摘要:

AbstractHeat treatment of intact leaves and of isolated thylakoid membranes from spinach (Spinacia oleracea L. cvs. Monatol and Montako) caused inactivation of photochemical processes such as electron transport through photosystem II and photophos‐phorylation. Membrane lipid analysis demonstrated that heat‐induced damage to thylakoids is not caused by chemical alterations in the lipids such as oxidation of unsaturated fatty acids, or release of free fatty acids due to hydrolysis of lipids. Partial extraction of lipids from isolated chloroplast membranes before and after thermal inactivation do not point to drastic changes in the binding relations of the lipids within the membranes. However, it cannot be excluded that during high temperature treatment changes in lipid‐lipid interactions and/or delocalization of specific lipids within the thylakoids might be responsible for the disorganization of the functional integrity of the membranes. Since thermostability of chloroplast membranes is decreased when they are exposed to free unsaturated fatty acids, small amounts of membrane lipids which become hydrolyzed during extended heat treatment may partly contribute to primary heat d

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08638.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractRNA fractions from leaves of pea (Pisum sativumL.) were labelled by placing dark‐grown shoots in32P‐phosphate for 1 h in darkness and 3 h in light. Membrane‐associated RNA and soluble RNA was isolated from an organelle fraction containing plastids and mitochondria. A cytoplasmic RNA fraction was also isolated. These RNA fractions were hybridized to nuclear, chloroplast or mitochondrial DNA isolated from fully green leaves. The organelle RNA fractions hybridized significantly only to chloroplast DNA. This result suggests that at early stages of greening, light initiates transcription of part of the chloroplast DNA. Some of the newly transcribed RNA species are associated with the developing plastid memb

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08639.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractAs the first part of a comprehensive study of the hormonal control of lateral root initiation and development, the effect of surgical treatments such as removal of the root tip, one or more cotyledons, the young epicotyl, or combination of these treatments, on the induction and emergence of lateral roots on the primary root of pea seedlings has been examined. Results show that removal of the root tip leads to a rapid but transitory increase in the number of lateral primordia, the largest number arising in the most apical segment of decapitated roots suggesting the accumulation of acropetally moving promoter substances in this region. The cotyledons appear to be the main source of promoter substances for both the induction and emergence of lateral roots, although one or more promoters also appear to be produced in the epicotyl. The data further indicate that the root tip is possibly the source of a substance which moves basipetally and interacts with acropetally moving promoters to regulate the zone for lateral primordia initiation; the root tip also appears to be the source of a powerful inhibitor of lateral root emergence.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08640.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractA previous report (Bilderback 1974) presented evidence for embryo enhancement of isocitrate lyase (threo‐L, isocitrate glyoxylate lyase, EC 4.1.3.1) activity in the megagametophytes of stratified germinatingPinus ponderosaLaws. var.ponderosaseeds. Our data indicate that the rate of increase in specific activity of this enzyme was greater during the first four days under germination conditions in ponderosa pine megagametophytes from which embryos had been excised than in megagametophytes with embryos left in situ for a 12‐day incubation period. Enzyme activity also increased more rapidly in megagametophytes with embryos removed after 2 days incubation than in those that retained their embryos for the full incubation period. Although rate of increase in enzyme activity was greater in embryoless megagametophytes than in those retaining their embryos, highest levels of activity ultimately occurred in the latter. Thus embryo presence was associated with inhibition of the rate of development of enzyme activity but it was also responsible for a pattern of sustained enzyme activity. These phenomena were not dependent on stratification. Possible reasons for differences between certain aspects of our study and the above cited report are discus

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08641.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThe effects of 20 μMtentoxin on mesophyll chloroplast ultra‐structural development, chlorophyll organization and accumulation, and pigment transformations in cotyledons of dark‐grown, 4‐day‐old ivyleaf morningglory [Ipomoea hederacea(L.) Jacq. var.hederacea]were monitored. After 6 h of white light (200 μEm−2T.s−1), many plastids of tentoxin‐treated tissues contained prolamellar bodies or inconsistent internal membrane orientation in contrast to the uniform internal membrane orientation and absence of prolamellar bodies in controls. Grana stacking did not progress beyond three to four disc loculi in tentoxin‐treatments, and fret membranes were usually discontinuous and reduced. Cylindrical or cupped grana appeared in many chloroplasts after 3 days of light, while other chloroplasts in which disruption was more pronounced had few grana except for remnants, but usually did possess vesicles or structures resembling prolamellar bodies. Tentoxin had no apparent effect on stroma density or plastoglobuli size and number. No starch grains appeared in any of the tentoxin treatments, whereas they appeared after 24 h in controls. Initial protochlorophyllide content and its photoconversion to chlorophyllide and subsequent Shibata shift were not affected by tentoxin. Chlorophyll accumulation rates in tentoxin‐treated cotyledons were about 10% of control rates during the first 24 h of greening and about 20% of controls from 48 to 72 h of greening. Chlorophyllalbratio and PSU size (total Chl/P700) were not significantly a

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08642.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractIn a study of N2fixation in nodules of beans (Phaseolus vulgarisL.) cv. Venezuela‐350 of different ages and kept under controlled light and temperature conditions, three parameters ‐15N2fixation, C2H2reduction and H2evolution—were measured.C2H2reduction was positively related to the N fixed. A standardization of sampling is necessary to keep experimental errors to a minimum. To decrease the variation between replications, the nodules should be carefully incubated (adequate time and temperature), and the samples for chromatography should also be carefully stored. No significant difference was found in C2H2reduction in the systems studied ‐ nodulated roots, disturbed whole plants and intact plants—during the first hour of measurement.H2evolution was detected in nodules over 20 days of age and was positively related to N2fixation and C2H2reduction. This measurement was essential to account for the equilibrium between the three parameters in the electron balance ratio. Under phytotron conditions, maximum H2evolution occurred 20–30 days after planting.Nodulated roots from different plants were used to determine the N2fixed and C2H2reduction, and on average the ratios C2H2:N2varied between 7.3 and 8.3 for all ages.In vivoC2H4/(3N2+ H2) electron balance values were over 1, varying from 1.32 to 1.43. These data suggest that overestimation of actual N2fixation might be occurring when using the C2H2reduction technique, even if taking account for H2evolution. In this case, this method should be used with great care to avoid an overestimation of on average 32‐43% of the actual value. Variation was smaller between the measures of the three parameters when younger nodu

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08643.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractLoss in the content of pigments and decline in the efficiency of thylakoid membranes to reduce 2,6‐dichlorophenol indophenol (DCPIP) have been investigated during dark induced senescence of attached leaves of maize seedlings. The chlorophyll degradation during senescence is differentially inhibited by indoleacetic acid (IAA), gibberellic acid (GA) and kinetin. IAA and GA behave as mild senescence inhibitors in comparison to kinetin. However, in comparison to light, kinetin is relatively less efficient in counteracting senescence. Dark‐induced loss in chlorophyll content is fully recovered by light when the dark incubation period is relatively short. The pattern of light recovery of loss in photoelectron transport during dark‐aging is similar to the recovery kinetics of chlorophyll. Continuous kinetin treatment of dark‐incubated seedlings inhibits the chlorophyll degradation but with decreased duration of kinetin treatment, the efficiency of the hormone to inhibit chlorophyll loss is reduced. The kinetin‐induced inhibition of pigment loss is small in comparison with the effect

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08644.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractRespiratory activities in soybean seeds (Glvcine max(L.) Merr. cv. Chippewa 64) have been examined in the first minutes after water imbibition and after three hours of imbibition, using either particles or intact axes. Cyanide and azide were utilized as inhibitors of the cytochrome oxidase pathway of respiration, and SHAM inhibitions were interpreted as effects on the alternative pathway, since in unaged axes inhibitions by SHAM were obtained only when respiratory activity had either been restricted with inhibitors of the cytochrome oxidase pathway or expanded by an uncoupler (CCCP). From the experiments with these inhibitors, it is suggested that unaged seeds utilize both respiration pathways in the cotyledon but only the cytochrome pathway in the axis. Accelerated aging causes a marked deterioration of respiration, especially that through the cytochrome pathway, and there is an associated engagement of the alternative pathway in the seed axis. It is suggested that the lowering of respiratory activity and the shift in respiratory pathways may play a major role in the decline of germinability and vigor.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08645.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractInfluence of continuous supply with a solution of glucose on the changes in the content of soluble sugars and proteins in various organs of the cut rose(Rosa hybridacv. Carina).Exogenous glucose continuously supplied to the cut rose is immediately converted into saccharose in the stem tissues. This saccharose migrates to the flower, where it is immediately hyd‐rolysed, and to the leaves where its hydrolysis occurs more slowly. The reducing sugars resulting from the hydrolysis of saccharose in the flower and, therefore, possibly from the hydrolysis of saccharose in leaves, induce a large accumulation of hexoses (glucose and fructose) in the flower. The protein content does not depend on the level of reducing sugars in the flowe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08646.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractElhylene production and epinastic growth of leaf petioles of tomato (Lycopersicon esculentumMill. cv. Moneymaker) plants sprayed with 0.1 mMnaphthyl‐1‐acetic acid were suppressed when 1 mMα‐aminooxyacetic acid (AOA) was simultaneously sprayed on the plants. AOA had no effect on ethylene evolution and epinastic growth resulting from the application of 5 mM1‐aminocyclopropane‐1‐carboxylic acid, the immediate precursor

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1980.tb08647.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY