摘要:

AbstractFree and bound amino acids in the mycorrhizal and nonmycorrhizal root systems ofPinus nigraArnold andCorylus avellnaL. grown under semi‐natural conditions were analyzed through automatic amino acid analyzers.Tuber brumaleVitt. andT. melanosporumVitt. were the respective fungal symbionts. Arginine and citrulline were found to accumulate in large quantities in the free pool of the uninoculated P. nigra and C. avellana root systems respectively. In the mycorrhizal root systems these substances decreased in their levels with a parallel increase in the concentrations of glutamine and asparagine. Implications of these changes are discussed with reference to ectomycorrhizae. In general the majority of the identified free amino acids were found in larger concentrations in both the types of mycorrhizal root systems. Results obtained suggested that this may not be due to proteolysis but due to increased biosynthesis. Possible interrelationships in ectomycorrhizal root systems with reference to nitrogen metabolism are presented in the form of a schem

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01143.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractChorismate mutase fromQuercus pedunculataEhrh. leaves has been purified by ammonium sulfate precipitation, molecular sieving and hydroxyapatite chromatography. Some results obtained during the purification suggest the presence, in oak, of two isofunctional forms of the enzyme, the one sensitive, the other insensitive to the action of aromatic amino acids. The regulable form exhibits a molecular weight of about 45,000. It is inhibited by tyrosine and by phenylalanine and is activated by tryptophan. In addition to its activating properties, this latter compound, endowed with a great affinity for the enzyme, reverses the inhibition due to the two other amino acids.The H+concentration of the medium plays an important role in the sensitivity of the enzyme with regard to its effectors. Inhibition by tyrosine and by phenylalanine is maximal at pH 6.5, at which value the two ligands present an identical effect. At alkaline pH values, the rate of inhibition decreases regularly, tyrosine becoming the most effective inhibitor. Activation by tryptophan is particularly acute in a mildly acid medium; at pH 6.5, this effector increases the enzymatic activity threefold. Its action is weak (20% activation) in the optimum pH zone (pH 7.8) and increases towards the more basic pH values. As a result, tryptophan maintains a constant level of enzymatic activity throughout a large pH zone (between 6.5 and pH 9.0). The physiological significance of these results is discussed.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01144.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractChanges in protein content and cell proliferative activity were followed after a cytokinin‐requiring strain of culturedGlycine maxtissue was transferred to freshly prepared media which either contained or lacked cytokinin. Cell numbers doubled within the first two days after transfer, both in the presence and absence of cytokinin. However, after the second day no further increase in cell number was observed in the absence of cytokinin, while cell numbers continued to increase logarithmically in the presence of cytokinin. The size of the cell population attained after the first six days of growth was a function of the cytokinin concentration of the culture medium. However, the amount of3H‐thymidine incorporated into nuclear DNA bore no relation to the rate of cell proliferation. Tissues cultured on medium lacking cytokinin incorporated the greatest amount of3H‐thymidine per microgram of DNA, while the actively dividing tissues incorporated somewhat less. Using autoradiography and isopycnic CsCl gradient centrifugation, it was shown that the radioactivity derived from3H‐thymidine was associated with nuclear DNA in the cytokinin‐deprived cells. Biochemical measurements demonstrated that cells cultured for six days without cytokinin had approximately twice the DNA content of the actively proliferating cells cultured on cytokinin‐containing medium. Furthermore, in autoradiographs labeled cells were found to average nearly three times as many silver grains per nucleus in tissues cultured without cytokinin as the cytokinin‐grown tissues. This suggests that the3H‐thymidine incorporation in the non‐proliferating soybean cells results from nuclear DNA synthesis and that some of the cells became polypoid in the absence of cytokinin. These findings would be consistent with the idea that cytokinin acts as a specific trigge

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01145.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe nature, seasonal variation and mobilization of reserves inMalus × domesticahave been studied by means of14C, carbohydrate analyses and extractions of xylem sap.Following exposure to14CO2in the autumn, the majority of the14C absorbed is found in the root. During the winter and in particular the spring the amounts of14C in the top and root are reduced to approximately 40 per cent of the autumn values; in the root the amount of dry matter was also considerably reduced. In the tops, most of the14C absorbed was found as methanol (80 %)‐soluble14C which also showed the greatest seasonal reduction; sorbitol, sucrose or glucose in particular are responsible for the decrease in concentration within this fraction. Maximum values for methanol‐insoluble14C were found in March. In the root, the highest values for absolute changes were found for methanolinsoluble14C. Hydrolysis of this fraction showed considerable activity in glucose. In the root there was also considerable activity in a precipitated fraction of the methanol extract.Eluates of xylem sap from apple branches contained primarily sorbitol, the highest concentration of which was found at the beginning of March.For a tree with a dry matter weight of about 300 g, the utilization of reserves from the tree in the spring was calculated to be at least 13 g of dry matter. However, only a minor part (less than 25 per cent) of the latter appears to serve as building material for new gr

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01146.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractProtoplasts, enzymatically isolated from cell suspension cultures ofDaucus carota, have been grown in small Petri‐dishes. After enzyme treatment and washing the protoplasts were plated in agar media. Growth and divisions were viewed through the bottom of the Petri‐dishes with a light microscope. Different osmotic stabilizers were tested with respect to their ability to promote wall formation and growth of the protoplasts. Combinations of sucrose, sorbitol and “Modopeg” gave the best results. Electron micrographs of cultured protoplasts revealed normal as well as abnormal nuclear con

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01147.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractOscillations in transpiration and water uptake of individual, young oat plants have been studied. The free‐running period of these oscillations was about 30 minutes. Conditions were reached under which the oscillations were sustained for about two days.Short perturbations were given to the transpiration oscillations, the perturbations consisting of a short time increase or decrease in the illumination. The phase shifts of the oscillations as well as the amplitude effects caused by these perturbations were investigated.Simultaneous recordings of transpiration and water uptake of a single plant showed that these functions were oscillating in phase. Both oscillations disappeared if the leaf was excise

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01148.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe effect on growth and rhizomorph formation of 12 alcohols (methanol, ethanol, 1‐propanol, 2‐propanol, 1‐butanol, 2‐butanol, iso‐butyl alcohol, tert‐butyl alcohol, 1‐pentanol, iso‐amyl alcohol, ethylene glycol and glycerol) at different concentrations has been examined for 2 isolates ofArmillaria mellea(Vahl ex Fr.) Quél. and 1 ofClitocybe geotropa(Bull. ex Fr.) Quél. The fungi were cultivated for 28 days on a synthetic, liquid glucose medium with the alcohols as supplement.The following alcohols strongly stimulated growth and rhizomorph formation: ethanol, 1‐propanol and 1‐butanol. A great variation was demonstrated between the isolates in relation to rhizomorph production, morphology, and ability to be stimulated

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01149.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractSeeds ofLepidiumandSinapiswere germinated and grown for 3 days in different concentrations of Triton X‐100 (0.001–0.1 % v/v). The elongation of the primary root was slightly stimulated by low concentrations. In concentrations above 0.01 %, Triton inhibited root growth and forked root hairs developed. The hairs elongated both at the apex and at the base, exhibited protoplasmic streaming and activity of particulate non‐specific esterase. In contrast the growth of the hypocotyl of bothLepidiumandSinapisdiminished steadily in increasing concentrations of Triton. Triton also affected the percentage germination ofLepidium, which increased or decreased according to the concentration used. The changes in root growth and germination and the appearance of branched root hairs in abundance coincide with a change in the detergent solution from monomer to aggregated mole

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01150.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractTheRumex alpinusL. achenes show a special type of positive photosensitivity: several red light irradiations are necessary to induce optimal germination. The achenes deprived of their pericarp lose their photosensitivity and germinate readily in the dark. By spectrophotometryin vivo, the presence of the Pr form of phytochrome is revealed in these seeds.Short periods at extreme temperatures (30°C or 5°C) induce a good proportion of achenes to germinate. The gibberellins are inefficient on achene germination contrary to benzyladenine which exhibits some activity. A slight improvement of GA4effects has been detected on scarified fruit

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01151.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractExtracts from different organs of 30 plant species belonging to 16 families have been analysed for tryptophan transaminase activity. Only the brown alga Fucus spiralis was found to be devoid of the enzymes. Among the other plants tested, a difference in activity of two orders of magnitude was recorded. None of the genera or families investigated could be considered as particularly rich or poor sources of the enzyme. Extracts from leaves and stem tips contained generally more transaminase activity than extracts from stems and roots. The results are discussed in relation to other reports on the occurrence of the enzyme in plants.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb01152.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY