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71.
The influence of nicotianamine (NA) on formation and elongation of adventitious roots in hypocotyls of de-rooted NA-less mutant seedlings of Lycopersicon esculentum Mill, was examined in relation to the iron supply [ferric N-N'-ethylenediaminedi-(2-hydroxyphenylacetate) (FEDDHA), ferric ethylenediaminetetracetate (FeEDTA), ferric N-(2-hydroxyethyl)-ethylenediaminetriacetate (FeHEDTA, Fe-citrate and FeCl3 ] in the nutrient solution. The initiation of root primordia in hypocotyl cuttings was independent of NA and occurred with about the same frequency in both, mutant and wild-type. In the mutant the development of primordia to adventitious roots was blocked at all iron sources used, except FeEDTA. Addition of NA (5x 10−6 to 2 × 10−5 M ) to the rooting medium resulted in a fast growth of adventitious roots in mutant cuttings with all iron sources tested. Rooting of wild-type cuttings was independent from NA application and iron sources. We suppose that NA is involved in the intracellular transport of iron. Its function is possibly linked with chelation of ferrous iron in the cell. 相似文献
72.
The levels of GA1 , 3-epiGA1 and GA8 in genotypes Le, le and led of Pisum sativum L. were determined by gas chromatography-selected ion monitoring (GC-SIM) after feeds of [3 H, 13 C]-GA20 to each genotype. The levels of endogenous and [13 C]-labelled metabolites were determined by reverse isotope dilution with unlabelled GA1 , 3-epiGA1 and GA8 . The results demonstrate a quantitative relationship between the level of GA1 and the extent of elongation both on a per plant and a per g fresh weight basis. These results are consistent with previous findings in peas and other species possessing a predominant early 13-hydroxylation pathway for GA biosynthesis.
The levels of 3-epiGA1 also decreased in the genotypic sequence Le, le, led although not as rapidly as for the level of GA1 . This may suggest that the alleles at the le locus also influence the formation of 3-epiGA1 . 相似文献
The levels of 3-epiGA
73.
74.
Effects of UV-B on flavonoids, ferulic acid, growth and photosynthesis in barley primary leaves 总被引:14,自引:0,他引:14
Barley (Hordeum vulgare L.) was grown with UV-B (280–320 nm) at levels simulating 25 nr 5% ozone depletion on the date of the summer solstice al 40°N latitude, with UV-A (320–400 nm), or with no supplemental irradiation. In plant growth chambers providing 300 μmol m?2 s?1 photosynthetically active radiation (PAR). UV-B-grown leaves elongated more slowly than controls but reached the same final length 1 day later. Leal specific fresh weight (mass leaf area?1) was significantly increased by UV-B after the 7th day of growth. IV-B did not significantly affect leaf area, fresh weight, dry weight, total chlorophylls, total carotenoids or photosynthetic quantum efficiency. CO2 assimilation was decreased by UV-B only at internal CO2 levels above 250 μl l?1. By the 8th day of growth, UV-B increased flavonoid (saponarin and lutonarin) accumulation in both the lower epidermis and the mesophyll: about 40% of the saponarin and 20% of the lutonarin were in the lower epidermis under all experimental conditions. Glasshouse conditions proved too variable for reproducible determination of growth and photosynthesis but were reliable for determining developmental changes in flavonoid (saponarin and lutonarin) accumulation and provided up to 800 μmol m?2 s?1 PAR. In the glasshouse UV-B-grown leaves had more flavonoids than controls al all stages from 5 to 30 days after planting: ca 509 more saponarin and 100% more lutonarin. Levels of soluble (vacuolar) ferulic acid esters were similar under all conditions on day 5. and on day 20 or later, but were significantly higher in UV-B-grown plants on days 10 and 15. UV-B decreased insoluble (cell-wall-bound) ferulic acid esters on a whole leaf basis but significantly increased this fraction in the lower epidermis. UV-A had no significant effects on growth, photosynthesis or ferulic acid, but it slightly increased flavonoid accumulation. The results are discussed in terms of secondary phenolics as a tissue-specific, developmentally regulated adaptive response to UV-B. 相似文献
75.
M. A. C. Demeulemeester W. Rademacher A. Van de Mierop M. P. De Proft 《Plant Growth Regulation》1995,17(1):47-52
Root explants of chicory (Cichorium intybus L.) were cultured in vitro under continuous light or darkness. On a standard medium (no plant growth regulators added), flowering-stems were initiated under continuous light while under continuous dark, vegetative-stems were formed. Different types of GA (gibberellin) biosynthesis inhibitors were added to the culture medium. Paclobutrazol and compounds belonging to the group of cyclohexanetriones clearly reduced flowering-stem growth under light conditions and vegetative-stem growth under dark conditions. Under light conditions, flower bud initiation was not affected. These and other results suggest that GA1 may be synthesized during the in vitro culture period and that it controls flowering-stem growth but not floral initiation.Abbreviations CCC
chlormequat chloride
- GA
gibberellin
- LAB 198 999
3,5-dioxo-4-butyryl-cyclohexane carboxylic acid ethyl ester
- BAS 111..W
1-phenoxy-3-(1H-1,2,4-triazol-1-yl)-4-hydroxy-5,5-dimethylhexane 相似文献
76.
J. Dossett-Mercer H. Green E. R. Chin F. Grange 《Molecular and cellular biochemistry》1995,146(1):23-33
To examine the effect of short term intense activity on sarcoplasmic reticulum (SR) Ca2+ sequestering function, the gastrocnemius (G) muscles of 11 anaesthetized male rats (weight, 411±8 g,X±SE) were activated using supramaximal, intermittent stimulation (one train of 0.2 msec impulses per sec of 100 msec at 100 Hz). Homogenates were obtained from stimulated white (WG-S) and red (RG-S) tissues, assayed for Ca2+ uptake and maximal Ca2+ ATPase activity and compared to contralateral controls (WG-C, RG-C). Calcium uptake (nmoles/mg protein/min) determined using Indo-l and at [Ca2+]f concentrations between 300–400 nM was unaffected (p>0.05) by activity in both WG (6.14+0.43 vs 5.37+0.43) and RG (3.21+0.18 vs 3.07+0.20). Similarly, no effect (p>0.05) of contractile activity was found for maximal Ca2+ ATPase activity (mole/mg protein/min) determined spectrophotometrically in RG (0.276+0.03 vs 0.278+0.02). In WG, Ca2+ ATPase activity was 15% higher in WG-S compared to WG-C (0.412+0.03 vs 0.385+0.04). Repetitive stimulation resulted in a reduction in tetanic tension of 74% (p<0.05) by 2 min in the G muscle. By the end of the stimulation period, ATP concentration was reduced (p<0.05) by 57% in the WG and by 47% in the RG. These results indicate that the repeated generation of maximal tetanic force, at least for short term periods, need not adversely affectin vitro homogenate determination of Ca2+ sequestering function in spite of severe alterations in energy potential and that some other mechanism must be involved to explain the depression in Ca2+ uptake and Ca2+ ATPase activity previously noted with short term intense exercise. 相似文献
77.
Fermentation of corn fibre sugars by an engineered xylose utilizing Saccharomyces yeast strain 总被引:2,自引:0,他引:2
Moniruzzaman M. Dien B.S. Skory C.D. Chen Z.D. Hespell R.B. Ho N.W.Y. Dale B.E. Bothast R.J. 《World journal of microbiology & biotechnology》1997,13(3):341-346
The ability of a recombinant Saccharomyces yeast strain to ferment the sugars glucose, xylose, arabinose and galactose which are the predominant monosaccharides found in corn fibre hydrolysates has been examined. Saccharomyces strain 1400 (pLNH32) was genetically engineered to ferment xylose by expressing genes encoding a xylose reductase, a xylitol dehydrogenase and a xylulose kinase. The recombinant efficiently fermented xylose alone or in the presence of glucose. Xylose-grown cultures had very little difference in xylitol accumulation, with only 4 to 5g/l accumulating, in aerobic, micro-aerated and anaerobic conditions. Highest production of ethanol with all sugars was achieved under anaerobic conditions. From a mixture of glucose (80g/l) and xylose (40g/l), this strain produced 52g/l ethanol, equivalent to 85% of theoretical yield, in less than 24h. Using a mixture of glucose (31g/l), xylose (15.2g/l), arabinose (10.5g/l) and galactose (2g/l), all of the sugars except arabinose were consumed in 24h with an accumulation of 22g ethanol/l, a 90% yield (excluding the arabinose in the calculation since it is not fermented). Approximately 98% theoretical yield, or 21g ethanol/l, was achieved using an enzymatic hydrolysate of ammonia fibre exploded corn fibre containing an estimated 47.0g mixed sugars/l. In all mixed sugar fermentations, less than 25% arabinose was consumed and converted into arabitol. 相似文献
78.
Expansion growth is limited if the difference between day and night temperature (DIF) is negative. Growth is also limited high salinity. Expansion growth of tomato seedlings was studied under day/night temperatures of 16/24°C and 24/16°C, and nutrient solution salinities of 3 and 15 mS cm-1 to ascertain whether interactions exist between the two stress forms. Water status was also studied in order to assess possible mechanisms of growth retardation. A significant interaction between DIF and salinity was found for all recorded growth variables. Hypocotyl length, plant height, leaf area and fresh and dry weight were lower at negative DIF than at positive, the reduction being greater at low salinity than at high. Increased salinity also reduced growth, more so at positive DIF than at negative. Growth reduction at negative DIF was accompanied increased shoot water and osmotic potentials. Pressure potential was unaffected DIF. Growth reduction at high salinity was accompanied reduced water and osmotic potentials. Pre-dawn pressure potential was increased at high salinity, whereas no effect of salinity on pressure potential at midday was found. The differences in effects on water status between the two stress forms may suggest differing mechanisms of growth retardation. 相似文献
79.
Hendrica A. Akster Jan-Willem van de Wal Tineke Veenendaal 《Cell and tissue research》1995,281(3):517-524
At muscle-tendon junctions of red and of white axial muscle fibres of carp, new sarcomeres are found adjacent to existing sarcomeres along the bundles of actin filaments that connect the myofibrils with the junctional sarcolemma. As the filament bundles that transmit force to the junction originate proximal to new sarcomeres, they probably relieve these new sarcomeres from premature loading. In red fibres, these filament bundles are long (up to 20 m) and dense, permitting light-microscopical immunohistochemistry (double reactions: anti-titin or anti--actinin and phalloidin). New sarcomeres have clear I bands; their A band lengths are similar to those of older sarcomeres and the thick filaments lie in register. T tubules are found at the distal side of new sarcomeres but terminal Z lines are absent. The late addition of -actinin suggests that -actinin mainly has a stabilizing role in sarcomere formation. The presence of titin in the terminal fibre protrusions is in agreement with its supposed role in sarcomere formation, viz. the integration of thin and thick filaments. The absence of a terminal Z line from sarcomeres with well-registered A bands suggests that this structure is not essential for the anchorage of connective (titin) filaments. 相似文献
80.
HISASHI OKAMOTO AKIKO MIZUNO KIYOSHI KATOU YOSHINA ONO YASUKO MATSUMURA HIROSHI KOJIMA 《Plant, cell & environment》1984,7(2):139-147
Abstract A new experimental system was devised for the simultaneous measurement of elongation rate and the activity of the spatially separate electrogenic ion pumps of a hypocotyl segment excised from a seedling of Vigna unguiculata L. Walp. under enforced intra-organ perfusion by artificial solutions. The pathway of the perfusion medium was apoplastic space, including xylem vessels as main routes. The elongation rate of the segment was highly dependent on the perfusion pressure applied. It was possible to increase the growth rate under pressurized perfusion by 10-30 times as much as that without perfusion. Elongation rate was also dependent on respiration under perfusion, being retarded reversibly by anoxia a few minutes after the activities of the electrogenic ion pumps were stopped. Perfusion pressure had a little influence on the membrane potential (Vpx) below a breakdown level (c. 130 kPa). Perfusion of mannitol or sorbitol solution of appropriate concentration reduced the elongation rate reversibly. 相似文献