摘要:

AbstractMobilization of protein nitrogen in the spring was studied in bark of stems of unringed and double stem‐ringed apple rootstocks M.7 given different nitrogen treatments.A ready protein hydrolysis occurred; the proteins contributed the greater part of the storage nitrogen exported to the growing parts. Protein hydrolysis was little affected by the supply of newly absorbed nitrogen. Movement of nitrogen out of the bark between the rings could not be demonstrated. Protein breakdown in the isolated bark sections was slightly reduced.Arginine was the predominant amino acid in the proteins of the trees with a high level of storage nitrogen but was not conspicuous in the low‐nitrogen trees. The protein composition changed little during hydrolysis. Only the share of arginine in the high‐nitrogen trees dropped appreciably. It is suggested that the high‐nitrogen trees possess a special storage protein characterized by a high arginine content.Analysis of the nitrogen fraction of isolated bark sections showed that the composition of the soluble nitrogen was characterized by a high level of asparagine and especially of arginine, and was quite different from the composition of the proteins. The data suggest that the asparagine in particular originated largely from transformation of the various amino acids set free during protein hyd

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04799.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractChlorella vulgariswas irradiated with UV doses allowing a 0.1 per cent survival. Dark recovery and photoreactivation were carried out either in the presence or in the absence of an inhibitor of protein synthesis. Faster growing and faster greening colonies were selected, and the amino acid composition of the mutant strains were evaluated. Higher growth and photosynthetic rates, higher chlorophyll content and lower respiration rate were shown by all mutants irrespective of the selection procedure. Selection against cycloheximide led to higher protein and RNA, but lower carotenoid content, whereas mutants selected against 6‐methylpurine showed, in addition to a protein and carotenoid increase, a more favourable protein: RNA rati

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04800.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractExcised soybean (Glycine max(L.) Merr.) hypocotyls, barley (Hordeum vulgareL.) coleoptiles, barley leaf sections, and Canada thistle (Cirsium arvense(L.) Scop.) leaf discs continuously absorbed14C‐picloram from a buffered solution over a 24 h period. After an 8 h uptake period excised sections released up to 30 % of the absorbed picloram into ‘clean’ buffer solution in a 4 h period. Leaf sections released less than did the other tissues. Uptake of14C‐picloram by soybean hypocotyl and barley coleoptile sections increased with an increase in temperature from 5 to 35°C. Uptake was promoted by added ATP and sucrose but inhibited by actinomycin D, cycloheximide, and DNP.After differential centrifugation of aqueous extracts of14C‐picloram‐treated excised tissues more than 95 % of the radioactivity was in the soluble fraction.In excised barley and Canada thistle leaf tissues, 3 days after treatment, part of the14C‐picloram was conjugated with plant constituents, largely with sugar(s). After acid hydrolysis of ethanol extracts of such tissues only unaltered picloram was detected. In barley coleoptile and soybean hypocotyl sections no conjugation products of14C‐piclor

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04801.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractIn black pine (Pinus nigra) chlorophyll was first detected two days after planting of the soaked seeds. There was a slight change in the chlorophyll content between two and five days, then a faster chlorophyll synthesis started. The maximum chlorophyll content was found after 15 days of germination. Thereafter the content showed a gradual decrease. The chlorophyll a/b ratio decreased from 10 at two days to 3 after five days. Protochlorophyllide did not accumulate after 6 days of germination.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04802.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractChlorophyll production in wheat (Triticum vulgare) leaves takes place in the dark when wheat embryos are transplanted to the megagametophytes of black pine (Pinus nigra).The chlorophyll content in the wheat leaves is about half that in black pine cotyledons of the same age.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04803.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractThe experiments characterize the inhibition by kinetin of auxin‐promoted elongation in excised hypocotyl sections of 3‐day soybean seedlings (Glycine maxcv. Hawkeye 63). It was found that concentrations of kinetin above 4.2 μMdid not further inhibit auxin‐promoted elongation. Kinetin is as potent an inhibitor of elongation as actinomycin D or cycloheximide. Tissue incubated for 3 or 5 h in the absence of auxin or cytokinin would, upon addition of auxin, exhibit a new growth rate similar to that of tissue grown in auxin for the entire incubation period. Similarly, tissue grown for 3 and 5 h in the presence of auxin would revert to the control rate of elongation upon addition of kinetin. A 10 to 30 min preincubation in kinetin yielded the tissue incapable, for the ensuing 6 h, of increasing its rate of elongation in response to auxin. Zeatin and isopentenyladenine were more potent than kinetin and benzyladenine in the inhibition of elongation. Levels of ethylene produced in the presence of auxin plus cytokinin indicated that it was not involved in this auxin‐cytokinin interaction. Kinetin by itself did not promote elongation; nor did it enhance auxin‐promoted elongation at low auxin conc

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04804.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractTo localize the metabolic block(s) in the biosynthesis of glucosinolates in theBrassica napusL. cv. Bronowski, 5‐methylthiopentanal oxime‐1‐14C was synthesized and fed to this cultivar and cv. Regina II, which has average levels of glucosinolates. The aldoxime was as efficient as a precursor of 3‐butenylglucosinolate in both cultivars, but less efficient as a precursor of 2‐hydroxy‐3‐butenylglucosinolate in Bronowski. These results suggest that there is a block in the biosynthesis of 3‐butenylglucosinolate in Bronowski that is situated before the synthesis of the intermediate 5‐methylthiopentanal oxime, as well as a block in the hydroxylation step.The silique walls of Bronowski contained increased amounts of total sulphur and i

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04805.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractSoybeans [Glycine max(L.) Merr.] were harvested at various periods after a 2 h exposure to determine the effects of ozone on nitrate reductase and selected metabolites related to nitrate reduction. Ozone initially depressed the concentrations of reducing sugars, amino acids, and nitrate reductase activity. On subsequent days following exposure, amino acid and protein levels were higher than the respective controls while the levels of reducing sugars and nitrate reductase activity returned to control levels. The ozone depression of nitrate reduction was not the result of a direct ozone reaction with the nitrate reductase protein but rather an interference with reactions that supplied the NAD(P)H needed for nitrate reduction.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04806.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractAt intervals through the year a study was made of the absorption and metabolism of arginine‐C 14(U) which had been perfused into the wood of apple stem internodes. Absorption was greater during the period May to September than at any other time of the year. The metabolic breakdown of arginine took place only after absorption but the products found varied widely with season. From the analyses it is concluded that arginine is metabolized by the Krebs‐Henseleit cycle at all times of the year, in addition to which during the period from May to August there are other pathways in operation that result in a more extensive breakdown so that all the N in arginine becomes available for new gro

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04807.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY

摘要:

AbstractSeedlings ofAlnus incana(L.) Moench were studied in controlled environmental conditions. Net photosynthetic capacity of four plants simultaneously as well as light, temperature, and atmospheric water pressure deficit were continuously recorded during approximately two months. The potted plants were continuously given known quantities of water.Two different effects of water stress were found in the experimental plants. When sufficient amounts of water had been available to them, photosynthetic CO2fixation rates largely followed the variation in temperature and light. On the other hand, after prolonged water stress, higher temperatures caused a large decrease in net CO2uptake even if the plant apparently had sufficient water during the actual measurements. Possible mechanisms for this effect are discussed.Effects of water stress on photosynthesis were studied at a constant temperature as well as in conditions where temperature, light, soil water content, and atmospheric water vapor pressure were allowed to vary in a complex pattern. Mathematical models for expressing net CO2uptake as a function of environmental variables were constructed for both of these experimental situations. However, only the latter approach clearly demonstrated the fundamental role of temperature in controlling the photosynthesis of plants under water stress.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1973.tb04808.x

出版商:Blackwell Publishing Ltd    

年代:1973

数据来源: WILEY