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21.
Aldehyde dehydrogenase has been purified to homogeneity from mitochondria of potato tubers and pea epicotyls. Although the enzyme had a high affinity for glycolaldehyde it also had a high affinity for a number of other aliphatic and arylaldehydes. It is proposed that the codification glycolaldehyde dehydrogenase (EC 1.2.1.22) should be abandoned in favour of mitochondrial aldehyde dehydrogenase (EC 1.2.1.3). The purified enzyme showed esterase activity and had properties similar to those reported for the mammalian mitochondrial aldehyde dehydrogenase. Although the natural substrate(s) for the enzyme is not known, the kinetic properties of the enzyme are consistent with it playing a role in the oxidation of acetaldehyde, glycolaldehyde and indoleacetaldehyde. 相似文献
22.
Gibberellins (GAs) A17, A19, A20, A29, A44, 2OH-GA44 (tentative) and GA29-catabolite were identified in 21-day-old seeds of Pisum sativum cv. Alaska (tall). These GAs are qualitatively similar to those in the dwarf cultivar Progress No. 9 with the exception of GA19 which does not accumulate in Progress seeds. There was no evidence for the presence of 3-hydroxylated GAs in 21 day-old Alaska seeds. Dark-grown shoots of the cultivar Alaska contein GA1, GA8, GA20, GA29, GA8-catabolite and GA29-catabolite. Dark-grown shoots of the cultivar Progress No.9 contain GA8, GA20, GA29 and GA29-catabolite, and the presence of GA1 was strongly indicated. Quantitation using GAs labelled with stable isotope showed the level of GA1 in dark-grown shoots of the two cultivars to be almost identical, whilst the levels of GA20, GA29 and GA29-catabolite were significantly lower in Alaska than in Progress No. 9. The levels of these GAs in dark-grown shoots were 102- to 103-fold less than the levels in developing seeds. The 2-epimer of GA29 is present in dark-grown-shoot extracts of both cultivars and is not thought to be an artefact.Abbreviations cv
cultivar
- GAn
gibberellin An
- GC
gas chromatography
- GC-MS
combined gas chromatographymass spectrometry
- HPLC
high-pressure liquid chromatography
- KRI
Kovats retention index
- MeTMSi
methyl ester trimethylsilyl ether 相似文献
23.
Abstract We tested the hypothesis that electrogenic ion pumps, working at the parenchyma symplast/xylem interface of pea hypocotyls, provide the driving force for K+ uptake from the xylem. Solutions of known composition were perfused through a hypocotyl segment. The K+ activity of the solution flowing out of the xylem (K+out) increased (i.e. K+ uptake decreased) when aerobic respiration was inhibited by lack of O2, and this was preceded by a decrease in Vpx (electrical potential difference between parenchyma symplast and xylem). Perfusion with auxin (1AA) and fusicoccin (FC) stimulated the electrogenic activity of the ‘xylem pumps’ (111 and 205% respectively) and stimulated uptake of K + from the xylem (with 71% and 29% respectively). The close correlation between xylem pump activity and K+ uptake corroborated the aforementioned hypothesis. Interestingly, inhibition of pump activity by anoxia was incomplete in the presence of FC. It is thought that FC increases the affinity of the ATP-requiring xylem pump for ATP, thus ensuring that ATP production during fermentation is sufficient to fuel the pump in the absence of O2. 相似文献
24.
Summary Eight transfer RNA (tRNA) genes which were previously mapped to five regions of the Pisum sativum (pea) chloroplast DNA (ctDNA) have been sequenced. They have been identified as tRNAVal(GAC), tRNAAsn(GUU), tRNAArg(ACG), tRNALeu(CAA), tRNATyr(GUA), tRNAGlu(UUC), tRNAHis(GUG), and tRNAArg(UCU) by their anticodons and by their similarity to other previously identified tRNA genes from the chloroplast DNAs of higher plants or from E. gracilis. In addition,two other tRNA genes, tRNAGly (UCC) and tRNAIle(GAU), have been partially sequenced. The tRNA genes are compared to other known chloroplast tRNA genes from higher plants and are found to be 90–100% homologous. In addition there are similarities in the overall arrangement of the individual genes between different plants. The 5 flanking regions and the internal sequences of tRNA genes have been studied for conserved regions and consensus sequences. Two unusual features have been found: there is an apparent intron in the D-loop of the tRNAGly(UCC), and the tRNAGlu(UUC) contains GATTC in its T-loop. 相似文献
25.
At the developmental stage at which the apical hook passed the 3rd and 4th nodes, dark-grown seedlings of pea ( Pisum sativum L. cv. Progress No.9) opened the hook upright and then formed a new hook above the node nearly in the opposite direction to the previous one. In cv. Alaska, in contrast, many (about 84%) seedlings closed the hook in the original direction after they partially (up to about 110°) opened it at the 3rd node, thus doing a wagging movement, while a small percentage (about 16%) of the seedlings reversed the hook direction. Exposure to red light of cv. Alaska seedlings for 10 min increased the percentage of the hook reversion up to 71% or more. The hook reversion was never observed except when the hook part passed the nodes, suggesting the involvement of the nodes in the phenomenon. 相似文献
26.
Beneficial interaction between photosynthesis and respiration in mesophyll protoplasts of pea during short light-dark cycles 总被引:1,自引:0,他引:1
The respiratory uptake or photosynthetic evolution of oxygen by mesophyll protoplasts of pea ( Pisum sativum L. cv. Arkel) were monitored during successive short. (3–5 min) cycles of darkness and illumination. The rate of respiration was nearly doubled after 3–4 short periods of illumination while there was a 15–20% enhancement in photosynthesis with cycles of illumination and darkness preceding illumination. Such interaction between photosynthesis and respiration was statistically significant when bicarbonate was present in the reaction medium. The inhibitors of photosynthesis [3(3,4–dichlorophenyl)-l,l-dimethylurea (DCMU), glyceraldehyde] decreased respiration after periods of illumination, whereas inhibitors of respiratory electron transport (Rotenone, antimycin A, NaN3 ) suppressed photosynthesis, as well. We suggest that a rapid beneficial interaction exists between photosynthesis and respiration in protoplasts, even during short cycles of light and darkness. 相似文献
27.
Ian C. Murfet 《Physiologia plantarum》1990,79(3):497-505
Dwarf pea (Pisum sativum L.) plants with genotypes cryc and crys responded differently when an 8 h photoperiod (8 h daylight, 16 h dark) was extended to 24 h (8 h daylight, 16 h incandescent light). Genotype cryc showed up to a 4-fold increase in internode length, sustained by increases in both cell length (particularly of epidermal cells) and cell number (particularly of cortical cells) while crys plants showed up to a 2-fold increase in internode length sustained mostly by an increase in cell number. Under an 8 h (daylight) photoperiod the two genotypes did not differ in their sensitivity to applied gibberellin A1 (GA1) and they showed a similar pattern of response. GA1 significantly increased internode length, cell length and cell number in both genotypes. Incandescent light did not increase the size of the response to GA1 except for crys plants at high dose rates of GA1 (29–58 nmol). At saturating doses of GA1 the two genotypes attained a similar peak internode length; incandescent light increased the peak by about 40%. GA1 increased the rate of leaf appearance by up to 33% while incandescent light reduced the rate by 4–7%. The elongation response of the more mature internodes of cryc plants to GA1 or incandescent light was due primarily to an increase in cell length whereas increased cell number made a significant contribution in the case of internodes which were relatively immature at the time the stimulus was applied. The progressive increase in internode length of both genotypes during ontogeny was due primarily to an increase in cell number. In conclusion, alleles cryc and crys (background le La) do not confer a difference in sensitivity to GA1 and the increase in internode length in response to incandescent light is probably not the result of a real or perceived increase in GA1 level. Allele crys may partially block a phytochrome mediated response to light and the key difference between genotypes crys and cryc may lie in the greater elongation (extensibility?) of cryc epidermal cells in incandescent light. 相似文献
28.
The kinetics of NADH oxidation by the outer membrane electron transport system of intact beetroot (Beta vulgaris L.) mitochondria were investigated. Very different values for Vmax and the Km for NADH were obtained when either antimycin A-insensitive NADH-cytochrome c activity (Vmax= 31 ± 2.5 nmol cytochrome c (mg protein)?1 min?1; Km= 3.1 ± 0.8 μM) or antimycin A-insensitive NADH-ferricyanide activity (Vmax= 1.7 ± 0.7 μmol ferricyanide (mg protein)?1 min?1; Km= 83 ± 20 μM) were measured. As ferricyanide is believed to accept electrons closer to the NADH binding site than cytochrome c, it was concluded that 83 ± 20 μM NADH represented a more accurate estimate of the binding affinity of the outer membrane dehydrogenase for NADH. The low Km determined with NADH-cytochrome c activity may be due to a limitation in electron flow through the components of the outer membrane electron transport chain. The Km for NADH of the externally-facing inner membrane NADH dehydrogenase of pea leaf (Pisum sativum L. cv. Massey Gem) mitochondria was 26.7 ± 4.3 μM when oxygen was the electron acceptor. At an NADH concentration at which the inner membrane dehydrogenase should predominate, the Ca2+ chelator, ethyleneglycol-(β-aminoethylether)-N,N,-tetraacetic acid (EGTA), inhibited the oxidation of NADH through to oxygen and to the ubiquinone-10 analogues, duroquinone and ubiquinone-1, but had no effect on the antimycin A-insensitive ferricyanide reduction. It is concluded that the site of action of Ca2+ involves the interaction of the enzyme with ubiquinone and not with NADH. 相似文献
29.
Some pseudomonads produce a toxin that specifically inhibits winter wheat (Triticum aestivum L.) root growth and the growth of several microorganisms. The toxin does not inhibit pea (Pisum sativum) root growth, but the organisms are aggressive root colonizers and their effect on Rhizobium leguminosarum growth, colonization, and nodulation of peas was not known. Peas were grown in Leonard jars in the greenhouse. Pea roots
were inoculated with R. leguminosarum, a toxin-producing Pseudomonas sp., both, or neither (control). The Pseudomonas sp. colonized pea roots more rapidly and in greater number than R. leguminosarum after ten days. In the presence of the Pseudomonas sp., the R. leguminosarum population on the rhizoplane was less at ten days. When the roots were inoculated with both R. leguminosarum and Pseudomonas sp., the number of nodules were greater than when R. leguminosarum was inoculated alone, but nodule dry weight and pea shoot biomass were similar to plants inoculated with only R. leguminosarum. Although these results need confirmation with non-sterile soil and field studies, these preliminary results indicate that
peas will not be affected by wheat root-inhibitory rhizobacteria. 相似文献
30.
Effects of abscisic acid on the orientation and cold stability of cortical microtubules in epicotyl cells of the dwarf pea 总被引:1,自引:0,他引:1
Summary The effects of abscisic acid (ABA) on the orientation and cold stability of cortical microtubules (MTs) in epidermal cells of epicotyls of the dwarf pea,Pisum sativum L. cv. Little Marvel, were examined by immunofluorescence microscopy. The effect of ABA on the elongation of epicotyls and on the orientation of cortical MTs was opposite to that of gibberellin A3 (GA3). Treatment with ABA, which reduced the promotion of epicotyl elongation by GA3, eliminated the GA3-induced predominance of transverse MTs and resulted in a predominance of longitudinal MTs. The effect of ABA on the cold stability of cortical MTs was also opposite to that of GA3. ABA increased the cold stability of MTs, while GA3 decreased it. The predominance of longitudinal MTs brought about by ABA may have some relationship to ABA-induced inhibition of the elongation of the epicotyl. ABA may alter membrane proteins to stabilize cortical MTs and induce cold hardiness of plants.Abbreviations ABA
abscisic acid
- DMSO
dimethylsulfoxide
- FITC
fluorescein isothiocyanate
- GA3
gibberellin A3
- MT
microtubule
- PBS
phosphate-buffered saline
Dedicated to the memory of Professor Oswald Kiermayer 相似文献