摘要:

AbstractCalli were isolated from root, stem and leaf segments ofNigella sativa(Fam. Ranunculaceae) on White's medium containing napthaleneacetic acid and coconut milk. From all the three types of calli, roots were differentiated. Shoot development occurred in stem and leaf calli only after the omission of first coconut milk and then of auxin from the basal medium and also in IAA (2.0 mg/ml) and coconut milk (15 % v/v) in the medium. Frequency of organ formation and the maintenance of this capacity depend upon the nature as well as the age of the callus tissue.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03790.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractDuring the senescence of the leaves ofParthenocissus tricuspidataPlanchon, the high level of Ca2+ions liberated from pectic membranes in the aqueous medium of the blade causes a decrease in photophosphorylation and chlorophyll regeneration, while carboxylation and diffusion resistances increase. After the hydrolysis of its carbohydrate and protein reserves, the leaf blade can no longer contribute to the nutrition of the plant and abscission is prepared.

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03791.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractTreatment with 6‐benzylaminopurine (6‐BAP; 10−5g/ml) accelerates the growth of detached cucumber cotyledons (Cucumis sativasL.), primarily through an increased water uptake by the tissues. A comparative study of pigment composition and ultrastructure in 6‐BAP treated and untreated cotyledons shows that cytokinin, in the presence of light, accelerates the transformation of etioplasts into chloroplasts. 6‐BAP also enhances the synthesis of membrane precursors as indicated by the formation of a dense prolamellar body and by the persistence of a pseudo‐cristalline structure in 6‐BAP treated material. Stimulation of biosynthetic activity by cytokinin leads simultaneously to an increase in the rate of the pigment synthesis and to an acceleration in the building of the lamellar system. Furthermore, chloroplasts of 6‐BAP treated cotyledons show abnormal features such as a striking increase in the number of thylacoids per granum and a poor development of the int

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03792.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe oxygen exchange, obtained when isolated chloroplasts ofTriticum aestivum, wheat, are irradiated without the addition of a Hill oxidant has been investigated using an oxygen electrode. Ascorbate, catalase, 2,5‐dibromo‐3‐methyl‐6‐isopropyl‐p‐benzoquinone(DBMIB), diethyldithio‐carbamate (DEDT), dichlorophenylmethylurea (DCMU), and potassium cyanide were added to the Chloroplasts in order to investigate the oxygen exchange. At least two oxygen uptake reactions, one sensitive to catalase and one catalase‐insensitive, appeared upon irradiation. Hydrogen peroxide was the product of the oxygen uptake in the former process, and water was the reductant. The formation of hydrogen peroxide was probably associated with photosystem I. The other oxygen consuming reaction was found to be insensitive to both catalase and potassium cyanide. After the chloroplasts had been treated with DCMU, it was possible to show that the catalase‐insensitive oxygen uptake was localized in photosystem I, and that a cyclic electron transport system or some endogenous reductant (‐s) acted in the oxygen uptake.Addition of ascorbate or DEDT to the chloroplasts led to an enhanced oxygen uptake in 710 nm light. This was probably due to the effect of these compounds on the superoxide radical ion formed in photosystem I. The stimulated oxygen uptake was only weakly affected by catalase, indicating that hydrogen peroxide was not a product of this oxygen uptake. Addition of DEDT and potassium cyanide inhibited (strongly respectively weakly) the oxygen uptake when photosystem II was functioning. The effect of these compounds was probably due to an inhibition of the electron transport at the plastocyanin.DBMIB inhibited the oxygen uptake reactions and the cooperation between the two photosystems. The cooperation between the photosystems was also studied in DCMU‐treated chloroplasts. The reactions in photosystem II, measured as oxygen evolution, were more inhibited than the coupling between the photosystems.The oxygen “gush” appearing upon irradiation in light of 650 nm was not affected by a DBMIB‐treatment, showing that the oxygen evolution was due to the reduction of plastoquinone. The reoxidation in the dark of the plastoquinone pool was stimulated by DBMIB and potassium cyanide indicating that an oxygen uptake could be associated with plastoquinone.The sites of interaction of oxygen with the electron transport pathways in chloroplasts, and the different reductants for the oxygen cons

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03793.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractWater uptake rate of decapitated root systems of cotton (Gossypium hirsutumL.), tomato (Lycopersicon esculentumL. cv. Rutgers), and kidney bean (Phaseolus vulgarisL.) plants shows an exponential increase with applied suction up to about —1 bar. The water uptake rate was higher on the descending path of applied suction than on the ascending path, indicating a hysteresis effect in the roots. The root resistance in a cotton plant increased between 3‐to 5‐fold during the photoperiod of 12 hours. The water uptake rate increased with increasing temperature of the root medium up to 30°C in cotton and 25°C in tomato and bean

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03794.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractAspen (Populus tremuloidesMichx.) callus tissue grown on a synthetic medium containing either an auxin (2,4‐dichloro‐phenoxyacetic acid) or cytokinin [6‐(3‐methyl‐2‐butenylamino) purine] differed in growth rate, total peroxidase activity, peroxidase isoenzyme expression, and in lignin, cell wall sugars and extractive content. Tissue treated with auxin increased more rapidly in fresh weight, but stopped growing sooner than did the cytokinin‐treated tissues. Lignification also proceeded more rapidly, and lignin formed a greater fraction of the cell wall weight in auxin‐treated tissue. For both treatments, peroxidase activity and growth rate were positively related (r = 0.96). Polyacrylamide gel electrophoresis showed some quantitative, but few qualitative, isoenzyme differences with hormonal treatment

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03795.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractActive phosphate uptake by the roots of young sunflower plants was stimulated nonspecifically by increasing the total salt concentration of the uptake solution. Inhibition of active uptake by DNP‐treatment removed the salt stimulation. Independently of the rate of active uptake the amount of phosphate present in the free space of the roots increased as the salt concentration was raised. It is suggested that at low ionic strength of the nutrient solution the initial passive step of ion transport through the root free space can limit the overall uptake rat

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03796.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe scab fungusCladosporium cucumerinumcan use pectins and polygalacturonic acid as sole sources of carbon. Cellulose and Ca‐polygalacturonate are not available carbon sources for the fungus. When growing on sucrose or pectin, pectinase is produced. In these cases the production of cellulase is insignificant. On a mixture of pectin and carboxymethylcellulose also cellulase is produced.Both pectinase and cellulase are released into the culture filtrate when the fungus grows on cell walls without ionic proteins, whereas only cellulase is released when cell walls with ionic proteins are the carbon source. Pectinase produced by the pathogen can bind to isolated cell walls. The bound pectinase can be extracted with 1 M NaCl from cell walls without ionic proteins, but not from cell walls with ionic proteins.A water‐extract or 1 M NaCl‐extract of cucumber hypocotyls with visible disease symptoms contains cellulase but no pectinase activity. Lack of pectinase activity in the 1 M NaCl‐extract may be due to inhibition by a component that could be extracted by NaCl from the cucumber cel

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03797.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effect of indoleacetic acid, gibberellic acid, 2,4‐dichloro‐phenoxyacetic acid and amitrole at various concentration levels ranging from 0.05 to 1.0 mM on the photosynthetic evolution of O2and14CO2fixation by isolated leaf cells was studied. The plant growth regulators enhanced O2evolution and14CO2fixation at low concentrations and were inhibitory beyond a critical level. The amitrole had an inhibitory effect at all the concentration levels used. All the substances exhibited similar patterns of effect on the ferricyanide reduction by isolated chloroplasts and on the electron transport rates of sub‐chloro‐plast particles containing PS‐I and PS‐II independently, under non‐phosphorylating conditions. As was seen from the response in all the three electron transport systems of the chloroplast studied, the electron transport chain connecting PS‐II and PS‐I could be considered as a possible site of action at least for the growth regulating substances as it is the only part that is common to all the three reactions. The phosphorylation associated with this part of the electron transport was “inhibited” by the substances even at the lowest concentration used. The stimulation of non‐phosphorylating electron flow, with a simultaneous reduction in the rate of ATP synthesis, at low concentration levels indicated that these substances played a possible uncoupling role. The amitrole on the other hand appeared to have a generalized non‐specific inhibitory action on all the partial re

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1975.tb03798.x

出版商:Blackwell Publishing Ltd    

年代:1975

数据来源: WILEY