamines and increased activity of α‐amylase in rice suspension cells cultured in the presence of sucrose. Our results indicate that the induction of α‐amylase activity by sucrose starvation in rice suspension cells is mediated, at least partly, through the inte

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00410.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Evolution of HCN from both rice (Oryza sativa) and cocklebur (Xanthium pennsylvanicum) seeds increased during a pre‐germination period and preceded the evolution of (C2H4). These two species were adopted as the representatives of starchy and fatty seeds, respectively. Ethylene promotes seed germination of many species. However, HCN evolution declined abruptly when the radicles emerged and before the peak in C2H4evolution. More‐over, both rice and soybean (Glycine max) seeds showed some activity of β‐cyanoalanine synthase (CAS, EC 4.4.1.9) even in the unimbibed dry state. The activities of CAS in the lower seed of cocklebur and in soybean seeds increased rapidly after emergence of the radicle. However, the CAS of rice seeds, with high activity in the dry state, exhibited a bimodal change, gradually decreasing until radicle emergence had occurred, but then increaing. It is thus likly that HCN evolution during initial imbibition may be derived from cyanogenic reserves and controlled by both pre‐existing and subsequently‐developing CAS. The exogenous application of C2H4stimulated the activities of CAS in both rice and upper cocklebur seeds and reduced their cyanogen contents. Therefore, the decline of HCN evolution after germination seems to be due to the increased activities of CAS by endogenously pro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00411.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Two protein kinase activities were found in plasma membrane‐enriched preparations from red beet (Beta vulgarixL.). The kinases in these preparations produced the phosphorylation of several membrane polypeptides. These kinases also phosphorylated histone III‐S and casein. The activities of two different kinases could be distinguished: one was half‐maximally stimulated by 1 μMfree Ca2+phosphorylated histone III‐S better than casein, showed half‐maximal activity at an ATP concentration of 0.071 mM. had an optimum pH of 7, and was poorly inhibited by GTP, CTP or UTP. Another, much lower, kinase activity that phosphorylated casein was also observed; it was Ca2+independent, showed half‐maximal activity at ATP concentrations of 0.017 and 0.287 mM, exhibited a broad pH optimum about pH 7 and was inhibited by GTP, CTP, UTP or GDP to a greater extent than the calcium‐stimulated activity. When plasma membrane proteins were solubilized with lysophosphatidyicholine and treated with [γ‐32P]ATP at several dilutions, a 125‐kDa polypeptide was autophosphorylated in the absence of Ca2+, while 77‐, 71‐ and 65‐kDa polypeptides were autophosphorylated in its presence. Autophosphorylation in gels after electrophoresis showed a Ca2+‐stimulated ph

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00412.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

APotentilla‐specific plastome fraction in a predominantlySolanum‐type regenerant from a protoplast co‐culture was detected by RFLP. Fifty variegated lines from mixed protoplast populations of wildtypePotentilla caulescensand aSolanumhybrid containing albino‐mutant potato plastids were studied. The nuclear genome of all lines was uniparentalSolanum, as indicated by morphology, isozyme patterns and chromosome number. Heterofamily plastid DNA was detected in one line by using 6 plastid DNA probes of barley. All of theSolanumrestriction fragments were recovered. Additionally, probes of thepsbA gene and16SrDNA revealedPotentllia‐specific signals, and anndhE+G gene probe detected a nonparental fragment. OnlySolanum‐type fragments hybridized with thepshA gene probe in albino sublines. Protoplast‐derived clones were either albinic or variegated. It is proposed that the line represents a cybrid with recombinantSolanum(+)Potentillaplastid DNA transmitted in combination with the entireSolan

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00413.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The effects of short‐term NaCl‐salinity on nodules of soybean (Glycine maxL. cv. Kingsoy) were studied on hydroponically‐grown plants. Both acetylene reducing activity (ARA) and nodule respiration (O2uptake and CO2evolution) were immediately inhibited, and the stimulation of them by rising the external partial pressure of O2(pO2) was diminished by the application of 0.1MNaCl in the nutrient solution. The permeability of the nodule to O2diffusion, estimated by O2consumption or CO2evolution, was significantly lower in the stressed nodules than in the cootrol ones. The respiratory quotient of intact nodules and the ethanol production of excised nodules were increased by low pO2and by salt stress. These data confirm that in salt‐stressed soybean nodules, O2availability is reduced and fermentative pathways are sti

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00414.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

Hemicellulosic polysaccharides from persimmon fruit (Diospyros kakiL.) pericarp were extracted from depectinated cell walls with 0.5, 1 and 4MKOH at different stages of development: (I) maximal growth corresponding to the first sigmoidal growth phase; (II) cessation of growth corresponding to the lag between the first and the second sigmoidal phases; (III) maximal growth corresponding to the second sigmoidal phase; and (IV) cessation of growth when the fruit had reached its maximum size and the change in colour (green to red) had taken place. During fruit development the amount of total hemicelluloses per unit dry mass cell wall decreased twofold. Xyloglucan was present in the three hemicellulosic fractions, and also decreased with fruit age, although its amount relative to other hemicelluloses increased. The amount of xyloglucan was especially high in the hemicelluloses extracted with 4MKOH, representing more than 50% at stages III and IV. The average molecular mass of xyloglucan increased from stage I through stage II (0.5 M hemicellulosic fraction) or through stage III (I and 4Mhemicellulosic fractions) and decreased after that. The xyloglucan endotransglycosylase (XET: EC 2.4.1.‐) activity was measured as the incorporation of [3H]XXXGol (reduced xyloglucan heptasaccharide labelled at position 1 of the glucitol moiety) into partially purified persimmon fruit xyloglucan. XET specific activity increased greatly between stages I and II. The importance of this enzyme during fruit ripening is discusse

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00415.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The kinetics of wilt‐induced abscisic acid (ABA) biosynthesis were investigated in shoots ofArabidopsis thaliana(L.) Heynh Landsberg erecta. ABA concentrations were measured using a radioimmunoassay (RIA) based on the monoclonal antibody MAC 252, and the RIA validated by comparison with combined gas chromatography‐mass spectrometry using a [2H3] labelled internal standard. The basal ABA content ofArabidopsisshoots was ca 10 ng g−1fresh weight; the concentrations had increased ca 4‐fold within 30 min of the initiation of wilting, increased ca 8‐fold after 4 h and 11‐fold after 8 h. This stress‐induced ABA production was dependent on de novo gene expression; pre‐treatment of leaves and shoots with the metabolic inhibitors cordycepin and cycloheximide reduced the rate of subsequent stress‐induced ABA biosynthesis from 12.5 ng g−1h−1to 1 ng g−1h−1and 0 ng g−1h−1, respectively. In vitro translation of mRNA isolated from shoots subjected to wilting or ABA treatment followed by one‐dimensional sodium dodecyl sulphate polyacrylamide gel electrophoresis revealed only minor changes. The effects of wilting and ABA on the content of total ribulose 1,5‐bisphosphate carboxylase/oxygenase small sub‐unit (rbcS) mRNA were also determined. Both wilting and exogenous ABA resulted in a substantial reduction in the amount ofrbcSmRNA, an effect readily reversed by rehydration of wilted shoots. However, the effects of wilting were not mediated solely by newly‐synthesised endogenous ABA, as wilting also reducedrbcSmRNA levels in the ABA‐deficientaba‐1mutant, which did not produce ABA in response to loss of turgor. The amount ofrbcSmRNA was higher inaba‐1shoots, suggesting that cellularrbcSmRNA levels are normally down‐regulated by ABA. Cold treatment induced ABA production in wild type shoots only, but resulted in an increasedrbcS

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00416.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

We examined how anticipated changes in CO2concentration and temperature interacted to alter plant growth, harvest characteristics and photosynthesis in two cold‐adapted herbaceous perennials, alfalfa (Medicago sativaL. cv. Arc) and orchard grass (Dactylis glomerataL. cv. Potomac). Plants were grown at two CO2concentrations (362 [ambient] and 717 [elevated]μmol mol−1CO2) and four constant day/night temperatures of 15, 20, 25 and 30°C in controlled environmental chambers. Elevated CO2significantly increased total plant biomass and protein over a wide range of temperatures in both species. Stimulation of photosynthetic rate, however, was eliminated at the highest growth temperature inM. sativaand relative stimulation of plant biomass and protein at high CO2declined as temperature increased in both species. Lack of a synergistic effect between temperature and CO2was unexpected since elevated CO2reduces the amount of carbon lost via photorespiration and photorespiration increases with temperature. Differences between anticipated stimulatory effects of CO2and temperature and whole plant single and leaf measurements are discussed. Data from this study suggest that stimulatory effects of atmospheric CO2on growth and photosynthesis may decline with anticipated increases in global temperature, limiting the degree of carbon storage in these two perennial sp

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00417.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

To assess if cuticular transpiration could contribute significantly to the high rates of water loss often observed in micropropagated plants after transfer to the nursery, it was tested whether adaxial cuticular water permeance (P) of leaves grown in vitro was higher than that of leaves grown ex vitro. For four species of micropropagated plants with hypostous leaves (Delphinium elatumhybrid,Doronicumhybrid,Hosta sieboldianavar.elegans, Rodgersia pinnata), P was determined with two independent techniques which gave similar results. Minimum adaxial overall conductance was measured with the same methods for aHeucherahybrid which had amphistomatous leaves. Leaves of all species exceptHeucheralost 36–65% of their original weight within 25 min after excision. Detached leaves whose abaxial surfaces had been coated lost only 25–38% of their original weight within 5–9 h. Permeances (P) were between 1 × 10−5m s−1and 1 × 10−4m s−1, which was within the range of typical values found with leaves grown ex vitro. From these results and a critical assessment of the literature it is concluded that there is no evidence that P of micropropagated plants was high enough to contribute significantly to the desiccation problem at the

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00418.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY

摘要:

The occurrence of ubiquitin‐protein conjugates and the expression of ubiquitin genes during floral development and senescence ofHemerocallis fulva(daylily) is reported. Daylily petal proteins were extracted at various stages of floral development and the abundance of ubiquitinated proteins determined by western blotting with affinity purified antibody to ubiquitin. Up to 100 ubiquitin conjugates in the molecular mass range 22–220 kDa were detected within the petals during bud development through to flower opening. The intensity of several of the ubiquitinated protein bands changed markedly during flower opening and/or senescence. Ubiquitinated proteins of apparent molecular masses 160, 105 and 29 kDa were intense in the daylily bud, but rapidly disappeared after flower opening, whereas ubiquitinated proteins of apparent molecular masses 26 and 15.5 kDa increased in intensity as the flowers senesced. Treatment of daylily buds with a 1‐h pulse of cycloheximide as the flowers commenced opening prevented these changes; this treatment also delayed the onset of visual signs of senescence by 5–6 days. Analysis by northern blotting demonstrated differential expression of ubiquitin transcripts by the multi‐ubiquitin gene family during floral development and senescence. Inhibition of petal senescence by treatment with cycloheximide resulted in the accumulation of several ubiquitin‐encoding transcripts and the down‐regulation of a 3.4 kb transcript. Overall, these studies suggest that ubiquitin is involved in the degradation of many petal proteins during floral development and senescence and that, during senescence, this selective degradation is occurring against a background of ne

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1994.tb00419.x

出版商:Blackwell Publishing Ltd    

年代:1994

数据来源: WILEY