摘要:

SUMMARYThe synergids ofPetuniashow a number of changes in size, shape and ultrastructure during anthesis. Before anthesis, the immature synergids are small cells with a rather simple ultrastructure. During anthesis, they greatly enlarge.Between the tops of the synergids a filiform apparatus is formed. The numbers of mitochondria and dictyosomes increase, whereas the number of plastids does not. The mature synergids contain an extensive rough ER. From the ultrastructural data, the author concludes that the metabolic activity in the synergids increases sharply during anthesis. The mature synergids are proposed to produce and secrete substances which direct the growth of the pollen tube.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00633.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYIn this second and final part suggestions are made towards a holotaxonomic major classification of the Angiosperms based on a pleiophyletic origin.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00634.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYMembrane‐bound and free IAA degrading enzymes from pea roots both consist of a peroxidative and a non‐peroxidative moiety. Retention of the latter protein is probably not due to the constituent amino acids.Polyvinylpyrrolidone shows gel‐chromatographic properties comparable with Sephadex G‐100, but with a lower exclusion molecular weight and with a higher degree of ads

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00635.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYIt has been shown that inhibition of anaerobic phosphate uptake by fatty acids and by 2,4‐dinitrophenol is not immediate but that the inhibition develops gradually in time. This rules out the possibility that these compounds interact with phosphate uptake via carrier competitio

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00636.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYWood samples of a number ofCinchoneaeandNaucleeaesensu Schumann were studied, and the results compared with data found in the literature. On the whole the representatives of theCinchoneaeappeared to show a rather high degree of similarity among each other with the exception, however, of the generaCoutarea, Exostemma, Corynanthe, Crossopteryx, andHymenodictyon. The creation of the tribeCoptosapelteaeand its inclusion in theIxoroideaeseem to be corroborated by the particular character of the wood anatomy. The restriction of theNaucleeaetoNaucleaL. (SarcocephalusAfzel.) is not supported by the anatomy of the wood.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00637.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe rates of regeneration of protochlorophyll (Pchl) in leaves of dark grown seedlings of bean, pea and maize were studied, following a saturating dose of either red alone, or red followed by far red. In neither material have we found evidence for red – far red control of the initial rates of pigment regeneration. In older maize leaves, an effect was observed but only upon the final level of Pchl, reached in prolonged darkness, indicating that in this plant the rate of pigment production decreases less rapidly during the last stages of regeneration after terminal red than after far red. There is considerable pigment photobleaching in red light. It is concluded that the effect of a red pre‐illumination upon the kinetics of the greening process in subsequent continuous light, is not due to a red – far red control of Pchl regeneration as such, but to a latent formative process, becoming manifest during the earlier part of a subsequent prolonged light p

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00638.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYThe presence of auxins has been demonstrated in extracts from pollen and styles ofPetunia hybrida. The presence of gibberellins was demonstrated in extracts of pollen, styles and ovaries ofPetunia hybridaas well as of threeLiliumspecies. Pollen contains relatively high amounts of auxins as well as bibberellins compared with styles or ovaries. No significant effect was found of either compatible or incompatible pollinations inPetuniaon the auxin and the gibberellin content of the pollinated styles, since the small increases of auxins and gibberellins found could be attributed to the auxins and gibberellins present in the pollen used for pollination.The gibberellin content of pollen ofLilium henryidropped sharply during the first hour of germination, indicating the importance of gibberellins for germination.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00639.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYInChenopodium albumseeds the influence of the dark incubation time before a red irradiation on the subsequent germination processes was studied.During dark incubation at least two preparative reactions take place. The first one, a rehydratation of the phytochrome pigment, is both at 23 °C and 4 °C a function of the water uptake of the seeds. It regulates the rate of increase in reactivity of the seeds to red light, as measured by the final germination percentage. In the second one a reaction component for the far‐red absorbing form of phytochrome (Pfr) is synthesized. This synthesis does not occur at 4 °C. The amount of this component synthesized before onset of a red irradiation, determines the reaction rate of Pfr and consequently the escape from the antagonistic effect of a far‐red irradiation, which in turn determines the moment of visible germination. The processes between the moment of escape and the moment of the protrusion of the rootlet through the inner seed‐coat layer are not influenced.The lower final germination percentage, after a 4 °C pre‐treatment, as compared with incubation at 23 °C, is supposed to be caused by the dark conversion of Pfr to Pr in the absence, at the lower temperature, of the product of the sec

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00640.x

年代:1970

数据来源: WILEY

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00641.x

年代:1970

数据来源: WILEY

摘要:

SUMMARYFeeding with various nitrogen compounds led to marked changes in the total amount and in the relative composition of the nitrogen pool in the radish slices. Possible modes of utilization of these compounds are given. Iodoacetate greatly retarded the uptake and utilization of NH4Cl and aspartic acid. Whereas the uptake of KNO3was inhibited by iodoacetate, its utilization was markedly enhanced. The losses of nitrogen fractions from the differently treated tissues were almost recovered in the culture media.The marked losses in carbohydrates would almost correspond in amount with the increased CO2output and with the synthesis of nitrogenous constituents. However, some of the lost carbohydrates from tissues treated with iodoacetate + either NH4Cl or aspartic acid could be markedly accounted for in the culture media.The rise in CO2output in iodoacetate is mainly attributed to increased accessibility, in the metabolic region, of substrates to enzymes. The differential rates of CO2production by tissues incubated in nitrogen media, either alone or supplemented with iodoacetate are interpreted on the bases that different rates of uptake of nitrogen compounds and of utilization of ATP are possible. Also the relation between nitrogen assimilation and the breakdown of carbohydrates is discussed.

ISSN:0044-5983    

DOI:10.1111/j.1438-8677.1970.tb00642.x

年代:1970

数据来源: WILEY