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161.
Effects of agar brand and concentration on the tissue culture medium 总被引:13,自引:0,他引:13
P. C. Debergh 《Physiologia plantarum》1983,59(2):270-276
In tissue-cultured Cynara scolymus L. (globe artichoke) vitrification (hyperhydric transformation) can only be overcome by increasing the concentration of agar. However, with increasing concentrations of Difco Bacto agar (8–15 g/I) the availability of labelled kinetin is decreased. There is some evidence for postulating that cytokinins under inductive conditions of low agar concentration or high matrix potential are evocators of vitrification.
Both the brand and concentration of agar also affect the chemical and physical characteristics of a culture medium.
Impurities introduced with the agar are responsible for significant differences in the concentration of an element in comparable media with different levels of agar, and are easily detected by conductance.
Penetrometer measurements also show large ranges in solidity of media with increasing concentrations, not only within the type of agar, but also for the same concentration within different brands. 相似文献
Both the brand and concentration of agar also affect the chemical and physical characteristics of a culture medium.
Impurities introduced with the agar are responsible for significant differences in the concentration of an element in comparable media with different levels of agar, and are easily detected by conductance.
Penetrometer measurements also show large ranges in solidity of media with increasing concentrations, not only within the type of agar, but also for the same concentration within different brands. 相似文献
162.
When slices of Jerusalem artichoke tubers were incubated at 25°C, their concentration in fructose 2,6-bisphosphate increased up to 250-fold within 2 h. Fructose 2,6-bisphosphate was also formed, although at a slower rate, in slices incubated at 0°C. Its formation could not be explained by an increase in the concentration of fructose 6-phosphate or of ATP either by an activation of phosphofructo-2-kinase. Pyrophosphate—fructose-6-phosphate 1-phosphotransferase was the only enzyme present in a tuber extract which was found to be sensitive to fructose 2,6-bisphosphate. An improved procedure for the assay of fructose 2,6-bisphosphate is also reported. 相似文献
163.
Matteo Giannattasio Giovanna Carratù Gian Franco Tucci Anna Maria Carafa 《Phytochemistry》1979,18(10):1613-1616
A cyclic AMP binding protein has been purified to electrophoretic homogeneity from Jerusalem artichoke rhizome tissues. Its MW is ca. 240 000 and the apparent constant of cyclic AMP binding to the protein is 2.3 × 10?7 M. When tested using Millipore filter assay, cyclic AMP binding activity was enhanced by protamine and histone, but not by casein and phosvitin. Of several purine derivatives tested, only 5′-AMP and adenosine inhibited significantly the binding of cyclic AMP by the protein. The protein also binds adenosine and this binding is not affected by cyclic AMP or by other purine derivatives. The apparent binding constant for adenosine is 1.0 × 10?6 M. The binding protein did not show protein kinase activity. In addition, it did not affect the chromatin-bound DNA dependent RNA polymerase of homologous origin, either in the presence or absence of cyclic AMP. The binding protein is devoid of the following activities: cyclic AMP phosphodiesterase, 5′-nucleotidase, adenosine deaminase and ATPase. 相似文献
164.
A. V. Sturz 《Plant and Soil》1995,175(2):257-263
Healthy potato tubers (Solanum tuberosum L.) cv. Kennebec were found to be internally colonized by non-pathogenic bacterial populations originating from root zone soil. These endophytic bacteria were categorized, on the basis of bioassays, as plant growth promoting (PGP), plant growth retarding (PGR) and plant growth neutral (PGN). Genera isolated from tubers included Pseudomonas, Bacillus, Xanthomonas, Agrobacterium, Actinomyces and Acinetobacter. The PGP and PGR isolates were similarly distributed throughout these genera. Bacterial populations increased in the root zone soil directly adjacent to the seed piece during and immediately following seed piece decay. Bacteria sampled at this time were capable of promoting tuber number and weight. The proportions of PGP, PGR and PGN bacteria in the root zone were altered as endophytic bacteria were released from the decaying seed piece. The study indicates that endophytic bacteria present in the seed tubers may play an important role in seed piece decay, tuberization and plant growth. 相似文献
165.
Hydrilla tuber formation in response to single and sequential bensulfuron methyl exposures at different times 总被引:1,自引:0,他引:1
K. A. Langeland 《Hydrobiologia》1996,340(1-3):247-251
Hydrilla (Hydrilla verticillata (L.f.) Royle) grown in outdoor tanks was exposed to bensulfuron methyl concentrations of 25, 50, or 100 ppb on June 16, August 20 or October 15; 50 ppb June 16 and August 20, or 25 ppb on June 16, July 21, August 20, and October 15, 1990, with a 35-day contact time. Hydrilla was also exposed to the compound on August 9, 1991 at concentrations of 10, 20, 30, 40, or 50 ppb. In 1990, the August 20 exposure resulted in the greatest inhibition of tuber production for a single application. Exposure in June caused hydrilla to produce at least twice as many tubers as unexposed plants by April 10, 1991. Exposure in October arrested tuber production, which had already begun. Exposure in June and August delayed tuber formation until after February 9, 1991. Exposure in June, July, August, and October inhibited tuber formation for the entire growing season. Hydrilla treated with all concentrations of bensulfuron methyl on August 9, 1991 produced tubers only sporadically through March 16, 1992, compared to unexposed hydrilla, which produced an average of 48 tubers/531 sq cm by January 4, 1992. With the onset of warmer weather after March 16, tubers produced by unexposed hydrilla more than doubled, and comparable numbers of new tubers were produced by plants that were exposed to 10 or 20 ppb. Tuber production was inhibited for the entire growing season by exposure to 50 ppb on August 9, 1991. In spite of the promise that bensulfuron methyl showed for use in aquatic plant management, the Experimental Use Permit was not renewed in 1992 and efforts to register the compound were discontinued. 相似文献
166.
M.-L. Fauconnier J. Rojas-Beltrán J. Delcarte F. Dejaeghere M. Marlier P. du Jardin 《Plant biology (Stuttgart, Germany)》2002,4(1):77-85
Abstract: Potato tubers ( Solanum tuberosum L. cv Bintje and Désirée) were stored for 12 months under three different storage conditions: 4 °C, 20 °C with sprout inhibitor and 20 °C without sprout inhibitor. Independent of the storage conditions, our results show that the increase of membrane permeability, as revealed by electrolyte leakage, is not correlated with the lipid saturation status. Moreover, there is no simple correlation between cold sweetening and membrane permeability or lipid saturation status. During storage at 20 °C without sprout inhibitor, the increase in membrane permeability is inversely correlated to sucrose accumulation, but this is not the case when tubers were stored with sprout inhibitors. Lipoxygenase (LOX) is often proposed as responsible for peroxidative damage to membrane lipids. The gradual peroxidation resulting in double bond index decrease is regarded as a cause of senescence sweetening. Our results revealed that the role of LOX in aging and senescence of potato tubers is far from clear. LOX activity and gene expression are not correlated with the fatty acids composition of the membrane. Moreover, LOX activity and fatty acid hydroperoxide content are low in older tubers, whatever the storage conditions or the varieties. On the basis of our results, the correlation between sugar accumulation (low temperature and senescence sweetening) and peroxidative damage occurring during storage of potato tubers is discussed. 相似文献
167.
168.
Gibberellic-acid (GA3) treatment, when applied within a period ranging from the start of short-day (SD) treatment until about 10 SD, GA3 strongly inhibited formation of aerial tubers in response to SD and brought about sprouting of developing aerial tubers. In contrast, when applied after about 10 SD or more, GA3 hastened the completion of the dormant state in the tubers and prolonged their dormancy. The dormancy-promoting effect of GA3 on detached tubers increased with their degree of maturation. Application of growth retardants N-dimethylaminosuccinamic acid (B-9), 2-isopropyl-4-dimethylamino-5-methylphenyl-1-piperidine carboxylate methyl chloride (AMO-1618) and 2-chloroethyltrimethylammonium chloride (CCC) to the cuttings delayed the onset of dormancy in the aerial tuber. When the retardants were applied to detached aerial tubers, however, such a delay of dormancy was not observed, and GA3 application did not inhibit sprouting in aerial tubers detached from CCC-treated cuttings.Abbreviations GA
gibberellin
- GA3
gibberellic acid
- SD
short day(s)
- LD
long day(s)
- SDP
short-day plant
- LDP
long-day plant
- CCC
2-chloroethyltrimethylammonium chloride
- B-9
N-dimethylaminosuccinamic acid
- AMO-1618
2-isopropyl-4-dimethyl-amino-5-methylphenyl-1-piperidine carboxylate methyl chloride 相似文献
169.
Horst Joachim Schirra Rosemary F. Guarino David J. Craik 《Journal of molecular biology》2010,395(3):609-626
The 53-amino-acid trypsin inhibitor 1 from Nicotiana alata (T1) belongs to the potato type II family also known as the PinII family of proteinase inhibitors, one of the major families of canonical proteinase inhibitors. T1 contains four disulfide bonds, two of which (C4-C41 and C8-C37) stabilize the reactive-site loop. To investigate the influence of these two disulfide bonds on the structure and function of potato II inhibitors, we constructed two variants of T1, C4A/C41A-T1 and C8A/C37A-T1, in which these two disulfide bonds were individually removed and replaced by alanine residues. Trypsin inhibition assays show that wild-type T1 has a Ki of < 5 nM, C4A/C41A-T1 has a weaker Ki of ∼ 350 nM, and the potency of the C8A/C37A variant is further decreased to a Ki of ∼ 1.8 μM. To assess the influence of the disulfide bonds on the structure of T1, we determined the structure and dynamics of both disulfide variants by NMR spectroscopy. The structure of C4A/C41A-T1 and the amplitude of intrinsic flexibility in the reactive-site loop resemble that of the wild-type protein closely, despite the lack of the C4-C41 disulfide bond, whereas the timescale of motions is markedly decreased. The rescue of the structure despite loss of a disulfide bond is due to a previously unrecognized network of interactions, which stabilizes the structure of the reactive-site loop in the region of the missing disulfide bond, while allowing intrinsic motions on a fast (picosecond-nanosecond) timescale. In contrast, no comparable interactions are present around the C8-C37 disulfide bond. Consequently, the reactive-site loop becomes disordered and highly flexible in the structure of C8A/C37A-T1, making it unable to bind to trypsin. Thus, the reactive-site loop of T1 is stabilized differently by the C8-C37 and C4-C41 disulfide bonds. The C8-C37 disulfide bond is essential for the inhibitory activity of T1, whereas the C4-C41 disulfide bond is not as critical for maintaining the three-dimensional structure and function of the molecule but is responsible for maintaining flexibility of the reactive-site loop on a microsecond-nanosecond timescale. 相似文献
170.
Antioxidant enzymes and physiological characteristics in two Jerusalem artichoke cultivars under salt stress 总被引:1,自引:0,他引:1
The effects of NaCl stress on the activity of antioxidant enzymes, lipid peroxidation, cell membrane stability, net photosynthetic rate, gas-exchange, and chlorophyll content were investigated in two Jerusalem artichoke cultivars, Dafeng (salt-tolerant) and Wuxi (salt-sensitive), grown under control (nutrient solution) or salt stress (nutrient solution containing 75, 150, and 225 mM NaCl) conditions for 7 days. In leaves of salt-tolerant cv. Dafeng, superoxide dismutase (EC 1.15.1.1), peroxidase (EC 1.11.1.7), and catalase (EC 1.11.1.6) activities significantly increased as compared to the controls, whereas no significant change was observed in cv. Wuxi. Lipid peroxidation and cell membrane injury were enhanced in both cultivars. Net photosynthesis and stomatal conductance decreased in response to salt stress, but cv. Dafeng showed a smaller reduction in photosynthesis than cv. Wuxi. The results indicated that stomatal aperture limited leaf photosynthetic capacity in the NaCl-treated plants of both cultivars. However, significant reduction in the leaf chlorophyll content due to NaCl stress was observed only in cv. Wuxi. These results suggested that salt-tolerant Jerusalem artichoke varieties may have a better protection against reactive oxygen species, at least in part, by increasing the activity of antioxidant enzymes under salt stress. 相似文献