摘要:

As in all organogenetic studies, sex differentiation implies three fields of research: the identification of macsomalecular markers specific for stamens or carpels }expression program); the analysis of the signals (such as phytohormones{ inducing them: and finally the knowledge of the regulator genes (sex detsrmination genes).In dioecious plants, sex determination (male and female genes or combinations of heterochromosomes) occurs at the fertilization stage. These regulators probably act early by means of inducers; their action is perceptible mainly when reproductive organs develop, and the existence of target cells able to respond to the inductive message is obvious. Experimental control of sex expression by phytohormones leads to the repression of the normal organogenetic program (induced by the presence of the sex genes) arrd to the induction of the opposite program (normally incompatible with these genes).Analogous mechanisms occur in monoecious plants, but here the male program is always expressed before the female one. Experimental control of sex expression suggests that the successive induction of first male and then the female program results from inverse gradients of male and female signals. Sex differentiation studies of monaeciousness are more difficult than studies on dioeciousness since, in all the cells. not only male and female programs co‐exist as in dioeciousness, but also male and female sex penes and signals.The present model has been tested in the dioeciousMercurialisannua(2n = 16) and some other species, and the results that have been established are describe

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06061.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Ethylene is involved in at least two discrete mechanisms in the control of apical dominance: the release of lateral buds from inhibition and their subsequent growth and development. Generally, high levels of freely diffusible ethylene in the apical region of the shoot are conducive to lateral‐bud‐outgrowth, while high ethylene levels in the region of the lateral buds themselves tend to be inhibitory. Threshold ethylene levels concerned with the release of buds from inhibition and with the growth that follows may differ between species. Thus, in some species (e.g.Gossypium) lateral‐bud growth proceeds in the continuing presence of ethylene supplied to the whole plant, whereas in others (e.g.Petunia) the growth of the released lateral buds occurs only when the ethylene is remaved.When ethylene production inPisumnodal sections is enhanced by exomgenous auxin, growth of the attached buds is suppressed. In the intact plant system, unequivocal evidence has not been established for a role of endogenous ethylene acting directly on lateral buds to effect their inhibition. Apical dominance is not affected by the apptication of ethylene antagonists to the lateral buds of intact plants. Results from different studies have been inconsistent regarding the changes in endogenous ethylene levels in the node/lateral‐bud tissue when the plant is decapitated or when auxin is applied to the stump of the decapitated plant to maintain lateral bud inhibition.While exogenous ethylene supplied to the lateral bud generally increases inhibition, the availability of ethylene, regulated endogenously, is essential to the released bud on the decapitated plant in order to sustain its subsequent development into a lateral shoot. There is evidence that, in certain instances, endogenous ethylene may also be essential in the initial stages of bud development, e.g. in thee early growth that is promoted bmy auxin inPhaseolusor by kinetin

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06062.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A rapid purification procedure for glycerol‐3‐phosphate dehydrogenase fromDunaliella tertiolecta(strain 19‐6 of the algal collection of the Univ. of Göttingen), the initial enzyme in the glycerol cycle, has been developed on the basis of affinity chromatography on Blue Sepharose and subsequent desalting by Sephadex G‐50. The achieved purification was 126‐fold. The pH optimum of dihydroxyacetone phosphate reduction is 7, that of glycerol‐3‐phosphate oxidation is about 9. The in vitro enzymatic activity obtained from cell extracts is higher than the required activity for the observed glycerol production rates under osmotic

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06063.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The effects of AMP, ATP, inorganic phosphate and fructose‐1, 6‐bisphosphate on glycerol‐3‐phosphate dehydrogenase (NADH) fromDunaliella tertiolectawere investigated. In addition the salt effects and the influence of different anions were studied. The results support the assumption that concentration changes of intermediates and salts by cell shrinkage during osmotic stress can account for the control of glycerol sy

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06064.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Antisera specific for two commercial acidic peroxidases from horseradish (Amoracea rusticanaL.) were used to determine the degree of homology between isoperoxidases from horseradish, turnip (Brassica rapaL. cv. Purple White Top Globe) and radish (Raphanus sativusL. cv. Cherry Belle). Ouchterlony agar diffusion, precipitin tests and anticatalaytic assays were used to show that acidic horseradish peroxidases could be distinguished by immunological methods but were closely related. Antisera specific for either horseradish acidic isoperoxidase gave a lesser degree of cross reaction with the basic isoenzyme from this plant. Acidic isoperoxidases from turnip and radish were more closely related to acidic horseradish peroxidases than the basic isoperoxidase from horseradish as assessed by immunological cross‐reaction. Basic isoperoxidases from carrot (Daucus carotaL. cv. Danvers), radish or turnip did not react with antisera prepared against acidic horseradish peroxidases. Finally, acidic horseradish peroxidases were shown to be poor immnnogens in rabbits in contrast to the basic horseradish isoenzym

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06065.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A rapid isolation procedure was developed for purification of peroxidaseafromPetunia hybrida. Rapid isolation was possible since about 15% of the extracellular protein from stem tissue obtained by vacuum infiltration followed by centrifugation of the tissue represents peroxidase. Purification of peroxidaseafrom intercellular fluid was achieved by two acetone precipitation steps followed by DEAE‐cellulose chromatography.Three different forms of peroxidase were eluted from DEAE‐cellulose at different NaCl concentrations. Isoelectric focusing showed, however, a pI of 3.8 for all three forms of peroxidasea. Only part of the peroxidaseaenzymes bound to Concanavalin A indicating heterogeneity in the carbohydrate part. Homology of peroxidaseato the peroxidase G1group from tobacco is discus

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06066.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Ammonia can be incorporated into amino acids by reductive amination of oxoglutarate, or by the glutamate synthase cycle via glutamine. The majority of plants possess the enzymes necessary for the operation of both these pathways although nitrogen is thought to be assimilated via the glutamate synthase cycle in most cases. Measurements of glutamate dehydrogenase, glutamine synthetase, and glutamate synthase activities are presented from a selection of bryophytes. The genusSphagnumwas found to be unique in lacking measurable glutamate dehydrogenase activity. The relevance of this in the nitrogen‐poor acid bog is briefly considere

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06067.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

The influence of naphthylacetic acid, abscisic acid, gibberellic acid and kinetin on the formation of aerenchyma in seedling roots ofZea maysL. cv. Capella has been studied in relation to reported changes of their concentration in poorly aerated roots, which readily form aerenchyma, and to the effects of these hormones on the production of ethylene, a major factor promoting aerenchyma formation. Because the absence of nitrate accelerates aerenchyma formation in aerated roots, their influence on these roots was compared. The growth regulators were added to roots growing in non‐aerated and aerated nutrient solutions, and aerenchyma formation and the production and endogenous concentration of ethylene were measured. Naphthylacetic acid prevented aerenchyma formation in both aerated roots without nitrate and in non‐aerated roots although it enhanced the ethylene concentration of the roots. Abscisic acid also prevented aerenchyma formation, but without affecting the ethylene concentration. Gibberellic acid promoted aerenchyma formation in aerated roots only, but ethylene production in both aerated and non‐aerated roots. Kinetin promoted aerenchyma formation in both aerated and non‐aerated roots. It stimulated ethylene production in aerated roots, but slightly inhibited it in non‐aerated roots. Co2+and Ag+, which suppress ethylene production and action, respectively, reduced the promoting effects of gibberellic acid, but not those of kinetin. It is concluded that the effects of the plant growth regulators on aerenchyma formation in maize roots were, with a possible exception for gibberellic acid, not the result of altered ethylene concentrations in the roots. Their influence on aerenchyma formation is discussed in relation to their reported actions on cell

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06068.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

A viable wheat hybrid intermediate of the same height as the parents was obtained by crossing the female parent of tall variety NP4 with the male parent of the dwarf variety HD2160. Seeds of the hybrid and its parents were germinated and their growth pattern as well as the activities of peroxidase, indolyl‐3‐acetic acid oxidase and amylase in extracts made from them were studied at the early seedling stages i.e. up to 96 h.A positive correlation existed between the length of the axis at the early seedling stage and at mature plant height as far as the parental varieties are concerned but no such correlation was observed with the hybrid. Growth of the hybrid seedlings was less than of its parents. Light appeared to stimulate the longitudinal growth of the axis to different extents in the parents and hybrid. Higher activities of peroxidase, indolyl‐3‐acetic acid oxidase and amylase were observed in the hybrid as compared to both of its parents. Lethal wheat hybrid also exhibits increased activities of amylase, indolyl‐3‐acetic acid oxidase and peroxidase. Therefore, it appears that seedling growth and enzyme activities at the seedling stage are not always correlated with hy

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06069.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY

摘要:

Nuclear DNA content of adventitious buds and shoots of Picea abies(L.) Karst. developed in vitro was compared to that of buds collected from field‐grown trees. Protoplasts were isolated from the different tissues and after fixation and staining with ethidium bromide the DNA content of their interphase nuclei was determined cytofluorometrically. The DNA pattern of the different tissues was within the same range and had the same distribution with one main pea

ISSN:0031-9317    

DOI:10.1111/j.1399-3054.1984.tb06070.x

出版商:Blackwell Publishing Ltd    

年代:1984

数据来源: WILEY